CEC-ICMC 2015 - Timetable, Abstracts and Presentations

Jun 28, 2015, 8:00 AM → Jul 2, 2015, 1:00 PM Etc/GMT-7

JW Marriott Starr Pass Resort

Jennifer Marquardt (CEC Program Co-Chair), Jonathan Demko (CEC Program Chair), Michael Sumption (for ICMC), Peter Kittel (for CEC), Timothy Haugan (ICMC Program Chair)

 

The Technical Program can be accessed via the Timetable Views on the left side navigation bar.

In addition to preparing your presentation, all presenters are requested to electronically publish their presentations prior to or during the Conference. Detailed information can be found on the left side navigation bar, see "Orals and Posters Upload Information". 

Presenters of oral talks are reminded that their presentation MUST also be submitted to the Speaker Preparation room one (1) day prior to their scheduled presentation.  

Anyone presenting at and attending CEC/ICMC 2015 MUST be a registered attendee. Pre-conference registration closes on Wednesday, June 17.  Click here for detailed Conference Registration information.

The Conference Program Book is now available, see left side navigation bar. The book contains content as of June 1. Any changes as of June 1 will be added to an 

 

 

Sunday, June 28

8:00 AM → 5:00 PM CSA Short Courses (8:00 - 17:00)

3:00 PM → 8:00 PM Registration Open (15:00 - 20:00)

7:30 PM → 9:00 PM Welcome Reception (19:30 - 21:00)

Monday, June 29

7:50 AM → 7:50 AM Cryo Expo Open (9:00 - 17:00)

For a list of Exhibitors, please visit: http://www.cec-icmc.org/exhibition/exhibitors/.

7:55 AM → 8:15 AM Opening & ICMC Awards

8:15 AM → 9:00 AM M1PL - Monday ICMC Plenary Session

Convener: Eric Hellstrom (Florida)

8:15 AM Bulk Superconducting Materials – Ready for Applications?

In 2003 Tomita and Murakami set the record for the trapped field in a bulk superconductor of a shade over 17.2 T. Last year, not without significant effort, this record was raised to 17.6 T. This apparently slow progress may suggest that the pace of progress in Bulk Superconductors has been very slow. In fact nothing could be further from the truth. The growth of bulk materials from (RE)BCO has seen innovations which have permitted a wider range of materials to be successfully grown, engineered pinning enhancement to provide improved critical currents, progressively larger samples and significant progress towards batch processing. In the meantime MgB₂ has emerged, in spite of its relatively low critical temperature, as a cheap, easy to make and rare earth free competitor. In this presentation I will discuss the significant advances that have taken place over the last ten or so years in the materials science of (RE)BCO and MgB₂ bulk superconductors. I will address the challenges to practical application, in particular that of charging, and discuss the approaches being taken around the world to solve them. In parallel with rapid materials development a range of innovative applications for Bulk Superconductors have appeared. I will outline some of these applications which are in domains as diverse as non- destructive testing, energy storage and medicine.

Speaker: Dr John Durrell (University of Cambridge)

Slides DURRELL_ICMC_Plenary.pptx

9:00 AM → 11:00 AM C1PoA - Cryogenics for Power Applications, Energy, Fuels and Transportation I

Conveners: Gary Mills (Ball Aerospace & Technologies Corp.), Pat Kelley (TechSource, Inc.)

9:00 AM Commercialization of a Turbo-Brayton cycle refrigerator for HTS power applications

Approaching to commercializing of High Temperature Superconducting (HTS) power applications is becoming more active. And cooling system is very important and essential for practical HTS power applications. HTS power applications on commercial scale will require cooling system which has cooling capacity from 2kW to 10kW at 65K, high reliability (long maintenance interval) and compactness. Taiyo Nippon Sanso Corporation (TNSC) is developing a turbo-Brayton cycle refrigerator using neon gas as working fluid (Neon-Refrigerator) for HTS power applications. And a 2kW class Neon-Refrigerator has been marketed in May 2013. Some Neon-Refrigerators were supplied for cable projects in Japan. Furthermore, development of 10kW class Neon-Refrigerator is under going. Detail of commercial type 2kW class Neon-Refrigerator and present status of development of 10kW class Neon-refrigerator will be introduced in this presentation.

Speaker: Hirokazu Hirai (Taiyo Nippon Sanso Corporation)

Poster CEC2015_poster_upload.pdf

9:00 AM Cooling topology options for HTS rotating superconducting machinery

Cryogenic system complexity presents a major challenge to the implementation of superconducting technologies. At MIT, we have developed concepts to simplify the cryogenic environment for superconducting rotating machinery, such as HTS motors and generators. We present cooling schemes for the rotor of a high-speed rotating machine that avoid the use of rotating cryogenic seals, which are particularly difficult to implement at high rotating speeds. We describe passive cooling methods, using a variety of gases, mixtures and pressures, to indirectly remove, at temperatures in the range from 30K to 50K, the relatively small cryogenic load (tens of Watts) originating in the rotor. Computational fluid dynamics models of the thermal performance of the system, and windage due to the finite gas pressure, are presented. The impact of the indirect rotor cooling scheme on cryostat design is presented. We have developed complementary cooling schemes for superconducting stators. Forced flow cooling of the stator is needed because of its significantly higher heat load, either distributed within the winding (for coils wound from cable-in conduit conductor) or indirectly through the use of conduction cooling plates (for potted monolithic coils). We show characteristics of the stator cooling system for different cooling fluids, and cable geometries for both direct and indirect cooling. We describe the design of a cooling system manifold to address electrical isolation requirement both within and between the stator’s phase group windings. We discuss the applicability of the proposed cooling schemes to stationary systems.

Speakers: Dr Leslie Bromberg (MIT - Plasma Science and Fusion Center), Dr Philip Michael (MIT - Plasma Science and Fusion Center)

Poster C1PoA-02_poster_complete.pdf

9:00 AM Development of a cooling system for 66/6.9kV-20MVA REBCO superconducting transformers with a Ne turbo-Brayton refrigerator and subcooled liquid nitrogen

In Japan, we have developed 3φ-66/6.9kV-20MVA RE1Ba2Cu3O7-δ(RE:Rare Earth, Y, Gd and so on, REBCO) superconducting transformers with a current limiting function as a national project. First we made a basic research on the ac loss reduction and the enhancement of current capacity of REBCO superconducting tapes, the dielectric strength of liquid nitrogen, a current limiting function of REBCO superconducting windings and so on. The subcooling of liquid nitrogen was required from the viewpoint of dielectric strength. We have finished the design of a 20MVA transformer and fabricated a 1/10 model, i.e. 3φ-66/6.9kV-2MVA one. The superconducting windings were installed in a GFRP cryostat and cooled with subcooled liquid nitrogen at 65 to 77 K. The iron core was located at room temperature. For the sake of a long maintenance interval and a high cooling efficiency, we developed a turbo-Brayton refrigerator with neon gas as a working fluid. The cooling capacity was 2kW at 65K. Here an expansion turbine and a two-stage turbine compressor with non-contact magnetic bearings were adopted. In the 2MVA model, liquid nitrogen was forced-flowed between the GFRP cryostat and an additional cryostat in which a pumping system and a heat exchanger between the neon gas and the liquid nitrogen were installed. In addition, for the future system, we are making a research and development of a new cooling system in which a radiator-type heat exchanger was directly installed into the GFRP cryostat. In this paper we will report the progress of the research and development. *This work was supported in part by New Energy and Industrial Technology Development Organization (NEDO) as Technological Development of Yttrium-based Superconducting Power Equipment.*

Speaker: Masataka Iwakuma (Kyushu University)

Poster CEC_ICMC_2015_Iwakuma_Poster-C1PoA-03.pdf

9:00 AM Peak Current Limiting Properties of SFCL with Parallel Connected Coils using Two Magnetic Paths

In this study, a superconducting fault current limiter (SFCL) with two magnetic paths using E-I iron core was proposed and its peak current limiting characteristics were analyzed. For the suggested SFCL to effectively perform the peak current limiting operation, the design of the SFCL considering its electrical equivalent circuit for E-I iron core was needed. In addition, the analysis on the influence of the magnetic flux on its peak current limiting characteristics was essential. Through the analyses for the fault current limiting experiments with this SFCL, two magnetic paths using E-I iron core were confirmed to be contributed to the peak fault current limiting operation of the SFCL.

Speaker: Seok-Cheol Ko (Kongju National University)

Poster E-poster(Seok-Cheol_Ko).pdf E-poster(Seok-Cheol_Ko).pptx

9:00 AM Performance analysis of superconducting generator electromagnetic shielding

The magnetic induction intensity of superconducting generator can reach a few Tesla, relative to the conventional generator, it has small volume and weight, compact structure, high power density and efficiency, big ultimate capacity, good stability, so superconducting generator is regarded as one of the attractive and novel generator with business competitiveness in the near future. Electromagnetic shielding is one of the unique special structure of superconducting generator. When superconducting windings work in an alternating magnetic field, AC losses are produced in the windings. The losses increase the low temperature medium dosage and refrigeration power consumption and cause temperature rise, so that the efficiency of the generator is reduced. When serious, temperature rise will lead to the quench of superconducting tapes. The electromagnetic shielding is used to shield the superconducting windings from the alternating magnetic field and reduce the effect of alternating magnetic field on the superconducting windings, in order to ensure the normal work of the superconductor in the superconducting state, improve the efficiency of generator. For the superconducting generator, the electromagnetic shielding is a very important key part. Using Maxwell equation of electromagnetic field and the mechanical motion equation, it is established the steady state and transient finite element analysis model, which is suitable for the problem of thin wall cylinder of high temperature superconducting generator electromagnetic shielding. In different operation state of a high temperature superconducting generator, the magnetic field and eddy current distribution in the monolayer and multilayer shielding cylinder are calculated, shielding coefficients of the electromagnetic shielding are obtained, and the calculation results are analyzed and compared. The results provided in this paper are helpful to optimization design of superconducting generator electromagnetic shielding.

Speaker: dong XIA (Chinese Academy of Sciences)

Poster CEC_poster.ID58.pdf

9:00 AM Performance of a 10 kJ SMES Model Cooled by Liquid Hydrogen Thermo-Siphon Flow for ASPCS Study

From the point of view of environment and energy problems, the renewable energies have been attracting attention. However, fluctuating power generation by the renewable energies affects the stability of the power network. Thus, we propose a new electric power storage and stabilization system, Advanced Superconducting Power Conditioning System (ASPCS), which consists of a Superconducting Magnetic Energy Storage (SMES) and a hydrogen - energy - storage converge on a liquid hydrogen station for fuel cell vehicles. A 10 kJ small SMES system, in which Di-BSCCO coil cooled by liquid hydrogen is installed, has been developed to compose an experimental model of the ASPCS. The SMES coil is conductively cooled by liquid hydrogen flow through a thermo-syphon line under a liquid hydrogen buffer tank. A fabrication of the cryogenic system has been completed, and then it was cooled down by liquid hydrogen. The SMES coil has been successfully charged up to a nominal current of 200 A DC. Then Eddy current loss, which is mainly induced in pure aluminum plates pasted onto each pancake coils for conduction cooling, was also measured. Experimental results will be reported.

Speaker: Dr Takakazu Shintomi (KEK)

Poster Poster-C1PoA-06.pdf

9:00 AM → 11:00 AM C1PoB - Intermediate Temperature Systems

Conveners: John Jurns (European Spallation Source ESS AB), Matt Barrios (NHMFL/FSU)

9:00 AM Development of cryogenic installations for large liquid argon based neutrino detectors

A proposal for a very large liquid argon (40 kt) based neutrino detector is being studied. To validate the design principles and detector technology, and to gain experience in the development of the cryostats and the cryogenic systems needed for such large experiments, several smaller scale installations will be developed and implemented, at Fermilab and CERN. A small-scale prototype (35 t) is already operational at Fermilab, while two larger-scale experiments (500 t each) will be developed, built and tested at CERN. In parallel, two other detectors will be developed, built and installed on a neutrino beam line at Fermilab: a Near Detector (260 t) at about 110 meter and a Far Detector (760 t) at about 600 meter from the target. The final experiment (ELBNF) will receive a neutrino beam from Fermilab and will be installed at the Surf Underground Research Facility in Lead, SD, situated at about 1300 km from Fermilab at about 1.5 km below ground level. The cryogenic systems for these installations will be developed, constructed, installed and commissioned by an international engineering team. These installations shall bring the required cooling power under specific conditions to the experiments for the initial cool-down and the long term operation, and shall also guarantee the correct distribution of the cooling power within the cryostats to ensure a homogeneous temperature distribution within the cryostat itself. The cryogenic systems shall also include gaseous and liquid phase argon purification devices to be used to reach and maintain the very stringent purity requirements needed for these installations (parts per trillion of oxygen equivalent contamination). This paper gives an overview of the installations involved in this cryogenic project, describes the functional demands made to these cryogenic systems and presents the initial studies on which these future cryogenic systems will be based.

Speaker: Johan Bremer (CERN)

Poster C1PoB-02.pdf

9:00 AM HTS cooling below 60 K with two-stage mixed-refrigerant cascades using low-flammability mixtures

High-temperature superconductors offer new perspectives for efficient transportation of electrical energy in urban and industrial power grids. The size of the components is in many cases limited by the available refrigeration technology. In the operating temperature range of 65 – 70 K, cooling is presently achieved by liquid nitrogen, turbo-Brayton plants or batteries of regenerative cryocoolers. However, none of these options is practicable in applications requiring a few kilowatt of cooling power. Also a reduction of the temperature to below 60 K is desirable in order to increase the current density in the superconductors. Two-stage mixed-refrigerant Joule-Thomson cascades can present a reliable and highly scalable refrigeration alternative in this temperature range. The first stage of the envisioned process consists of a classical mixed-refrigerant cycle for pre-cooling to 120 K. The second, low-temperature stage operates with a mixture of nitrogen, oxygen and neon at high pressure. In order to avoid combustible hydrocarbon refrigerants in the pre-cooling stage, this work examines the use of a new mixture with low flammability consisting of nitrogen, argon, R-14, R-23 and R-1234yf. The applicability of different equations of state for the prediction of the thermophysical behavior of the mixture by is discussed.

Speaker: Mr Thomas M. Kochenburger (Karlsruhe Institute of Technology, Institute for Technical Thermodynamics and Refrigeration)

Poster Poster_Kochenburger_CEC-09_C1PoB.pdf

9:00 AM Performance Test of the Cryogenic Cooling System for the Superconducting Fault Current Limiter

The Superconducting Fault Current Limiter (SFCL) is an electric power device which limits the fault current immediately in a power grid. The SFCL must be cooled to below the critical temperature of HTS(High Temperature Superconductor) modules. In general, they are submerged in sub-cooled liquid nitrogen for their stable thermal characteristics of HTS modules. To cool and maintain the target temperature and pressure of the sub-cooled liquid nitrogen should be designed well with a cryocooler and circulation devices. The pressure of the cryostat for the SFCL should be pressurized to reduce the generation of nitrogen vapor in quench mode of the SFCL. In this study, we tested the performance of the cooling system for the prototype 154 kV SFCL, which consist of a 4 kW stirling cryocooler, a subcooling cryostat, a pressure builder and a main cryostat for the SFCL module, to verify the design of the cooling method and the electric performance of the SFCL. The normal operation condition of the main cryostat is 71 K and 500 kPa. This paper present results of tests of the overall cooling system.

Speaker: Dr Yong-Ju Hong Hong (Korea Institute of Machinery & Materials)

Poster CEC-Poster(C1PoB-05).pdf

9:00 AM Progress in Development of a 10 kW Brayton Cryocooler for HTS Cable in Korea

Recent progress in the development of a 10 kW Brayton cryocooler is presented for HTS cable systems under installation in Jeju Island, Korea. The role of this cryocooler is to continuously cool a liquid-nitrogen flow from 78 K to 67 K, and the liquid is pumped to three-phase 154 kV cable over a length of 1 km. The refrigerant of cryocooler is helium, whose operating pressure and flow rate was determined earlier from a thermodynamic study on reversed-Brayton cycle. As main components, heat exchangers and turbo-expanders are designed and fabricated by custom-orders. The heat exchangers are made of aluminum-brazed plate-fins, and the coldest part is arranged as two-pass cross-flow in accordance with our experimental study for preventing the freeze-out of liquid nitrogen. Two identical turbo-expanders are employed in parallel at the cold end, where the maximum rotating speed with gas bearings reaches 180,000 rpm and the output power is dissipated with eddy current brakes. The assembly is completed and the refrigeration capacity is measured with a dummy thermal load on the liquid-nitrogen stream. Details of thermal performance and short-term plans are reported towards an immediate application to the HTS cable systems. *This research is supported by a grant of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) for Power Generation & Electricity Delivery Program (No. 2014101050231B), funded by the Ministry of Trade, Industry and Energy of Korean Government.*

Speaker: Ho-Myung Chang (Hong Ik University)

Poster Poster_(Cable).pdf

9:00 AM THE SAFE REMOVAL OF FROZEN AIR FROM THE ANNULUS OF AN LH2 STORAGE TANK

Large Liquid Hydrogen (LH2) storage tanks are vital infrastructure for NASA. Eventually, air may leak into the evacuated and perlite filled annular region of these tanks. Although the vacuum level is monitored in this region, the extremely cold temperature causes all but the helium and neon constituents of air to freeze. A small, often unnoticeable pressure rise is the result. As the leak persists, the quantity of frozen air increases, as does the thermal conductivity of the insulation system. Consequently, a notable increase in commodity boil-off is often the first indicator of an air leak. Severe damage can result from normal draining of the tank. The warming air will sublimate which will cause a pressure rise in the annulus. When the pressure increases above the triple point, the frozen air will begin to melt and migrate downward. Collection of liquid air on the carbon steel outer shell may chill it below its ductility range, resulting in fracture. In order to avoid a structural failure, as described above, a method for the safe removal of frozen air is needed. A thermal model of the storage tank has been created using SINDA/FLUINT modeling software. Experimental work is progressing in an attempt to characterize the thermal conductivity of a perlite/frozen nitrogen mixture. A statistical mechanics model is being developed in parallel for comparison to experimental work. The thermal model will be updated using the experimental/statistical mechanical data, and used to simulate potential removal scenarios. This paper will address methodologies and analysis techniques for evaluation of two proposed air removal methods.

Speaker: Angela Krenn (NASA)

Poster CEC_Poster_Final.pdf

9:00 AM → 11:00 AM C1PoC - Vuilleumier Cryocoolers and Cooler Analyses

Conveners: Franklin Miller (University of Wisconsin - Madison), John Brisson (MIT)

9:00 AM Numerical studies on the phase adjustment systems of high frequency pulse tube cryocooler with a gradient temperature distribution

Some single-stage high-frequency pulse tube cryocoolers (HPTCs) have been developed in recent years. At present, with an electric input power of 250 W and a frequency of 30 Hz, the lowest temperature achieved is around 15 K and the typical cooling capacity is about 350±50mW/ 20 K. Although single-stage is more attractive to customers compared with multi-stages because of its mechanical simplicity, it is difficult to achieve lower temperature, thus the employment of double-stage is a compromise approach. At the beginning of structure design, the liquid nitrogen (LN2) was employed as the pre-cooling stage to cool the hot end of the HPTC that has been developed in our lab. In the aspect of compactness and simplification, coaxial configuration has been adopted, and the inertance tube was arranged passing through the compressor internal space and wrapped in the reservoir, integrating the reservoir, pulse tube and compressor together .Therefore, a gradient temperature distribution from the liquid nitrogen temperature to room temperature is set up along the inertance tube. Furthermore, in order to reduce the adjustment difficulty, the double-inlet was also installed at the position of room temperature. Thus, for the gases, passing through the double inlet and then flowing into the pulse tube is also a process of temperature changes. Through some preliminary experiments, we discovered that the mechanism of the phase adjustment systems with a gradient temperature distribution is different from that with uniform temperature distribution. In this paper, the mechanism of the phase adjustment systems with temperature gradient will be numerical studied, and some preliminary experimental results will be presented.

Speakers: Prof. Junjie Wang (Technical Institute of Physics and Chemistry, CAS), Mr Liubiao Chen (Technical Institute of Physics and Chemistry, CAS), Mr Sixue Liu (Technical Institute of Physics and Chemistry,CAS)

Poster C1PoC-04-poster.pdf

9:00 AM TRANSIENT ANALYSIS OF SINGLE STAGE GM TYPE DOUBLE INLET PULSE TUBE CRYOCOOLER

Transient analysis of single stage GM type double inlet pulse tube cryocooler is carried out using a one dimensional numerical model based on real gas properties of helium. The model solves continuity, momentum and energy equation for gas and solid to analyse the physical process occurring inside of the pulse tube cryocooler. Finite volume method is applied to discretize the governing equations with realistic initial and boundary conditions. Input data required for solving the model are the design data and operating parameters viz. pressure waveform from the compressor, regenerator matrix data, and system geometry including pulse tube, regenerator size and operating frequency for pulse tube cryocooler. The model investigates the effect of orifice opening, double inlet opening, and pressure ratio, system geometry on no load temperature and refrigeration power at various temperatures for different charging pressure. The results are compared with experimental data and reasonable agreement is observed. The model can further be extended for designing two stage pulse tube cryocooler.

Speaker: Prof. HEMANT NAIK (S. V. National Institute of Technology)

Poster C1POC-hbnaik.pdf

9:00 AM → 11:00 AM C1PoD - Cryogenic Distribution Systems

Conveners: Jaroslaw Fydrych (European Spallation Source ESS AB), Kelly Dixon (Jefferson Lab)

9:00 AM European XFEL-linac Feed and End cap dimensional tolerance validation

Feed and End caps are connection boxes between Helium transfer lines and Cryomodules of the European XFEL project at DESY. Feed and End caps are characterised extreme narrow dimensional tolerances at the Cryomodule interface, in order to keep the XFEL linac beam pipe aligned perfectly during cryogenic operation. The expected movements of the beam pipe and process pipes due to pressure loading and thermal contraction are of the same order of magnitude as the specified tolerances. The purpose of the test was to validate if the dimensional tolerance specifications at the Cryomodule interface are fulfilled and the position of the beam pipe can be guaranteed. The Demaco contribution will show the test method, some test results and the positive conclusions.

Speakers: Mr Marinco Lefevere (Demaco), Mr Ronald Dekker (Demaco), Dr Ruud Woude van de (Demaco)

Slides CEC-ICMC_2015_Demaco_poster_-_European_XFEL-linac_Feed_and_End_cap_dimensional_tolerance_validation_-_29062015.pdf

9:00 AM FRIB Cryogenic Distribution System

The MSU-FRIB cryogenic distribution system supports the 2 K, 4 K, and 35 K operation of more than 70 loads in the accelerator and the experimental areas. It is based on JLab and SNS experience with bayonet-type disconnects between the loads and the distribution system for phased commissioning and cryomodule maintenance. The linac transfer line, which features three separate transfer line segments for additional independence during phased commissioning at 4 K and 2 K, connects the folded arrangement of 49 cryomodules and 4 superconducting dipole magnets. The pressure reliefs for the transfer line process lines, located in the refrigeration room outside the tunnel/accelerator area, are piped to be vented outdoors. The transfer line designs integrate supply and return flow paths into a combined vacuum space. The main linac distribution segments are produced in a small number of standard configurations; a prototype of one such configuration has been fabricated at Jefferson Lab and has been installed at MSU to support testing of a prototype FRIB cryomodule.

Speaker: Mr Nathaniel Laverdure (Jefferson Lab)

Poster FRIB_Cryogenic_Distribution_System_and_Status_rev3.pdf

9:00 AM Load specification and embedded plate definition for the ITER cryoline system

The ITER cryoline (CL) system is part of overall ITER cryogenic system involving the cryoplant and the cryodistribution. The CLs are complex network of vacuum-insulated multi and single process pipe lines, distributed in three different areas at ITER site. The conceptual design phase of the lines has been completed and the detailed design, fabrication and installation will be performed by contractors appointed by India, responsible for in-kind supply of CL system to the ITER project. The CLs will have to support different operating conditions during the machine life-time of 20 years; either considered as normal, occasional or exceptional and will be designed to withstand these scenarios. The major loads considered for the design are inertial, pressure, temperature, assembly, magnetic, snow and enforced relative displacement. All the loads cases and the various load combinations which forms the design basis are put together in Load Specification. Based on the defined load combinations, conceptual estimations for the reaction loads, has been carried out for the lines located inside the Tokamak building. Adequate numbers of embedded plates (EPs) per line have been defined, integrated in the building design. The finalization of building EPs to support the lines, before detailed design, is one of the major design constraints as the usual logic of the design is altered and has made the cryoline project technically more challenging. At the ITER project level, it was important to finalize EPs to allow adequate design and timely availability of the Tokamak building. After the brief description of CL system, the paper will describe single loads and load combinations considered in load specification. The paper will also describe the approach for conceptual load estimation and selection of EPs for Toroidal Field Cyoline as example by converting all load combinations in two main load categories; pressure and seismic.

Speaker: Mr Hiten Vaghela (ITER-India, Institute for Plasma Research)

Poster C1PoD-05_Loads_specification_and_embedded_plate_definition_for_the_ITER_cryoline_system.pdf

9:00 AM Value Engineering in System of Cryoline and Cryodistribution for ITER: In-kind Contribution from India

System of cryoline and cryodistribution for ITER has matured to a stage of preliminary design phase with the advent of industrial associates. Starting from the cold power source, the system of cryoline and cryodistribution transfers the controlled cold power through a large network to the superconducting magnets and cryopumps. The functional responsibility also includes very high reliability and availability with respect to the operation of the ITER machine. Following the completion of conceptual design, it was necessary to perform a detailed engineering study of the complete network of distribution system in totality, before entering in to the industrial phase. This is to ensure the functional responsibility of the system. Industrial contracts have been established for the system of cryoline and cryodistribution with the objective to enter into the detailed design and construction phase of the overall systems. Value engineering in the area of distribution boxes including interfacing cryolines has been performed in order to access the integrated reliable performance with respect to the overall cryogenic system, reducing the risk transferred to the industrial partners. These include technical risk assessment, analysis, mitigation plan and implementation with the industrial partners. The paper will describe the methodology of technical risk management, value engineering performed to ensure fulfilment of licensing and regulatory obligations, functional reliability as well as testing and manufacturability by standard industrial processes, so that highly reliable integrated distribution system is delivered for the project.

Speaker: Mr Hitensinh Vaghela (ITER-India, Institute for Plasma Research)

Poster C1PoD-08_C30_Value_Engineering_in_System_of_Cryoline_and_Cryodistribution_for_ITER_In-kind_Contribution_from_INDIA_v3.pdf

9:00 AM → 11:00 AM C1PoE - Thermal Fluids (Non-Aerospace)

Convener: Steven Van Sciver (Florida State University)

9:00 AM Dynamics of liquid nitrogen cooling process of solid surface at wetting contact surface.

Liquid cryogens cooling by direct contact with cooled surface is very often use as a method to drop the temperature of the devices or equipment i.e. HTS cables. Somehow, cool down process conducting in that way could not be optimized, because of cryogen pool boiling characteristic and low heat transfer coefficient. One of the possibility of increase the efficiency of heat transfer, as well the efficiency of cooling itself, is to use the spray cooling method. The paper shows dynamics analysis of liquid nitrogen cooling solid surface process. The model of heat transfer for the single drop of liquid nitrogen, which impact the flat and smooth surface with respect to the different Weber numbers, is shown. The temperature profiles in the solid are presented, as well, the required cooling time of solid. The numerical calculations are perform for different initial and boundary conditions such as: droplet size, initial velocity, temperature of surface etc., to study how the wetting contact surface is change, and how it contributed to heat transfer between solid and liquid cryogen.

Speaker: Mr Przemyslaw Smakulski (Wroclaw University of Technology)

Poster PS_DynamicsOfLiquidNitrogen.pdf

9:00 AM Occurrence of thermoacoustic phenomena at 0.8 K, 4 K and above

Thermoacoustics in cryogenics continues to be a very interesting phenomenon which is still poorly understood but often experienced unexpectedly in experiments where it causes unacceptable heat leaks. The authors report on the appearance and onset of this unwanted occurrence at temperatures below 1 K. Based on experiments, quantitative measurements of the heat leak caused by these pressure oscillations in bent tubes with 4.55 and 4.7 mm inner diameter with heat stationing links are presented. Parameters most likely affecting the magnitude of these thermoacoustic oscillations are studied and means of avoiding them are given. Furthermore, we had the rare opportunity to record and analyze 4 K TAOs experienced on a test setup and present simple means of avoiding them.

Speaker: Wolfgang Stautner (GE Global Research)

Paper CEC_2015_TAOs_WS-5.pdf

Poster C1PoE-94_CEC_2015_Poster_3.pdf

9:00 AM Time resolved cryogenic cooling analysis of the Cornell Injector Cryomodule

Managing parallel cryogenic flows has become a key challenge in designing efficient and smart cryo-modules for particle accelerators. In analyzing the heating dynamics of the cornell high current injector module a power-full computational tool has been set-up allowing time resolved analysis and optimization. We will describe the computational methods and data sets we have used, report the results and compare them to measured data from the module being in good agreement. Mitigation strategies developed on basis of this model have helped pushing the operational limitations.

Speaker: Ralf Eichhorn (Cornell University)

Slides CEC2015-C1PoE-05.pdf CEC2015-C1PoE-05.pptx

9:00 AM → 11:00 AM M1PoA - Superconducting Materials and Applications

Conveners: Quan Li (University of Edinburgh), Takanobu Kiss (Kyushu University)

9:00 AM Measurements of YBCO pancake coils: thermal conductivity, quench, and NZP at 4.2 K and 10 T.

High energy physics (HEP) magnets require high magnetic fields, demanding the use of new superconducting materials. YBCO coated conductors are of interest in a number of possible HEP applications, including high field solenoids for muon colliders. The temperature distribution, quench, the normal zone propagation, and conductor protection are highly important in these applications. In the present work we have measured thermal conductivity, stability, and normal zone propagation in a YBCO pancake coil at 4.2 K in liquid helium bath. The experiments have been done in applied magnetic fields up to 10 T at transport currents of a certain percentage of the coil critical current. A pancake coil with 27 mm ID and 37 mm OD was measured. It was instrumented for voltage and temperature measurements at several places around the winding, such that both radial and azimuthal quench propagation could be measured. Several heaters were placed on the inner-most part of the winding. Thermal conductivity was measured by applying a steady heater power and measuring the temperature gradient. Heat pulses of various powers and durations were generated to measure quench and NZP. This work was performed on a “dry” winding; these results are baselines for comparisons of several different epoxy and insulation winding modes.

Speaker: Dr Milan Majoros (The Ohio State University)

9:00 AM Optimizing Flux Pinning of YBa2Cu3O7-δ (YBCO) Thin Films with Unique Large Nanoparticle Size and High Concentration of Y2BaCuO5 (Y211) Additions

Addition of second-phase nanosize defects to YBa2Cu3O7-z(YBCO) superconductor thin films is known to enhance flux pinning and increase current densities (Jc). The addition of Y2BaCuO5 (Y211) was studied previously in (Y211/YBCO)N multilayer structures, and in Y211+YBCO films deposited from pie-shaped targets. This research systematically studies the effect of Y211 addition in thin films deposited by pulsed laser deposition from YBCO1-xY211x (x = 0 - 20 vol. %) single targets, at temperatures of 785 - 840 °C. Interestingly, the resulting size of Y211 particles is 20 to 40 nm, with reduced number density. This is in contrast to 10 to 15 nm in previous studies of Y211, and 5 - 10 nm for other 2nd-phase defect additions. A slight increase of Jc(H,T) was achieved, compared to previous optimization studies. Results and comparisons of flux pinning, intrinsic stresses imaged by TEM, current densities, critical temperatures, and microstructures will be presented. The overall low intrinsic stress on YBCO from Y211 lattice mismatch is smaller than previously studied 2nd-phase defect additions known, which is hypothesized to be the driving force in achieving the unusually large 2nd-phase nanoparticle size and volume fraction thus-far in YBCO thin films.

Speaker: Timothy Haugan (U.S. Air Force Research Laboratory)

9:00 AM Optimizing Flux Pinning of YBCO Thin Films with BZO + Y2O3 Double-Mixed Phase Additions

Adding nanophase defects to YBa2Cu3O7-z (YBCO) superconductor thin films is well-known to enhance flux pinning; resulting in an increase in current density (Jc). While many previous studies focused on single phase additions, the addition of several phases simultaneously shows promise in improving current density by combining different pinning mechanisms. This paper encompasses the effect of the addition of insulating, nonreactive phases of barium zirconium oxide (BZO) and yttrium oxide Y2O3. Processing parameters varied the target composition volume percent of BZO from 2 - 6 vol. %, while maintaining 3 vol. % Y2O3, and the remaining vol. % YBCO. Pulsed laser deposition produced thin films on LaAlO3 (LAO) and SrTiO3 (STO) substrates at various deposition temperatures. Comparison of strong and weak flux pinning mechanisms, current densities, critical temperatures, and microstructures of the resulting films will be presented.

Speaker: Timothy Haugan (U.S. Air Force Research Laboratory)

9:00 AM Physical properties of material useful for predicting stability and quench propagation in high-field Bi-2212 magnets

Quench initiation and growth in high-field Bi-2212 magnets can be described by 3-D heat diffusion equations and well simulated using modern finite element modeling tools. However, the usefulness of this simulation is often limited by the lack of good physical properties of important components, such as the magneto-resistivity of silver and silver alloys in a heat-treated commercial wire, which may or may not suffer from reduction of residual resistivity ratio due to Cu loss from the Bi-2212 filaments into the silver matrix. Further uncertainty arises from the fact the Cu loss depending on heat treatment parameters and Cu has different solubility in different silver alloy wires, and the fact that heat treated Bi-2212 wires have a Tc of up to 92 K, making difficult measurement of resistivity of silver at 4.2-90 K. In this study, we measure the temperature dependence of the resistivity of Ag, Ag-0.2wt%Mg, AgAl, and several commercial Ag/Bi-2212 wires, in magnetic field up to 9 T from 300 K down to 4.2 K. Wires to be measured include a wire with pure silver sheath, a wire with Ag and Ag-0.2wt%Mg sheathes, and a wire with Ag and AgAl sheathes. Critical current temperature and critical fields of these wires will also be determined. We also measured the thermal conductivity of silver and epoxy (CTD101k). These data will be fed into a finite elemental model (COMSOL), developed here at Fermilab and bench marked with experimental data at 0-7 T, to study the high-field quench behavior of Bi-2212/Ag conductors in fields up to 30 T. *This work is supported by the U.S. Department of Energy, Office of High Energy Physics through a FY12 early career award.*

Speaker: Pei Li (Fermi National Accelerator Laboratory)

Poster Pei_ICMC_poster_final150627.pdf

9:00 AM Quench induced critical current degradation in REBCO coated conductor and Bi2223 tape

One of the remaining challenges for high temperature superconducting magnets is quench protection. To develop an effective quench protection system, it is important to understand the conditions that must be avoided during a quench so that the conductor is not degraded. Our previous study on Ag/Bi2212 round wires has shown that the quench degradation is a strain-driven effect and strongly depends on the hotspot temperature, *T*_quench, during the quench; critical current *I*_c of Bi-2212 wires gradually degraded irreversibly when *T*_quench exceeds 350-500 K, above which *I*_c of Bi-2212 dropped quickly to zero. Here, similar quench experiments are performed on commercial REBCO coated conductors from Superpower and CT-OP Bi2223 tapes from Sumitomo. REBCO coated conductor has a Hastelloy substrate whereas Bi-2223 tapes include bare tapes, tapes reinforced with stainless steel and Ni-Cr. The dependence of their *I*_c on *T*_quench will be determined for various test setups, for example with or without epoxy impregnation. Microstructure of the degraded samples will be investigated using optical and electron microscopy to further reveal the degradation mechanism at microscopic level. *This work is supported by the U.S. Department of Energy, Office of High Energy Physics through a FY12 early career award.*

Speaker: Liyang Ye (Fermi National Accelerator Laboratory)

Poster CECICMC_2015_Poster_-_YBCO&Bi2223_degradation-final.pdf

9:00 AM Single-strand excitation for examining current sharing and ICR in Nb3Sn Rutherford Cable at 4.2K up to 15 Tesla

S.S. Cored 27-strand Nb3Sn Rutherford Cable was pressed onto a U-shaped holder and kept at magnet-relevant conditions throughout reaction, instrumentation, epoxy-impregnation, and measurement. Current was injected into a single strand of the cable under applied fields up to 15 Tesla and with varying I/Ic. Then, a graphite-paste heater pulse was used to initiate current sharing. ICR and current sharing was then measured using a hall-probe array and voltage taps. These measurements were performed using a small research magnet and are screening for cable and cable preparation protocol for larger scale measurements.

Speaker: Chris Kovacs (Ohio State University)

9:00 AM → 9:30 AM Morning Break

11:00 AM → 12:00 PM C1OrA - Cryocoolers for Superconducting Applications

Conveners: Jonathan Demko (LeTourneau University), William Hassenzahl (AEA)

11:00 AM The Cost of Coolers for Cooling Superconducting Devices from 4.2 to 4.7 K, from 20 to 30 K, and from 65 to 80 K

This author and other authors have written papers concerning the cost of refrigeration at liquid helium temperature and higher temperature as a function of the refrigeration delivered. These papers have included small coolers as well. The lowest temperature range from 4.2 K to 4.7 K (the liquid helium temperature range) is covered using coolers that have two stages. The use of magnets and power equipment that use MgB2 conductors and HTS conductors have spurred the development of coolers that work well temperature ranges from 20 K to 30 K (for potential hydrogen temperature applications) and from 65 K to 80 K (for applications in the liquid nitrogen temperature range). This paper will present some cost data for a number of commercial two-stage and single-stage coolers. This data will be fitted to allow one to estimate the cost of coolers as a function of refrigeration for the three temperature ranges given above. The efficiency of several coolers over a range of temperatures will be discussed.

Speaker: Michael Green (Lawrence Berkeley Laboratory)

Slides C1OrA-01_Slides.pdf

11:15 AM Second stage Cooling from a PT-415 Cooler at Second-stage Temperatures up to 125 K with Heat Loads on the First-stage from 0 to 60 W

The amount of cooling delivered to the second stage of a two stage cooler is dependent on the second stage temperature and the amount of refrigeration provided by the cooler first stage. The second stage cooling as a function of temperature for a Cryomech PT415 cooler (1.5 W at 4.2 K with 42 W on the first stage) has been estimated by scaling similar data that was measured for a Cryomech PT410 cooler (1.0 W at 4.2 K with 28 to 30 W on the first stage). In order to accurately calculate the cool-down time for a superconducting magnet using PT415 K coolers one must know how much cooling can be delivered by the cooler second-stage as a function of the second-stage temperature and the added cooling delivered to the cooler first-stage. There are applications where PT415 coolers are used in the temperature range from 15 to 22 K to cool and liquefy hydrogen. This report describes the method for measuring the cooler performance as well as the results of the measurements.

Speaker: Michael Green (Michigan State University)

Slides C1OrA-02_Slides.pdf

11:30 AM Development of high efficiency Stirling cryocooler for high temperature superconducting motor

For the wide spread of high-temperature superconductor (HTS) devices, a cryocooler having COP of >0.1, compact size, light-weight, high efficiency and high reliability is required. For practical use of superconductive devices, especially HTS motor used for electric vehicle. We developed a high efficiency Stirling pulse-tube cryocooler (STP). STP has high reliability and low vibration. However its efficiency was not enough to meet the demands of HTS motor. To further improve the efficiency, we reconsidered the expander of cryocooler and developed a Stirling cryocooler. A cooling capacity of 151W at 70K and a minimum temperature of 33K have been achieved with compressor input power of 2.15kW. Accordingly, the COP was about 0.07. The detail of cryocooler and the experimental results will be reported in this paper. *This work was supported by Strategic Innovation Program for Energy Conservation Technologies Project of the New Energy and Industrial Technology Development Organization (NEDO) of Japan and a joint research with Sumitomo Electric Industries, Ltd.*

Speaker: Nakano Kyousuke (Sumitomo Heavy Industries, Ltd.)

Slides C1OrA-03_20150629_CEC-ICMC2015_slide.pdf

11:45 AM R&D status of highly efficient Stirling-type cryocooler for superconducting drive motor

In this paper, we try to develop highly efficient Stirling-type cryocooler for the next generation drive motor. Target motor is a High Temperature Superconducting Induction/Synchronous Motor (HTS-ISM). Although basic structure of HTS-ISM is almost the same as that of the conventional squirrel-cage induction motor, it can rotate at synchronous speed by use of the superconducting rotor windings. It has been clarified that the torque density can be enormously enhanced at the synchronous rotation. By enhancing torque density, it is possible to realize the direct-drived operation without transmission gears. The transmission system brings some loss because the gears always rotate during the driving. In order to improve the overall energy conversion efficiency of power-train system, the direct-drive motor is expected to be realized. On the other hand, HTS-ISM has been operated in liquid nitrogen. This method,　however, has several disadvantages such as the mechanical loss due to the viscosity of liquid nitrogen, the safety reason, etc. Therefore, we have studied the conducting cooling system. It is necessary to develop small sized high power cryocooler in order to realize the high efficiency of overall HTS-ISM power-train system. Generally speaking, Stirling-type cryocooler has advantages in terms of size and efficiency. We firstly designed, fabricated, and tested the actuator at various frequency and in several wave patterns, and we realized the high efficiency of the actuator. Next, we set up pulse-tube cryocooler to this compressor, and measured the cooling capacity of this Stirling-type cryocooler. Experimental and analysis results are to be reported and discussed. *This work has been supported by Japan Science and Technology Agency under the program of Advanced Low Carbon Technology Research and Development Program (JST-ALCA).*

Speaker: Mr Jun Watanabe (Kyoto University)

Slides JunWatanabe-CECICMC.pdf JunWatanabe-CECICMC.pptx

11:00 AM → 12:15 PM C1OrB - Cryogenic Heat Transfer

Conveners: Bertrand Baudouy (CEA Saclay), James Tuttle (NASA/GSFC)

11:00 AM ULTRA-FLEXIBLE THERMAL BUS FOR USE IN THE ASTRO-H ADIABATIC DEMAGNETIZATION REFRIGERATOR

The adiabatic demagnetization refrigerator (ADR) developed for the Astro-H Soft-Xray Spectrometer (SXS) is a multi-stage solid-state cooler. It is capable of holding the SXS detector array at 0.050 K for greater than 24 hours with a recycle time of less than one hour. This quick recycle time relies upon high-conductivity thermal straps to couple the individual stages to a pair of heat switches without imposing a lateral load on the paramagnetic salt pills. To accomplish this we construct thermal straps using a technique of diffusion bonding together the ends of high-purity copper straps leaving the length between as individual foils. A thermal bus created this way has a thermal conductivity comparable to a solid strap of the equivalent thickness but with much-increased flexibility. The technique for selecting the base material, machining, cleaning, forming into final shape, and finally bonding together individual foils will be discussed along with examples of complete straps in various geometries.

Speaker: Dr Mark Kimball (NASA/Goddard Space Flight Center)

Slides Kimball_CEC_2015_Heat_Strap_Presentation.pdf Kimball_CEC_2015_Heat_Strap_Presentation.pptx

11:15 AM A thermally-conductive electrical isolator for use at ultra-low temperatures in the Astro-H Adiabatic Demagnetization Refrigerator

The Soft X-ray Spectrometer (SXS) destined for the Japanese Astro-H mission contains a 6x6 array of microcalorimeters. To achieve ultimate resolution the array must be electrically isolated from the rest of the instrument as well as cooled to 0.050 K. The latter is achieved by directly coupling it to the coldest stage of a multi-stage Adiabatic Demagnetization Refrigerator (ADR). Thus, the electrical isolation is in-line with a portion of the cooling chain demanding the dielectric be thermally conductive at sub-Kelvin temperatures. We present here the design that balances electrical isolation with reasonable thermal conductance below 1~Kelvin.

Speaker: Mark Kimball

Slides Kimball_CEC_2015_Electrical_Break.pdf Kimball_CEC_2015_Electrical_Break.pptx

11:30 AM Low-temperature thermal conductivity of highly porous copper

The development and characterization of new materials is of extreme importance in the design of cryogenic apparatus. Recently the Versarien company developed a technique capable of producing copper foam with controlled porosity and pore size. Such porous materials could be interesting for cryogenic heat exchangers as well as of special interest in some cryogenic devices for microgravity environments. For instance, in our Energy Storage Units [1, 2] for potential use in space applications, a porous ceramic is used to retain a cryogenic liquid (N$_2$, Ne, H$_2$, He) by capillarity. However, due to the ceramic’s low thermal conductivity, a high thermal gradient builds up for low filling ratios. A high thermal conductivity material like copper with small pore size and high porosity (up to 80%) would combine the same capillary effect with a good thermal homogeneity in this type of devices with the possibility of easy soldering. In the present work, a system was developed to measure the thermal conductivity of four Versarien samples of copper foam for a porosity between $50 \%$ and $80 \%$, within the range of temperatures $20$ – $260$ K, using a $2$ W @ $20$ K cryocooler. The coherence of our measurements is validated using a copper control sample and by electrical resistivity measurements at room temperature, by the estimation of the Lorenz number. With these measurements, the purity (Resistivity Residual Ratio) and the tortuosity were obtained for all samples. [1] J. Afonso et al., Cryogenics $51$ ($2011$) $621$-$629$. [2] P. Borges de Sousa et al. « $15$ K LIQUID HYDROGEN THERMAL ENERGY STORAGE UNIT FOR FUTURE ESA SCIENCE MISSIONS », this conference.

Speaker: Gonçalo Tomás (LIBPhys, Physics Department, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa)

Slides Gonçalo_Tomás.pdf Gonçalo_Tomás.pptx

11:45 AM Single-phase ambient and cryogenic temperature heat transfer coefficients in microchannels

Micro-scaling cryogenic refrigerators, in particular the Joule-Thomson (JT) variety requires very good information about heat transfer characteristics of the refrigerants flowing in the microchannel for optimal design and performance. There are numerous studies regarding heat transfer coefficient measurements of liquid flow in microchannels at/near ambient temperature and high Reynolds flow (Re>2000), that well agree with the conventional correlations. However, results from these studies of gaseous flow in microchannels at low Reynolds flow (Re<1000) disagree with conventional theory. Moreover, the studies performed at cryogenic temperatures are quite limited in number. Because extremely low Reynolds flow is present when micro-scaling a cryogenic JT refrigerator to MEMS fabrication levels, due to low pressure ratios provided by a single stage MEMS compressor the heat transfer characteristics at these conditions require investigation. In this paper, the single-phase heat transfer coefficients and friction factors for nitrogen are measured at ambient and cryogenic temperatures. The hydraulic diameters for this study are 60, 110 and 180 μm for circular microchannels. The Reynolds numbers varied from a very low value of 10 to 3000. The measured friction factors are comparable to those in macro-scale tubes. The experimental results of the heat transfer indicate that Nusselt numbers derived from measurements are significantly affected by axial conduction at low Reynolds flow (Re<500). The Nusselt numbers at high Reynolds flow (Re>1000) follow conventional theory. The detailed experiment, procedure, and measured results are presented in this paper and discussed regarding deviation from ideal theory at low Reynolds flow.

Speaker: Mr Peter Bradley (NIST)

Slides Presentation_for_CEC_06192015_v4_upload_for_CEC.pptx

12:00 PM Flow of nitrogen gas in a liquid helium cooled vacuum tube: Condensation heat transfer

Linear accelerators (LINACs) using superconducting radio frequency (SRF) technology comprise of a long string of SRF cavities housed in discreet cryomodules. This cavity string is operated immersed in liquid helium (LHe) with high vacuum on its inside. Sudden loss of this cold vacuum to surrounding atmosphere perceivably is the worst failure mode of the LINAC. An accidental rupture at any cryomodule interconnect will initiate an air in-flow, which will solidify on the inner wall of the cold cavity and transfer heat to the LHe bath. Here, we study such a condensing flow with an emphasis on the associated heat deposition onto the cold walls, and the subsequent heat transfer to LHe. The flow is generated by rapidly venting a large reservoir of nitrogen gas to a long vacuum tube immersed in 4.2 K LHe. Experiments are carried out with different mass in-flow rates of nitrogen, and the rise of the pressure and temperature of the tube are recorded at several locations along the flow. As the gas pressure in the tube rises we observe that the rate of heat deposition due to condensation initially increases, attains a maximum, and then sharply drops. Irrespective of the mass in-flow rate of the gas (severity of the loss of vacuum accident) the maximum rate of condensation heat transfer to the tube occurs when the tube temperature is in 22-26 K range, and the pressure in the tube typically below 1 kPa. These observations are discussed in context of the cryopumping theory. With increasing gas pressure the tube temperature continues to gradually rise and eventually attains a steady value. The estimate of the peak heat load to the LHe bath is deduced from the maximum temperature attained by the tube. *This work is supported by US Department of Energy grant DE-FG02-96ER40952.*

Speaker: Ram Dhuley (Florida State University)

Slides CEC2015DhuleyVanSciver.pptx

11:00 AM → 12:15 PM C1OrC - Compressors & Expanders

Conveners: Joel Fuerst (ANL), Thomas Peterson (Fermilab)

11:00 AM Testing of Full-Scale Prototype Cryoviscous Compressor at SNS for ITER Vacuum System

To pump the ITER torus exhaust gas from the regenerating torus cryopumps, which will be a mixture of deuterium, tritium, and helium with trace impurities, a prototype cryoviscous compressor (CVC) has been designed, fabricated, and is under test. This prototype, which was based on success ful demonstration of a sub-scale version, consists of a set of 24 5-cm diameter, 1.27-m long stainless steel tubes with embedded static mixer flow enhancements that is cooled with supercritical helium (SCHe) to cryopump the hydrogenic species while allowing helium to be exhausted through the CVC. In order to test the CVC, flow controls and vacuum jacketed piping were installed at a connection to the Cryogenic Test Facility (CTF) at the Spallation Neutron Source to cool the CVC with SCHe supplied at 4.5K and 3 bar. Helium heated to 20-30 K is used to regenerate the CVC. The CVC is designed to pump up to 20,000 Pa-m3 of deuterium that is mixed with 100 Pa-m3 helium gas with a flow rate of 200 Pa-m3/s. The integrated operation of the CVC with the CTF will be presented along with the performance test results of the CVC. *This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan.*

Speaker: Robert Duckworth (Oak Ridge National Laboratory)

11:15 AM Design of cold compressor systems in terms of operational and economical aspects

In the past, cooling at 2K used to be an exotic application in large scale cryogenics. The required sub-atmospheric helium bath was established with the help of one of the following two technical approaches – rough vacuum pumping at ambient temperature or turbo compression at cryogenic temperature – or a combination of both. The aforementioned approaches are still being applied, but the optimum distribution between warm and cold stages is not always obvious. In the last few years, 2K cooling became a new state-of-the-art in the fields of experimental and applied physics. Standardisation of the machinery and its controlling significantly reduced commissioning time which has clearly been demonstrated during start-up of refrigeration plants such as Fermilab and DESY. Thus, the technological readiness of cold compressors has successfully been proved. This paper presents criteria for the optimisation of a cold compressor system under operational and economical aspects depending on the required 2K cooling capacity.

Speaker: Mr Lutz Decker (Linde Kryotechnik AG)

Slides C1OrC-Design_of_CC-Systems_LDecker.pptx

11:30 AM Adaptation of refrigeration compressors for Joule-Thomson cryocoolers fed with gas mixtures

Closed cycle Joule-Thomson (J-T) refrigerators supplied with gas mixtures are perspective coolers in many applications requiring low-cost and reliable sources of cooling power below 100 K. They are characterized by relatively simple construction and lack of moving parts working at low temperatures. The refrigerants are composed of nitrogen and hydrocarbons. Working pressure can as low as about 2 MPa, and thanks to its solubility in hydrocarbons, some fraction of compressor lubricating oil can circulate in the system. The main advantage of the J-T refrigerator using gas mixtures is the possibility of use of commercially available hermetic refrigeration compressors. The limiting factor is temperature increase of the mixture during compression. The paper is focused on the problems of adaptation of hermetic compressors to J-T cryocoolers requirements. Temperature limits as well as possible technical solutions to improve the compressor cooling and lubrication have been analyzed and discussed. Working parameters of the J-T refrigerator fed with gas mixture and will be presented together with the influence of compressor adaptation means.

Speaker: Dr Agnieszka Piotrowska (Wroclaw University of Technology)

Slides C1OrC-03.pdf C1OrC-03.ppt

11:45 AM Development of an oil-free compressor for GM and pulse tube cryocoolers

Pressure Wave Systems GmbH has developed an oil-free compressor for GM and pulse tube cryocoolers. The concept is based on hydraulically driven metall bellows which compress the Helium working gas. The system has 1kW of electrical input power and has been successfully tested with a SHI SRDK-101D GM cryocooler cold head. Set-up, performance and reliability of the compressor system will be discussed.

Speaker: Dr Jens Höhne (Pressure Wave Systems GmbH)

Slides C1OrC_Hoehne.pdf

12:00 PM Engineering, Manufacture and Preliminary Testing of the ITER Toroidal Field (TF) Magnet Helium Cold Circulator

The ITER cryodistribution system provides the supercritical Helium (SHe) forced flow cooling to the magnet system using cold circulators. The cold circulators are located in each of five separate auxiliary cold boxes planned for use in the facility. Barber-Nichols Inc. has been awarded a contract from ITER-India for engineering, manufacture and testing of the Toroidal Field (TF) Magnet Helium Cold Circulator. The cold circulator will be extensively tested at Barber-Nichols’ facility prior to delivery for qualification testing at the Japan Atomic Energy Agency’s (JAEA) test facility at Naka, Japan. The TF Cold Circulator integrates features and technical requirements which Barber-Nichols has utilized when supplying Helium cold circulators worldwide over a period of 35 years. Features include a vacuum jacketed hermetically sealed design with a very low Helium leak rate, a heat shield for use with both Nitrogen & Helium cold sources, a broad operating range with a guaranteed isentropic efficiency over 70%, and impeller design features for high efficiency. The cold circulator will be designed to meet MTBM of 17,500 hours and MTBF of 36,000 hours. Vibration and speed monitoring are integrated into a compact package on the rotating assembly with operation and health monitoring in a multi-drop PROFIBUS communication environment using an electrical cabinet with critical features and full local and network PLC interface and control. For the testing in Japan and eventual installation in Europe, the cold circulator will be certified to the Japanese High Pressure Gas Safety Act (JHPGSA) and CE marked in compliance with the European Pressure Equipment Directive (PED)including Essential Safety Requirements (ESR). The test methodology utilized at Barber-Nichols’ facility and the resulting test data, validating the high efficiency of the TF Cold Circulator across a broad operating range, are important features of this paper.

Speaker: Mr Chris Rista, P.E. (Barber-Nichols Inc.)

Slides Barber-Nichols_Inc_-_Engineering,_Manuf,_&_Prelim_Testing_ITER_(TF)_Magnet_Helium_Cold_Circulator.pptx

11:00 AM → 12:30 PM C1OrD - Low Temperature Aerospace Cryocoolers

Conveners: Carl Kirkconnell (Iris Technology), Dean Johnson (JPL)

11:00 AM Performance Testing of a 15K Pulse Tube Cooler for Space Applications

Air Liquide has been working with ESA, CEA and Thales Cryogenics since 2010 to design, manufacture and test a 15K Pulse Tube Cooler system. This cooler is particularly adapted to the pre-cooling needs of cryogenic chains designed to reach 0.1-0.05K for focal plane cooling on scientific space missions such as ATHENA. The cooler is designed to provide cooling power >0.3W at temperatures from 15 to 18K with an electrical power budget less than 300W (excluding electronics) and a 288K rejection temperature. Significant cooling power at an intermediate temperature (typically 80-100K) is also available. The design includes two cold fingers mounted on a common warm flange driven by a single high power compressor (240W PV power) specially developed for this application. The first cold finger is used to pre-cool the second, low temperature stage. An Engineering Model has been manufactured and the design and test results will be presented in this paper.

Speaker: James Butterworth (Air Liquide Advanced Technologies)

Slides C1OrD-01_Butterworth_CEC_15K_PTC.pdf

11:30 AM Lockheed Martin Joule-Thomson Compressor Development

This paper describes the development and testing of a space-quality compressor capable of delivering closed-loop gas flow with a high pressure ratio, suitable for driving a Joule-Thomson cryocooler. The compressor is based on a traditional “Oxford style” dual-opposed piston compressor with linear drive motors and flexure-bearing clearance-seal technology for high reliability and long life. This J-T compressor retains the approximate size, weight, and cost of the ultra-compact, 200 gram Lockheed Martin Pulse Tube Micro Compressor, despite the addition of a flow-rectifying system to convert the pressure wave into a steady flow. Key to this program was the development of a custom miniature check valve, small enough to be incorporated into the compressor without affecting overall size and with fast enough response time to capture the pressure pulses. One of the major challenges of working at this small scale is that components must be conceived within the confines of a plausible manufacturing process to be viable and cost effective. Incorporating the micro check valves into the compressor body was done with a goal of minimizing dead volumes in order to maximize pressure ratio output. The result is a system of bores and passages that comprise an efficient two-stage, four-valve circuit integrated into a single-piece compressor hub. The size, weight, and manufacturing costs of this J-T compressor are nearly the same as our Pulse Tube Micro compressor. And since it uses many of the same parts and processes, it can be readily adapted to the same high-volume, low cost manufacturing. Other uses for this compressor include long-life low power pumping of circulating systems, such as ambient or cryogenic remote cooling loops. ©2015 Lockheed Martin Corporation. All Rights Reserved

Speaker: Patrick Champagne (Lockheed Martin)

Slides C1OrD-03-Champagne.pdf C1OrD-03-Champagne.pptx

11:45 AM Qualification campaign of the 50 mK sorption-ADR cooler for SPICA/SAFARI

SAFARI (SpicA FAR-infrared Instrument) is an infrared instrument planned to be part of the SPICA (SPace Infrared telescope for Cosmology and Astrophysics) Satellite. It will offer high spectral resolution in the 30 – 210 µm frequency range. SAFARI will benefit from the cold telescope of SPICA and to obtain the required detectors sensitivity, a temperature of 50 mK is required. This temperature is reached thanks to the use of a hybrid sorption – ADR (Adiabatic Demagnetization Refrigerator) cooler presented here. This cooler provides respectively 14 µW and 0.4 µW of cooling power at 300 mK and 50 mK. The cooler is planned to advantageously use two thermal interfaces of the instrument at 1.8 and 4.9 K. One of the challenges that will be discussed is the low power available at each intercept. A dedicated laboratory electronic is being designed based on previous development with a particular focus on the 50 mK readout. Temperature regulation at 50 mK will also be discussed. This cooler has been designed following flight constraints and will reaches a high TRL, including mechanical and environmental tests at the end of the on going qualification campaign.

Speaker: Mr Jean-Marc duval (CEA)

12:00 PM Coupled tests of the Closed Cycle Dilution Refrigerator and 3He compressor for space

Institut Néel - CNRS and Air Liquide are presently developing a Closed-Cycle Dilution Refrigerator for Space. Recent sub-system level tests have demonstrated the operation of the low temperature components : the mixing chamber can provide close to 1µW at 50mK, the Still (in which the phase separation between liquid and gas occurs) can confine the liquid against gravity, and 4He can be efficiently re-circulated by means of a superfluid fountain pump. Yet, one of the major components for the system is the 3He compressor to re-circulate the 3He pumped at still level. In the tests at sub-system level, this compressor would be a commercial pump not adapted for space use. JAXA and SHI have been developing 3He compressors for use in a JT cooler (the so-called "1K class cooler"). Through recent developments, the minimum inlet pressure could be lowered towards CCDR requirements. A common program between JAXA and CNES has been set up to issue a coupled test of the CCDR with the modified 3He compressor. We present both subsystems and recent results obtained when coupling these 2 subsystems. We discuss potential next steps.

Speaker: Gerard VERMEULEN (Institut Neel (CNRS))

Slides cec-vermeulen.pdf

12:15 PM Test results of sorption-based helium-3 pump for a closed-cycle dilution refrigerator

A sorption-based helium-3 pump is developed to be incorporated in a closed-cycle dilution refrigerator (CCDR) that is realized by the Néel institute in Grenoble. This CCDR is to be used for future long-lifetime space missions requiring a cooling power of the order of 1 microWatt at typically 50 mK for at least 5 years. A crucial component in this zero-gravity dilution refrigerator is a pump to circulate helium-3 between 5 and 200 mbar. For this purpose, we designed a sorption-based pump that consists of a single sorption-compressor cell of which the sorber container measures 1 cm in diameter and 10 cm in length. It uses passive inlet and outlet valves and is thermally linked to a 15-K platform. Gas buffers are applied for stabilizing the low pressure and for storing the gas at 300 K thus reducing the filling pressure to below 20 bar. The pump is manufactured and tested. A compressor-cell input of 60 mW is required to establish a flow of 20 micromol/s between 5 and 200 mbar. The pressure fluctuation in that case at the low-pressure side is about 1,5 mbar. If needed, this fluctuation can be reduced to about 0,5 mbar by controlling the temperature of the low-pressure buffer (requiring an additional power input of 60 mW). Compared to mechanical pumps the main advantages are lower mass and less complex interfacing. Both advantages result from the fact that the pump is fully integrated with the cold part of the CCDR, whereas the alternative mechanical pumps need to be operated at the 300 K level. The construction of the sorption-based pump and test set-up will be presented as well as the test results.

Speaker: Marcel ter Brake (University of Twente, The Netherlands)

Slides CEC_2015_Ter_Brake_He_3_pump.pdf

11:00 AM → 12:30 PM M1OrA - Superconductor Cables I: HTS and LTS

Conveners: Arend Nijhuis (University of Twente), Goldacker Wilfried (Karlsruhe Institute of Technology / ITEP)

11:00 AM [Invited] Record engineering current density of 246 A/mm2 at 17 T in HTS Conductor on Round Core (CORC) cables made at Advanced Conductor Technologies

Advanced high-energy physics magnets, high-field research magnets and fusion reactors require the development of high-temperature superconducting cables for magnetic fields exceeding 20 T, or allow for operating temperatures above the boiling point of liquid helium. Using ReBCO coated conductors, Advanced Conductor Technologies is developing Conductor on Round Core (CORC) cables that will enable this next generation of magnets. We will discuss some of the latest results of CORC magnet cable development at Advanced Conductor Technologies, which have reached a critical current of close to 7 kA in a 6 mm diameter CORC cable at 4.2 K and a background field of 17 T. This is a record engineering current density of 246 A/mm2 at 17 T, or about 213 A/mm2 at 20 T, making CORC cables a viable candidate for use in the next generation of accelerator magnets. This record current density was reached by winding the cable from a new generation of SuperPower tapes with 38 μm thin substrate. A new type of CORC cable termination was used for injecting the high currents into the cable. The tapes with thinner substrates not only reduce the cable thickness, but also limit the bending strain of the superconducting layer, minimizing the performance degradation of the tapes during cabling. The new terminals and the availability of tapes with even thinner substrates will allow us to raise the current density in CORC cables towards 400 A/mm2 at 20 T before the end of 2015.

Speaker: Danko van der Laan (Advanced Conductor Technologies)

Slides van_der_Laan_ICMC_2015_Final.pdf

11:30 AM Persistent Magnetization and Decay in Bi:2212, YBCO, and Nb3Sn and influence on Accelerator Magnet Field Errors

Cable magnetization leads to field errors in precision beam-line accelerator magnets. These errors are particularly problematic at the injection field, both in their base value, as well as their temporal drift. Drift in NbTi cable magnetization is due to the influence on strand magnetization of the decay of long-range coupling currents. But with HTS cables and magnets, a new drift mechanism will come into play – flux creep. Negligible for LTS, creep will be significant for HTS even at low temperatures, at least in the context of high precision field requirements. We have measured the magnetization of HEP relevant Nb3Sn, Bi:2212, and YBCO conductors; these are compared and estimates made of their relative impact on error fields in accelerator magnets, as compared to NbTi. We have also measured the magnetization creep of these strands for a time span of ~1200 s (20 min)—the time of a typical injection plateau in the Large Hadron Collider. Short samples and small helical coils of Nb3Sn and Bi:2212, as well as short samples of YBCO, were measured in applied magnetic fields of 1 T (“injection”) and 12 T (“collision”). From a persistent magnetization viewpoint, Bi:2212 is seen to be comparable to Nb3Sn once correcting for the flatness of the Jc vs B curve; YBCO magnetization contributions will be highly dependent on magnet and cable design. Creep led to magnetization changes of 15-20% for YBCO, and 20-30% for Bi:2212 over the 1200 s time span (20 min). This led to estimates of b3 drift in units for Bi:2212, and tens of units or (much) more, for YBCO (depending heavily on cable and magnet geometry). A YBCO striation target is suggested to reduce the large magnetization and drift.

Speaker: Mike Sumption (The Ohio State University)

Slides IMCM2015-M1OrA-Sumption.pdf IMCM2015-M1OrA-Sumption.pptx

11:45 AM Subsea Superconducting Power Cables for Offshore Renewable Energy Integration

Offshore renewable energy, such as wind, tidal and wave energy, represents a potential solution to the future energy demand, while the world’s energy consumption continues to grow rapidly and the production of both oil and gas is waning. Serious consideration has been given to the development of offshore wind farms, particularly in Europe, North America and Asia. Many projects have been approved and several farms are already under construction. To integrate these offshore farms and transfer power from them to shore-based power networks, efficient subsea power cables are urgently required, since conventional cables cannot play this irreplaceable role with very limited power capacity and considerable loss. Superconductors, which are only being utilized for developing land power cables so far, are a perfect solution. Prof. Li, on behalf of the Applied Superconductivity Centre in the University of Edinburgh, will for the first time present their research work on applying superconductors to develop subsea superconducting power (SSP) cables. Such SSP cables are expected to entirely upgrade the present power network. Both advantages and potential risks of SSP cables will be presented, followed by analysis of their reliability. An SSP cable with suitable configuration for subsea power transmission is proposed. Based on numerical modelling, its electrical and magnetic properties are studied and its loss characteristics are analysed. Results show that the SSP cables can greatly benefit subsea power networks with ultimate power capability and extremely low loss. However, efficient cooling is essential along with the protection of physical damage and fault current. All results will be presented and relevant discussion will be carried out.

Speaker: Prof. QUAN LI (University of Edinburgh)

12:00 PM Dielectric Properties of Cryogenic Gas Mixtures Containing Helium, Neon, and Hydrogen

Past efforts of cooling high temperature superconducting (HTS) power cables by gaseous cryogens focused exclusively on helium [1]. We are working on exploring the benefits of gas mixtures containing helium with small amounts of hydrogen and neon gas to mitigate the limited dielectric strength of pure helium gas. This could potentially improve dielectric characteristics while maintaining the thermal, non-flammable and non-corrosive properties of pure helium gas. From the dielectric point of view, hydrogen gas is far superior to helium and neon. Hydrogen gas has approximately 50% of the dielectric strength of nitrogen gas at room temperature [2]. The noble gases helium and neon exhibit dielectric strength 15% and 25% respectively that of nitrogen gas at room temperature. It is known from other gas mixtures studies that even a small amount of a superior gas can considerably improve the dielectric strength of the mixture more than the ratio would suggest [3]. The dielectric properties of pure helium gas at temperatures in the range of 50 K to 77 K have been studied in past HTS cable projects at Florida State University. The challenges with low breakdown voltage have led to the investigation of potential alternative cooling gases. The dielectric strength of helium gas mixtures containing 2% and 4% of neon and hydrogen have been measured and compared to that of pure helium. The limit of 4% of hydrogen was to ensure to keep the gas mixture non-flammable in air. All experiments were performed at 77 K at pressures between 0.1 and 2.0 MPa. [1] S. Pamidi et al., 11th EPRI Superconductivity Conference, Houston, TX, October 28-30, 2013. [2] A. K. Vijh, IEEE Trans. on Electrical Insulation, 12, 313, 1997. [3] N. H. Malik et al., IEEE Trans. Electr. Insul., Vol. 14, pp. 1-13, 1979.

Speaker: Lukas Graber (Florida State University)

12:15 PM Development of MgB2 conductors for low field coils and feeders in DEMO fusion energy reactors

An International Collaboration for Advancement of Magnesiumdiboride Superconductors (ICAMS) has been initiated to develop MgB2 superconductors for fusion reactor magnets. Today NbTi is the undisputed superconductor for use in the Poloidal Field coils (PF), Correction Coils (CC), graded Toroidal Field (TF) coils and Feeders of a fusion machine. A major advantage of MgB2 is it’s higher operating temperature and larger temperature margin. The larger temperature margin allows cost reduction of the cryogenic system and improvement of reliability. For any fusion machine design in the next decade, it is likely that NbTi will be used for the lower field PF, CC or graded TF coils and feeders but MgB2 wire is a serious candidate for future machines. A Cable-In-Conduit Conductor (CICC) concept is adopted with a strand cable pattern designed for minimum interstrand coupling loss to limit the heat load and maximum strand mechanical support to avoid degradation from thermal and electromagnetic stress. The lead for the design and eventual test is a full-size MgB2 Poloidal Field conductor. The prospective to use state of the art MgB2 strands for the PF and CC superconductors of a fusion device is analyzed with the code JackPot-ACDC. The strand critical parameters for second-generation multifilamentary HyperTech MgB2 strand with a diameter of 0.83 mm serve as a critical input for the analysis of the computed conductor performance. The predicted MgB2 PF CICC performance is compared with the requirement of the present ITER PF design with maximum operating current of 45 kA and nominal peak field of 6 T. The organization scheme of the ICAMS collaboration and first results are presented.

Speaker: Arend Nijhuis (University of Twente)

11:00 AM → 12:30 PM M1OrB - Cryogenic Materials I: Testing and Methods

Conveners: Osamu Umezawa (Yokohama National University), Robert Walsh (Florida State University)

11:00 AM [Invited] DESIGN AND FABRICATION OF A CRYOSTAT FOR LOW TEMPERATURE MECHANICAL TESTING FOR THE MECHANICAL AND MATERIAL’S ENGINEERING GROUP AT CERN

Mechanical testing of materials at low temperatures is one of the cornerstones of the Mechanical and Material’s Engineering (MME) group at CERN. A long tradition of more than 20 years and a unique know - how of such tests has been developed with a 18 kN double-walled cryostat. Large campaigns of material qualification have been carried out and the mechanical behavior of materials at 4 K has been vastly studied in sub–size samples for projects like LEP, LHC and its experiments. With the aim of assessing the mechanical properties of materials when submitted to higher loads, a new 100 kN cryostat capable of hosting different shapes of normalized samples has been carefully designed and fabricated in-house together with the associated tooling and measurement instrumentation. It has been conceived to be able to adapt to different test frames both dynamic and static, what will be of paramount importance for future studies of fracture mechanics at low temperatures. The cryostat features of a double-walled vessel consisting of a central cylindrical section with a convex lower end and a flat top end closure. The transmission of the load is guaranteed by a 4 column system and its precise monitoring is assured by an internal load cell positioned next to the sample in the load train. This innovative approach will be discussed together with other non-conventional instrumentation solutions such as optical fiber extensometry. A validation of the whole system has been carried out at both room and cryogenic temperature. Bending efforts have been measured and dedicated tooling fabricated for the device’s optimization. The results obtained confirm an excellent performance of the system and enhance the analysis of materials under extreme conditions with state of the art instrumentation.

Speaker: Stefanie Langeslag (CERN)

Slides PPT_IAviles_ICMC2015_29062015.pdf

11:30 AM Thermal Contraction of Electrical Insulators

The thermal contraction from room temperature to 4 K of electrical insulation materials has been measured using a modified Invar 36 rod-in-tube dilatometer.The test assembly permitted independent measurement, simultaneously, of two samples. This permitted the use of a reference and an insulation sample for each thermal run. Materials that were measured included a conventional epoxy resin, Kapton film, and a series of glass/epoxy resin, glass/polyimide resin, and glass/ epoxy resin/Kapton laminates. The glass contents of the glass/epoxy resin laminates were varied to obtain the dependency of thermal contraction on volume percent glass. Data are compared to previous measurements and the laminate data are presented as a function of temperature and volume percent glass.

Speaker: Dr Richard Reed (Cryogenic Materials, Inc.)

11:45 AM Apparatus and method for low-temperature training of shape memory alloys

An apparatus and method for the low-temperature mechanical training of shape memory alloys has been developed. The shape memory alloy (SMA) materials are prototypes being developed for novel thermal management systems in future cryogenic applications. Alloys providing two-way actuation at cryogenic temperatures are the chief target. The mechanical training regime was focused on the controlled movement of rectangular strips, with S-bend configurations, at temperatures as low as 30 K. The custom holding fixture included temperature sensors and a low heat-leak linear actuator with a magnetic coupling. The fixture was mounted to a Gifford-McMahon cryocooler providing up to 35 W of cooling power at 20 K and housed within a custom vacuum chamber. Operations included both training cycles and verification of shape memory movement. The system design and operation are discussed. Results of the training for select prototype alloys are presented.

Speaker: Adam Swanger (NASA Kennedy Space Center)

Slides CEC2015_M1OrB-03_SMA_Training.pdf

12:00 PM DESIGN OF LOAD-TO-FAILURE TESTS OF HIGH-VOLTAGE ELECTRIC INSULATION BREAKS FOR ITER’S CRYOGENIC NETWORK.

The development of new generation superconducting magnets for fusion research, such as the ITER experiment, is largely based on coils wound with so-called ‘cable-in-conduit’ conductors. These cable-in-conduit conductors consist of various types of stainless steel jackets, densely filled with superconducting strands based on either Nb3Sn or NbTi, and subsequently compacted. The concept of the cable-in-conduit conductor is based on a direct cooling principle, by supercritical helium, flowing through the central region of the conductor, in close contact with the superconducting strands. Originating from this principle is a direct connection between the electrically grounded helium coolant supply line and the highly energized magnet windings. Various insulated regions, constructed out of high-voltage insulation breaks, are put in place to isolate sectors with different electrical potential. These axial insulation breaks are essentially build up from stainless steel end fittings, hermetically connected via a glass-reinforced resin composite body, of sufficient length, to prevent electrical breakdown during magnet operation. In addition to high voltages and significant internal helium pressure, the insulation breaks will experience various mechanical forces resulting from differential thermal contraction phenomena and electro-magnetic loads. Special test equipment was designed, prepared and employed to assess the insulator breaks’ mechanical reliability. A binary test setup is proposed, where mechanical failure is assumed when permeability to gaseous helium exceeds 10-9 Pa*m3/s. The test consists of a load-to-failure insulation break charging, in tension, while immersed in liquid nitrogen at the temperature of 77 K. Leak tightness during the test is monitored by measuring the permeability of gaseous helium directly surrounding the insulation break, with respect to the existing vacuum inside the insulation break. The experimental setup is proven effective, and various insulation breaks performed beyond expectations.

Speaker: Stefanie Langeslag (CERN)

Slides PPT_SLangeslag_ICMC2015_29062015.pdf

12:15 PM SOFI/Substrate Integrity Testing for Cryogenic Propellant Tanks

Liquid propellant tank insulation for space flight requires low weight as well as high insulation factors. Use of Spray-On Foam Insulation (SOFI) is an accepted, cost effective technique for insulating a single wall cryogenic propellant tank and has been used extensively throughout the aerospace industry. Determining the bond integrity and the SOFI’s ability to withstand the strains, both physical and thermal, applied during fill and drain cycles is critical to the longevity of the insulation. This determination has previously been performed using highly volatile, explosive cryogens, which increases the test costs enormously, as well as greatly increasing the risk to both equipment and personnel. CTD has developed a new test system, based on previous NASA testing, that enables a relatively small SOFI/substrate test sample to be monitored for any deformations, delaminations, or disjunctures within during the cooling and mechanical straining process of the substrate, as well as enabling the concurrent application of thermal and physical strains to two specimens at the same time. The thermal strains are applied by cooling the substrate to the desired temperature (from 4 K to 250 K) while maintaining exposure to ambient conditions at the surface of the SOFI foam. Multiple temperature gaging points are exercised to ensure even cooling across the substrate, while surface temperatures of the SOFI can be monitored to determine the heat flow through the SOFI. The system also allows for direct measurement of the strains in the substrate during the test. The test system as well as test data from testing at 20 K for liquid Oxygen simulation testing will be discussed.

Speaker: Mr Mark Haynes (Composite Technology Development)

Slides M1OrB-05-Haynes.pdf M1OrB-05-Haynes.pptx

12:30 PM → 2:00 PM Lunch (on your own)

2:00 PM → 4:00 PM C1PoF - Circulators, Pumps and Regnerators

Conveners: Peter Bradley (NIST), Sastry Pamidi (The Florida State University)

2:00 PM DESIGN REALIZATION TOWARDS THE QUALIFICATION TEST OF ITER COLD CIRCULATOR

Cold circulators, part of ITER Cryo-distribution system, have now reached to a stage of final qualification to demonstrate the design to cater the maximum mass flow and operational demands of the toroidal field (TF) superconducting magnet of ITER with a very high isentropic efficiency. The design of the TF cold circulators are now complete, gratifying additionally the operational requirements of poloidal field & central solenoid superconducting magnet as well as the cryopumps towards the fulfillment of standardization aspects. Management of physical and functional interfaces has been identified as one the most critical aspect towards the final performance of ITER cold circulator. Mechanical, instrumentation and control as well as utilities are recognized as physical interfaces; whereas, operating modes of the cold circulator as an integrated component in the Test Auxiliary Cold Box (TACB) is the functional interface. All the interfaces of cold circulators have been analyzed with the help of optimized interfacing parameters of TACB and test facility at JAEA, Naka, Japan during the course of design finalization of two numbers of TF cold circulators as well as a TACB. Testing at the warm conditions after completion of precise manufacturing of cold circulators will be performed before final integration into the TACB in order to fulfill the Japanese as well as European regulatory requirement simultaneously. Components forming the pressure boundaries, such as the in-cryostat casing as well as on-cryostat mounting flange of cold circulators have been separately manufactured, tested and certified in order to mitigate the envisaged risk during the manufacturing processes. The paper will elaborate the methodology of interface management and control, analysis performed towards the interface management and preliminary test results towards the qualification test of the ITER cold circulator.

Speaker: Mr Hitensinh Vaghela (ITER-India, Institute for Plasma Research)

Poster C1PoF-02_[C2]_Design_realization_towards_the_qualification_test_of_ITER_cold_circulator_v4.pdf

2:00 PM → 4:00 PM C1PoG - Thermal Analysis and Design

Conveners: Jose Rodriguez (JPL), Michael DiPirro (NASA/Goddard Space Flight Center)

2:00 PM Neon Helium Mixtures as a Refrigerant for the FCC Beam Screen Cooling: Comparison of Cycle Design Options

In the course of the studies for the next generation particle accelerators, in this case the FCC-hh, different aspects are being investigated. One of these is the heat load on the beam tube, which results mainly from the synchrotron radiation. In case of the FCC-hh, a heat load of 500 kW is expected. The heat has to be absorbed at 40 to 60 K due to vacuum restrictions. In this range, refrigeration is possible with both helium and neon. Our investigations are focused on a mixed refrigerant of these two components, which combines the advantages of both. Especially promising is the possible substitution of the oil flooded screw compressors by more efficient turbo compressors. This paper investigates different flow schemes and mixtures compositions with respect to complexity and efficiency. Furthermore, thermodynamic aspects, e.g. whether to use cold or warm secondary cycle compressors are discussed.

Speaker: Steffen Kloeppel (TU Dresden)

Poster C1PoG-01_Neon_Helium_mixtures.pdf

2:00 PM Preliminary design of the beam screen cooling for the Future Circular Collider of hadron beams

Following recommendations of the recent update of the European strategy in particle physics, CERN has undertaken an international study of possible future circular colliders beyond the LHC. This study considers an option for a very high energy (100 TeV) hadron-hadron collider located in a quasi-circular underground tunnel having a circumference of 80 to 100 km. The synchrotron radiation emitted by the high-energy hadron beam increases of more than two orders of magnitude compared to the LHC. To reduce the entropic load on the superconducting magnets’ refrigeration system, beam screens are indispensable to extract the heat load at a higher temperature level. After illustrating the decisive constraints of the beam screen’s refrigeration design, this paper presents a preliminary designing of the length of a continuous cooling loop comparing helium and neon, for different cooling channel geometries with emphasis on the cooling length limitations and the exergetic efficiency.

Speaker: Mr Laurent Jean Tavian (CERN)

Poster C1PoG-02_Poster.pdf

2:00 PM Proposed Thermodynamic Nomenclature of Cryogenic Refrigeration Cycles for Liquefaction of Natural Gas

A new and systematic naming method is proposed as academic nomenclature of cryogenic refrigeration cycles for liquefaction of natural gas. Over decades, a large number of LNG processes have been designed and patented, even though only a few are operational in practice, including SMR (single mixed-refrigerant), C3-MR (propane-precooled mixed-refrigerant), cascade, or AP-X processes. These processes have been named and widely called by the refrigerants used in the cycles, by a technical term, or even by a proper noun (or a “product” name). In order to identify and reasonably compare the thermodynamic nature, it is necessary to name the closed refrigeration cycles more logically from an academic point of view. The nomenclature is composed of three components: (1) the refrigerant (methane, nitrogen, mixed-refrigerant, etc.) (2) the number of stages (1, 2, 3, etc.), and (3) the cycle type (JT, Brayton, Claude, etc.) In addition, the series or parallel combination of two or more cycles is denoted by symbols (+, //, etc.). Abbreviation (with “factorization” formula) is also presented for short and convenient notation. *This research is supported by a grant from the LNG Plant R&D Center funded by the Ministry of Land, Infrastructure and Transport (MOLIT) of Korean government.*

Speaker: Ms Hye Su Lim (Hong Ik University)

Slides Poster_(Gas).pdf

2:00 PM Pumping speed studies of activated carbons at 4.2 K adhered to indigenously developed hydroformed cryopanels

For the fabrication of a cryopump with large pumping speeds for use in tokamaks, in particular, for gases such as helium and hydrogen, different activated carbon sorbents (with surface areas ~ 2000 m2/g) in the form of granules, spheres and cloths have been developed. These sorbents are adhesively bonded on a small size hydroformed (in-house developed technology) cryopanel of size ~500mm x 100 mm, and this constituted a Small Scale Cryopump Facility (SSCF). The pumping speeds of this SSCF for various gases have been measured as per AVS standards which comprises of a dome mounted with pressure gauges, calibrated leak valve and gas analyser. The SSCF cryopanel was shielded by LN2 cooled radiation shields and chevron baffles to minimize the heat in leak. The measured average pumping speeds for SSCF with the surface area of ~1000 cm2 for He and H2 at the constant panel temperature of 4.5 K, in the pressure range of 10-7 to 10-4 mbar, are ~ 2500 l/s and 2700 l/s respectively. The Pump performances for SSCF were also studied by using the test particle Monte Carlo simulation in Molflow+. The pumping speeds for different gases were analysed by varying the sticking coefficient and compared with the experimental results to find the sticking coefficients for helium and hydrogen. This paper describes the characterization and performances of different activated carbons, details of the SSCF experimental setup and the experimental results, the Monte Carlo simulation results and their comparison towards realizing the large scale cryopump.

Speaker: Ms Ranjana Gangradey (Institute for Plasma Research, India)

Poster CEC-ICMC-2015_Ranjana_SSCF_final.pdf

2:00 PM Status of ITER thermal shield development

Thermal shield (TS) will be installed in the ITER Tokamak to protect the superconducting magnet from thermal radiation from cryostat and vacuum vessel. The TS is cooled by 80 K helium supplied from cryoplant. The emissivity of TS surface must be maintained below 0.05 by bath-type silver electroplating. The TS is to be fully procured by Korea and it will be assembled in the ITER Tokamak by ITER organization. This paper describes the overall status of the ITER TS procurement: the manufacturing design and the current manufacturing status of vacuum vessel thermal shield (VVTS). Some mock-ups were fabricated and tested to validate the TS design and manufacturing: in-pit joint assembly, 3D shape bending method of long cooling tube, specimen tests for silver coating and cooling tube welding. Prior to the manufacturing of the TS, full-scale prototype of VVTS 10 degree section was developed in order to assess the overall manufacturing procedure of the TS except silver coating. After the completion of manufacturing design, R&D and prototype fabrication, the VVTS manufacturing started in October 2014. The current status of VVTS manufacturing is summarized in this paper.

Speaker: Kwanwoo Nam

Poster Status_of_ITER_thermal_shield_development.pdf

2:00 PM Thermal Design and Performance results of the first High Beta Cryomodule for HIE-ISOLDE at CERN

The High Energy and Intensity HIE-ISOLDE is a facility under construction at CERN whose target is ultimately to produce radioactive ion beams at 10MeV/u maximum energy in order to significantly expand the nuclear physics programme carried out by REX-ISOLDE. In its final stage the new upgrade will be composed of two low-β and four high-β superconducting cryomodules. The first high-β cryomodule, currently being assembled at CERN, presents an optimum vacuum and cryogenics environment aimed at offering the highest beam quality output to the scientific community for a first physics run starting from 2015. Since thermal control is essential to the performance of the whole cryomodule, a combination of a passive (materials, coatings, and surface finishes) and active (cryogenic loops, heaters) control has been implemented to keep the cryostat operating within the allowable thermal budget. Moreover in order to preserve the cavities from the risk of surface contamination, a thermal insulating system without multilayer insulation has been adopted with consequent effect on the global strategy of heat loads optimization. A numerical model based on Finite Elements has been developed in order to generate a faithful global mapping of temperatures and heat fluxes inside the cryomodule. This simulation tool has as primary aim to reproduce as precisely as possible the most significant heat exchange phenomena, but it also represents a validation and diagnostic tool for interpreting the experimental data obtained from numerous temperature sensors located inside the cryostat. The numerical model, combined with the experimental results of the first test campaign, will serve as an optimization tool for the future cryomodules in terms of improvements in the global and specific heat loads management.

Speaker: Luca Valdarno (CERN)

Poster 20150625_CEC2015_poster_LV.pdf

2:00 PM → 4:00 PM C1PoH - Aerospace Cryocoolers Analysis and Experimentation

Conveners: Brian Schaefer (Raytheon Company), Eric Roth (Lockheed Martin Space Systems Company)

2:00 PM Air Force Research Laboratory Spacecraft Cryocooler Endurance Evaluation Final Report

The Air Force Research Laboratory (AFRL) Spacecraft Component Thermal Research Group has been devoted to evaluating lifetime performance of space cryocooler technology for over twenty years. Long-life data is essential for confirming design lifetimes for space cryocoolers. Continuous operation in a simulated space environment is the only accepted method to test for degradation. AFRL has provided raw data and detailed evaluations to cryocooler developers for advancing the technology, correcting discovered deficiencies, and improving cryocooler designs. At AFRL, units of varying design and refrigeration cycles were instrumented in state-of-the-art experiment stands to provide space-like conditions and were equipped with software data acquisition to track critical cryocooler operating parameters. This data allowed an assessment of the technology's ability to meet the desired lifetime and documented any long-term changes in performance. This paper will outline a final report of the various flight cryocoolers tested in our laboratory. The data summarized includes seven cryocoolers with a combined total of 433,326 hours (49.5 years) of operation.

Speaker: Ms Jordan Armstrong (Glacier Technical Solutions, Air Force Research Laboratory)

Poster CECICMC_Poster_Armstrong_final.pdf

2:00 PM Effect of DC flow on a three-stage Stirling pulse tube cryocooler working at liquid helium temperatures

Multi-stage Stirling pulse tube cryocoolers (SPTC) have great potentials in liquid helium temperatures applications with advantages of high reliability, low vibration, and convenience of stage coupling for lacking cold moving parts. Studies have shown that performance of GM type pulse tubes working at liquid helium temperatures can be improved by introducing DC flow, which decreases regenerator loss at liquid helium temperatures and increases cooling capacity. However, few study of DC flow in multi-stage Stirling pulse tube has been reported. In this study, we report the calculation results on a numerical model built on a home-made three-stage SPTC working at 4.2K, and its hot end of the third-stage pulse tube and third-stage regenerator are connected by a capillary tube to introduce DC flow. The results indicated that a suitable DC flow can significantly improve the performance of the pulse tube cryocoolers. Several capillary tubes with different diameters and lengths were tested. Temperature distributions along the pulse tube were measured and DC flow was monitored in our experiments. Also parameters of the capillary tube were optimized for different operation conditions and the performance of STPC was improved.

Speaker: Chen Huang (Zhejiang University)

Poster poster-Chen_Huang-273.pdf

2:00 PM Properties of two stage Adiabatic Demagnetization Refrigerator

In recent years, many space missions using cryogenic temperatures are being planed. In particular, a high resolution sensor like Transition Edge Sensor needs very low temperatures below 100 mK. It is well known that Adiabatic Demagnetization Refrigerator (ADR) is one of most useful methods to produce ultra-low temperatures in space because of independence on the gravity. We have studied a continuous ADR system consisting of 4 stages and it demonstrated to provide continuous temperatures around 100 mK. But there were some amounts of heat leaks from power leads which resulted to reduce the cooling power. In this study, several efforts to upgrade our ADR system will be presented. First, we will show the effect of using the HTS power leads. Then, a cascaded Carnot cycle consisting of 2 ADR units will be discussed.

Speaker: Mr Hidehito Fukuda (Environment and Energy Materials Division, National Institute for Materials Science)

Paper C1PoH-06.pdf

Poster CEC2015_poster_.pdf

2:00 PM Theoretical and experimental investigations on impedance of pulse tube cold fingers to match with linear compressors

The impedance match between the cold finger and the linear compressor of the Stirling-type pulse tube cryocooler (SPTC) is significant to optimize the compressor efficiency and to improve the cold finger cooling performance. Several researches ever studied the impedance match and concluded that there existed the optimal acoustic impedance of the cold finger to acquire the highest compressor efficiency. However, few researches have been done to design the cold finger with the optimal impedance. In this paper, an electrical circuit analogy model has been developed according to continuity equation and momentum equation. The model is used to design the specific dimensions of the cold finger. And furthermore, through the calculation of the pressure and the volume flow rate with the model, the impedance of each component of the cold finger such as regenerator, pulse tube, heat exchanger, phase shifter and reservoir can be achieved, respectively. The total impedance is the sum of every component. For a series of linear compressors developed in the authors’ laboratory, their respective mechanical parameters such as linear motor force factor, piston damp, coil resistance etc. have been tested and then the optimal acoustic impedances to match each compressor have been acquired. According to the model, specific cold fingers with optimal acoustic impedances have been worked out. Experimental investigations on acoustic impedance of these cold fingers have been made through measurements of pressure and mass flow rate at several positions of the cold finger, to compare with the theoretical values in the model. The actual performance of a series of SPTCs based on the theoretical and experimental investigations have been measured, the motor efficiencies of the compressors reach 74.2%–83.6% and the relative Carnot efficiency of the cold fingers achieve 3.0%@40 K, 9.6%@60 K, 16.2%@80 K, etc.

Speaker: Mr Jun Tan (Shanghai Institute of Technical Physics)

Poster Theoretical_and_experimental_investigations_on_impedance_of_pulse_tube_cold_fingers_to_match_with_linear_compressors.pdf

2:00 PM → 4:00 PM C1PoJ - Novel Concepts and New Devices I

Conveners: Dr Jason Hartwig (NASA / GRC), Philip Spoor (Chart Industries)

2:00 PM Development of membrane cryostats for large liquid argon neutrino detectors

A new collaboration is being formed to develop a multi-kton long baseline neutrino experiment that will be located at the Surf Underground Research Facility (SURF) in Lead, SD. In the present design, the detector will be located inside a cryostat filled with 40 kton of ultra pure liquid argon (less than 200 parts per trillion of oxygen equivalent contamination). To qualify membrane technology for future very large-scale and underground implementations, a strong prototyping effort is ongoing: several smaller detectors of growing size with associated cryostats and cryogenic systems will be designed and built at Fermilab and CERN. They will take physics data and test detector elements in different configurations, filtration systems for liquid argon, design options, tank configurations and installation procedures. A 35 ton prototype is already operational at Fermilab and will take data with single-phase detector in the spring. A similar size prototype with dual-phase detector is being constructed at CERN and will be operational next year. In the coming years a 260 ton prototype with single-phase detector will be constructed and exposed to a neutrino beam at Fermilab. The refurbished ICARUS T600 (760 ton) will be on the same beam line at 600 m. In parallel two larger cryostats will be constructed at CERN and exposed to beams of particles, 500 ton with single-phase, 800 ton with dual-phase detectors. After the prototyping phase, the multi-kton detector will be constructed. After commissioning, it will detect and study neutrinos from a new beam from Fermilab. These cryostats will be engineered, constructed, commissioned, qualified by an international engineering team. This contribution will present the ongoing effort on development of the cryostats, and detail requirements, current status of design and construction and how we plan to go from 35 ton to multi-kton device.

Speaker: David Montanari (Fermi National Accelerator Laboratory)

Poster Montanari-C1PoJ-01.pdf

2:00 PM Expansion Vessel for Supercritical Hydrogen in a Spallation Neutron Source Moderator Circuit

High-energy neutrons are being decelerated by passing through supercritical parahydrogen circulated by pumps in a closed loop. Fluctuations in neutron heat load cause changes of the circuits’ local and average temperature and hence significant pressure variations if it is not taken care of the nearly incompressible behavior of hydrogen. Solutions by adding a variable volume in form of a helium gas-backed metal bellow to mitigate pressure deviations are already in use. This paper presents an alternative approach by introducing a vertical storage vessel for supercritical hydrogen in a side arm of the moderator loop, with cold incompressible high density hydrogen at the bottom and warmer compressible lower density hydrogen at the top. The engineering challenge is to keep the temperature profile in the vessel stable under all operating conditions.

Speaker: Marcel Klaus (Technische Universitaet Dresden)

Poster CEC_2015_Klaus_Poster_expansion_vessel.pdf

2:00 PM Hydrogen refrigeration via kinetic para-ortho manipulation in a vortex tube

Hydrogen has two separable nuclear-spin isomers, denoted by ortho and para, with potentially significant differences in thermophysical properties. The entropy change with ortho-para conversion is the largest of any material phase change known to occur at cryogenic temperatures. A prior experimental study demonstrated that the endothermic reaction of para-ortho conversion can be utilized to increase the effective cooling capacity of liquid parahydrogen boil-off vapors below 100 K. This work expands the concept of endothermic para-ortho conversion to primary refrigeration below 77 K via kinetic manipulation in a vortex tube. Vortex tubes are non-moving devices that utilize a kinetic energy differential to partition a fluid into hot and cold streams. The vortex tube could use a hydrogen stream pre-cooled in a liquid nitrogen bath and catalyzed to the 50-50 equilibrium composition at 77 K. By catalyzing the hot fluid on the outer wall of the vortex, endothermic para-ortho conversion will cause bulk cooling after which the orthohydrogen is separated and recycled to the liquid nitrogen bath. The statistical partition function is utilized to establish performance limits of the concept. Initial experimental results in bare and catalyzed vortex tubes are presented. Based on the theoretical analysis and initial experiments, the potential for para-ortho conversion as a new approach to hydrogen refrigeration is assessed.

Speaker: Elijah Shoemake (Washington State University)

Poster VortexTubeCEC.pdf

2:00 PM Modeling Thermal Parasitic Load Lines for an Optical Refrigerator

Optical refrigeration is currently the only completely solid state cooling method capable of reaching cryogenic temperatures from room temperature. Optical cooling utilizing Yb:YLF as the refrigerant crystal has resulted in temperatures lower than 123K measured via a fluorescence thermometry technique. However, to be useful as a refrigerator this cooling crystal must be attached to a sensor or other payload. The phenomenology behind laser cooling, known as anti-Stokes fluorescence, has a relatively low efficiency which makes the system level optimization and limitation of parasitic losses imperative. We propose and model a variety of potential designs for a final optical refrigerator, enclosure and thermal link; calculate conductive and radiative losses, and estimate direct fluorescence reabsorption. We generate parasitic load-lines; these curves define temperature-dependent minimum heat lift thresholds that must be achieved to generate useful cooling.

Speakers: Mr Christopher Dodson (Air Force research labs), Mr Thomas Fraser (air force research labs)

Poster CEC_2015_poster_KM.pdf CEC_2015_poster_KM.pptx

2:00 PM Theoretical research of helium pulsating heat pipe under steady state

As a new-type heat pipe, pulsating heat pipe (PHP) has several outstanding features, such as great heat transport ability, strong adjustability, small in size and simple construction. PHP is a complex two-phase flow system associated with many physics subjects and parameters, which utilizes the pressure and temperature change in volume expansion and contraction during phase changes to excite the pulsation motion of liquid plugs and vapor bubbles in capillary tube between the evaporator and condenser. At the present time, some experimental investigation of helium PHP have been done. We developed a mechanical-thermal switch working as a novel pre-cooling system for the helium PHP, and the measured effective thermal conductivity of helium PHP was 16760 W/m∙K with a heating power of 49.2 mW. However, theoretical research of helium PHP is rare. In this paper, the physical and mathematical models of operating mechanism for helium PHP under steady state are established based on the conservation of mass, momentum, and energy. Several important parameters are correlated and solved, including the filling ratio, advanced and receded contact angles of the liquid helium, flow velocity, and temperature etc. Based on the results, the operational driving force and flow resistances of helium PHP are analyzed, and the flow and heat transfer are further studied.

Speaker: Dr Huiming Liu (Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences)

Poster C1PoJ-05

2:00 PM → 4:00 PM C1PoK - Superconducting Magnets I

Conveners: Thomas Nicol (Fermilab), Dr Vadim Kashikhin (Fermilab)

2:00 PM Design of a REBCO HTS Superconducting Undulator

Undulators are very important insertion devices for storage ring and free electron laser based light sources to produce high-brilliance hard X-ray photon beams. NbTi based superconductive undulators (SCUs) have been recently developed and shown to reach higher on-axis peak fields compared to the field values achieved with conventional undulators. However, cooling NbTi coils to 4.2 K requires complicated and expensive cryogenic equipment. High temperature superconductors (HTSs) have larger temperature stability margin; therefore, they can be operated at higher temperatures than NbTi greatly simplifying the cryogenic design. The engineering current densities of REBCO HTS wires have been also enhanced drastically during the past years. Because of these reasons, HTS undulators have recently become very attractive. Here, we discuss a design for a second-generation (2G) HTS undulator and address some of the problems related to resistive joints and winding schemes of the coils. In addition, the achievable on-axis peak field at 4.2 K has been calculated and shown to surpass that reached in NbTi-undulators.

Speaker: Dr Ibrahim Kesgin (Argonne National Laboratory)

Poster Poster_CEC_ICMC_IK.pdf

2:00 PM Development of tools for advanced quench diagnostics at LBNL Magnet Test Facility

Testing of high-field superconducting accelerator magnets aims at identifying potential causes of quenching, localizing quench origins and measuring quench propagation velocity along the coil winding. This information is essential for establishing protection limits and providing useful feedback to the magnet designers. Traditionally, quench studies are conducted using voltage taps. However, for the long or complex magnets this approach becomes impractical due to large number of taps required to track quench propagation and difficulty of incorporating them without jeopardizing magnet integrity. At LBNL, we develop and implement alternative methods of quench diagnostics based on time-correlated multi-point sensing of magnetic and mechanical disturbances. We have built a novel inductive quench antenna comprising a pc-board array of dipole-bucked coils interfaced to a cryogenic 16:1 multiplexed amplifier, capable of input scanning at rates up to 1 MHz. Spatial resolution of the antenna for quench localization is approx. 1 cm, and multiple pc-board arrays can be stacked together to cover full length of the magnet. A six-channel cryogenic acoustic detection system is implemented and operated simultaneously with the quench antenna. Such combined acquisition setup allows for a high-accuracy quench localization. In addition, it enables separation of mechanical and electromagnetic events, spatial mapping of mechanically-unstable areas in the magnet, and estimation of an instantly released mechanical energy during magnet ramping. Quench diagnostics examples derived from recent testing of high-field block-type Nb3Sn dipole HD3b and Canted Cosine Theta NbTi dipole will be shown. A future upgrade path for the MTF diagnostic capabilities will be presented.

Speaker: Maxim Marchevsky (Lawrence Berkeley National Laboratory)

Slides poster_MM.pdf

2:00 PM High resolution NMR measurements by using a 400 MHz (9.39 T) LTS/REBCO NMR magnet with a best mix use of various field correction methods ~ Towards a super-high field/compact type of NMR magnet ~

We have started a project to develop a high field compact NMR magnet using high-temperature superconducting (HTS) inner coils. As a first step towards such a magnet, a LTS/REBCO NMR magnet was developed and operated at 400 MHz (9.39 T) in a previous work [1]. However, a homogeneous magnetic field required for high-resolution NMR measurements could not be obtained using conventional field correction methods, due to an effect of a screening current induced in the inner REBCO coil. The REBCO coil had large field error harmonics; performance of a superconducting shim (SC) coils were remarkably reduced due to the diamagnetic effect of the REBCO coil, resulting in a residual field error harmonics. In the present work, we operated the magnet with the best mix of field correction methods including a newly installed inner-SC shim coil and ferromagnetic shims in combination with conventional SC shim coils and room temperature (RT) shim coils. Major field error harmonics, which could not be corrected in the previous experiment, were successfully corrected; then higher-order field error harmonics generated by the ferromagnetic shims as a side effect, and lower-order harmonics due to a magnetization of the NMR probe and a sample were fully corrected using the RT shim coils. Eventually, a high-resolution 2D-NOESY NMR measurement for a protein solution sample, which is inevitable for structural biology, was successfully achieved. The field correction method achieved here is promising for a super-high field compact NMR magnet with HTS coils operated beyond 1 GHz (23.5 T). [1]Y. Yanagisawa et. al., Journal of Magnetic Resonance, 249, 38-48 (2014).

Speaker: Mr Renzhong Piao (Graduate School of Engineering, Chiba University)

Poster 2015_CEC__poster_piao_final.pdf 2015_CEC__poster_piao_final.pptx

2:00 PM Infulence of neutron irradiation on conduction cooling superconducting magnets

The conduction cooling superconducting magnets are now widely used in various application because of their minimum usage of helium. In the accelerator science field, they are also widely used for particle detector solenoids because they can minimize the materials needed for the magnet such that they can be more transparent against irradiated particles. For the same reason they are now used at irradiation environments because they can reduce the heat load due to the irradiation. However, the hadronic irradiation, such as neutron irradiation, can degrade thermal conductivity of pure aluminum that are used as thermal conductor. This leads to a pure cooling condition of the magnets. At J-PARC, there are two conduction cooling superconducting magnets; one is already built and under operation, the other is now under construction. The paper reports the influence of the neutron irradiation on those magnets, and discuss the possibilities of HTS based conduction cooling magnets under high irradiation environments.

Speaker: Toru Ogitsu

Poster C1PoK-4-Poster2-MY1.pdf

2:00 PM Magnetic and Structural Design of a 15 T Nb3Sn Accelerator Dipole Model

Hadron Colliders (HC) are the most powerful discovery tools in modern high energy physics. A 100 TeV scale HC with a nominal operation field of at least 15 T is being considered for the post-LHC era. The choice of a 15 T nominal field requires using the Nb3Sn technology. Practical demonstration of this field level in an accelerator-quality magnet and substantial reduction of the magnet costs are the key conditions for realization of such a machine. FNAL has started the development of a 15 T Nb3Sn dipole demonstrator for a 100 TeV scale HC. The magnet design is based on 4-layer shell type coils, graded between the inner and outer layers to maximize the performance. The experience gained during the 11-T dipole R&D campaign is applied to different aspects of the magnet design. This paper describes the magnetic and structural designs and parameters of the 15 T Nb3Sn dipole and the steps towards the demonstration model. *Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.*

Speaker: Vadim Kashikhin (Fermilab)

Poster C1PoK-5_poster.pdf

2:00 PM Mechanical problems for a Ni-alloy reinforced Bi-2223/Ag conductor -Towards a super-high field compact magnet-

Recently, tensile stress tolerance of a Bi-2223 conductor has been drastically improved. Conventional Bi-2223 conductors with copper-alloy reinforcements or stainless steel reinforcements show tensile stress tolerance of ~250 MPa. The stress tolerance has been improved to 400-500 MPa with Ni-alloy reinforcements in combination with a pre-compression of Bi-2223 filaments/Ag-matrix [1]. This type of high mechanical strength Bi-2223 conductors are promising for developments of super high field magnets as they tolerate high hoop stress, resulting from high current density and a high magnetic field beyond 23.5 T. However, it is probable that this type of composite conductor is easily damaged by a release of strain energy inside the conductor; note that the Bi-2223/Ag conductor has a compressive strain, while the reinforcement tensile strain. In fact, a notable fracture of a conductor after a thermal runaway was observed [2]. From the standpoint of coil protection, mechanism and a method to prevent this phenomenon are important. In this work, these are systematically investigated with a model experiment. A piece of a high-mechanical strength Bi-2223 conductor was heated on a hot plate. Temperature and strain along the conductor longitudinal direction on a surface of the conductor were measured with a thermocouple and a strain gauge, respectively. The strain gauge showed a drastic change in strain at a temperature of ~200 °C. After the experiment, the Bi-2223/Ag conductor shows a curve among the delaminated Ni-alloy reinforcements; i.e. the Bi-2223/Ag conductor was buckled. The result shows that strain energy was released by a melting of a solder which bonds the conductor and the reinforcements, resulting in a collapse of the composite conductor. The method to prevent the phenomenon will be investigated.

Speaker: Mr Masato Nawa (Graduate School of Engineering, Chiba University)

Poster CEC_ICMC_poster_yy.pdf

2:00 PM Transport testing of MgB2 and Nb3Sn solenoid coils for magnet applications

Advancements in superconducting wire manufacturing has enabled the design and fabrication of superconducting coils for practical magnet applications. To apply superconducting wire for most commercial applications requiring many kilometers of wire, long-length characterization in coil form is important. This study discussed the transport properties of two different solenoid coil wound with long length of MgB2 and Nb3Sn strands by Hyper Tech. The MgB2 coil was wound on a solenoidal 101 OFE copper former with 18” ID using the react-and-wind method. The stainless steel former with 30” ID was used for Nb3Sn coil. The strands were insulated with single S-glass braid insulation for both coils. The total lengths of conductor used for MgB2 and Nb3Sn coils were ~330 m and ~1.5 km, respectively. Transport Ic measurements were performed at various taps along the coil lengths. Measurements were made at various temperatures by conduction cooling. Homogeneity of response along the coils was investigated and a comparison to the short sample results was made. Temperature gradient of coil was also monitored for transition region between current leads and coil.

Speaker: Hyun Sung Kim (The Ohio State University)

Poster ICMC2015_C1PoK-08_[C32]__KIM.pdf

2:00 PM → 4:00 PM C1PoL - Thermal Insulation

Conveners: David Plachta (NASA / GSFC), Kathleen Amm (GE Global Research)

2:00 PM Cylindrical Boiloff Calorimeters for Testing of Thermal Insulation Systems

Several cryostat instruments for the testing of thermal insulation systems in a cylindrical configuration have been developed and standardized for laboratory operation. The measurement principal is boiloff calorimetry for the determination of the effective thermal conductivity (ke) and heat flux (q) of a test specimen at a fixed environmental condition (boundary temperatures, cold vacuum pressure, and residual gas composition). Liquid nitrogen is the energy meter through heat of vaporization properties, but the design is adaptable for different cryogens. The main instrument, Cryostat-100, in guarded on top and bottom and provides directly measured absolute thermal performance data. A cold mass assembly, including the upper and lower guard chambers and a middle test vessel, is suspended from a lid of the vacuum canister. Each of the three chambers is filled and vented through a single feedthrough for minimum overall heat leak and simplified operation. The cold mass design provides thermal isolation by precluding direct solid conduction heat transfer from one liquid volume to another. Such isolation is critical for the very low heat measurement capability to be achieved as small variations in liquid temperatures between chambers can easily lead to dramatic errors in the results. All fluid and instrumentation feedthroughs are mounted and suspended from a top-domed lid to allow easy removal of the cold mass. A lift mechanism allows manipulation of the cold mass assembly and insulation test specimen. The cryostat system design details and laboratory standard test methods are discussed. Results for select thermal insulation materials including multilayer insulation, powders, foams, and aerogel blankets are presented. Additional cylindrical boiloff calorimeters including the comparative apparatus, Cryostat-200, and progress toward a liquid hydrogen apparatus are also discussed.

Speaker: James Fesmire (NASA)

Poster 2015_CEC_Tucson_C100_Cylindrical_15jun2015.pdf

2:00 PM Design and performance of a 3D printed liquid hydrogen tank with vapor cooled shielding for use in unmanned aerial vehicles

Liquid hydrogen storage systems utilize various insulation methods that have direct bearing on the mass and overall volume of the tank which can be inversely related. When utilizing liquid hydrogen as a fuel source for fuel cells, the vaporized fuel must be warmed to minimize ice build-up on fuel lines and to ensure compatible temperatures with fuel cell membranes. Advances in 3D printing technologies have enabled the incorporation of the traditionally external heat exchanger into the tank structure itself, thereby reducing mass and volume while providing vapor cooling for the stored liquid hydrogen. Integrating the heat exchanger creates a complex structure that conventional manufacturing methods (e.g. machining, injection molding) are not well suited for. We use selective laser sintering (SLS) of a low density engineering polymer to create the tank liner which is then overwrapped with carbon fiber (Type IV configuration) to carry the pressure loads. Estimated final mass of the tank system is 2.8 kg resulting in a gravimetric capacity of hydrogen to tank material mass of 13.3% and 55% volumetric efficiency, while energy density of the tank is 4.5 GJ/m^3 and specific energy is 15 MJ/kg. Thermodynamic modeling of the tank system indicates a mass flow rate of 1.05E-05 kg/s at steady state operating conditions. Initial comparisons between tank performance and modeling estimates are made. The resulting tank has improved performance for utilization in small portable power applications not previously amenable to cryogenic hydrogen.

Speaker: Mr Patrick Adam (Washington State University)

Slides CEC2015.pdf

2:00 PM Flat Plate Boiloff Calorimeters for Testing of Thermal Insulation Systems

Several cryostat instruments for the testing of thermal insulation systems in a flat plate configuration have been developed and standardized for laboratory operation. The measurement principal is boiloff calorimetry for the determination of the effective thermal conductivity (ke) and heat flux (q) of a test specimen under a wide range of real-world conditions. The main instrument, Cryostat-500, is thermally guarded to provide absolute thermal performance data when properly calibrated with a known reference material. An adjustable edge guard ring enables calibration. Using liquid nitrogen as the energy meter, the cold boundary temperature can be adjusted to any temperature between 77 K and approximately 300 K by interposing a thermal resistance layer between the cold mass and the specimen being tested. The cold mass assembly, comprised of the heat measurement vessel and thermal guard vessel, is suspended from the vacuum chamber lid. A low thermal conductivity suspension system includes adjustable compliance rod assemblies for a given test specimen thickness and for amount of compression force. Different materials and varied test objectives require an appropriate combination of apparatus and method. Material type, thickness, density, flatness, compliance, outgassing, and temperature sensor placement are important considerations. Edge effects and calibration techniques for the flat plate apparatus are crucial in design and test operation. Over the full vacuum pressure range, the thermal performance capability is shown to be nearly four orders of magnitude. Compared to vertical cylindrical cryostats, the horizontal flat plate configuration provides key advantages for testing at ambient pressure conditions. The Cryostat-500 design details and laboratory standard test methods are discussed. Results for select thermal insulation materials including composites, foams, and aerogels are presented. Additional flat plate boiloff calorimeters including comparative instruments Cryostat-400 and Macroflash (Cup Cryostat) are also addressed.

Speaker: James Fesmire (NASA)

Poster 2015_CEC_Tucson_C500_Flat_Plate_15jun2015.pdf

2:00 PM Multi-Layer Aerogel Insulation for Cryogenic Applications

Aspen Aerogels, Inc. validated the key process step for a next generation aerogel manufacturing technology to enable the fabrication of thin, low density aerogel materials. When the thin aerogel is stacked with reflector layers to form an aerogel based insulation system, called Multi-Layer Aerogel Insulation (MLAI), it provides thermal performance advantages compared to incumbent insulation systems. Thermal performance testing was performed on various aerogel-based systems at cryogenic temperatures across a vacuum range from 10-5 to 760 torr by the Cryogenics Test Laboratory at NASA Kennedy Space Center to select the optimized aerogel insulation system for prototype development and testing. System-level cryogenic testing at Ball Aerospace & Technologies will also be presented. Like other aerogel systems, this breakthrough thermal insulation is also found to be much more durable and consistent than traditional multi-layer insulation, keeping costs down by minimizing/eliminating rework.

Speaker: Dr Shannon White (Aspen Aerogels, Inc.)

2:00 PM New measurements of multilayer insulation at variable cold temperature and elevated residual gas pressures

New MLI measurements at the TU Dresden flow type calorimeter have been carried out. Specimens of 10 and 20 layer double side aluminized polyester film were tested. A cylindrical cold surface of 0.9 m²is held at the desired cold boundary temperature between approximately 30 K and 300 K. The heat transfer through the MLI is measured by recording the mass flow as well as the inlet and the outlet temperature of the cooling fluid. Measurements at varied cold boundary temperatures have been performed. Moreover the effect of an additional vacuum degradation – as it might occur by decreasing getter material performance in real systems at elevated temperatures – is studied by a controlled inlet of nitrogen gas. Thus the vacuum pressure was varied over a range of 10-7 mbar to 10-2 mbar. Different cold boundary temperatures between 35 K and 110 K were investigated. Test results of the bare test cylinder as well as 10 and 20 layer MLI are presented.

Speaker: Thomas Funke (Technische Universitaet Dresden)

Poster CEC_2015_Funke_C1PoL-06.pdf

2:00 PM → 4:00 PM M1PoB - Cryogenic Materials II: Properties and Treatments

Conveners: Karl Hartwig (Texas A&M University), Robert Walsh (Florida State University)

2:00 PM Fabrication of Biomedical Titanium Alloys with High Strength and Low Modulus by Spark Plasma Sintering

Ti–24Nb–4Zr–8Sn, abbreviated as Ti2448 from its chemical composition in weight percent, is a multifunctional β type titanium alloy with body centered cubic (bcc) crystal structure, and its highly localized plastic deformation behavior contributes significantly to grain refinement during conventional cold processing. In the paper, In order to explore an effective method to fabricate biomedical Ti alloy with high strength and low modulus, Ti2448 alloy powders were synthesized via mechanical alloying，and，subsequently，ultrafine-grained Ti alloy with high strength and low modulus were fabricated via the spark plasma sintering. The effects of sintering temperature on the microstructure of the synthesized Ti2448 were investigated using scanning electron microscope (SEM) and transmission electron microscope (TEM). Also the effects of ball milling and SPS conditions on the mechanical property in the low temperature of the Ti2448 alloy have been discussed. Such Ti alloys with noteworthy mechanical properties in low temperature region promote their potential applications for cryogenic and biomedical equipments.

Speaker: Mr Wei Wang (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences)

Poster poster-CEC-2015wangwei.pdf

2:00 PM Qualification of Electron-Beam Welded Joints between Copper and Stainless Steel for Cryogenic Application

Joints between copper and stainless steel are commonly applied in cryogenic systems. A relatively new and increasingly important method to combine these materials is electron-beam (EB) welding. Typically, welds in cryogenic applications need to withstand a temperature range from 300 K down to 4 K and pressures of several MPa. However, very little data is available for classifying EB welds between OFH copper and 316L stainless steel. Therefore, a broad test program has been conducted in order to qualify this kind of weld. The experiments started with destructive tensile tests at room temperature, at liquid nitrogen and at liquid helium temperatures, yielding information on the yield strength and the tensile strength of the welds at these temperatures. The tests were followed by nondestructive tensile tests up to yield strength, i.e. the range in which the weld can be stressed during the operation. To verify the leak-tightness of the joints, integral leak tests at operating pressures of 5 MPa were carried out before and after each tensile test, each at room¬- and at liquid nitrogen temperature. Finally, the hardness of the EB weld was measured in the weld area. The results of the qualification indicate that EB welded joints between OFH copper and 316L stainless steel are reliable and present an interesting alternative to other technologies such as brazing or friction welding.

Speaker: Dr Klaus-Peter Weiss (KIT, Institute for Technical Physics)

Poster.pdf

2:00 PM → 4:00 PM M1PoC - Cryogenic Electronics

Conveners: Charles Rong (U.S. Army Research Laboratory), Eric Hellstrom (Florida)

2:00 PM Computational Investigation of Superconducting Magnetic Energy Storage (SMES) Devices to Maximize Energy Density

Superconducting magnetic energy storage (SMES) devices offer attractive and unique features including no theoretical limit to specific power, high cycling efficiencies and charge/discharge rates, and virtually no degradation with cycling. The mass specific energy density (MSED) of SMES systems; however, falls short of many needs. This paper examines SMES energy densities of solenoid-type magnets for YBCO, MgB2 and Nb3Sn using present-manufactured wires and future advancements predicted from lab-scale samples. Scaling of maximum energy density with the stored energy, length of the conductor and radius of the bore were established with numerical simulations, and studied for a range of stored energies from 0.1 MJ to 250 MJ and operating temperatures of 4.2, 18, 40 and 65 K. With dependence of critical current on field taken into account, the optimum magnet design for varying superconducting wires also including H//c is a pancake coil with scaling of energy density ε ~ E1/3. Thus, current and magnetics limits achievable ε only at a fixed E. The overall limit on ε is also imposed by the virial theorem. Without additional structural support ε of SMES magnets is limited to ~ 30Wh/kg. However with introduction of light-weight and strong support materials the upper limit MSED of SMES is expected to exceed that of the best batteries ε ~ 150 Wh/kg.

Speaker: Timothy Haugan (U.S. Air Force Research Laboratory)

3:00 PM → 3:30 PM Afternoon Break

4:00 PM → 5:00 PM C1OrE - Refrigeration and Liquefaction - sponsored by TechSource, Inc.

Conveners: Jay Theilacker (Fermilab), Philipp Arnold (European Spallation Source ESS AB)

4:00 PM [Invited] ESS Cryogenic System Process Design

The European Spallation Source (ESS) is a neutron-scattering facility funded and supported in collaboration with 17 European countries in Lund, Sweden. Cryogenic cooling at ESS is vital particularly for the linear accelerator, the hydrogen target moderators, a test stand for cryomodules and the neutron instrument sample environments. The paper will focus on specific process design criteria, design decisions and their motivations for the cryoplants and auxiliary equipment. Key issues for all plants and their process concept are energy efficiency, reliability, smooth turn-down behavior and flexibility. The accelerator cryoplant (ACCP) and the target moderator cryoplant (TMCP) in particular, need to be prepared for a range of refrigeration capacities due to the intrinsic uncertainties regarding heat load definitions. Furthermore questions regarding process arrangement, 2K cooling methodology, LN2 pre-cooling, helium storage, helium purification and heat recovery will be addressed.

Speaker: Philipp Arnold (European Spallation Source ESS AB)

Slides C1OrE-01-for_Upload.pdf ESS Cryogenic System Process Design

4:30 PM ESS accelerator plant process design

The European Spallation Source (ESS) is a neutron-scattering facility being built with extensive international collaboration at Lund, Sweden. The ESS accelerator will deliver protons with 5 MW of power to the target at 2.0 GeV, with a nominal current of 62.5 mA. The superconducting part of the accelerator is about 300 meters long and contains 43 cryomodules. The ESS accelerator cryoplant (ACCP) will provide the cooling for the cryomodules and the cryogenic distribution system that delivers the helium to the cryomodules. The cryoplant will cover three cryogenic circuits: Bath cooling for the cavities at 2 K, the thermal shields at around 40-50 K and the power couplers thermalisation with 4.5 K liquid helium. The open call-for tender for the ACCP had taken place in 2014 with Linde Kryotechnik AG being selected as the cryoplant vendor. This paper summarizes the progress in the ACCP development and engineering. Current status including basic process design, system configuration, machine concept and layout, main parameters and features, solution for the acceptance tests and further optimization is presented.

Speaker: xilong wang (European Spallation Source ESS AB)

Slides WANG_-_C1OrE.pdf WANG_-_C1OrE.pptx

4:45 PM ITER: Test protocol to demonstrate the Cryogenic Helium plant performances

The ITER Tokamak requires an average 75kW of refrigeration power to maintain the nominal operation condition of the ITER superconducting magnets and cryopumps. This is produced by three identical liquid helium (LHe) Plants. Air Liquide Advanced technologies, as the supplier of the entire ITER liquid Helium plant, should demonstrate through various running conditions, that the expected functionnalities and performances will be achieved. In particular, a high power test cryostat will simulate the 75 kW isothermal loads in a liquid Helium bath. This proceeding will present the tests phases as well as the main functionalities and equipments implemented to allow the cryogenic Helium plant acceptance by ITER.

Speaker: Mr Yannick FABRE (AIR LIQUIDE Advanced Technologies)

Slides C10rE-04-Fabre.pdf C10rE-04-Fabre.pptx

4:00 PM → 6:00 PM C1OrF - Thermal Insulation Applications and Measurements

Conveners: Sergey Koshelev (Fermilab), Shannon White (Aspen Aerogels, Inc.)

4:00 PM Performance of Cryogenic Thermal Insulation Materials under Liquid Hydrogen Environment

Many researchers have studied performance of cryogenic thermal insulation materials with various cryogenic liquids. However, there are not many cases under liquid hydrogen environment. KIST has been operating a 1 L/hr scale hydrogen liquefaction and storage facility since 2013. The KIST liquid hydrogen system can liquefy hydrogen gas to liquid, store and transfer to a dedicated storage tank. In this study, KIST has built a cryogenic insulation material testing apparatus according to the ASTM C1774, and conducted insulation performance tests for selected materials at liquid hydrogen environment. A series of experiments were carried out under various cold vacuum pressures ranging from high vacuum to ambient pressure, and the results are compared for several cryogenic insulation materials such as aerogel and perlite powders under liquid hydrogen environment.

Speakers: Mr Kyeong Ho Kim (Korea Institute of Science and Technology), Dr Sarng Woo Karng (Korea Institute of Science and Technology), Ms Soojin Shin (Korea Institute of Science and Technology)

4:15 PM Influence of tailored MLI for complex surface geometries on heat transfer

Complex, non-developable surfaces require a tailored multi-layer insulation (MLI) for lowest heat loads. The most experiments showing the heat transfer through MLI are performed under quasi-ideal conditions determining the principle insulation quality. But the surface to be insulated in real cryostats implies feed-throughs and other non-developable surface parts. The thermal performance of MLI is degraded significantly at cutting points. To investigate this degrading effect a LN2– filled cylinder with a diameter of 219 mm and a length of 1820 mm was insulated with MLI and the heat load was measured calorimetrically. In addition the heat load to an insulated cylinder with eighteen branches was measured. Both the cylinders have the same surface of 1.37 m2 for a comparison of the results. This article describes the experiments with different ways of tailoring the MLI for the cylinder with branches and discusses their results. It was shown that the cutting points at the branches have a significant degrading influence on the thermal performance of MLI.

Speaker: Thomas Richter (Karlsruhe Institute of Technology (KIT))

Slides 2015_07_Presentation_Neumann_Mayrhofer_Richter.pdf

4:30 PM ADVANCED AND ENERGY SAVING THERMAL INSULATIONS FOR CRYOGENIC APPLICATIONS

The power consumption in large scale superconducting devices is due to the refrigeration system and the cryogenic devices used in special applications often require an extremely long cryogen holding time. All cryogenic devices and superconducting instruments, regardless of size, small, large or huge, are all working at cryogenic temperature. To economically maintain the device at its operating temperature and minimize the refrigeration losses, high performance thermal isolation is essential. This includes the thermal insulation system as well as minimizing heat leaks from penetrations and supports. The current advanced developments of various cryogenic thermal insulation technologies are briefly and systematically introduced, discussed and reviewed in the paper as follows: 1. Highly thermal efficient and energy saving cryogenic transfer lines for LH2 and LHe. 2. Advanced designs to reduce the heat transfer through sophisticated support structures in large accelerator magnets, SRF cavities, detectors and electric power leads. 3. The traditional evacuated powers insulation and newly developed aerogels insulation for large scale cryogenic tanks and special applications. 4. The performance, materials and design combinations of various super-insulations (MLI) for commercial products and research labs. 5. The specific design and implements of MLI with various penetrations, slots and cracks in its MLI for large cryogenic applications. 6. The development of novel thermal isolation devices, such as the energy efficient cryogenic transfer line with magnetic suspension; a smart cryogenic actuator as the warm support structure automatically operated by temperature changes; superconducting thermal switch for interception of heat transfer, etc. are also briefly reviewed.

Speaker: Dr QuanSheng Shu (Retired Senior Scientist)

Slides CEC-2015-Shu_jef.pdf

4:45 PM Demonstration of Hybrid Multilayer Insulation for Fixed Thickness Applications

Once on orbit, high performing insulation systems for cryogenic systems need just as good radiation (optical) properties as conduction properties. This requires the use of radiation shields with low conductivity spacers in between. By varying the height and cross-sectional area of the spacers between the radiation shields, the relative radiation and conduction heat transfers can be manipulated. However, in most systems, there is a fixed thickness or volume allocated to the insulation. In order to understand how various combinations of different multilayer insulation (MLI) systems work together and further validate thermal models of such a hybrid MLI set up, test data is needed. The MLI systems include combinations of Load Bearing MLI (LB-MLI) and traditional MLI. To further simulate the space launch vehicle case wherein both ambient pressure and vacuum environments are addressed, different cold-side thermal insulation substrates were included for select tests. The basic hybrid construction consists of some number of layers of LB-MLI on the cold side of the insulation system followed by layers of traditional MLI on the warm side of the system. The advantages of LB-MLI on the cold side of the insulation blanket are that its low layer density (0.5 – 0.6 layer/mm) is better suited for lower temperature applications and is a structural component to support heat interception shields that may be placed within the blanket. The advantage of traditional MLI systems on the warm side is that radiation is more dominant than conduction at warmer temperatures, so that a higher layer density is desired (2 - 3 layer/mm) and less effort need be put into minimizing conduction heat transfer. Liquid nitrogen boil-off test data for a cylindrical calorimeter are presented along with analysis for spacecraft tank applications.

Speaker: Wesley Johnson

Slides C1OrF-04-Johnson.pdf C1OrF-04-Johnson.pptx

5:00 PM OPERATIONAL HISTORY OF LIQUID HYDROGEN TANK WITH GLASS BUBBLES INSULATION

Culminating years of extensive research and development, field demonstrations have proven glass bubbles to be a superior insulation material for spherical liquid hydrogen storage tanks. Six years of operational history has been accumulated on a spherical 218,000-liter liquid hydrogen (LH2) storage tank with glass bubbles insulation in the evacuated annulus. Over this period of time the tank has been subjected to two complete LH2 fillings and thermal cycles. Each load of LH2 took approximately two years to boil away, representing an approximate 100% performance improvement over the original perlite powder insulation. No special maintenance was necessary and the tank sustained normal vacuum levels. Infrared imagery showed the outer surface temperatures to be uniform. The full-scale field application of glass bubbles insulation builds upon years of laboratory testing (compatibility, vacuum, vibration, structural, thermal performance) and custom 1000-liter tank testing with both liquid nitrogen and LH2. To extend application of the technology to tanks of non-spherical geometry, analysis of a targeted application of glass bubbles insulation to a horizontal 830,000-liter LH2 storage tank is presented. Also discussed is a survey of other vacuum-jacketed cryogenic tanks operating around the world with glass bubbles insulation.

Speaker: Jared Sass (NASA Kennedy Space Center)

Slides 2015_CEC_Tucson_Stennis_LH2_Tank_Bubbles.pdf

5:15 PM Comparison tests of cellular glass insulation for the development of cryogenic insulation standards

Standards for thermal insulation used in applications between ambient and low temperatures, below 100 K, require test data under relevant conditions and by different laboratories to develop data sets for the proper comparisons of materials. This critically important technology is needed to provide reliable data and methodologies for industrial energy efficiency and energy conservation. Under ASTM International’s Committee C16 on Thermal Insulation, two standards have been issued that including C1774 Standard Guide for Thermal Performance Testing of Cryogenic Insulation Systems and C740 Standard for Multilayer Insulation in Cryogenic Service. Thermal conductivity data sets have been taken using identical flat-plate boiloff calorimeter instruments independently operated at the Cryogenics Test Laboratory of NASA Kennedy Space Center (KSC) and the Thermal Energy Laboratory of LeTourneau University (LETU). Precision specimens of cellular glass insulation were produced for both laboratories to provide the necessary comparisons to validate the thermal measurements and test methodologies. Additional specimens of commercial cellular glass pipe insulation were tested at LETU to compare with the flat plate results. The test data are discussed in relation to the experimental approach, test methods, and manner of reporting the thermal performance data. This initial Inter-Laboratory Study (ILS) of insulation materials for sub-ambient temperature applications provides a foundation for further ILS work to produce standard data sets for several key commercial materials.

Speaker: Jonathan Demko (LeTourneau University)

Slides CEC-2015-C1OrF06-Demko-Pres.pdf

5:30 PM Quantifying MLI Thermal Conduction in Cryogenic Applications from Experimental Data

Multilayer Insulation (MLI) uses stacks of low-emittance metalized sheets combined with low-conduction spacer features to greatly reduce the heat transfer to cryogenic applications from higher temperature surrounds. However, as the hot-side temperature decreases from room temperature to cryogenic temperatures, the level of radiant heat transfer drops as the forth power of the temperature, while the heat transfer by conduction only falls off linearly. This results in cryogenic MLI being dominated by conduction, a quantity that is extremely sensitive to MLI blanket construction and very poorly quantified in the literature. To develop useful quantitative data on cryogenic blanket conduction, multilayer nonlinear heat transfer models were used to analyze extensive heat transfer data measured by Lockheed Palo Alto on their cryogenic dewar MLI and measured by JPL on their spacecraft MLI. The data-fitting aspect of the modeling allows the radiative and conductive thermal properties of the tested blankets to be explicitly quantified. Results are presented showing that MLI conductance varies by a factor of 1000 between spacecraft MLI and Lockheed's best cryogenic MLI. It is clear from the three-order-of-magnitude range of values that MLI conductance is a high-uncertainty parameter in MLI performance. The analysis also demonstrates that conductance governs the thermal performance of both high-temperature spacecraft MLI as well as low-temperature cryogenic MLI. For both of these temperature extremes, MLI emittance is found to play a secondary role to spacer conductance in establishing MLI thermal effectiveness. Thus, MLI performance is critically dependent on the achieved MLI conductance.

Speaker: Dr Ronald Ross (Jet Propulsion Laboratory)

Slides Ross_CEC-VGs_ID=108.pdf

5:45 PM Thermal Performance Testing of Cryogenic Multilayer Insulation with Silk Net Spacers

Early comprehensive testing of cryogenic multilayer insulation (MLI) focused on the use of silk netting as a spacer material. Silk netting was used for multiple test campaigns designed to provide baseline thermal performance estimates for cryogenic insulation systems. As more focus was put on larger systems, the cost of silk netting became a deterrent and most aerospace insulation firms began using Dacron (or polyester) netting spacer material by the early 1970s. In the midst of the switch from silk netting there was no attempt to understand the difference between silk and polyester netting, though it was widely believed that the silk netting provided slightly better performance. Without any better reference for thermal performance data, the silk netting performance correlations continued to be used. In order to quantify the difference between the silk netting and polyester netting, a brief test program was developed. Silk netting was obtained from the remnants of legacy flight programs and was tested on the Cryostat-100 boil-off calorimeter in three different configurations. The data shows good agreement with the historical silk netting based correlations and indicates a performance improvement when compared to previous testing performed using polyester netting and aluminum foil/microfiberglass paper MLI systems. Additionally, the data further reinforce a recently observed trend that the heat flux is not directly proportional to the number of layers installed on an MLI system.

Speaker: Wesley Johnson

Slides C1OrF-08-Johnson.pdf C1OrF-08-Johnson.pptx

4:00 PM → 5:15 PM C1OrG - Superconducting RF Systems I

Conveners: Arkadiy Klebaner (Fermilab), Matthew Howell (UT Battelle/ORNL)

4:00 PM A new 2 K superconducting half-wave cavity cryomodule for PIP-II

Argonne National Laboratory has developed and is implementing a novel 2 K superconducting cavity cryomodule operating at 162.5 MHz and designed for the acceleration of H-/proton beams from 2.1 to 10 MeV as part of the Fermilab Proton Improvement Project-II (PIP-II). The cryomodule supports operation of up to 2 mA average beam current and bunch population of up to 3.8x108 ppb. This work is an evolution of techniques recently implemented in two previous heavy-ion accelerator cryomodules now operating at Argonne National Laboratory [1, 2]. The 2 K cryomodule is based upon low-velocity superconducting half-wave cavity technology comprised of 8 half-wave cavities operated in the continuous wave mode with 8 superconducting magnets located in front of each cavity. All of the solenoids and cavities operate off of a single gravity fed 2 K helium cryogenic system expected to provide up to 50 W of 2 K cooling. Here we review the mechanical design of the cavities and cryomodule which were developed using methods similar to those required in the ASME Boiler and Pressure Vessel Code, overview the cryomodule layout and select subsystem design, and provide a status report on the cryomodule fabrication. Some of the subsystems to be discussed include the support and precision alignment of the cavity-solenoid assembly to within +/-0.5 mm at 2 K, the 5 and 70 K cooling of thermal intercepts and heat exchangers, and the 5 to 2 K cryogenic liquefaction system.

Speaker: Zachary Conway (Argonne National Laboratory)

Slides C1OrG-01_Conway.pdf

4:15 PM First results from the Cornell high Q cw full linac cryo-module

Cornell University has finished building a 10 m long superconducting accelerator module as a prototype of the main linac of a proposed ERL facility. This module houses 6 superconducting cavities- operated at 1.8 K in continuous wave (CW) mode - with individual HOM absorbers and one magnet/ BPM section. In pushing the limits, a high quality factor of the cavities (2•10^10) and high beam currents (100 mA accelerated plus 100 mA decelerated) were targeted. We will review the design shortly and present the results of the components tested before the assembly. The main focus of the paper will be on preparation of the first cool-down, being scheduled by the time of the conference.

Speaker: Ralf Eichhorn (Cornell University)

Slides CEC2015-C1OrG-03.pdf CEC2015-C1OrG-03.pptx

4:30 PM Commissioning and Operation of the Horizontal Test Apparatus at SNS

The Spallation Neutron Source (SNS) at Oak Ridge National Lab (ORNL) has built and commissioned an independent Cryogenic Test Facility (CTF) in part to support 4.5 K operation of a Horizontal Test Apparatus (HTA) vessel in the Radiofrequency Test Facility (RFTF) test cave. The HTA provides the functionality for testing a single dressed SNS medium or high beta Superconducting Radiofrequency (SCRF) cavity. The vessel’s capability to provide for in-situ plasma processing of the cavity’s inner niobium surface will be discussed. The design and commissioning of the HTA at 4.5 K will be presented as well as results from operating the HTA including cool-down, warm-up and steady state operations. Result from plasma processing a warm SCRF cavity in-between cold HTA tests will also be addressed.

Speaker: Brian DeGraff (ORNL)

Slides C1OrG-04-Degraff.pdf C1OrG-04-Degraff.pptx

4:45 PM Computational and experimental investigation of hydroformed niobium tubes for superconducting RF cavities

Superconducting radio frequency (SRF) cavities are a well-established technology for imparting energy to the charged particles. Hydroforming technique has been researched to achieve higher accelerating fields and drastic reductions in resonator production time and costs. This study discussed the characterization of hydroformed niobium tubes to support for the subsequent hydroforming of Nb tube into seamless cavities. The niobium tubes were heat treated and characterized by tensile strength, residual resistance ratio (RRR), and grain size. The optimally heat treated Nb tubes were subjected to hydraulic bulge testing. Finally, finite-element models (FEM) incorporating constitutive relationships analytically derived from the tensile and bulge tests, respectively, were constructed to replicate the bulge test. In addition, crystal plasticity model incorporating microstructure was investigated.

Speaker: Hyun Sung Kim (The Ohio State University)

Slides ICMC2015_C10rG-05_KIM.pdf

5:00 PM Stainless Steel to Titanium Bimetallic Transitions

In order to use stainless steel piping in an LCLS-II cryomodule, stainless steel to titanium bimetallic transitions are needed to connect the stainless steel piping to the titanium cavity helium vessel. Explosion bonded stainless steel to titanium transition pieces and bimetallic transition material samples have been tested. A sample transition tube was subjected to tests and x-ray examinations between tests. Samples of the bonded joint material were impact and tensile tested at room temperature as well as liquid helium temperature. The joint has been used successfully in horizontal tests of LCLS-II cavity helium vessels and is planned to be used in LCLS-II cryomodules. Results of material sample and transition tube tests will be presented. *Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy*

Speaker: Joshua Kaluzny (Fermilab)

Slides CEC_ICMC_2015_Kaluzny_presentation_C1Org-06.pdf

4:00 PM → 5:15 PM C1OrH - Aerospace Cryocoolers

Conveners: Ronald Ross (Jet Propulsion Laboratory), Sidney Yuan (The Aerospace Corporation)

4:00 PM Raytheon Advanced Miniature Cryocooler Characterization Testing

The Raytheon Advanced Miniature (RAM-100) cryocooler is a flight packaged, high frequency pulse tube cooler with an integrated surge volume and inertance tube. Its design has been fully optimized to make use of the Raytheon Advanced Regenerator, resulting in improved efficiency relative to previous Raytheon pulse tube coolers. In this paper, thermodynamic characterization data for the RAM-100 cryocooler is presented along with details of its design specifications.

Speaker: Ted Conrad (Raytheon)

4:15 PM In-Flight Performance of the OCO-2 Cryocooler

The Orbiting Carbon Observatory-2 (OCO-2) will have completed its first year in space on July 2, 2015. The OCO-2 instrument incorporates three bore-sighted, high-resolution grating spectrometers, designed to measure the near-infrared absorption of reflected sunlight by carbon dioxide and molecular oxygen. OCO-2 currently flies in a sun-synchronous, near-polar orbit at an inclination of 98.1 degrees, mean altitude of 705 kilometers, 99 minute orbit period and 1:30 pm ascending node. The OCO-2 spacecraft forms part of a constellation of six Earth observing satellites known as the “A-Train” and leads this procession ahead of the JAXA GCOM-W1 spacecraft. The cryocooler system design is coupled with the instrument’s thermal control design to maximize the instrument’s performance. A single-stage NGAS pulse tube cryocooler provides refrigeration to three focal plane arrays to 120 K via a high conductance flexible thermal strap. A variable conductance heat pipe (VCHP) based heat rejection system (HRS) transports waste heat from the instrument located inside the spacecraft to the space-viewing radiators. The HRS provides tight temperature control of the spectrometer to 267 K and maintains the cryocooler at 300 K. Soon after entering the A-Train on August 3, 2014, the spectrometer and focal planes were cooled to their operating temperatures. Evidence of ice accumulation on the cryogenic surfaces was deduced from increased cryocooler loads and drove a need for two focal plane decontamination cycles on August 31, 2014 and October 23, 2014. This paper provides a general overview of the cryogenic system design and reviews the in-flight cryogenic performance over the Observatory’s first year.

Speaker: Arthur Na-Nakornpanom (Jet Propulsion Laboratory)

Slides OCO-2_CEC_06182015.pdf

4:45 PM MatISSE Microcryocooler

Lockheed Martin Space Systems Company has built and delivered an engineering model microcryocooler to the Jet Propulsion Laboratory for use with instruments for deep space and earth science missions. Funding for this cryocooler was through JPL’s Maturation of Instruments for Solar System Exploration (MatISSE). This cooler is nearly identical to the compact coaxial microcryocooler presented at the 2014 International Cryocooler Conference. The cryocooler mass is just 320 grams for the entire thermal mechanical unit, and is compact enough to be packaged in a CubeSat. This paper describes the measured performance of the MatISSE cryocooler, including the performance at the very cold heat rejection temperatures expected for JPL deep space missions.

Speaker: Jeff Olson (Lockheed Martin Space Systems Company)

4:00 PM → 6:00 PM M1OrC - Superconductor Stability and AC Losses

Conveners: Francesco Grilli (Karlsruhe Institute of Technology), Prof. Naoyuki Amemiya (Kyoto University)

4:00 PM [Invited] Effectiveness of laser striation for AC loss reduction in SuperOx coated conductor.

The physical properties of REBCO (RE=rare earth) high temperature superconductors require a flat tape architecture enabling them to carry high current densities. This architecture has an enormous ratio between the width and the thickness of the tape, typically ranging between 1,000 and 10,000. This very large aspect ratio has a detrimental effect on the AC losses, specifically the losses caused by the presence of an AC magnetic field perpendicular to the tape’s flat face. Since the magnitude of the magnetization loss is proportional to the square of the tape’s width, one obvious way to reduce it is by dividing the tape into narrow striations. This can be done either during the tape’s manufacture process or successively on the end product. Different techniques have been successfully applied on tapes with just a thin Ag layer on top of the superconducting film. Unfortunately, most CC applications require tapes with Cu stabilization and an effective method to reliably achieve striation on Cu-stabilized tapes needs to be optimized. For this purpose, we used pico-second laser to produce samples with different numbers of filaments from 12 mm-wide tape manufactured by SuperOx. In order to produce Cu-stabilized samples with filaments, two different approaches were followed: 1) striation of Ag-stabilized coated conductor followed by electroplating; 2) striation of already Cu-stabilized coated conductor with different copper thicknesses. In this work the results of the different approaches will be shown and compared by means of microscopic analysis as well as of DC current and AC loss characterization. These results are expected to provide useful insight on the efficiency of this technique to produce application-ready low-loss coated conductors.

Speaker: Dr Anna Kario (Karlsruhe Institute of Technology, Institute for Technical Physics)

Slides AnnaKario_ICMC_28062015.pptx

4:30 PM Electromagnetic behavior of striated coated conductors wound into pancake coils

Large magnetization of coated conductors is one of the most serious concerns of their applications to MRI or NMR magnets, because it deteriorate the uniformity and stability of the magnetic fields. As the counter measure against large magnetization, the striation of coated conductors was proposed, and its effect was demonstrated in small coils. Even if filaments (narrow conductor strips in a striated coated conductor) are insulated electrically, filaments are connected one another electrically at both ends of the coated conductors. Therefore, a current can circulate through both ends, and its decay time constant should be large. Of course, MRI or NMR magnets are not operated at 50 / 60 Hz, and, if the decay time constant of the circulating current is small enough as compared to the time scale of the operation of a magnet, the striation might be effective. We study the electromagnetic behavior of striated coated conductors wound into pancake coils through numerical electromagnetic field analyses. The length of conductors, resistances between filaments at the ends, the magnetic field to which a conductor is exposed in a coil, the ramping up rate of the current and the magnetic field, etc. are varied to look at their influence on the decay time constant of the circulating current, in other words, the current imbalance between filaments. We also vary the resistance between filaments (not insulated completely). Based on the numerical results, the effect of striation is discussed. *This work is supported in part by the Ministry of Economy, Trade and Industry (METI) as Development of Fundamental Technologies for HTS Coils Project.*

Speaker: Prof. Naoyuki Amemiya (Kyoto University)

4:45 PM Calorimetric Measurements of AC losses in HTS coils and tapes in a Stator Environment

Long HTS tapes have been fabricated in a variety of formats for the purpose of reducing the sensitivity to AC magnetic fields, from both conducted AC and external fields. Some of the conductors have been made more resistant to AC losses by HTS film composition and many others have been based on geometric arrangements of the conductors, such as different filament patterns in striated tapes, and helical twist shapes that do not exceed the minimum bend radius of the HTS films. Characterization by applying variable frequency AC and variable frequency strong magnetic fields, both synchronous and asynchronous, to samples of these conductors provides insight into their utility without the time and expense of building a complete motor or generator. The measurements are taken using a modified previously reported calorimeter system that measures the total power losses in smaller high temperature superconducting coils or wire. The calorimeter measures self-field losses with the sample mounted in the stator environment of a generator/motor where a 0.6 Tesla alternating magnetic field is produced by an eight pole rotor designed to provide frequencies up to 400 Hz. The systems allow samples to carry direct or alternating current with the ability to concurrently expose them to a variable frequency alternating magnetic field. For this paper we will discuss differences in results from combination of synchronous and asynchronous losses on several conductor geometries.

Speakers: John Murphy (University of dayton Research Institute), Dr Timothy Haugan (USAF)

Slides CECICMC_John_P_Murphy_UDRI_AFRL_Sumption_b.pdf CECICMC_John_P_Murphy_UDRI_AFRL_Sumption_b.pptx

5:00 PM Pulsed field stability and AC loss of Nb3Sn CICCs by quantitative modeling and experiments

The performance during an operating plasma scenario of Nb3Sn Cable-in-Conduit Conductors (CICCs) designs envisaged for the ITER Central Solenoid has been analyzed with the code JackPot-ACDC. At present there is no experimental facility available to test the stability of the conductors under relevant pulsed plasma operating conditions. Only limited experimental data is existing that is suitable for quantitative analysis but the time and magnetic field amplitude scales are different from the actual ITER operating conditions. Nevertheless, such tests are particularly useful for benchmarking of the code. To better assess the stability margins for the ITER magnets, the computed local electric field on the strands at most severe conditions during the plasma scenario is compared with the one obtained from the single harmonic pulse test performed in the SULTAN facility and DC transport current tests determining the current sharing temperature. The results of the stability test with the single harmonic magnetic field pulse is scaled to the ITER plasma operating conditions by using the numerical model. The first results are presented and discussed.

Speaker: Arend Nijhuis (University of Twente)

Slides Stability_CICC_Nb3Sn_ICMC_Jun2015_ANijhuis_Final.pdf

5:15 PM Calorimetrically Measured Interstrand Contact Resistances and Coupling Magnetizations in Cored QXF-Type Nb3Sn Rutherford Cables for the LHC Quadrupole Upgrade

When exposed to a ramping magnetic field the Rutherford cable is the seat of coupling magnetization produced by interstrand coupling currents passing through the interstrand contact resistances (ICR) -- the strand crossover resistances, Rc, and the side-by-side (adjacent-strand) resistances, Ra. The coupling magnetization, is greatest when the applied field is normal to the cable’s surface in which case it is proportional to 1/Rc + 20/N^3Ra, which defines an effective reciprocal ICR, 1/Reff, For an uncored cable Reff is essentially Rperpc while the introduction of a fully insulating core raises it to (N^3/20)Ra. The transport-current ramping of LHC quadrupole magnets has been shown to produce field errors of about 2 units of b1 and less than 0.2 units of cn, consistent with Rcs of on-average 125 μΩ. Evidently such ICRs have contributed to the successful operation of the LHC quadrupoles to date and hence could be recommended as target values for the QXF cable after the appropriate values of N and the other the cable-design parameters, w/t (width/thickness), Lp (semi-transposition pitch), have been included. Since the Rc of a typical uncored Nb3Sn cable is 0.25 μΩ a core needs to be included to raise its Reff into the multi-100 μΩ range. In preparation for investigating the effect of core-insertion on Reff a series of five QXF-type Rutherford cables have been wound with cores of widths ranging from 11.9 to 15.9 mm, representing core coverages, W, of from 72 to 97%. Interstrand contact resistances, Reff, were extracted from the results of low-frequency calorimetric AC-loss measurements, presented in the format Reff versus W%, and compared with predictions derived from the fortran program CUDI©.

Speaker: Prof. Ted Collings (MSE, OSU)

Slides M1-OrC-5-III-Sumption-final.pdf M1-OrC-5-III-Sumption-final.pptx

5:30 PM Magnetization losses in MgB2 wire matrix material

Magnesium diboride conductors are considered for use on fully superconducting wind turbine generators and, as a results, being able to quantify the AC losses in MgB2 wound stators is paramount. AC losses were measured on several MgB2 conductors based on NiCu matrix material. The measurements were done calorimetrically at about 15 K and at applied magnetic fields up to 100 mT and frequencies up to 400 Hz. The AC losses measured are consistent with magnetization losses in magnetic materials and not with classic AC losses (magnetization, coupling and eddy). As previously reported in literature, the matrix material composed of NiCu alloys, while non-magnetic at room temperature, might present magnetic properties at cryogenic temperature. This paper deals with the characterization of the matrix material of several MgB2 conductors from different manufacturers through the measurement of the susceptibility with respect to temperature and the measurement of the major hysteresis loop showing the saturation field and the maximum energy dissipated per cycle. The results are then used to correlate the AC losses measurements.

Speaker: Philippe Masson (University of Houston)

5:45 PM Modelling AC ripples in HTS coated conductors

DC transmission using high temperature superconducting (HTS) coated conductors offers a promising solution to the globally growing demand for effective, reliable and economic transmission of green energy up to GW level over very long distances. The credible estimation of the losses and thereby the heat dissipation involved is highly essential for the rational design of practical HTS DC transmission cables and corresponding cryogenic systems to fulfill this demand. In this respect, the evaluation of the dissipation caused by AC ripples (introduced in rectification / AC-DC conversion) is needed. Here we report a targeted modelling study into the AC losses in a HTS coated conductor subject to DC currents and AC ripples simultaneously, by solving Maxwell’s equations using the finite element method (FEM) in the commercial software package COMSOL. It is observed that the instantaneous loss exhibits only one peak per cycle in a HTS coated conductor subject to sinusoidal ripples and DC currents that are within our targeted conditions. This is a distinct contrast to the usual observation of two peaks per cycle in a HTS coated conductor subject to AC currents only. The unique mechanisms behind are also discussed. Finally, the magnitude of the AC ripple losses and their importance in the design of HTS DC transmission cables are estimated.

Speaker: Francesco Grilli (Karlsruhe Institute of Technology)

4:00 PM → 6:00 PM M1OrD - Superconductor Materials I: Bulk and New Materials

Conveners: David Cardwell (University of Cambridge), Yanwei Ma (Institute of Electrical Engineering, Chinese Academy of Sciences)

4:00 PM [Invited] The Processing of Bulk, Melt Processed (RE)BCO Superconductors with World Record Fields

(RE)-Ba-Cu-O [(RE)BCO, where RE = rare earth element such as Y, Nd, Sm, Eu, Gd, etc.] high temperature superconductors (HTS) have significant potential for high field engineering applications at 77 K when fabricated in the form of large single grains by the so-called top seeded melt growth process (TSMG). A novel Y2Ba4CuMOy (Y-2411, where M = U, Zr, Hf, Nb, Ta, W and Mo) phase that is effective at pinning magnetic flux quanta in bulk (RE)BCO HTS on the nm scale has been developed at Cambridge with a number of desirable properties, including crystallographic compatibility with the superconducting (RE)Ba2Cu3O7 (RE-123) phase, chemical stability at the melt processing temperature and an ability to resist coarsening during the melt process. This novel phase, which is more effective at pinning flux than the RE2BaCuO5 (RE-211) phase produced as a by-product of the melt growth process, has been used to develop a practical processing method for the fabrication in air of large, single grain RE-Ba-Cu-O superconductors. The process also includes a new type of generic seed crystal (Mg-doped NdBCO) that can promote effectively the epitaxial nucleation of any (RE)-Ba-Cu-O system and secondly by suppressing the formation of (RE)/Ba solid solution in a controlled manner within large (RE)BCO grains processed in air. This process has enabled fabrication of single grain samples of GdBCO that exhibit a record trapped field of 17.6 T at 26 K. The recent development of multi-seeding and recycling techniques for the fabrication of larger sample of conformal geometry has improved further the prospects of these technologically important materials for practical applications.

Speaker: David Cardwell (University of Cambridge)

4:30 PM [Invited] Giant Field Leap in Bulk HTS – A Systematic Failure of the Critical State Model

Pulsed activation studies previously done on zero-field-cooled high Jc YBCO bulks have exhibited giant field leaps (GFL), among other anomalies.[1] Additional experiments, with varying Jc, have now been performed, searching for regularities to illuminate the underlying physics. Thirty single-grain melt-textured YBCO samples with varying Jc (6,700 ≤ Jc ≤ 60,000 A/cm2 at 77 K) were prepared. These had dominant pinning centers (PCs) of either broken-columnar or point geometry. GFL was observed for all samples with Jc ≥ 15,000 A/cm2. Results showed that PC geometry does not modify GFL magnitude or systematics, at least to first order. The threshold of the field leap, measured 2 minutes after the pulse, was found to decrease monotonically with increasing Jc. The magnitude of the field leap was found to increase monotonically from zero at Jc ≈ 15,000 A/cm2 to ~3 Tesla at highest Jc. The Bean model rule that the ratio of applied field, BA, required to activate maximum trapped field, BT,max, is BA/BT,max ≥ 2. We find this rule holds only for Jc < 10,000 A/cm2. BA/BT,max decreases sharply at about the same value of Jc which initiates GFL, and has a value of ~1.2 at the highest value of Jc. It is difficult to reconcile results with the critical state model (CSM). We suggest that two dominant GFL modifications are needed. Creep, at short times is a “cascade” not a “creep,” and the very large Lorentz force, FL ∝ Jc × B, enhances the fluxoid cascade. These effects combine to cause large internal flux transfers whereas the CSM assumes no internal flux transfer. [1] R. Weinstein, Drew Parks, Ravi-Persad Sawh, Kent Davey, Keith Carpenter, “Observation of a Bean Model Limit – A Large Decrease in Required Applied Activation Field for TFMs,” IEEE Trans. Appl. Supercond., 25, Article 6601106, 2015.

Speaker: Roy Weinstein (University of Houston)

Slides ICMC_2015_Invited_Oral_Weinstein.pdf

5:00 PM Influence of ZnO and Dy2O3 on MgB2 Bulks Fabricated by High Temperature and Pressure Reaction

Recently, ZnO and Dy2O3 have been considered as dopants for the improvement of superconducting properties in MgB2 bulks. However, the effect of these dopants is still unclear: some studies reported these metal oxides worked as new pinning centers and others was attributed the effects to Mg site substitution. In addition, low temperature reactions may explore limited solubility regimes for these dopants. In order to study the intrinsic effect of ZnO and Dy2O3 in MgB2, a high temperature sintering method has been used to fabricate dense and homogeneous MgB2 bulks. To do this we used an induction furnace built inside of a high pressure vessel which allowed us to reach 1700oC and 1500 Psi. A slow cooling rate (2oC/min) was used in an attempt to obtain a homogeneous nucleation and phase distribution. A series of MgB2 bulk samples with ZnO and Dy2O3 additives were synthesized through this high pressure and temperature procedures. The resulting microstructures of these bulk samples were revealed by SEM and TEM. Atomic substitution were evaluated by high resolution XRD. The upper critical field Bc2, irreversible field Birr and Tc were obtained from both magnetic and resistivity measurements. The roles of substitution vs precipitate induced strain on Bc2 enhancements with adding ZnO and Dy2O3 were discussed.

Speaker: Yuan Yang (OSU)

5:30 PM [Invited] Recent advances in iron-based superconducting wires and tapes

122 type pnictide superconductors are of particular interest for high-field applications because of their large upper critical fields Hc2 (> 100 T), low anisotropy γ (< 2) and the materials and processes to fabricate wires appear to be relatively inexpensive. However, the porous nature of powder-in-tube (PIT) processed iron-based tapes is one of the important reasons for low critical current density (Jc) values. Here we report our recent achievement in the developing Sr0.6K0.4Fe2As2 tapes with transport Jc up to 1.2 ×10^5 A/cm^2 at 10 T and 4.2 K. More importantly, the field dependence of Jc turns out to be very weak, such that in 14 T the Jc still remains ~ 1.0×10^5 A/cm^2. These Jc values are the highest ever reported so far for iron-pnictide wires and tapes, and have surpassed the threshold for practical application. These results clearly demonstrate that PIT pnictide wire conductors are very promising for high-field magnet applications.

Speaker: Yanwei Ma (Institute of Electrical Engineering, Chinese Academy of Sciences)

6:00 PM → 7:30 PM Exhibitor Reception (18:00 - 19:30)

Tuesday, June 30

7:55 AM → 7:55 AM Cryo Expo Open (9:00 - 17:00)

For a list of Exhibitors, please visit: http://www.cec-icmc.org/exhibition/exhibitors/.

8:00 AM → 8:15 AM CEC Awards

8:15 AM → 9:00 AM C2PL - Tuesday CEC Plenary Session - sponsored by Cryomech, Inc.

Convener: Eric Marquardt (Ball Aerospace & Technologies Corp)

8:15 AM The Role of Cryogenics in the U.S. Hydrogen Bomb Program and Vise Versa

Research on the H-bomb (called the “super” during early work) began at a low level at Los Alamos National Laboratory during the early- to mid-1940s as part of the Manhattan Project. Theorist felt the thermonuclear reaction within liquid deuterium was the simplest and best understood at that time. On January 31, 1950, President Truman gave the order to pursue the H-bomb, which resulted in an arms race with the Soviet Union at a cost of trillions of dollars. Another outcome was the construction of the world’s largest hydrogen liquefier (320 L/hr) at that time, along with the establishment of the NBS Cryogenic Engineering Laboratory (CEL) in Boulder. A duplicate liquefier on Eniwetok Atoll in the Marshall Islands of the Pacific was used to liquefy deuterium gas generated from electrolysis of heavy water at NBS CEL and shipped to Eniwetok. The first full-scale test of thermonuclear fusion used a liquid deuterium secondary enclosed inside a thick steel shell containing the fission primary. Details of the massive cryogenic program, including declassified video clips, leading up to the test of this “wet” device will be discussed. The yield of 10.4 Mt in the November 1, 1952, Ivy Mike test was about 500 times that of the WWII fission bombs. During the next year and a half, lighter versions of the “wet” device were under development, but their tests were cancelled after the success of the first “dry” bomb that used lithium deuteride. Funding from the Atomic Energy Commission for further cryogenic research pertaining to weapons quickly evaporated, but the newly acquired expertise at NBS in liquid hydrogen and cryogenics in general was put to good use in the space program, which had just begun, and in some other classified programs. The first Cryogenic Engineering Conference held at NBS/Boulder in September, 1954, was organized because of the need to quickly spread the word about the cryogenic expertise available to new programs. Some of the significant cryogenic advances that came out of the H-bomb program will be discussed.

Speaker: Dr Ray Radebaugh (National Institute of Standards and Technology)

9:00 AM → 11:00 AM C2PoA - Cryogenic Systems I

Conveners: John Weisend II (European Spallation Source ESS AB), Michael White (Fermilab)

9:00 AM Commissioning of the helium cryogenic system for the HIE-ISOLDE accelerator upgrade at CERN

The High Intensity and Energy ISOLDE project is a major upgrade of the existing ISOLDE and REX-ISOLDE facilities at CERN. The most significant improvement will come from replacing most of the existing REX accelerating structure by a superconducting linear accelerator (SC linac) composed ultimately of six cryo-modules installed in series, each containing superconducting RF cavities and solenoids operated at 4.5 K. In order to provide the cooling capacity at all temperature levels between 300 K and 4.5 K for the six cryo-modules, an existing helium refrigerator, manufactured in 1986 and previously used to cool the ALEPH magnet during LEP operation from 1989 to 2000, has been refurbished, reinstalled and recommissioned in a dedicated building located next to the HIE-ISOLDE experimental hall. This helium refrigerator has been connected to a new cryogenic distribution system, consisting of a 30-meter long vacuum insulated transfer line, a 2000-liter storage dewar and six interconnecting valve boxes, one for each cryo-module. This paper describes the whole cryogenic system and presents the commissioning results including the preliminary operation at 4.5 K of the first cryo-module in the final experimental hall.

Speaker: Nicolas Delruelle (CERN)

Poster CEC2015_Poster_26jun2015.pub

9:00 AM Construction of the Cryogenic System for IHEP-ADS Injector I

Accelerator driven sub-critical system（ADS）in China is a kind of transmutation machine to minimize the nuclear wastes. As one of the important parts in ADS, InjectorⅠwill be built in IHEP,CAS which needs two cryomodules operating at 2K cryogenic environment to realize 10MeV Proton beam energy; Each cryomodule contains seven Spoke cavities and sevensuperconducting magnets. This paper describes the design of the cryogenic system, which include flow chart analysis, key equipment, heat loads analysis, infrastructure and the progress.

Speakers: Shaopeng Li (Institute of High Energy Physics(IHEP),Chinese Academy of Science(CAS),China), zhuo zhang (IHEP,CAS,China)

Poster The_construction_and_commissioning_of_ADS_injector_I_cryogenic_system(CEC_Poster)20150623.pdf

9:00 AM FRIB Cryogenic Plant Status

After practical changes were approved to the initial conceptual design of the cryogenic system for the MSU FRIB and an agreement was made with JLab in 2012 to lead the design effort of the cryogenic plant and later the cryo-distribution system, many activities are in place leading toward a cool-down of the linacs prior to 2018. This is mostly due to using similar equipment used at CHLII for the 12 GeV upgrade at JLab and an aggressive schedule maintained by the MSU Conventional Facilities department. This paper provides an updated status of the cryogenic plant, including the equipment procurement status plant layout, facility equipment and project schedule.

Speaker: Kelly Dixon (Jefferson Lab)

Poster FRIB_Cryo_Plant_Status_4.pdf

9:00 AM Liquid Nitrogen Historical and Current Usage of the Central Helium Liquefier at SNS

The main cryogenic system for the Spallation Neutron Source (SNS) is comprised of a 4 K cold box, a 2 K cold box, six warm compressors, and ancillary support equipment. This system has been cold and operating with little disruption since 2006. Design and operation of Liquid Nitrogen (LN2) supplied from a single 20,000 gallon supply dewar will be discussed. LN2 used to precool the 4 K cold box heat exchanger started to increase around 2011. Consumption during 2012 and 2013 was almost double the nominal usage rate. Studies of this data, plant parameter changes to respond to this information, and current interpretations are detailed in this paper. The usage rate of LN2 returned to normal in late 2013 and has since remained there. Future study plans to understand potential causes of this including contamination migration within the 4 K cold box will also be addressed.

Speaker: Brian DeGraff (ORNL)

Poster C2PoA_-_LN2_-_Poster.pdf C2PoA_-_LN2_-_Poster.pptx

9:00 AM Preliminary Design of Helium Refrigeration System for RAON

A large-scale helium refrigeration system is under designing by Rare Isotope Science Project for a new superconducting Linac, RAON. Heat loads of cryogenic components including cryomodules for superconducting, LTS magnets for IF (In-flight) Separator, and helium distribution system are predicted. The coldbox will supply 4.5 K supercritical helium and 40 K gas helium to each cryomodule through the distribution system. The cavities will be cooled at sub-atmospheric temperature, 2.1 K which is generated by recuperating systems in each cryomodule. 40 K helium is also used for the cooling of HTS magnets which will be installed at the front section. This paper presents current status of the helium refrigeration system for RAON.

Speaker: Sungwoon Yoon (Institute for basic science)

9:00 AM → 11:00 AM C2PoB - Stirling and Pulse Tube Cryocoolers

Conveners: Marcel ter Brake (University of Twente), Robert Boyle (NASA / GSFC)

9:00 AM A Study on the CryoTel® DS 1.5 Cryocooler for Higher Cooling Capacity

The CryoTel® DS 1.5 is a split type Stirling cryocooler which was developed by Sunpower for systems requiring compact size, high efficiency, and high reliability. The DS 1.5 has a lift of about 1.4 watts at 77 K with 30 watts of input power. The cooler design includes gas bearings on the pistons and displacer for non-contact operation, and achieves low vibration by using dual opposed pistons inside the wave generator and a passive balancer on the cold head to offset the displacer motion. The efficiency of the DS 1.5 is ranked highly compared to other cryocoolers at 16% Carnot efficiency, but there are many customers who want more lift with the same size and reliability. Therefore, Sunpower performed a feasibility study of the DS 1.5 to maximize the lift without increasing the size. This paper describes the analysis and test results of increasing the cooler power density by using a higher operating frequency and charge pressure. Prototype testing showed good agreement with the model. Testing performed at various frequencies and charge pressures with a few internal component changes resulted in a maximum lift of 2.4 watts with an input power of 43 watts, achieving 15.9 % of Carnot. The prototype high capacity DS 1.5 achieved 0.7 watts more lift with only one percentage point lower efficiency, and with negligible cooler mass increase. The impact on the cool-down time on a thermal mass system was simulated and the cool-down time was 40% faster while consuming less input energy overall. Sunpower plans to build more units to gain a broader range of performance data and will then decide whether to proceed with a commercial product.

Speaker: Mr Yongsu Kim (Ametek Sunpower Inc)

Poster CEC_ICMC_2015_Yongsu_Kim,_Jimmy_Wade,_and_Kyle_Wilson_poster.pdf

9:00 AM Development of 1 kW Stirling cryocooler with using linear compressor

Cryogenic cooling systems for HTS electric power devices require a reliable and efficient high-capacity cryocooler. A Stirling cryocooler with a linear compressor can be a good candidate. It has advantages of low vibration and long maintenance cycle compared with a kinematic-driven Stirling cryocooler. In this study, we developed dual-opposed linear compressor of 12 kW electric input power with two 6 kW linear motors. It is experimentally measured the electromagnetic parameters of fabricated linear motor such as thrust constant, effective resistance and inductance. The developed Stirling cryocooler has gamma-type configuration. Moving components of piston and displacer is supported with flexure spring. A slit-type heat exchange is used for cold and warm-end, and the generated heat is rejected by cooling water. In cooling performance test, electric heat is loaded to measure cooling capacity and spatial temperature distribution in cold-end heat exchanger surface. In addition, displacement of moving parts, dynamic pressure, input voltage and current are also measured during operation. With the measured experimental data, the dynamic behavior of linear compressor is discussed.

Speaker: Dr Junseok Ko (Korea Institute of Machinery & Materials)

Poster C2PoB-03_jsko_poster.pdf

9:00 AM Linear Resonance Compressor for Stirling-Type Cryocoolers Activated by Piezoelectric Stack-Type Elements

A novel type of the PZT based compressor operating at mechanical resonance, suitable for pneumatically-driven Stirling-type cryocoolers was developed theoretically and built practically during this research. A resonance operation at relatively low frequency was achieved by incorporating the piezo ceramics into the moving part, and by reduction of the effective piezo stiffness using hydraulic amplification. The detailed concept, analytical model and the test results on the preliminary prototype were reported earlier and presented at ICC17. A fine agreement between the simulations and experiments spurred development of the actual compressor intending to drive a miniature Pulse Tube cryocooler, particularly our MTSa model, which operates at 103 Hz and requires an average PV power of 11 W, filling pressure of 40 Bar and a pressure ratio of 1.3. The paper concentrates on design aspects and optimization of the governing parameters. The large diameter to stroke ratio (about 10:1) allows for the use of a composite diaphragm instead of a clearance-seal piston. The motivation is to create an adequate separation between the coolant and the buffer gas of the compressor, thus preventing possible contamination in the cryocooler. Providing a similar to conventional linear compressors efficiency and power density, the piezo compressor may serve as a good alternative for cryogenic applications requiring extreme reliability and absence of magnetic field interference.

Speaker: Mr Sergey Sobol (Technion - Israel Institute of Technology)

Poster CEC-ICMC_2015_SergeySobol_Poster.pdf

9:00 AM Theoretical and experimental investigations on the performance characteristics of the linear compressor for the pulse tube cryocooler

The linear compressor providing powers for the Stirling-type pulse tube Cryocooler (SPTC) is endowed with remarkable merits such as high reliability and long life which have a strong appeal to aerospace applications. The pulse tube cold finger (PTCF) exerts evident and complicated influences on the compressor’s performance. However, there is seldom systematic investigation on the influences, which often leads to a poor cooler performance when a linear compressor is developed and then coupled to the PTCF. In this paper, theoretical and experimental investigations on the linear compressor’s performance characteristics and the PTCF’s influences have been made. The compressor and the PTCF are assumed as a one-dimensional thermodynamic model. The governing equations of the working gas’ operating characteristics are summarized, such as the dynamic pressure, the mass flow rate, and the phase angle between them. The cooling performance’s effects on the characteristics of the working gas in the compression space are determined. Based on the characteristics of the working gas in the compression space, the governing equations of the compressor’s performance characteristics are deduced, such as the input electric power, the PV power, and conversion efficiencies of powers. The principles for achieving the compressor’s optimal performance are discussed in detail. The experimental investigations are conducted on a series of linear compressors which drive SPTCs operating at 25-200 K. Varying with cooling capacities and operating temperatures, the linear compressors’ input electric powers, conversion efficiencies, and the working gas’ operating characteristics in the compression space are measured to verify the model. The SPTCs achieve input compressor capacities of 0-500 W with motor efficiencies of 74.2-83.6%, and 2.9%, 9.6%, 16.2% of Carnot efficiency at 40 K, 60 K, 80 K, respectively.

Speaker: Mr Lei Zhang (Shanghai Institute of Technical Physics, Chinese Academy of Sciences)

Poster 展板.pdf

9:00 AM → 11:00 AM C2PoC - Instrumentation and Controls I

Conveners: Adam Kurland (Scientific Instruments, Inc.), Michael Capers (Cryocomp)

9:00 AM Operating parameters of liquid helium transfer lines used with continuous flow cryostats at low sample temperatures

Continuous flow cryostats are used to cool samples to a variable temperature level by evaporating a cryogen, e.g. liquid helium (LHe). For this purpose LHe is usually stored outside the cryostat in a mobile dewar and supplied with a transfer line. In general, the complete setup has to be characterised by a low consumption of LHe. Additionally, a minimum sample temperature is favourable from an experimental point of view. The achievement of both requirements is determined by the respective cryostat design, as well as by the transfer line performance. Characteristic operating data, e.g. the LHe consumption during cool-down and steady state, the sample temperature and the outlet quality, are achieved with a test rig similar to a common continuous flow cryostat setup. In addition, an experimental transfer line with built-in pressure sensors has been commissioned to examine the frictional pressure drop of the LHe flow inside the transfer line. The presented operating data provide the basis for the development of an improved transfer line design as part of an ongoing research project. A decreased LHe consumption will reduce the operating costs of a continuous flow cryostat. Furthermore, decreased sample temperatures widen the field of application for continuous flow cryostats operated with LHe.

Speaker: Mr Nico Dittmar (Technische Universitaet Dresden)

Poster C2PoC-04.pdf

9:00 AM Test procedures and functional verification of cryogenic valves considering operating conditions

Cryogenic and high-pressure control valves have to meet topmost requirements as a result of extreme operating conditions. Of prime importance are accuracy and high reproducibility of the control performance and further maximised reliability and service life time. To verify these requirements several procedures are implemented which are partially defined with general standards. Furthermore long-time experiences by user and manufacturer are of great importance. The poster presentation describes already established routines as well as specific test procedures for particular applications. The interpretation of these procedures, their relevance and limits are clearly described. Examination of leakage and welding seams under ambient and cryogenic conditions; endurance and reliability tests; measurement of valve specific characteristics such as kv-values as well as material specific inspection are in focus of our approach.

Speakers: Michael Boersch (WEKA AG), Pascal Erni (WEKA AG)

Poster No_423_WEKA-Poster_2015_TestProcedures.pdf

9:00 AM → 11:00 AM C2PoD - Superconducting RF Systems II

Conveners: Kelly Dixon (Jefferson Lab), Thomas Peterson (Fermilab)

9:00 AM Cryogenic System for the Cryomodule Test Stand at Fermilab

This paper describes the cryogenic system for the Cryomodule Test Stand (CMTS) at the new Cryomodule Test Facility (CMTF) located at Fermilab. CMTS is designed for production testing of the 1.3 GHz and 3.9GHz cryomodules to be used in the Linac Coherent Light Source II (LCLSII), which is an upgrade to an existing accelerator at Stanford Linear Accelerator Laboratory (SLAC). This paper begins with a description of the design and installation progress of the CMTS cryogenic distribution system. Next, the key cryomodule interface and operational requirements will be listed, followed by an overview of the installation and cooldown plans. The paper will conclude with a description of the heat load measurement plan. *Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.*

Speaker: Michael White (Fermilab)

9:00 AM Design of a symmetric coupler for superconducting elliptical cavities.

As kicks from fundamental power couplers become a concern for low emittance future accelerators, a design for a symmetric coupler for superconducting accelerating cavities has been started. In this coupler, a rectangular waveguide transforms into a coaxial line inside the beam pipe to feed the cavity. So far the RF design revealed an extremely low transversal kick on which we will elaborate. We will also adress concerns about cooling and the thermal stability of the coaxial transition line. Therefore, we will calculate the heat, heat transfer and thermal stability of this coupler and evaluate the risk of quenching due to particle losses on the coupler.

Speaker: Ralf Eichhorn (Cornell University)

Poster CEC2015-C2PoD-03-1.pdf CEC2015-C2PoD-03-1.pptx

9:00 AM Progress on fabricating seamless RRR Nb tubes for SRF applications

The objective of the work reported is to demonstrate a fabrication method for developing reproducible uniform fine-grained microstructures in seamless RRR Nb tube. The target application is the inexpensive manufacture of RRR Nb superconducting radio frequency (SRF) cavities. Present methods to manufacture seamless Nb tubing from rolled Nb sheet by deep drawing, spinning, and flow forming indicate inconsitencies in microstructure along the through thickness of the tube. To tackle these problems and obtain seamless tubes that hydroform well, we have been developing a severe plastic deformation (SPD) process in combination with traditional tube extrusion by forward and backward extrusion. Forward extruded tubes in combination with SPD have indicated tremendous promise with similar mechanical characteristics, hardening exponents of 0.2 along the major tube axes, and ductilities greater than 40%. In order to increase process yield, a multi-step fabrication process involving an initial back extrusion and subsequent forward extrusion has been developed. Preliminary results on the effect of process path changes will be presented. Microstructure variations in terms of grain size, grain size distribution, and formation of novel textures along the tube circumference will be compared to previously fabricated Nb tubes by forward extrusion. Measurements of concentricity and thickness variations of the seamless Nb tubing will also be reported.

Speaker: Shreyas Balachandran (Texas A&M University)

Poster ICMC_2015_Seamless_Nb_tube_for_SRFcavities.pdf

9:00 AM Test stand for routine thermal conductivity measurements of SRF cavity material.

Thermal conductivity of SRF cavity material influences Q factor in many different ways. RRR and grain size are insufficient to characterize quality of the material and additional control of thermal conductivity is required. We have developed a test stand to perform regular thermal conductivity measurements of samples from cavity material sheets from 1.6 to $\approx$10 K. Thermal conductivity of C101 copper measured with the test stand is consistent with NIST model. We report thermal conductivity of fine grain and single grain samples and comparison with results obtained by other authors.

Speaker: Dr Sergey Koshelev (Fermilab)

Poster cec2015_poster.pdf

9:00 AM → 11:00 AM C2PoE - CFD Modelling and Measurements Techniques

Conveners: Bertrand Baudouy (CEA Saclay), Parthasarathi Ghosh (Indian Institute of Technology, Kharagpur, India)

9:00 AM CFD Simulation of the Gas Flow in a Pulse Tube Cooler with two Pulse Tubes

In order to realize larger and heavier mass supporting without additional supporting components, a new structural pulse tube cooler based on traditional U-shape pulse tube cooler and with one regenerator and two parallel pulse tubes has been proposed. In previous works, two prototypes of U-shape two-pulse-tube paralleled cooler have been designed and tested. In this paper, to help characterize the gas flow in the new structural pulse tube cooler, a two-dimensional axisymmetric Computational Fluid Dynamics (CFD) model is also developed to simulate oscillating fluid flow and heat transfer in the cooler. Results obtained from experiments and CFD simulations are presented and discussed in this paper.

Speaker: Mr Yin Chuanlin (Institute of Cryogenics and Electronics)

Poster CFD_Simulation_of_the_Gas_Flow_in_a_Pulse_Tube_Cooler_with_two_Pulse_Tubes（POSTER).pdf

9:00 AM Computational Fluid Dynamic Investigation of Loss Mechanisms in a Pulse-Tube Refrigerator

In predicting Pulse-Tube Refrigerator (PTR) performance, One-Dimensional design and analysis tools such as Gedeon Associates SAGE® typically include models for performance degradation due to thermodynamically irreversible processes. SAGE®, in particular, accounts for convective loss, turbulent conductive loss and numerical diffusion “loss” via correlation functions based on analysis and empirical testing. While the simplicity of 1-D simulation tools facilitates PTR design and analysis, this convenience comes at the cost of modeling detail. An investigator wanting to drill-down into the constitutive relationships or governing principles can be shielded from low-level physical details that may otherwise lead to design insights. In these types of investigations, a higher-order Computational Fluid Dynamics (CFD) simulation complements a 1-D simulation. Whereas 1-D simulation is a sufficient starting point for PTR design, Two-Dimensional and Three-Dimensional CFD models enable an investigator to refine the design—to explore and visualize “real” physical heat-transfer and fluid flow behavior that has been condensed, simplified or omitted in 1-D modeling tools. In a 2-D or 3-D CFD model, the system dynamics and complexity between the input and output of a particular PTR component are not hidden. In this regard, higher order CFD is also a means of validating 1-D models, or of tuning lower-order design tools to new performance spaces before physical functional validation or prototyping. In this study, we compare CFD and SAGE® estimates of PTR refrigeration performance for four distinct pulse-tube lengths. Performance predictions from PTR CFD models are compared to SAGE® predictions for all four cases, and also compared to select published analytical and empirical models. Then, to further demonstrate the benefits of higher-fidelity and multidimensional CFD simulation, the PTR loss mechanisms are characterized in terms of their spatial and temporal locations.

Speaker: Mr Christopher Dodson (Spacecraft Component Thermal Research Group, Kirtland AFB)

9:00 AM → 11:00 AM C2PoF - Test Facilities

Conveners: Jay Theilacker (Fermilab), Mr Wolfgang Hees (European Spallation Source ESS AB)

9:00 AM Design details of the current lead test facility Karlsruhe (CuLTKa)

The new current lead test facility CuLTKa was successfully commissioned in 2014 at the Karlsruhe Institute of Technology (KIT), Germany. Towards the end of the year the first pair of current leads for the Japanese fusion experimental reactor JT-60 SA was tested. These current leads have to carry currents of up to 26 kA and are cooled with helium at two different temperature levels, 4.5 K and 50 K, respectively. After commissioning and test of the first pair of the HTS-current leads another 24 current leads will be tested within the next 2.5 years. The facility consists of two valve boxes, one control box, which houses a 400 l liquid helium reservoir and two test cryostats. All cryostats are connected by cryogenic transfer lines. Two helium mass flows at 4.5 K and 20 to 70 K at overcritical pressures are provided by the 2 kW refrigerator. This publication will describe the way of designing the facility starting from the basic demands. The overall setup is derived and particular details are explained. Some design calculations will be opposed to measured data from its real performance. In addition the design of safety aspects is discussed.

Speaker: Thomas Richter (Karlsruhe Institute of Technology (KIT))

Slides Tucson_1800x900-250615-V3_final.pdf

9:00 AM Helium Recovery at the National High Magnetic Field Laboratory

Helium conservation is becoming increasingly important as helium availability is on the decline and prices are on the rise. The Florida State University National High Magnetic Field Laboratory has taken several steps over the past five years to increase the percentage of helium recovered. These include the installation of a standalone purifier, recovery flow meters, contamination meters, and a new piping system. The improvements to the recovery system have reduced the amount of helium purchased by the Mag Lab by 50% while helium usage has increased by roughly 30%. This article will provide details about the recovery system as a whole and describe some of the main components. There will also be some examples of the problems we’ve had to overcome, and some that we are still working on. Finally, there will be an update on the current status of the recovery system and a description of our plans for the future.

Speaker: Matt Barrios

Poster Helium_Recovery_CEC_Poster.pdf Helium_Recovery_CEC_Poster.pptx

9:00 AM Study for cryogenic testing the Super-FRS magnets of FAIR in a new test facility at CERN

A new cryogenic test facility is currently under construction at CERN for future needs of the laboratory. This facility will be at first used for the cryogenic testing of the Super-FRS magnets of the International Facility for Antiproton and Ion Research (FAIR) being built at GSI in Germany. In total 57 magnets will be tested of which the largest magnets have a cold mass of 45’000 kg. The magnet test rate will be 27 magnets per year and each magnet test will take about 46 days. To obtain the required test rate, the test facility has to consist of three test benches. The cryogenic system of the test facility needs to cool-down the magnets to their operating temperature of 4.5 K, maintain the required temperature during the tests and warm-up the magnets after the tests. Two pre-cooler and heater units with a power of 15 kW will be needed for pre-cooling the magnets to 80 K and for warming-up the magnets after the tests. These units need to provide a gaseous helium flow up to 50 g/s at about 10 bar at the required temperature. A Sulzer TCF200 cold box will produce liquid helium up to a flow rate of 6 g/s to cool down the magnets to 4.5 K and maintaining the operating temperature during the tests. This paper will cover the cryogenic study of the main components of the test facility to match the needs for testing the Super-FRS magnets. The calculation results to define the main operational parameters for the various operating modes will be presented in detail. Also, flow schemes and the design of some of the main components will be discussed.

Speaker: Jan Hendrik Derking (CERN)

Poster CEC2015_C2PoF-04_HDerking.pdf

9:00 AM → 11:00 AM M2PoA - Superconductors Materials II: Nb3Sn, FeAs-based

Conveners: Carlo Ferdeghini (CNR-SPIN), Xuan Peng (Hyper Tech Research Inc.)

9:00 AM Heat Treatment Sensitivity of ITER Nb3Sn Wire for CS Magnets

Due to the potential spatial temperature variations during heat treatment of the large central solenoid (CS) coils, it is necessary to study the strand’s heat treatment sensitivity by characterizing the strands heat treated with slightly different temperature profiles. We present critical current (Ic) and residual resistivity ratio (RRR) results of ITER Nb3Sn strands made by two manufacturers for CS coils that were heat treated using varying temperatures and durations for the last stage of the heat treatment. Our results show that Ic is not very sensitive to the heat treatment for the range of temperature and time used, however, RRR did decrease with increasing heat treatment time and temperature. We will discuss the mechanisms responsible for the heat treatment sensitivity of Ic and RRR for the two strands. In particular, an expression of RRR as a function of heat treatment temperature and time is presented. *This work is funded by US-ITER under subcontract number 4000110684.*

Speaker: Mr David McGuire (National High Magnetic Field Laboratory)

Poster HT_Sensitivity_poster_CEC_ICMC_V2.pdf HT_Sensitivity_poster_CEC_ICMC_V2.pptx

9:00 AM Highly Formable Tantalum Barrier for Nb3Sn Conductors

Ta diffusion barrier integrity is critical in the development of higher Nb ratios in internal-tin (IT) conductors. Current fabrication methodologies predominantly employ conventional wrapped Ta sheet, which deform non-uniformly during wire drawing. This leads to non-uniform Ta layers, with thickness varying between 10-2 microns as evident from IT cross-sectional images. The objective of this work is to present strategies to replace conventional Ta sheet material with severe plastic deformation (SPD)-processed, uniform, fine-grain material. Preliminary work has demonstrated that simply replacing the sheet with SPD-processed sheet improves the layer drawability in wrapped composite tubular components. Innovative SPD strategies have led to the development of” weld- healing” of electron beam (EB) welds in Ta tube. We will present ongoing work on thr weld-healing path as well asdevelopment of seamless fine grained Ta capable of higher thickness reductions. Microstructural and mechanical test results will be discussed.

Speaker: Dr David Foley (Shear Form, Inc.)

Poster ICMC_2015_Poster_Ductile_Tantalum_Tube_for_Nb3Sn_superconductors.pdf

9:00 AM Suppression of persistent-current magnetization of Nb3Sn strands by transport current

For Nb3Sn strands used in magnets, persistent-current magnetization must be carefully considered because it is an important contributor to field errors in magnets. Compared with the usual measurements by magnetometers, the true magnetizations of Nb3Sn strands used in magnets are in fact smaller because the transport currents they are carrying suppress their magnetizations. In an earlier work we investigated this influence on a cylindrical wire with constant Jc(B) by finite element modeling (FEM). In this work we experimentally measure the magnetization of a practical Nb3Sn strand with transport current using a lab-designed device equipped with two Hall probe magnetometers. This experiment yields a quantitative estimation of the dependences of the strand magnetization on transport current and magnetic field.

Speaker: Xingchen Xu (the Ohio State University)

9:00 AM → 11:00 AM M2PoB - Cryogenic Materials III: Testing and Methods

Conveners: Karl Hartwig (Texas A&M University), Makoto Takayasu (MIT)

9:00 AM A cryogenic tensile testing apparatus for micro-samples cooled by miniature pulse tube cryocooler

This paper introduces a cryogenic tensile testing apparatus for micro-samples cooled by a miniature pulse tube cryocooler. At present, tensile tests are widely applied to measure the mechanical properties of materials; most of the cryogenic tensile testing apparatus are designed for samples with standard sizes, while for non-standard size samples, especially for micro-samples, the tensile testing cannot be conducted. The general approach to cool down the specimens for tensile testing is by using of liquid nitrogen or liquid helium, which is not convenient: it is difficult to keep the temperature of the specimens at an arbitrary set point precisely, besides, in some occasions, liquid nitrogen, especially liquid helium, is not easily available. To overcome these limitations, a cryogenic tensile testing apparatus cooled by a high frequency pulse tube cryocooler has been designed, built and tested. Samples with a diameter of as small as 3 mm and thickness less than 1 mm can be tensile tested. The operating temperatures of the developed tensile testing apparatus cover from 20 K to room temperature with a controlling precision of ±0.03 K and the whole deformation process of the specimen can be observed through a quartz window, which can be hardly realized by the way of liquid nitrogen or liquid helium cooling. The apparatus configurations, the methods of operation and some cooling performance will be described in this paper. *This research is supported by The National Natural Science Foundation of China (No. 51327806 and No. 51427806).*

Speakers: Prof. Junjie Wang (Technical Institute of Physics and Chemistry, CAS), Mr Kaixuan Gu (Technical Institute of Physics and Chemistry, CAS), Mr Liubiao Chen (Technical Institute of Physics and Chemistry, CAS)

Poster Chen_Liubiao-poster.pdf

9:00 AM Effect of Discontinuities and Penetrations on the Shielding Efficacy of High Temperature Superconducting Magnetic Shields

High Temperature Superconducting (HTS) materials have been demonstrated to be suitable for applications in shielding of both DC and AC magnetic fields. Magnetic shielding is required for protecting sensitive instrumentation from external magnetic fields and for preventing the stray magnetic fields produced by high power density equipment from effecting neighboring devices. HTS shields have high current densities at relatively high operating temperatures (40-77 K) and easily be fabricated using commercial HTS conductor. High current densities in HTS materials allow design and fabrication of magnetic shields that are lighter and can be incorporated into the body and skin of high power density devices. HTS shields are particularly attractive for HTS devices because a single cryogenic system can be used for cooling the device and the associated shield. Typical power devices need penetrations for power and signal cabling and the penetrations create discontinuities in HTS shields. Hence it is important to assess the effect of the necessary discontinuities on the efficacy of the shields and the design modifications necessary to accommodate the penetrations. This paper presents the details of the experimental and modelling efforts. Results of the experimental studies at variable amplitude and frequency of the magnetic field and a comparison of the results with those of the models are presented.

Speaker: Rajeev Hatwar (Florida State University)

Poster CEC-ICMC-2015_SHIELDING_Final.pdf

9:00 AM Material characterisation and preliminary mechanical design for the HL-LHC shielded beam screens operating at cryogenic temperatures.

The High Luminosity LHC (HL-LHC) project aims at increasing the luminosity (rate of collisions) in the Large Hadron Collider (LHC) experiments by a factor of 10 beyond the original design value (from 300 to 3000 fb-1). It relies on new superconducting magnets, installed close to the interaction points, equipped with new beam screen. This component has to ensure the vacuum performance together with shielding the cold mass from physics debris and screening the cold bore cryogenic system from beam induced heating. The beam screen operates in the range 40-60 K whereas the magnet cold bore temperature is 1.9 K. A tungsten alloy is used to absorb the energy of particles. In this paper, the measurements, at room and cryogenic temperatures, of the mechanical and some physical properties of this tungsten alloy are shown. The strength of soldering with copper is also assessed at cryogenic temperatures. Then, the design and the thermal mechanical behaviour of the beam screen assembly are presented. It includes the heat transfer from the tungsten absorbers to the cooling pipes and through the supporting system that has to minimise the heat inleak to the cold mass. The behaviour during a quench is also presented.

Speaker: Cedric Garion (CERN)

Poster M2PoB.pdf

9:00 AM Materials for damping the PTC-induced thermal fluctuations of the cold-head

The cold head on mechanical Pulse Tube Cryocoolers (PTCs) are subject to substantially less mechanical vibration and electromagnetic interference compared to that typically found in Gifford MacMahon coolers. However, thermal fluctuations at the PTC frequency are still present at the cold-head, typically at a level of 200 mK peak-to-peak at 1.4 Hz for a Cryomech Model PT405 cooler running at 4 K. It is highly desirable to damp out these fluctuations if PTCs are to be used successfully for running systems sensitive to such thermal fluctuations, for example, bolometeric detectors. We report here the characterization over the temperature range 2.5 K to 9 K of two materials, GOS and GAP, for use as low-pass thermal filters. These materials have antiferromagnetic transitions at around 4 K giving rise to an enhanced heat capacity and have a high thermal conductance when fired as ceramic discs. These are two highly desirable properties for thermal dampers in this application. Thermal filter assemblies with discs of diameter 75 mm and thickness 2.5 mm and 1.5 mm (GOS and GAP, respectively) mounted in a Cryomech Model PT405 cooler show thermal attenuation levels of x0.12 (GOS) and x0.11 (GAP) at 0.01Hz with a clean-side temperature of 4 K; the PTC induced fluctuations at 1.48 Hz are damped completely to within the noise limits (0.2 mK) of the thermometers. Experimentally determined thermal conductance and heat capacity data is reported. For this system, with a PTC cold-head (dirty-side) temperature of 2.5 K, a clean-side power dissipation of up to 30 mW before its temperature rises above 4.2 K.

Speaker: Ms Isabel Catarino (Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa)

Poster Poster_CEC_Tstab.pdf

9:00 AM Quench detection via Rayleigh scattering based fiber optic distributed sensors

A novel quench detection method is developed and tested using optical fibers as distributed sensors of temperature and strain. In particular, the technique is based on the comparison of Rayleigh backscattering signals of a reference and perturbed state. A spectral shift quantifies the mismatch between the two conditions, which depends on temperature and strain changes between the two compared states. Several HTS coils have been fabricated and instrumented with voltage taps, thermocouples and an embedded heater to initiate a quench. An optical fiber has been co-wound with YBCO tape using different schemes. The results showed that the spectral shift correlates with normal zones developed in the coil. In all the experiments the fiber optic based detection system was able to rapidly detect and locate normal zones, with very high spatial resolution (5 mm) and fast measurement (a measurement cycle lasts 30 ms). Moreover, the spectral shift raised as soon as a thermal perturbation occurred, without any time delay whatsoever, whereas the voltage signal started rising only after the temperature crosses Tcs. The combination of high spatial resolution (5 mm) and high speed (a measurement cycle lasts 30 ms) allowed for a very rapid detection and localization of a hotspot. These capabilities enable the use of a minimum propagating zone (MPZ) as a criterion to identify unstable (propagating) normal zones, instead of the conventional threshold voltage.

Speaker: Federico Scurti (NC State University)

Poster CEC-ICMC_2015_M2PoB_poster_Scurti.pdf

9:00 AM Recent NASA/GSFC Cryogenic Measurements of the Total Hemispheric Emissivity of Black Surface Preparations

High-emissivity (black) surfaces are commonly used on deep-space radiators and thermal radiation absorbers in test chambers. Since 2011 NASA Goddard Space Flight Center has been measuring the total hemispheric emissivity of such surfaces from room temperature down to 20 Kelvin using a test apparatus that fits inside a small laboratory cryostat. We report the latest data from these measurements, including Chemglaze Z307 paint, Black KaptonTM, and a configuration of painted aluminum honeycomb that was not previously tested. We also present the results of studies of batch-to-batch reproducibility in Ball Infrared BlackTM and painted aluminum honeycomb. This work was performed to support the development and testing of the James Webb Space Telescope.

Speaker: James Tuttle (NASA/GSFC)

Poster Poster2.pdf

9:00 AM → 9:30 AM Morning Break

11:00 AM → 12:15 PM C2OrA - Cryogenic Power Cables and Leads I: SESSION CANCELLED

11:00 AM → 12:15 PM C2OrB - Large Capacity Coolers

Conveners: Julien Tanchon (Absolut System SAS), Yatming Than (BNL)

11:00 AM 330 W Cryocooler Developments and Testing

Fabrum Solutions in association with Callaghan Innovation and Absolut System has developed a 330 W pulse tube cryocooler based on Callaghan Innovation’s diaphragm pressure wave generators (DPWG). A cost-effective, long life and robust cryocooler has been achieved due to the pulse tube’s lack of moving parts and the DPWG’s metal diaphragms separating the working gas from the oil lubricated drive mechanism. A 330 cc DPWG was designed and manufactured to run with an inline pulse tube. Absolut System carried out the pulse tube design, manufacture by Fabrum Solutions with integration and testing by Callaghan Innovation. Over 400 W of cooling power at 77 K was achieved (target was 330 W at 77 K) from the cryocooler, which is now being run in a commercial application. A sealed condensation chamber was added to the cold-head and connected to a Dewar via vacuum insulated lines for liquefaction of Nitrogen. Three of the 330 W pulse tubes have been mounted to a single 1000 cc DPWG to produce > 1 kW of cooling power at 77 K, which is one of the topics presented in another paper at this conference. Details of the design, development, testing and integration are presented.

Speaker: Mr Nick Emery (Callaghan Innovation)

11:15 AM Commercialisation of pulse tube cryocoolers to produce 330 W and 1000 W at 77 K for liquefaction.

Fabrum Solutions in collaboration with Callaghan Innovation has been developing large pulse tube cryocoolers based on Callaghan Innovation’s diaphragm pressure wave generators (DPWG). The pulse tube’s lack of moving parts in combination with the DPWG’s metal diaphragms produces a cost-effective, long life and robust cryocooler. The DPWG has had 10 years of development, resulting in a series of DPWGs ranging in input powers from 0.5 kW to 30 kW that have been coupled to a variety of in-line and coaxial pulse tubes. Two DPWGs have had in excess of 7000 hours running to date. The PT330 cryocooler is based on a new 330 cc DPWG and has produced over 400 W of cooling at 77 K during testing. The PT1000 combines three such pulse tubes on a single 1000 cc DPWG to produce over 1000 W at 77 K. This paper details the development of the PT330 and PT1000 cryocoolers from initial lab prototypes through to commercial products, integrated into liquefiers and ready for use in applications such as: Nitrogen liquefaction, re-liquefaction of boil-off from storage tanks, or cooling of cryostats for High Temperature Superconductor applications.

Speaker: Alan Caughley (Callaghan Innovation)

11:30 AM Large 'pulse-tube' oxygen liquefier for CVN-78 carriers: an update

Several years ago, we reported on a 50-gallon-per-day oxygen liquefier that uses Stirling-type pulse-tube coldheads driven by a large flexure-bearing pressure wave generator (PWG), in development for the new generation of U.S. Navy aircraft carriers. The first of these liquefiers is about to be deployed on the USS Gerald R. Ford. This presentation describes the completion and performance testing of the core cryocooler, and some of the balance-of-systems challenges encountered.

Speaker: Dr Philip Spoor (Chart Industries)

Slides CEC03-C2OrB03(Spoor2015)-slides.pdf

11:00 AM → 12:00 PM C2OrC - Pulsating Heat Pipes and Thermosyphons

Conveners: Kathleen Amm (GE Global Research), Venkatarao Ganni (Jefferson Lab)

11:00 AM Experimental study of stability and transients in a horizontally heated boiling helium thermosyphon

Boiling helium natural circulation loops are being used as the cooling systems of large magnet systems because they provide inherent safety and maintenance advantages. It is the case of the CMS detector magnet at CERN (already in operation) or R3B-GLAD spectrometer at GSI (in installation phase). Such cooling systems are mainly composed by a top helium reservoir that provides the coolant by one or several descending feeding branches to the bottom of a hydraulic network in contact with the magnet to be cooled. The heat transferred to the fluid produces vapor in this element of the circuit, and the resulting buoyant force creates a flow. The behavior of such systems has been studied before for loops with a vertical heated branch, but only preliminary studies were conducted on loops with a horizontal heated section. In this work experiments were conducted on a liquid helium thermosyphon facility with a 4 m length horizontal heated section. Wall temperatures on the heated section, mass flow rate and pressure drop were measured in steady and transient regimes and the stability limits of such a loop have been found. Also, different heating configurations were explored and their drawbacks and benefits were observed. The result is that the loop is stable only above a non-zero low power and below a certain upper power limit for certain configurations. The distance from the heating to the vertical riser plays a very important role on stability. It has been found that even the low power instabilities can produce considerable temperature oscillations, potentially dangerous from the magnet protection point of view. The values of critical heat flux were found too for stable and instable cases.

Speaker: Hernan Furci (CEA Saclay)

Slides FURCI-HorizontalThermosiphon.pdf FURCI-HorizontalThermosiphon.pptx

11:15 AM Theoretical analysis and experimental investigation on performance of the thermal shield of accelerator cryomodules by thermo-siphon cooling of liquid nitrogen.

Five beam line cryomodules with total 27 superconducting RF cavities are installed and commissioned at IUAC to enhance the energy of heavy ion from 15 UD Pelletron. To reduce the heat load at 4.2 K, liquid nitrogen cooled intermediate thermal shield is used for all these cryomodules. For three linac cryomodules, concept of forced flow LN2 cooling is used and for superbuncher and rebuncher, thermo-siphon cooling concept is incorporated. It is noticed that the shield temperature of superbuncher varies from 90 K to 110 K with respect to liquid nitrogen level. The temperature difference can’t be explained by using the basic concept of thermo- siphon with the heat load on upstream pipe. A simple thermo-siphon experimental set up is developed to simulate the thermal shield temperature profile.. Mass flow rate of liquid nitrogen is measured with different heat load on upstream pipe for different liquid level. It is noticed that small amount of heat load on downstream pipe have a significant effect on mass flow rate. The present paper will be investigating the data generated from thermo-siphon experimental set up and a theoretical analysis will be presented here to validate the measured temperature profile of the cryomodule shield.

Speaker: Dr Tripti Sekhar Datta (Inter- University Accelerator Centre. New Delhi. India)

Slides C2OrC-02.pdf C2OrC-02.ppt

11:30 AM Design and Operation of a Cryogenic Nitrogen Pulsating Heat Pipe

We report test results using an innovative passive cooling system called a “Pulsating Heat Pipe” (PHP) operating at temperatures ranging from 77 K to 80 K and using nitrogen as the working fluid. PHPs, which transfer heat by two phase flow mechanisms through a closed loop tubing have the main advantage that no electrical pumps are needed to drive the fluid flow. In addition, PHPs have an advantage over copper straps and thermal conductors since they are lighter in weight, exhibit lower temperature gradients and have higher heat transfer rates. PHPs consist of an evaporator section, thermally anchored to a solid, where heat is received at the saturation temperature where the liquid portion of the two-phase flow evaporates, and a condenser where heat is rejected at the saturation temperature where the vapor is condensed. The condenser section has been thermally interfaced to a CT cryocooler from SunPower, with a cooling capacity of 10 W at 77 K. Alternating regions of liquid slugs and small vapor plugs fill the capillary tubing, with the vapor regions contracting in the condenser section and expanding in the evaporator section due to an electric heater that will generate heat loads up to 10 W. This volumetric expansion and contraction provides the oscillatory flow of the fluid throughout the capillary tubing thereby transferring heat from one end to the other. The thermal performance and temperature characteristics of the PHP will be correlated as a function of average condenser temperature, PHP fill liquid ratio, and evaporator heat load. The experiment is also operated at different inclination angles in order to investigate whether Earth’s gravitational force has a significant effect on its efficiency.

Speaker: Mr Luis Fonseca (University of Wisconsin Madison)

Slides CEC_Presentation.pdf CEC_Presentation.pptx

11:45 AM Experimental investigation of a Hydrogen Pulsating Heat Pipe

The oscillating heat pipe (OHP) has been increasingly studied in cryogenic application, for its high transfer coefficient and quick response. Compared with Nb3Sn and NbTi, MgB2 whose critical transformation temperature is 39K, is expected to replace some high-temperature superconducting materials at 25K. In order to cool MgB2, this paper designs a Hydrogen Pulsating Heat Pipe, which allows to study how applied heat, filling ratio, and length of adiabatic section affect the thermal performance of the OHP, respectively. The thermal performance of the hydrogen OHP is investigated for filling ratios of 30% , 50% and 70% at different heat input, what’s more the starting power is received at these three filling ratios.

Speaker: Mr Haoren DENG (Zhejiang University)

Slides Experimental_investigation_on_a_pulsating_heat_pipe_with_hydrogen.pdf Experimental_investigation_on_a_pulsating_heat_pipe_with_hydrogen.ppt

11:00 AM → 12:00 PM C2OrD - CFD and Numerical Modelling

Conveners: Parthasarathi Ghosh (Indian Institute of Technology, Kharagpur, India), Peter Knudsen (Jefferson Lab)

11:00 AM CFD study on the effects of viscous shear in a hot cascade Ranque-Hilsch vortex tube

Ranque -Hilsch vortex tube is a device that is capable of splitting the highly compressed inlet gas into two streams of lower pressure gases, namely, central zone of cold fluid generated near the axis and peripheral zone of hot fluid around the inner wall of the tube. Though, vortex tube has many benefits over the conventional heating and cooling devices, low efficiency is the biggest drawback of it. Therefore, the method of hot cascading is an endeavor to make the use of the cold gas for cooling purposes while improving the heating capacity of the hot gas. Thus, the method of hot cascading enhances the overall efficiency of the whole system. The hot cascade vortex tube consists of two vortex tubes connected in series in such a way that, the hot gas emerging out of the first stage of vortex tube serves as the inlet fluid for the second stage vortex tube. This paper presents two predominant parameters which are utmost concern in the process of thermal separation, namely heat transfer and work transfer due to viscous shear along the radial, axial and tangential directions per unit length are studied. The Computational Fluid Dynamics (CFD) study has been carried out using RANS standard k-epsilon turbulence model with a two dimensional axi-symmetric structure mesh geometrical domain and air as working fluid. The CFD results reveal that the work transfer due to the action of viscous shear along the tangential direction increases considerably with hot cascading. However, the work transfer due to viscous shear along the axial direction degrades the performance of the device, as the heat transfer takes place from cold zone to the hot zone. The effect of radial shear stress is negligible due to low value of radial velocity gradient.

Speaker: Nilotpala Bej (Indian Institute of Technology, Kharagpur)

Slides C2OrD_262.pdf C2OrD_262.pptx

11:15 AM CFD analysis of straight and flared vortex tube

Vortex tube (VT) is a simple low refrigeration producing device having no moving part. However, the flow inside it is very complex. Recent studies show that the performance of VT improves with the increase in the divergence angle of a flared VT. To explore the temperature separation phenomenon in the VT, a three dimensional computational fluid dynamics (CFD) analysis of VT was carried out. For the present work, a VT having diameter of 12 mm, length of 120 mm, cold outlet diameter of 7 mm and hot outlet annulus of 0.4 mm with 6 straight rectangular nozzles having area of 0.5 sq. mm each is considered. The turbulence in the flow field of the VT is modeled by standard *k*-ε turbulence model with Redlich-Kwong real gas model. The effect of variation of divergence angle of hot tube in the VT is studied and compared with the experimental results available in the literature. The temperature separation between the hot outlet and cold outlet, in both straight and 2 degree divergent tube is studied. Analysis results indicate that for a hot mass fraction above 0.5, the divergent tube have better cold production capacity compared to the straight tube. Some parameters like temperature gradient, velocities (axial, radial and tangential), velocity gradients, effective thermal conductivity and viscosity of fluid etc., have been investigated for heat transfer and shear work transfer in the VT. To understand the temperature separation mechanism, heat transfer and work transfer along the axial direction have been evaluated in both straight and divergent tubes. The isentropic efficiency and COP as refrigerator as well as heat pump of straight tube and divergent tube have been computed.

Speaker: Mr Aman Kumar Dhillon (Indian Institute of Technology, Kharagpur)

Slides C2OrD-02.pdf

11:30 AM Experimental and CFD analyses of a thermal radiation shield dimple plate for cryogenic pump application

Large customized cryogenic pumps are used in fusion reactors to evacuate the plasma exhaust from the torus. They usually consist in an active pumping surface area cooled below 5 K and shielded from direct outer thermal radiation by plates cooled at about 80K. Cryopumps are exposed to excessively high heat fluxes during pumping operation and follow regeneration cycles with rapid warm-up and cool-down phases. Therefore, high cryogenic mass flows are required to operate the cryopumps and thus pressure drop and heat transfer characteristics become key issues in the design of the pump cryogenic circuits. For optimal flow distribution and enhanced heat transfer, actively cooled dimple plates are a preferred design option for the thermal radiation shield. A test dimple plate of 2310 mm x 520 mm with a typical rhomb pattern of circular welding spots has been manufactured and tested against pressure drops with a dedicated test facility using a water loop. In the present work, computational fluid dynamics (CFD) simulations of the test dimple plate have been performed and pressure drops have been compared to experimental results. Despite the complexity of the geometry and the size of the model, a good agreement with the experimental results was found. Then, the tried and tested CFD approach has been applied for further calculations with relevant operation conditions, using gaseous helium at cryogenic temperature as working fluid. The resulting pressure drop and heat transfer characteristics are finally presented.

Speaker: Mr Matthieu Scannapiego (Karlsruhe Institute of Technology)

11:45 AM Hierarchy of Two-Phase Flow Models for Autonomous Control of Cryogenic Loading Operation

We report on the development of a hierarchy of models of two-phase flow in cryogenic transfer line. The work is motivated by NASA plans to develop and maturate technology of cryogenic propellant loading on the ground and in space. The solution of this problem requires two-phase cryogenic flow models that are fast and accurate enough to identify flow conditions, to detect deviations from the nominal regime, and to propose optimal recovery strategy online without human interaction. The hierarchy of models described in this presentation is ranging from incompressible isothermal single-phase flow to separated non-equilibrium two-phase cryogenic flow. It includes heat transfer and pressure loss correlations for boiling flows based on the flow pattern recognition. We provide details of two models: (i) homogeneous, quasi-steady moving front model and (ii) the separated two-phase cryogenic flow model. Both models are based on the integration of energy and mass conservation equations on a one-dimensional grid of control volumes and solution of the momentum conservation equations on the staggered grid. The models are used to predict pressure, temperature, and liquid holdup during chilldown and loading of liquid nitrogen in a large scale cryogenic testbed at NASA-KSC. The heat transfer and pressure loss correlations are validated by comparison of the model predictions with chilldown test data obtained at the National Institute of Standards and Technology. The accuracy of the model predictions for cryogenic loading operation is validated by comparison with experimental data obtained from the cryogenic testbed at NASA-KSC. The speed and stability of the models is analyzed. The application of the models to the online fault detection and isolation during loading operation is discussed. The models performance is compared with the baseline model developed using a commercial SINDA/FLUINT software.

Speaker: Dr Dmitry Luchinsky (Mission Critical Technologies)

Slides Model_Hierarchy_ID203_Luchinsky_short.pptx.part

11:00 AM → 12:30 PM M2OrA - Superconductor Materials III: Nb3Sn

Conveners: Lance Cooley (Fermilab), Leszek Motowidlo (SupraMagnetics, Inc.)

11:00 AM [Invited] The origin of strain sensitivity in Nb3Sn

Externally applied strain affects the superconducting properties of Nb3Sn in a detrimental way. This is an important design issue in high-magnetic-field applications utilizing Nb3Sn technology where distortion due to Lorentz forces and differential thermal contraction is unavoidable. An overview is given of how the critical current density of Nb3Sn is affected by temperature, magnetic field and strain. Subsequently, it is demonstrated that the large strain sensitivity in Nb3Sn is a direct result of a strain-induced distortion of the niobium chains. Ab-initio calculations are combined with microscopic theory to determine how this distortion affects the superconducting properties and normal state resistivity in quantitative terms, and the results are validated with experimental observations. The same model is then used to explain the different degrees of strain sensitivity between Nb3Sn, Nb3Al, Nb and NbTi. Understanding the underlying mechanisms that determine the (strain-dependent) superconducting properties of Nb3Sn is an important step forward in maximizing the performance of Nb3Sn technology in high field applications.

Speaker: Matthias Mentink (CERN)

Slides M2OrA-01-Mentink.pdf M2OrA-01-Mentink.pptx

11:30 AM Shift of the Fp-B curve peak of Nb3Sn conductors with very fine grain sizes

In an earlier work we demonstrated on a monofilament that the internal oxidation method can significantly refine the grain size and improve the high-field Jc of Nb3Sn strands. In that work we found that as the Nb3Sn grain size was reduced down to 20-50 nm (with an average of 36 nm), the peak of the Fp-B curve shifted from 0.2Birr to 0.34Birr. In this work we further reduce the grain size by using a lower reaction temperature and a higher-Zr Nb-Zr alloy, in order to find out how the Fp-B curve peak shifts as grain size decreases. A pinning theory is also developed to explain the shift of the Fp-B curve peak as grain size is reduced. In this work we also work towards implementing the internal oxidation method in practical multi-filamentary tube type Nb3Sn strands. Schemes to apply this method to rod-restack-process (RRP) and powder-in-tube (PIT) strands are also proposed.

Speaker: Xingchen Xu (the Ohio State University)

11:45 AM Requirements for quadrupole magnet conductor for the United States contribution to the high-luminosity upgrade of the Large Hadron Collider

The LHC will undergo a replacement of the inner triplets at the two main interaction regions between 2020 and 2023. Leading up to this activity will be the production of approximately 90 quadrupole magnets starting in 2018, for which approximately 10 tons of Nb3Sn conductor will be procured. The lead time for this conductor requires orders to be placed starting in 2016. This presentation will outline the proposed production specification, its relationship to magnet functional requirements, and its evolution from previous “baseline” conductor designs supported by the LHC Accelerator R&D Program and the U.S. Conductor Development Program. In particular, we describe how certain design trade-offs and pre-production statistics were evaluated, and how these considerations were propagated through a change in the final conductor diameter to 0.85 mm and its cascading effect on sub-element number, copper fraction, and so on. The present specification strives to achieve a nexus of property distributions that guarantees ample production margin, high yield, and low cost.

Speaker: Lance Cooley (Fermilab)

12:00 PM Improvement of tube type Nb3Sn conductor in Hyper Tech

Tube type Nb3Sn conductor has been being explored by Hyper Tech Research Inc. Our standard conductor with 217 filament arrays have been generated with 12 T non-Cu Jc values of about 2400-2500 A/mm2 with filament size of 40 micros at the 0.85 mm strand. Recently we made 547 filament conductor which has filament size of 25 micros at the 0.85 mm strand without any drawing issue. We are working to improve the non-Cu Jc further. In this paper, creating artificial pinning centers has been used to increase flux pinning in order to raise the Jc overall in the 12-20T range within the tube type Nb3Sn strands. As a result, the artificial pinning centers refine the grain size by at least half, thereby increasing the layer Jc by at least 20%. Round Nb filament has been made to improve the filament array in the restack conductor to increase the reacted Nb3Sn area thereby increasing the Jc in the strand.

Speaker: Xuan Peng (Hyper Tech Research Inc.)

12:15 PM Digital evaluation of filament distortion and RRR degradation in drawn and rolled PIT and RRP® Nb3Sn wires

PIT and RRP® Nb3Sn strands are being studied as potential candidates for high field accelerator magnet upgrades for the LHC. It is well known that maintaining diffusion barrier integrity in these strands is vital to retaining adequate RRR for magnet stability. Here we report a quantitative study of the shape and position of filaments or sub-elements after rolling lengths of unreacted PIT and RRP® round wires to simulate cabling deformation. In the as-drawn condition shape deformation occurs preferentially in the outer ring filaments, increasing progressively with radial position, but rolling induces non-uniform shear bands that induce greater distortion of inner ring filaments. By making a full digitization of the shapes of all filaments, and by taking measurements of RRR, we find that a critical distortion occurs for thickness reductions between 10 and 20%. In this deformation range, the filament shapes transition from higher aspect ratio in outer filament rings to much larger aspect ratios in inner filament rings, especially in the vicinity of the strong 45˚ shear bands imposed by the rolling. We have benchmarked the deformation to determine a limit past which unacceptable damage has occurred, and will discuss how to best limit this damage, which inevitably leads to Sn leakage and RRR degradation when uncontrolled. Progress is currently being made toward an approach for accurate modeling and prediction of wire deformation in hopes of limiting degradation, thereby enhancing wire performance.

Speaker: Michael Brown (Florida State University)

Slides M2OrA-05-Brown.pdf M2OrA-05-Brown.pptx

11:00 AM → 12:30 PM M2OrB - Superconductor Wires I: Testing and Characterization

Conveners: Takanobu Kiss (Kyushu University), Tatiana Prikhna (Inst. for Superhard Materials of the Nat'l Academy of Sci. of Ukraine)

11:00 AM Non-destructive characterization of local Ic variation in a long length Bi-2223 tape

Spatial homogeneity of critical current, Ic, is one of the most important performances of practical HTS tapes. Such Ic homogeneity is typically characterized by the reel-to-reel transport measurement with a tap distance of several tens cm to several m. However, the spatial resolution is not enough in the conventional method to detect local Ic drop, especially in the case of Bi-2223 tape because of a small shunt resistance of the Ag sheath. In this study, we have succeeded in measuring in-plane Ic distribution in a commercial 100-m-class Bi-2223 tape with non-contact and non-destructive manner by using reel-to-reel high speed scanning Hall probe microscopy. This allows us to measure high resolution remanent flux image on the tape surface in liquid nitrogen bath with a spatial resolution of 34 um in width and 830 um in length. Traveling speed of the tape during the measurement was 36 m/h at maximum. By solving the inversion problem, we obtained in-plane Ic distribution in the tape. We have succeeded in analyzing Ic fluctuation over multi-scale length more than 5 decades. To check the validity of the Ic value, we also carried out site-specified four-probe measurements, then confirmed that these two measurements showed good agreement each other. Statistical behavior of the Ic fluctuation and the correlation with microstructure will be discussed. *This study was supported by the “JST: S-Innovation” and "JSPS: KAKENHI (24760235)”.*

Speaker: Takanobu Kiss (Kyushu University)

11:15 AM Irreversible tensile stress of 2G HTS wires made by IBAD-MOCVD on Hastelloy substrates

Irreversible tensile stress was experimentally studied at 77K self field for 2G HTS wires fabricated using the IBAD-MOCVD processes on Hastelloy substrates. The irreversible stress is a critical stress above which the critical current (Ic) retention of a wire is less than 99% of its original Ic after the complete release of the stress. As a characteristic electromechanical property, the irreversible stress defines a critical stress condition at which an unrecoverable mechanical damage to the superconductor starts. Irreversible stress as well as the corresponding irreversible strain was determined for different types of 2G HTS wires with variations in structure, specifically in the thickness of the substrate and/or stabilizer. The effect of the stabilizer to substrate thickness ratio on the irreversible tensile stress was analyzed, in combination with the basic tensile stress-strain relationships of the wires. It was found that the irreversible stress was dependent on a chord elastic modulus determined from the stress-strain curve. The measurement methodology of the electromechanical properties of 2G HTS wires under tension was also discussed.

Speaker: Dr Yifei Zhang (SuperPower Inc.)

Slides M2OrB-02-Zhang.pdf

11:30 AM Mechanical behavior of Bi2Sr2CaCu2O8+x wire with a detailed study of sample preparation techniques

High temperature superconductors (HTS) are an enabling technology for superconducting magnets generating magnetic fields greater than 25 T. The development of high field HTS magnets requires not only a conductor capable of carrying sufficient critical current density (Jc) at high magnetic field, but also one that is sufficiently strong to withstand the very large Lorentz forces and other stresses during fabrication, handling, and thermal cycling. Bi2Sr2CaCu2O8+x (Bi-2212) is the only HTS material available as round wire. Recently, significant progresses have been made to improve the Jc of Bi-2212 wire by use of over-pressure (OP) processing of the wire during heat treatment. This method has resulted in a more than doubling of the Jc of the wire to 640 A/mm2 at 4.2 K and 20 T. However, since Bi-2212 is a brittle material, the effect of these heat treatment changes on the mechanical properties of the material are not well understood. In this study, a double-restack Bi-2212/AgMg wire was heat treated using a partial melt processing in both pure O2 and Ar/O2 atmosphere at various pressures including 1 bar, 50 and 100 bar (OP). The wires then experienced various amount of mechanical strains in both tension and compression. The Bi-2212 wire properties are investigated in various conditions, including green wire, 1 bar and OP-heat treated wires pre- and post-applying mechanical strains. A detailed and efficient polishing procedure is developed to prepare scratch-free specimens and to prohibit introducing filament damages caused during preparation method. The relationships between sample preparation techniques and the filament microstructure, distribution of secondary phases including AEC and Cu-free, and various filament damages are studied using optical, scanning electron and confocal microscopy. *This work was supported by the DOE Award DE-FG02-13ER42036.*

Speaker: Dr Amir Kajbafvala (Materials Science Center, University of Wisconsin-Eau Claire)

11:45 AM Temperature dependence of critical current and transport current losses of 4 mm YBCO coated conductors manufactured using nonmagnetic substrate

AC losses in YBCO coated conductor tapes are one of the major heat load on the cryogenic systems in HTS cables, fault current limiters, and transformers. To reduce AC losses in tapes made using RABiTS process, a nonmagnetic substrate is being developed. Coated conductor tapes designed and manufactured using the new substrate have been characterized for critical current density and transport current losses at several temperatures between 63 and 77 K. Self-field critical current and transport current loss measurements were performed on several tape sections with the new nonmagnetic substrates and compared with regular RABiTS tapes. 4 mm wide tapes laminated by brass on both sides were measured. Temperatures below 77 K were achieved by pumping on liquid nitrogen and the temperature was controlled using a resistive heater and temperature controller. Loss measurements were performed at several frequencies in the 10 - 400 Hz interval. Critical current of the tape sections measured by standard four probe method was in 140 - 160 A range in the self-field at 77 K, and lowering of the temperature by 10 K the critical current increased by factor of two. Transport current losses were measured using a lock-in technique with compensation of inductive components. Measured transport current loss data were compared with Norris strip model. Results of the critical current and AC losses of the coated conductor samples with the new substrate will be discussed.

Speaker: Dr Sastry Pamidi (The Florida State University, Center for Advanced Power Systems)

12:00 PM The Development of Persistent joints for MgB2 Conductors

Two different routes have been developed for persistent joints in react and wind MgB2, relevant to MRI. The first uses superconducting solder, the second does not. The joints were developed using standard MgB2 multifilamentary in-situ type strand. Both joint types assumed a react and wind approach. Two types of tests were performed. The first type was a direct I-V (4-point) measurement of the joints. This measurement was made at 4.2 K in fields of up to 7 T, and also at self-field at temperatures up to 30 K. In the second, a persistent current was induced in a small coil and its decay measured. These measurements were performed at 4.2 K, but in some cases in the presence of a background field. Direct I-V measurements show R values of below 10-10 ohms, and an Ic above 100 A at 0.5 T and 4 K for the first joint type. The second joint type achieved 200 A at several Tesla and 4.2 K. Results of numerous direct I-V and several drift measurements are compared, and the utility for MRI systems is discussed.

Speaker: Mike Sumption (The Ohio State University)

Slides M2OrB-05-Sumption.pdf M2OrB-05-Sumption.pptx

12:15 PM AC LOSSES MODELS FOR LOW-TC SUPERCONDUCTORS

AC losses still represent an important heating source when operating superconducting magnets. This is even more the case when powering-up the superconducting magnet, even at DC currents. We have developed new methods to evaluate the heat produced by ac losses during powering procedures of superconducting magnets. These include the Bean model assuming the penetration in a cylindrical form, and also an approach with parabolic penetration, and general exponential penetration of the magnetic field (four sub-models). We then compare all the models between themselves and also with the classical models (Bean – flat and Wilson approach). 3D simulations were done for all the models considering several study cases for Nb3Sn and NbTi. These cases were selected bearing in mind the design options of a high to moderated field superconducting magnet (being designed for a new separating device), namely operating at 9T, 10T, 12T and 8T, 9T, 10T, respectively. All the models seem appropriate to describe the losses.

Speaker: Paulo Augusto (APLICAMA Research Group - Univ Salamanca - SPAIN)

12:30 PM → 2:00 PM Lunch (on your own)

2:00 PM → 4:00 PM C2PoG - Heat Exchangers

Conveners: Andrew Dalesandro (FNAL), Wolfgang Stautner (GE Global Research)

2:00 PM Testing of a 4 K to 2 K Heat Exchanger with an Intermediate Pressure Drop

Most large sub-atmospheric helium refrigeration systems incorporate a heat exchanger at the load, or in the distribution system in some cases, to counter-flow the sub-atmospheric return with the super-critical or liquid supply. A significant process improvement is theoretically obtainable by handling the exergy loss across the Joule-Thompson throttling valve supplying the flow to the load in a simple but different manner. As briefly outline in previous publications, the exergy loss can be minimized by allowing the supply flow pressure to decrease to a sub-atmospheric pressure concurrent with heat exchange with the flow from the load. One practical implementation is to sub-divide the supply flow pressure drop between two heat exchanger sections, incorporating an intermediate pressure drop. Such a test is being performed at Jefferson Lab’s Cryogenic Test Facility (CTF). This paper will briefly discuss the theory, practical implementation and test results and analysis obtained to date.

Speaker: Peter Knudsen (Jefferson Lab)

Slides Testing_of_a_4_K_to_2_K_HX_with_an_Intm_Press_Drop_-_Poster.pdf

2:00 PM → 4:00 PM C2PoH - Hydrogen Systems

Conveners: Jacob Leachman (Washington State University), John Barclay (Retired)

2:00 PM Design challenges of a 20kW liquid hydrogen cooling system for The European Spallation Source cold moderators.

A key feature of the target system at ESS will be the cold moderators. With the use of supercritical hydrogen at 17 K and1.5 MPa, the energy of the neutrons is reduced before they reach the instrument lines. The neutrons will deposit significant amounts of energy into the hydrogen that must be removed to maintain the hydrogen at its nominal operating temperature. The cooling for the hydrogen will be provided by the target moderator cryoplant (TMCP). This is the story behind the development of the world's largest LH2 cooling for a neutron source.

Speakers: Jesper Ringnér (ESS), John Jurns (European Spallation Source ESS AB)

Poster C2PoH-01-poster.pdf

2:00 PM Experimental investigation of 20 K two-stage layered active magnetic regenerative refrigerator

An active magnetic regenerative refrigerator (AMRR) is one of the useful technologies to improve the efficiency of hydrogen liquefaction process. The AMRR utilizes magnetocaloric effect to reduce the cold end temperature of the active magnetic regenerator (AMR). Since the magnetocaloric effect is a reversible process, it facilitates high thermodynamic efficiency of AMRR. However, the magnetocaloric effect only appears near the transition temperature. Therefore, in order to achieve a wide temperature span of the AMR, the layered AMR with four kinds of magnetic refrigerants (GdNi2, Gd0.1Dy0.9Ni2, Dy0.85Er0.15Al2, Dy0.5Er0.5Al2) has been considered. Because each magnetic refrigerant has different heat capacity, it is very important to determine the proper mass flow rate of the helium gas which is used as a heat transfer medium. In this paper, the performance of the two-stage layered AMRR is experimentally investigated. The test apparatus includes two-stage layered AMRs, low temperature superconducting (LTS) magnet which generates maximum magnetic field of 4 T, and the helium gas oscillating flow system. The mass flow rate of working fluid is controlled separately at the first and second stages of the AMR. Each mass flow rate at the cold end is measured by two hot-film sensors (1260A-10, TSI) calibrated at the cryogenic temperature (20 K ~ 80 K). The temperature span of the AMR is recorded 60 K and the performance of the AMR with the variation of the mass flow rate is analyzed. The results show that the mass flow rate of working fluid is a crucial factor in the AMR performance.

Speaker: Inmyong Park (KAIST)

Poster 2015_06_15_poster_CEC_inmyong.pdf 2015_06_15_poster_CEC_inmyong.pptx

2:00 PM Operational Experiences of J-PARC cryogenic hydrogen system for a spallation neutron source

At the J-PARC, the high-energy MeV-order neutrons, which are produced via a spallation reaction between 3-GeV protons and the mercury nucleus, are moderated to cold neutrons with MeV-order energy by passing them through a supercritical hydrogen moderator (1.5 MPa and around 20 K). The cryogenic hydrogen system, which provides it to three hydrogen moderators, has been completed in April 2008. We have encountered several troubles such as unstable operation of helium refrigerator due to some impurities, a leakage through a welded bellows of an accumulator, hydrogen pump impeller damage and so on until now. Furthermore, the Great East Japan Earthquake was occurred during the cryogenic hydrogen system operation in March 2011. The proton beam power has increased to 400 kW and stable long-lasting operation has been achieved for three months. A 530-kW proton beam operation has been completed on trial for a limited time of 60 s. In this paper, we describe the operation characteristics and experiences of the J-PARC cryogenic hydrogen system.

Speaker: HIDEKI TATSUMOTO (Japan Atomic Energy Agency)

Slides poster-CEC2015-operation.pdf

2:00 PM Performance evaluation of a developed orifice type heater for thermal compensation control at J-PARC cryogenic hydrogen system

The J-PARC cryogenic hydrogen system provides supercritical hydrogen with the para-hydrogen concentration of more than 99 % and the temperature of less than 20 K to three moderators so as to provide cold pulsed neutron beams of a higher neutronic performance. The nuclear heating is estimated to be 3.75 kW at the moderators for a 1-MW proton beam operation. The temperature rise is estimated to be 2.4 K at a circulation flow rate of 0.19 kg/s. There was concerned that the slight temperature rise would lead to a large pressure increase in the hydrogen loop since the supercritical hydrogen behaves as an incompressible fluid. Furthermore, temperature fluctuation of the feed hydrogen stream should be also reduced below 0.25 K because the neutron performance is affected by a hydrogen density change. We prepared a heater for thermal compensation and an accumulator, with a bellows structure, for volume control, so as to mitigate the pressure fluctuation caused by the proton beam on and off. We have developed a compact orifice type high-power heater and perform its performance evaluation during off and on beam operation. It is clarified through the commissioning processes that the heater control would be applicable for the 1-MW proton beam operation by extrapolating from the experimental data.

Speaker: HIDEKI TATSUMOTO (Japan Atomic Energy Agency)

Slides poster-ICEC24-heater0620.pdf

2:00 PM Pressure and temperature fluctuation simulation of J-PARC cryogenic hydrogen system

At the J-PARC spallation neutron source, high-energy MeV-order neutrons generated from a mercury target are reduced to the appropriate energy level (meV order) in three types of hydrogen moderators (coupled, decoupled, and poisoned).The J-PARC cryogenic hydrogen system provides supercritical cryogenic hydrogen to the moderators at a pressure of 1.5 MPa and temperature of 18 K and removes 3.8 kW of the nuclear heating for the 1 MW proton beam operation, when the nuclear heating is estimated to be 3.8 kW. The temperature rise is estimated to be 2.4 K at a circulation flow rate of 0.19 kg/s. We prepared a heater for thermal compensation and an accumulator, with a bellows structure, for volume control, so as to mitigate the pressure fluctuation caused by the proton beam on and off below the allowable pressure of 0.1 MPa because the slight temperature rise leads to a large pressure increase in the supercritical hydrogen loop because of its incompressibility. In this study, an 1-D simulation code has been developed to understand pressure and temperature propagation through the hydrogen loop when the proton beam is turned on and off. Pressure drop through each component was estimated using a CFD code, STAR-CD. Heat transfer of supercritical hydrogen was calculated using authour’s correlation. It was confirmed that the simulation results agreed with the experimental data under the same condition.

Speaker: HIDEKI TATSUMOTO (Japan Atomic Energy Agency)

Slides poster-CEC2015-simulation.pdf

2:00 PM The hydrogen circulation cold box of CSNS cryogenic system

CSNS cryogenic system offers 1.5 MPa hydrogen as a neutron moderator at 18 ~ 22 K, and the para hydrogen concentration is higher than 99%. Two cold boxes were adopted, one is hydrogen circulation cold box and the other is accumulator cold box. The main equipments in the hydrogen circulation cold box are ortho-para convertor, H2-He heat exchanger, hydrogen circulators and hydrogen heater. And the accumulator was arranged in the accumulator cold box. Design proposal of the CSNS hydrogen circulation cold box was analyzed, and the structure of the cold box was determined. Double-cold boxes with external instrument control cabinet were selected. This paper introduced the engineering design, strength check, thermal loss analysis and the processing technology of the two cold boxes.

Speakers: Dr Guoping Wang (Institute of High Energy Physics(IHEP)), Ms yaqiong wang (Institute of High Energy Physics)

Poster The_hydrogen_circulation_cold_box_of_CSNS_cryogenic_system.pdf

2:00 PM Thermo-physical performance prediction of the KSC Ground Operation Demonstration Unit for liquid hydrogen

The NASA Kennedy Space Center researchers have been working on enhanced and modernized cryogenic liquid propellant handling techniques to reduce life cycle costs of propellant management system for the unique KSC application. The KSC Ground Operation Demonstration Unit (GODU) for liquid hydrogen plans to demonstrate integrated refrigeration, zero-loss flexible term storage of liquid hydrogen, and densified hydrogen handling techniques. The Florida Solar Energy Center has partnered with the KSC researchers to develop thermal performance prediction model of the GODU for LH2. The model includes integrated refrigeration cooling performance, thermal losses in the tank and distribution lines, transient system characteristics during chilling and loading, and long term steady-state propellant storage. This paper will discuss recent experimental data of the GODU LH2 system and modeling results.

Speaker: JONG BAIK (FLORIDA SOLAR ENERGY CENTER)

Poster C2PoH-07[C10]_ppt.pdf

2:00 PM → 4:00 PM C2PoJ - Joule-Thomson Coolers

Conveners: John Pfotenhauer (University of Wisconsin - Madison), Michael Green (LBNL & FRIB/MSU)

2:00 PM Prediction of two-phase pressure drop in heat exchanger for mixed refrigerant Joule–Thomson cryocooler

The overall efficiency of mixed refrigerant Joule–Thomson (MR J–T) cryocooler is governed by the performance of recuperative heat exchanger which precools the refrigerant mixture prior to expansion in a J-T valve. In the heat exchanger, the hot stream of the mixed refrigerant undergoes condensation at high pressure while the cold stream gets evaporated at low pressure. The pressure drop in the low pressure stream is crucial since it directly influences the achievable refrigeration temperature. However, experimental and theoretical studies related to two-phase pressure drop in multi-component mixtures at cryogenic temperatures, are limited. Therefore, design of efficient MR J–T cryocooler is a challenging task due to lack of predictive tools. In the present work, the existing empirical correlations, which are commonly used for prediction of pressure drop in the case of pure refrigerants, evaporating at near ambient conditions, are assessed for the mixed refrigerants. Experiments are carried out to measure the overall pressure drop in the evaporating cold stream of the heat exchanger. The various mixture compositions of nitrogen and hydrocarbons are used to study the pressure drop variations. Several tests are conducted on simple tube-in-tube and multi tubes-in-tube helically coiled heat exchangers for the same mixture compositions. The predicted overall pressure drop in the heat exchanger is compared with the experimental data for both the heat exchangers. The suggested empirical correlations can be used to predict the hydraulic performance of the heat exchanger.

Speakers: Milind Atrey (Indian Institute of Technology Bombay), Dr P M Ardhapurkar (SSGMCE Shegaon, India)

Poster Poster-CEC_2015-Final_printed.pdf

2:00 PM Second-Law Analysis of a Cascade Joule-Thomson Microcooler

Cascade Joule-Thomson Microcoolers have been proposed in literature in which different compressors with low values of pressure ratio of order four using different working fluids are anticipated to drive the microcooler. A cascade of five stages is expected to provide cooling at a load temperature of 150 K. In this study a second-law analysis of such a microcooler is performed to quantify the effect of important design parameters representing the basic components and processes of the microcooler on its performance. The effects of several important design parameters including the effectiveness of all heat exchangers as well as the effect of possible pressure drop in the recuperative heat exchanger on cooling power and the exergetic efficiency of the microcooler are obtained. The inefficiency of the compressors is included using an exergetic efficiency parameter for the compressors. The heat transfer from each stage to other stages is modelled using an effectiveness parameter for the heat exchangers that can be varied to investigate their influence on cooling power and the efficiency of the microcooler.

Speakers: Mr Christopher Dodson (Air Force Research Labs), Mr Kyle Martin (Applied Technology Associates), Mr Tomas Fraser (Air Force Research Labs)

Poster CEC_2015_poster_JT.pdf CEC_2015_poster_JT.pptx

2:00 PM → 4:00 PM C2PoK - Instrumentation and Controls II

Conveners: Carl Kirkconnell (Iris Technology), Jack Sheldon (Scientific Instruments, Inc.)

2:00 PM Cryogenic thermometry for refrigerant distribution system of JT-60SA

JT-60SA is a fully superconducting fusion experimental device involving Japan and Europe. The cryoplant supplies supercritical or gaseous helium to superconducting coils through valve boxes (VBs) or coil terminal boxes (CTBs). There are 89 temperature measurement points at 4 K in VBs and CTBs. Resistance temperature sensors will be installed on cryogen pipes in vacuum. Two type of sensors and two installation methods were experimentally evaluated in terms of accuracy and manufacturability. The sensor in the well method is installed in a narrow stainless steel capillary which is inserted into a cryogen pipe. This method is relatively conventional and accurate measurement, but technical inspections have to be imposed because of machining and welding pipes. The sensor in the saddle method is installed in a copper block which is attached on a cryogen pipe by silver brazing. This method is easy to make and not necessary to conduct specific inspections, but relatively inaccurate measurement because of less thermal contact between the sensor and fluid. Two sensors installed on the pipe by each method have been examined at same time and compared with one reference sensor directly immersed in liquid helium in the pipe. The temperature of helium changes in the range of 3.34-5.06 K as an experimental parameter. The measured temperature difference between attached one and reference one has been within about 30 mK even by the saddle method. It is satisfied the accuracy requirement within 0.1 K.

Speaker: Kyohei Natsume (Japan Atomic Energy Agency)

Slides C2PoK-01_CEC2015.pdf C2PoK-01_CEC2015.pptx

2:00 PM First helium measurements with a new cryogenic flow meter

A new method for flow measurement in cryogenic systems was published recently. The caloric measuring principle is based on two analytical and linearly independent evaluation functions for the mass flow rate, both using the same temperature and heater power measuring data as input parameters. This enables a complete compensation of systematic errors, as well as in situ calibration of the flow meter during operation. The remaining measurement uncertainty, constituting only of random errors, is typically less than 1 % with regard to the actual flow rate. The Karlsruhe Institute of Technology and WEKA AG, Switzerland, are presently developing a commercial flow meter for application in helium cryostats. The flow meter, which consists of a cryogenic sensor and room temperature electronics, is designed for operating temperatures between 300 K and 4 K, for pressures up to 5 MPa and for helium flow rates of 0.2 to 12 g/s. The sensor design is compact, which enables the installation in most helium cryostat and transfer systems. This paper presents the results of first low-temperature experiments with supercritical helium, which were carried out in a control cryostat of the 2 kW helium refrigerator of the TOSKA test facility. The new flow meter was connected in series to an existing Venturi tube, which was used for reference measurements.

Speaker: Mr Andreas Janzen (Karlsruhe Institute of Technology, Institute for Technical Thermodynamics and Refrigeration)

Poster 150625_-_CEC2015-Poster.pdf

2:00 PM → 4:00 PM C2PoL - Thermal Fluids (Aerospace Applications)

Conveners: Adam Swanger (NASA Kennedy Space Center), David Plachta (NASA / GRC)

2:00 PM Astro-particle shielding superconducting magnet cryogenic design for space travel missions

For long term missions in deep space, a large superconducting toroid magnet to protect astronauts from ionizing radiations coming from Galactic Cosmic Ray is under studied in the frame work of the Space Radiation Superconducting Shield (SR2S) European project. This magnet is made of Titanium clad MgB2 superconductor to afford a bending power greater than 5 T.m at a cryogenic temperature of 10 K. A specific cryogenic system, combining both space and terrestrial technologies, is designed to cool down this 10 m long and 12 m diameter magnet. Two different types of cooling have been studied to maintain the superconducting magnet at 10 K. A V-groove sunshield is considered around the external side of the magnet to reduce the heat fluxes coming from the sun or planets. To optimized V-groove sunshield, several numerical simulations have been performed using surface-to-surface radiation solver from Fluent© CFD. The following parameters have been considered: number of layers, angle between multi-layer Insulation… To complete this design, pulse tube cryocoolers will be used to absorb the heat fluxes coming from the human habitat attached to the magnet. They will be linked on their first stage to the magnet and on their second stage to the surface of an 80 K thermal shield. Long cryogenic Pulsating Heat Pipe (PHP), using nitrogen as a working fluid, are pursued to be used as thermal link at the surface of the 80 K thermal shield. The cool down of the entire magnet, as a function of weight and possible material, is also presented when assembled in orbit or in case of quench in deep space.

Speaker: Bertrand Baudouy (CEA Saclay)

Poster SR2S_poster.pdf

2:00 PM Multi-slope warm-up calorimetry of Integrated Dewar-Detector Assemblies

Boil-off isothermal calorimetry of Integrated Dewar-Detector Assemblies (IDDA) is a routine part of their acceptance testing. In this traditional approach, the cryogenic liquid coolant (LN2, typically) is let to naturally boil and evaporate from the cold well to the atmosphere; the parasitic heat load is then evaluated as the product of the latent heat of vaporization and the "last drop" boil-off rate monitored by the mass flow meter. The inherent limitation of this technique is that calorimetry may be performed at only the fixed, namely boiling, temperature of the chosen liquid coolant. There is a need, therefore, in using other (often exotic) cryogenic liquids when calorimetry at other than 77K temperature is needed. Further drawbacks are related to the transitional type of last drop boiling manifesting itself in bubbles explosions and geysering; this results in uneven flow rate and also affects natural temperature gradient along the cold finger. Additionally, the mass flow meters are known to have limited measurement accuracy and repeatability. The above especially holds true for the advanced High Operational Temperature IDDAs typically featuring short cold fingers and working at 150K and above. The authors make adaptation of the well-known technique of dual-slope calorimetry. They show how the accurate calorimetry may be performed by precooling IDDA and comparing the slopes of the thermal transient processes during the warm-up at different trial added heat loads. Because of the simplicity, accuracy and ability to perform calorimetry literally at any temperature of interest, this technique shows good potential of replacing the traditional boil-off calorimetry.

Speaker: Dr Alexander Veprik (SCD)

Poster poster.pdf

2:00 PM Optimization of Cryogenic Chilldown and Loading Operation Using SINDA/FLUINT

A cryogenic advanced propellant loading (APL) system is being developed at NASA. The APL will be employed in a wide range of applications including autonomous cryogenic loading operations. The number of applications and a variety of loading regimes call for development of computer assisted design and optimization methods that will reduce time and cost and improve reliability of APL. An aspect of this development is modeling and optimization of non-equilibrium two-phase cryogenic flow in the transfer line. Previously, we reported on modeling the cryogenic chilldown and loading of the NASA-KSC testbed using SINDA/FLUINT. The model is based on the solution of two-phase flow conservation equations in one dimension and a full set of correlations for flow patterns, losses, and heat transfer in the pipes, valves, and at t-junctions. It was shown that the pressure, fluid and wall temperatures, obtained during chilldown of the facility were well represented by the model. For future cryogenic loading applications it is desired to optimize the entire chilldown process during system design. The objective of such an optimization could be multifold, including; (i) to attain system parameters that minimize chilldown time or (ii) minimize fluid loss. Many parameters may be varied during the optimization process. These include pipe sizing, valve opening and timing, for both flow valves as well as dump valves, pressure in the storage tank, etc. Currently an optimization procedure is being implemented in the existing KSC model to study the feasibility of such an approach in SINDA/FLUINT. Results of this development will be reported as well as refinement to the model since our last report. The optimization results will also be compared with those obtained using an unconstrained nonlinear optimization method applied to a homogeneous model of two-phase cryogenic flow.

Speaker: Dr Ali Kashani (Millennium Engineering & Integration Company)

Slides 2015_CEC_Poster_r1.pdf 2015_CEC_Poster_r1.ppt

2:00 PM Testing and analytical modeling for purging process of a cryogenic line

The purging operations for cryogenic main propulsion systems of upper stage are usually carried out for the following cases: 1) Purging of the Fill/Drain line after completion of propellant loading. This operation allows the removal of residual propellant mass; and 2) Purging of the Feed/Drain line if the mission is scrubbed. The lines would be purged by connections to a ground high-pressure gas storage source. The flowrate of purge gas should be regulated such that the pressure in the line will not exceed the required maximum allowable value. Exceeding the maximum allowable pressure may lead to structural damage in the line. To gain confidence in analytical models of the purge process, a test series was conducted. The test article, a 20-cm incline line, was filled with liquid hydrogen and then purged with gaseous helium (GHe). The influences of GHe flowrates and initial temperatures were evaluated. The Generalized Fluid System Simulation Program, an in-house general-purpose computer program for flow network analysis, was utilized to model and simulate the testing. The test procedures, modeling descriptions, and the results will be presented in the final paper.

Speaker: Ali Hedayat (NASA-MSFC)

Poster CEC2015-Presentation-for_publication2.pdf CEC2015-Presentation-for_publication2.pptx

2:00 PM → 4:00 PM C2PoM - Novel Concepts and New Devices II

Conveners: Patrick Adam (Washington State University), QuanSheng Shu (Retired Senior Scientist)

2:00 PM Effect of operating frequency and phase angle on performance of Alpha Stirling cryocooler driven by a novel compact mechanism

Literature suggests that Alpha configuration Stirling cryocooler shows better theoretical performance when compared with Gamma configuration cryocooler. However, this has not been confirmed experimentally due to non-availability of drive mechanism providing large stroke to diameter ratio for Alpha cryocooler. The concept of novel compact drive mechanism can be used to operate miniature Alpha Stirling cryocoolers. The drive mechanism allows the use of multi-cylinder system while converting rotary motion to reciprocating motion. A stroke to diameter ratio of three is chosen and the drive dimensions are calculated for four piston-cylinder arrangements with 90o phase difference between adjacent arrangements providing two Alpha Stirling cryocoolers working simultaneously. It is also possible to use the drive mechanism to drive two different configurations of Stirling cryocooler simultaneously viz., Alpha configuration and Gamma configuration with equal volume displacement for the compression space. Due to specific arrangement in this drive mechanism, the combined peak torque requirement falls by 26.81% below the peak torque needed when only one unit is considered separately, leading to use of a comparatively lower torque motor. For the thermodynamic analysis, second order cyclic analysis provides a simple computational procedure. Losses leading to decrease in refrigerating effect and increase in power requirement are calculated using appropriate equations from available co-relations for the conditions prevailing in the present system. The effects of phase angle between compressor and expander pistons as one parameter and the operating frequency as the other parameter, keeping other parameters fixed are presented in this paper. The maximum net refrigeration effect as well as COP is available at phase angle of 81o. However, in order to have a symmetrical system, the phase angle is fixed at 90o for both, the Alpha as well as Gamma cryocoolers. The cryocooler performance enhances with increase in operating frequency.

Speaker: Prof. SHRIDHAR BAPAT (Department of Mechanical Engineering, Indian Institute of Technology Bombay)

Poster C2PoM-02_poster.pdf

2:00 PM Estimation of magnetocaloric properties by using Monte Carlo method for AMRR cycle

Magnetic refrigeration uses solid magnetic materials as refrigerant without global warming gas and fluorocarbon. In addition, it is expected the higher efficiency than that of vapor refrigeration system. Active Magnetic Regenerative Refrigeration (AMRR) system has demonstrated as an environmentally attractive candidate in near room temperature. There are many studies for the magnetocaloric materials based on experimental results, however, few studies on the theoretical view, especially for the entropy property due to the magnetic interaction. Mean field theory is commonly used to calculate the properties of magnetocaloric materials, however, it is not in good agreement with the experimental data near the magnetic transition temperature. This is one of the issues to analyze the AMRR cycle by the computer simulation. In this study, we will take a different approach to estimate the magnetic properties more precisely by using the Monte Carlo method. We will compare the calculation results between classical mean field theory and Monte Carlo method for a typical magnetic material, and then, we will simulate the AMRR cycle by using this approach.

Speaker: Mr Ryosuke Arai (Environment and Energy Materials Division, National Institute for Materials Science)

Poster 241_poster.pdf

2:00 PM Liquid hydrogen Moderator optimization for Neutron Sources with high brilliance

Neutron scattering experiments benefit from an increasing brilliance of the neutrons supplied. In addition to more powerful neutron sources, the efficiency providing those neutrons is becoming more important. Focus of the report presented here is therefore the optimization of one of the key components, the cold moderator. A cold moderator is usually a pressure vessel, which is filled with liquid hydrogen. So far, only the pressure and the temperature as well as the vessel geometry have been optimized. However, the nuclear spin of the hydrogen molecules was not considered yet. Novel theoretical studies suggest that the nuclear spin of the hydrogen molecule strongly affects the efficiency of moderation process. Therefore, a concept is presented which allows the characterization of such liquid hydrogen moderators for the full range of ortho-to-para ratios.

Speaker: Yannick Bessler (Forschungszentrum Jülich)

2:00 PM → 4:00 PM C2PoN - Cryogenic Power Cables and Leads II

Conveners: Joseph Minervini (MIT), Thomas Nicol (Fermilab)

2:00 PM Liquid Nitrogen Spray Cooling for Superconducting Power Cable

Most modern-day high temperature superconducting (HTS) power systems are designed to immerse the entire cable in subcooled nitrogen, taking advantage of favorable thermal and electrical properties. This project investigates the use of nitrogen in two phases, gas and liquid. The latent heat of vaporization of nitrogen provides a means of absorbing heat leaked into the cryostat or generated in a power cable with without an associated temperature rise in the cryogen. Using this phase change approach cryostats of long length can be held at nearly constant temperatures using only fraction of the cryogen compared to a conventional sub-cooled liquid cryogen approach. This paper provides an overview of the demonstrator and its key design points, while discussing improvements planned for ongoing efforts.

Speaker: Dr Jacob Kephart (Navy)

2:00 PM Modelling and Testing of Fin-type Heat Exchangers for the ITER Current Leads

The ITER current leads will transfer large currents of up to 68 kA into the biggest superconducting magnets ever built. Following the development of prototypes and targeted trials of specific manufacturing processes through mock-ups, China is preparing for the series fabrication in ASIPP (Chinese Institute of Plasma Physics). A key component of the ITER HTS current leads are the resistive heat exchangers. Special R&D was conducted for these components at CERN and ASIPP in support of their designs. In particular several mock-ups were built and tested in room temperature gas to measure the dynamic pressure drop and compare to 3D CFD models. The benchmarking of the models on experimental data has helped in defining the proper modelling parameters. Finally this paper will also report on the results obtained during operation under nominal conditions on the heat exchanger sections of the ITER current lead prototypes.

Speaker: Pierre Bauer (ITER Organization)

Poster PB_CEC_2015_Poster_v2.pdf

2:00 PM Solid-cryogen-stabilized, cable-in-conduit superconductor cables

This paper considers the use of a solid cryogen as a means to stabilize, both mechanically and thermally, superconducting wires (MgB2, 2212 or 2G) within a dual channel cable-in-conduit (CIC) cable for use in AC applications, such as a generator stator winding. The cable consists of two separate channels; the outer channel contains the superconducting strands and is filled with a fluid (liquid or gas) that becomes solid at the device operating temperature. Several options for fluid will be presented, such as liquid nitrogen, hydrocarbons and other chlorofluorocarbons (CFCs) that have a range of melting temperatures and volumetric expansions (from solid at operating temperature to fixed volume at room temperature). Implications for the quench protection and conductor stability, enhanced through direct contact with the solid cryogen, which has high heat capacity, will be presented. We present options for filling and cooldown. For example, during cooldown, cold nitrogen gas could be pumped through the outer channel until the cable temperature reaches ~100 K. Liquid nitrogen would then be injected into the cable until the outer channel is filled with liquid, and cold helium gas would be pumped through the inner cooling channel (without the strands) until the cable reaches the target operating temperature, which may be in the range from 20K to 60 K. At this point, the cryogen in the stranded-channel will be solid, essentially locking the wires into the mechanical structure of the cable, preventing degradation due to mechanical deformation and providing enhanced thermal capacity for stability and protection. The relatively high heat capacity of solid cryogens at these lower temperatures (compared to gaseous helium) enhances the thermal stability of the winding. During operation, coolant flow through the open inner channel will minimize pressure drop.

Speaker: Leslie Bromberg (Massachusetts Institute of Technology)

Poster C2PoN-03_poster_complete.pdf

2:00 PM → 4:00 PM C2PoP - Mixed-Gas Properties

Conveners: Robert Boyle (NASA / GSFC), Ryan Taylor (Virginia Military Institute)

2:00 PM Contribution to the study of neon-nitrogen mixtures at low temperatures

Theoretical studies show that neon can influence the nitrogen phase diagram, lowering its triple-point temperature. The use of a neon-nitrogen mixture that could remain liquid at temperatures below the nitrogen triple-point (63.15 K) could solve some problems in the cryogenics field, namely to obtain a stable cryogenic fluid in the temperature range from 44 to 54 K, where no pure cryogenics liquids exist at all. This work consists of a contribution to the study of mixtures of neon and nitrogen at various compositions at low temperatures, in order to assess how far beyond 63.15 K can the temperature at which nitrogen solidifies be lowered. For this purpose, a thermosyphon-like pressure vessel was built, able to withstand pressures up to 25 bars and in which some experiments were performed. Indications that there may be a process of neon dilution in solid and liquid nitrogen are shown, as well as evidence of changes in the nitrogen phase diagram due to the introduction of neon, in comparison to a model that supposes no interaction between the two substances. Evidences of a change in the nitrogen triple-point temperature from 63.15 to 62.5 K are presented and discussed.

Speaker: Patrícia Borges de Sousa (LIBPhys, Physics Department, Faculty of Sciences and Technology, Universidade Nova de Lisboa)

Poster Poster

2:00 PM Visual investigation of solid-liquid phase equilibria for non-flammable mixed refrigerant

Mixed refrigerant (MR) which efficiently resolve the limitations of pure refrigerant for Joule-Thomson (J-T) cooling, draws a lot of attention from numerous researchers. Although MR can possess desirable characteristics for wide temperature range of cooling with partial evaporation and condensation, it has a significant operating challenge. Unlike hydrocarbon MRs, a non-flammable MR may have a fundamentally serious clogging problem at the J-T expansion part. This is due to the high freezing temperature of a constituent in the selected non-flammable MR. In this paper, the solid-liquid phase equilibria (i.e. freezing point) of the non-flammable MR which is composed of Argon, R14 (CF4), and R218 (C3F8), has been experimentally investigated by a visualized apparatus. Argon, R14 and R218 mixtures are selected to be efficiently capable of reaching 97 K in the MR J-T refrigerator system. Solid-liquid phase equilibria of mixtures have been tested with the molar compositions from 0 to 0.8 for each pure refrigerant. Each test result is simultaneously acquired by a camcorder for visual inspection and temperature measurement during a warming process. Experimental results show that the certain mole fraction of Argon, R14, and R218 mixture can achieve remarkably low freezing temperature even below 77 K. This unusual freezing point depression characteristic of the MR can be a useful information for designing a cryogenic MR J-T refrigerator to reach further down to 77 K.

Speaker: Cheonkyu Lee (KAIST)

Poster Poster_CEC_ICMC2015_KAIST_C2PoP-03.pdf

2:00 PM → 4:00 PM C2PoQ - Safety, Reliability, and Standards

Conveners: Adam Swanger (NASA Kennedy Space Center), Maciej Chorowski (Wroclaw University of Technology)

2:00 PM Final Report on the Controlled Cold Helium Spill Test in the LHC Tunnel at CERN

The 27-km circumference LHC underground tunnel is a confined space in which the helium-cooled LHC magnets are installed. The vacuum enclosures of the superconducting magnets are protected by over-pressure safety relief devices that open whenever cold helium escapes either from the magnet cold enclosure or from the helium supply headers, into this vacuum enclosure. A 3-m long no stay zone around these devices is defined, based on scale model studies, protecting the personnel against cold burns or asphyxia caused by such an eventual helium release. Recently several simulation studies have been carried out modelling the propagation of the helium/air mixture along the tunnel resulting from the opening of such a safety device, releasing a helium flow in the range between 1 kg/s and 0.1 kg/s. To validate these different simulation studies, real life mock-up tests have been performed inside the LHC confined space, releasing helium flow rates of 1 kg/s, 0.3 kg/s and 0.1 kg/s. For each test, up to 1000 liters of liquid helium were released under standard operational tunnel conditions. The data recorded include oxygen concentration, temperature and flow speed measurements, and video footage permit to assess qualitatively the visibility. These measurements were made in the up- and downstream directions, with respect to the ventilation flow, of the spill point in the LHC tunnel. This paper presents the experimental set-up under which these release tests were made, the effects of these releases on the atmospheric tunnel condition as a function of the release flow rate, and will discuss the modification to the personnel access conditions to the LHC tunnel that are presently implemented as a result of these tests.

Speaker: Mrs Laetitia Dufay-Chanat (CERN)

Poster PosterHespillC2PoQ.pdf

2:00 PM → 4:00 PM M2PoC - Superconductor Cables II: HTS

Conveners: Anna Kario (KIT), Milan Majoros (The Ohio State University)

2:00 PM Analytical Investigation in Bending Characteristic of Twisted Stacked-Tape Cable Conductor

The second generation High Temperature Superconductor (HTS) REBCO tapes are very attractive to various applications of transmission power cables and high field magnets. Cabling methods for the HTS tapes cabling such as Roebel Assembled Coated Conductor (RACC), Conductor-On-Round Core (CORC), Twisted Stacked-Tape Cable (TSTC) and a few other alternates have been proposed and are being investigated for high current, high field applications. We have been developing TSTC cabling method, which consists of stacking flat tapes and twisting them along the stack axis. This compact cabling technique using REBCO tapes is very useful for both power transmission and high field magnet conductors. TSTC conductors has been fabricated by several methods, including sheathing the tape stack with a copper tube and embedding the stack in single and multiple helical grooves formed in a circular rod. In the latter configuration, an untwisted stacked-tape cable or a twisted stacked-tape cable can be embedded in each groove. In real applications of a REBCO tape cable its bendability is very important to fabricate, transport a long cable and wind a magnet. We have experimentally examined bendability of a TSTC conductor. A TSTC conductor is bendable since it is twisted. In this paper bending characteristics of various TSTC conductors, such as a single stack 40-tape cable, double-channel and three-channel cables in a rod will be investigated by an analytical calculation method. Critical current degradation due to bending will be discussed. *This work supported by the U. S. Department of Energy, Office of Fusion Energy Science under Grants: DE-FC02-93ER54186.*

Speaker: Makoto Takayasu (MIT)

Poster ICMC_2015_M2PoC-01_Poster.pdf

2:00 PM Critical Current Properties of HTS Twisted Stacked-Tape Cable in Subcooled Liquid Nitrogen

Railway Technical Research Institute has developed superconducting cable applications for railway systems in Japan. Railway feeders of superconducting cables could significantly reduce the voltage decay. Therefore, DC HTS Electrification has various advantages, such as the reduction of transmission losses, the improvement of the regeneration factor, and the reduction of substations. From a practical application perspective in a railway system, a Twisted Stacked-Tape Cable (TSTC) has been focused on with its compact size and bendability. A 2 m long, 32-YBCO-tape (4 mm width) TSTC conductor with a 200 mm twist pitch was investigated at various temperatures near 77 K using subcooled liquid nitrogen. The measured critical current of the straight cable was 1.45 kA at 77 K which agrees with the expected values estimated from the self-field. By controlling the equilibrium vapor pressure, the temperature was changed from 64 K to 85 K. The critical currents of the TSTC conductor were varied from 3.65 kA at 64 K to 0.42 kA at 85 K by the vapor pressure of nitrogen bath. Temperature dependence agrees with that of 4 mm YBCO tape. These results encourage a compact Twisted Stacked-Tape Cable application in railway systems.

Speaker: Masaru Tomita (Railway Technical Research Institute)

2:00 PM Current sharing, quench, and normal zone propagation in YBCO CORC and Roebel cables

A two layer CORC (Cable on Round Conductor) cable, 156 cm long, was tested for stability and normal zone propagation at 77 K in liquid nitrogen bath. The cable was instrumented with potential taps and wires on each strand covering its central portion (i.e. excluding the end connections of the cable with the outside world). A heater was placed on top of the cable which allowed pulses of various powers and durations to be generated. DC transport currents of some percentage of the cable critical current were applied. During and after the heat pulse NZP was measured by a high speed data acquisition card (DAQ) controlled via LabView software. Shrinking as well as expanding normal zones have been detected. The cable showed a high degree of stability. It was able to carry a current of 0.58Ic with maximum temperature of 250 K for nearly 6 minutes and 0.635Ic with maximum temperature of 300 K for 1 minute without damage. The cable had relatively low current sharing, even with uninsulated strands. These results were compared to a Roebel cable measured for quench at 4.2 K in liquid helium and 10 T. It was mounted on a u-shaped holder and instrumented with voltage taps and a heater. This cable had intentional solder connections between the strands.

Speaker: Milan Majoros (The Ohio State University)

2:00 PM DESIGNING VAPOUR-COOLED AND FORCED-FLOW COOLED CURRENT LEADS FOR A NEW SEPARATING DEVICE

We are desiging a new separating device and among several other components we had designed vapour-cooled current leads. This current leads are based on a classical design (for proper stability and robustness of the full device that does not allow many degrees of freedom) and therefore made of Low-Tc material connected with copper wires and some parts of High-Tc material. Its design is calculated keeping in mind the heat transfer by diffusion to a vapour-cooled stream that surrounds the conductive materials. We have also designed forced-flow cooled current leads, for comparision purposes. The actual current lead heat influx is best determined in the vapor cooled mode. The design and the calculations performed, and also the background theory of the heat diffusion applied in this part of the device will be described.

Speaker: Paulo Augusto (APLICAMA Research Group - Univ Salamanca - SPAIN)

2:00 PM Measurements of magnetization of YBCO CORC and Roebel Cables at 4.2 K

Coated conductor YBCO cables are of interest for (among other applications) use in high energy physics accelerator magnets. In dipole and quadrupole magnets (where coated conductor YBCO cable may be used for a high field insert) field quality, especially at injection, is a key parameter, and limits the amount of acceptable magnetization in a cable. In this presentation a superconducting 3 Tesla cosine-theta racetrack dipole magnet was used to measure magnetization of coated conductor YBCO CORC and Roebel cables at 4.2 K and at low ramp rates of the applied magnetic field (< 1 Hz). A magnetometer consisting of a saddle-like pick-up coil and a nominally matched compensation coil (both wound using an insulated copper wire 0.1 mm OD) was used for magnetization measurements. The magnetometer allowed sample rotation with respect to the applied magnetic field direction. A calibration was made using calibration coils, of known magnetic moments, which mimic the current flow in the cables. Samples of 15 cm length were measured for a two layer CORC cable with six strands and a cable pitch of 34 mm and for a 30 cm twist pitch Roebel cable. The magnetization of CORC and Roebel cables are compared to each other and to the YBCO tape used in their manufacture. Hystertic losses were dominant over coupling losses for these cables.

Speaker: Milan Majoros (The Ohio State University)

2:00 PM Numerical and Experimental Investigation of the Electromechanical Behavior of REBCO Tapes and Cables

The Twisted Stacked-Tape Cable (TSTC) is one method for cabling flat REBCO tapes and may be a viable option for implementing high temperature superconductors in various applications including power transmission, fusion and high-energy physics. To fully characterize the electromechanical behavior TSTCs it is important to understand the performance of single REBCO tapes under various loading conditions. Tension and combined tension-torsion experiments on single REBCO tapes have been continued, from prior preliminary studies, to characterize three commercially available tapes of SuperPower, SuNAM and American Superconductor. To better understand how these loads affect the critical current of REBCO tapes a structural numerical finite element analysis was performed for single tapes and compared to the experimental data. In addition finite element analysis was also used to determine characteristic of a full scale TSTC after cabling.

Speaker: Nathaniel Allen (Tufts University)

Poster ICMC15_Poster_Allen_Final.pdf

2:00 PM Optimized and practical electrical joints for CORC type HTS cables

Within the Physics Department of CERN the development of CORC (Conductor on Round Core) type HTS cables is pursued in view of possible application in future detector and fusion magnets. An important issue is the design and qualification of terminations that connect CORC cables mutually or to bus-bar systems. A termination design is envisaged which combines a simple manufacturing process with a lowest possible joint resistance in the few nano-ohm range at 4.2 K, first for a single CORC cable and subsequently for a six-around-one CORC based Cable-in-Conduit Conductor. For the investigations a first 12 meter long single CORC cable of 38 tapes was manufactured at the company Advanced Conductor Technologies (ACT) in Boulder, Colorado that can carry 8 kA at 10 T and 4.2 K. Another 2 m long cable with 28 tapes was manufactured as well for testing joints. The investigation is on the effect of tapering the CORC cable within the joint to form a staircase like geometry on each end of the cable, which allows current to pass directly from the copper casing to the inner HTS tape layers within the CORC cable. Simulations have shown a substantial decrease in joint resistance at operating current in the case both CORC cable and join casing are tapered. Joint manufacturing has to cope with typical problems as delamination of the ReBCO tapes and the formation of gas-bubbles inside the joint as both cause an increase of electrical resistance between layers of ReBCO tapes and between the CORC cable and the copper casing. Various soldering alloys and filling techniques have been evaluated. The CORC cable samples and various terminations were tested at CERN. In this paper, various termination designs, the manufacturing process and experimental results are summarized.

Speaker: Tim Mulder (CERN / Twente Technical University (NL))

Poster Mulder_-_CORC_Joints_-_CEC-ICMC2015_-_Poster.pdf

2:00 PM → 4:00 PM M2PoD - Cryogenic Materials IV: Physical Properties

Conveners: Arend Nijhuis (University of Twente), Dick Reed (Cryogenic Materials, Inc.)

2:00 PM Low-temperature negative thermal expansion in Al doped La(Fe,Si)13 compounds

Negative thermal expansion (NTE) materials, which contract rather than expand when heated, can be blended with materials showing positive thermal expansion to form composite for obtaining precisely tailored thermal expansion coefficient. Low-temperature NTE materials have wide potential applications in cryogenic engineering. The NaZn13-type La(Fe,Si)13-based compounds are recently developed as promising NTE materials, the NTE properties of which, in this study, were modified by doping minor Al element in order to make it more suitable for practical applications in cryogenic engineering. The results indicate that the NTE operation-temperature window shifts toward a lower temperature region due to the decrease of the Curie temperature (Tc) with increasing the amount of Al element in LaFe11.5Si1.5-xAlx compounds. Furthermore, the NTE operation-temperature window of LaFe11.5Si1.5-xAlx was broadened with increasing Al content. Such La(Fe,Al,Si)13 compounds with noteworthy NTE properties in low temperature region promote their potential applications for cryogenic equipments and precise instruments.

Speaker: Mr Rongjin HUANG (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, P.R. China)

Poster Poster-CEC_ICMC_2015-Li_Shaopeng.pdf Poster-CEC_ICMC_2015-Li_Shaopeng.pptx

2:00 PM Relationship between the Thermal Expansion and Spontaneous Magnetization in LaFe13-xAlx (1.2≤x≤1.8) Rare Earth Intermetallic Compounds

The Fe-based NaZn13-type compounds LaFe13-xMx (M=Si, Al) have attracted considerable attention because of their intriguing properties, such as magnetocaloric effect and abnormal thermal expansion. These unusual properties are of fundamental interest and have potential technical applications in cryogenic engineering when related materials operate in low temperature environment. The thermal expansion coefficient and spontaneous magnetization of rare earth intermetallic compounds LaFe13-xAlx (1.2≤x≤1.8) have been investigated and relationships between them were considered. Results indicate that LaFe11.6Al1.4 and LaFe11.4Al1.6 show near zero thermal expansion behavior from room temperature to liquid helium temperature. And it has been found that the spontaneous magnetostriction is proportional to the square of the spontaneous magnetization, which proves that the thermal expansion has a close relation with the spontaneous magnetization.

Speaker: Mr Rongjin Huang (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, P.R. China)

Poster Poster-CEC_ICMC_2015-Zhao_Yuqiang.pdf Poster-CEC_ICMC_2015-Zhao_Yuqiang.pptx

2:00 PM Study of Thermocurrents in SCRF cavities via measurements of the Seebeck Effect in niobium, titanium, and stainless steel thermocouples

The goals of Fermilab’s Superconductivity and Radio Frequency Development Department are to engineer, fabricate, and improve superconducting radio frequency (SCRF) cavities in the interest of advancing accelerator technology. Improvement includes exploring possible limitations on cavity performance and mitigating such impediments. This report focuses on investigating and measuring the Seebeck Effect observed in cavity constituents titanium, niobium, and stainless steel arranged in thermocouples. These junctions exist between cavities, helium jackets, and bellows, and their connection can produce a loop of electrical current and magnetic flux spontaneously during cooling. Such currents could induce trapped flux in cavity surfaces, and lead to loss of quality factor after cool down. Our findings show that welded junctions behave differently than intrinsic junctions, perhaps due to inter-diffusion of elements. An estimate of thermally-induced current is made from the observed voltages and resistivity of the components.

Speaker: Victoria Cooley (University of Wisconsin-Madison)

Poster ICMC_poster.pdf

3:00 PM → 3:30 PM Afternoon Break

4:00 PM → 5:45 PM C2OrE - Cryogenic Systems II

Conveners: Arkadiy Klebaner (Fermilab), Xilong Wang (European Spallation Source ESS AB)

4:00 PM The Evolution of the Cryogenic System of the European Spallation Source

The European Spallation Source (ESS) is an intergovernmental project building a multidisciplinary research laboratory based upon the world’s most powerful neutron source to be built in Lund, Sweden. The ESS will use a linear accelerator which will deliver protons with 5 MW of power to the target at 2.0 GeV with a nominal current of 62.5 mA. A cryomodule test stand will be supplied with helium for the site acceptance tests. The target will have two moderators using supercritical hydrogen to cool down the neutrons. The neutron instruments and the experiments’ sample environment will use liquid helium and liquid nitrogen to cool detectors and samples. The ESS cryogenic system is designed to deliver cryogenic cooling capacity to all four client system. A first concept of the ESS cryogenic system was developed in 2010 and 2011 with a limited amount of input from the clients as well as from site infrastructure (i.e. buildings and utilities). The design had to be flexible enough to accommodate future changes in scope, schedule and available infrastructure. Over the following years the design has evolved together with these parameters to achieve a maturity today which allowed us to order the accelerator cryoplant and to start procurement of many of the other parts of the ESS cryogenic system. This paper presents the evolution of the design throughout the years and the factors influencing certain design choices, focusing on external design aspects, such as requirements for buildings and utilities.

Speaker: Mr Wolfgang Hees (European Spallation Source ESS AB)

Slides 2015-06-30_The_Evolution_of_the_Cryogenic_System_of_ESS_HEES.pdf

4:15 PM Cryogenic infrastructure supplied by Linde Kryotechnik AG for the Series Magnet Test Facility for FAIR

In order to test the fast-ramped superconducting magnets for FAIR (Facility for Antiproton and Ion Research), a cryogenic test facility with an equivalent overall capacity of 1.5 kW at 4.4 Kelvin was designed and commissioned at GSI Helmholzzentrum für Schwerionenforschung GmbH. For efficient testing of the 108 dipole magnets the cryogenic infrastructure consists of a refrigeration system and four main test benches. Due to the different operating modes and load fluctuations a dedicated process and control concept was developed which allows an independent operation of each test bench and ensures highest efficiency over the whole operating range. The system is designed in a way that one magnet can be cooled down to its operating temperature while simultaneously another magnet is kept at cold state for the measurements. The third and fourth test benches serve for warming up and exchanging the magnets respectively. The high flexibility of the set-up moreover allows the testing of other FAIR magnets like the SIS100 quadrupole modules or the operation of a string configuration. The project was executed in a close collaboration between GSI and Linde Kryotechnik AG. The presentation will show the key solutions of the refrigeration system and the test benches and highlight some commissioning results.

Speaker: Mr Jan Hildenbeutel (Linde Kryotechnik AG)

Slides Series_Test_Facility_for_FAIR._Hildenbeutel.pdf

4:30 PM Performance analysis of cryogenic system and cryomodules for the complete superconducting linear accelerator at IUAC, New Delhi.

The heavy ion superconducting linear accelerator as a booster of 15 UD pelletron accelerator is commissioned and operating for more than a year. The acceleration is achieved by a series of superconducting quarter wave bulk niobium cavities at 4.2 K. In the first phase, accelerator was partly commissioned with 8 cavities in first linac cryomodule along with superbuncher and rebuncher. In the second and final phase two more linac cryomodules with eight cavities each were installed in beam line. New helium refrigerator of Linde make LR 280 along with the additional section of liquid helium distribution line were integrated with existing CCI make helium refrigerator. The cooling philosophy for five beam line cryomodules with the new refrigerator was modified to have faster cooling rate of 20 – 25 K of the cavities against earlier 8- 10 K/hr in the critical zone of 150- - 70 K. Pressure fluctuation in the helium vessel of cavities was reduced significantly to avoid frequent breaking of RF locks. The paper will discuss in detail about the performance of new cryogenic system and the cryomodules during beam acceleration run. A detailed experimental analysis on thermal response of helium refrigerator with variable heat load from the cavities will be reported.

Speaker: Dr Tripti Sekhar Datta (Inter- University Accelerator Centre. New Delhi. India)

Slides C2OrE-04.pdf C2OrE-04.ppt

4:45 PM Cryogenic Supply for the Facility for Antiproton and Ion Research

At the site of the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt (Germany) the international accelerator Facility for Antiproton and Ion Research (FAIR) is currently under construction. FAIR is going to be one of the largest research facilities worldwide. In its accelerator chain there will be two large machines with superconducting magnets, the heavy-ion synchrotron SIS100 and the isotope separator SuperFRS, with a total helium cooling inventory of more than 8 tons, as well as several experiments and small users of liquid helium. Altogether 108 dipole magnets for the SIS100 have to be tested in advance in the recently commissioned Series Test Facility (STF) at GSI. The liquid helium supply for FAIR will be provided by one large refrigerator with a capacity of 25 kW (4.3 K equivalent), a cool-down and warm-up unit (CWU) with a capacity of 80 kW (at 80 K), and by several small refrigerators and liquefiers located over the FAIR campus, combined with approximately 1.6 km of transfer lines. In this presentation the progress of the cryogenic infrastructure at FAIR will be presented with a focus on the magnet testing, the distribution systems, and the large cryo plants.

Speaker: Holger Kollmus (GSI Helmholtzzentrum für Schwerionenforschung GmbH)

Slides CEC2015_Kollmus.pdf CEC2015_Kollmus.pptx

5:00 PM Cryogenic System for Turkish Accelerator Center

The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is proposed as the first facility of Turkish Accelerator Center (TAC) Project. It aims to be the first user laboratory in the region of Turkey in which both electromagnetic radiation and particles will be used. Main purpose of the facility is to use IR FEL for research in material science, nonlinear optics, semiconductors, biotechnology, medicine and photochemical processes. TARLA will use TESLA type superconducting linear accelerators operating at 1.3 GHz. Electrons will be After pre-acceleration by two normal conducting RF cavities, electron main acceleration system consists of two ELBE designed 20 MeV superconducting linear accelerator modules (cryo-modules) which can be operated in continuous mode. AL-AT (Air Liquide Advanced Technologies) takes part to the project by supplying cryogenic plant for 2K sub atmospheric superconductive cavity operation. The plant includes the He refrigerator associated to its compressor station, a Dewar, a storage tank for helium gas and transfer lines. In addition, an in-house cold compressor associated to ambient temperature helium vacuum pumps was designed to generate 2K Helium flows. Customized HELIAL MF has been designed and manufactured by AL-AT to match the refrigeration power need for the TARLA project which is around 200 W at 2 K.

Speaker: Simon CRISPEL (AIR LIQUIDE)

Slides C2OrE-06-TAC_Crispel.pdf

5:15 PM Local Cryogenics for the SIS100 at FAIR

In the coming years a new international accelerator Facility for Antiproton and Ion Research (FAIR), one of the largest research projects worldwide, will be build close to Darmstadt in Germany. FAIR will provide antiproton and ion beams with unprecedented intensity and quality. One of its major accelerators will be the SIS100 having a circumference of about 1100 meters. The SIS100 tunnel will house a complex cryogenic system supplying up to 20 kW cooling capacity @ 4 K to about 300 superconducting magnet modules and further physics equipment. The SIS100 local cryogenic system can be principally divided into three sections each fed from a separate Feed Box. Each Feed Box supplies 4 K helium for magnet and bus-bar cooling as well as 50 K helium for the current lead and thermal shield cooling to the left and right part of such a section which comprises one sixth of the ring. Each sextant consists of a cold arc and a straight warm section. By-pass Lines circumvent the straight warm sections of SIS100 to supply helium and cold electrical connections to the superconducting quadrupole doublets within these sections. The purpose of such an infrastructure is to be able to separate the ring into six sections which can be independently cooled down, warmed up and serviced. The By-pass Lines are polish in-kind contribution, coordinated by the Jagiellonian University of Krakow and will be designed, manufactured and commissioned by the Wroclaw University of Technology. The design and the first manufactured components will be presented.

Speaker: Thomas Eisel (GSI)

Slides 20150625_CEC_EISEL.pdf 20150625_CEC_EISEL.pptx

5:30 PM Helium Sourcing ... Calmer seas ahead ?

What was the last year Helium market figure ? How has changed the worldwide Helium sourcing balance and "center of gravity" ? Do we have to expect a continuous shortage period for the next 10 years or, on the contrary, will the market be over-supplied by the next coming large scale production units ? Facts will be presented on all these questions, view is given by Air Liquide, one of the world major Helium suppliers. Market repartition regarding Helium uses focused on cryogenic & scientific applications will also be given to illustrate how this domain can play a role on Helium projected needs.

Speaker: Mr David Grillot (Air liquide)

Slides C2OrE-08-Beauvisage.pdf C2OrE-08-Beauvisage.pptx

4:00 PM → 6:00 PM C2OrF - Superconducting Magnets II

Conveners: Luisa Chiesa (Tufts University), Michael Green (LBNL & FRIB/MSU)

4:00 PM [Invited] Superconducting Detector Magnets for the proposed 100 TeV Future Circular Collider

In February 2014 CERN launched a design study for a future 100 TeV circular proton-proton collider with collision energy 7 more than in the present Large Hadron Collider. A new 100 km circular tunnel for the collider is foreseen as well as at least two new general purpose detectors. The study will materialize as a conceptual design report is to be issued in 2018 and eventually leading to operation earliest medio 2040. The increase in collision energy from 7 to 100 TeV enforces a scaling up of the detector magnets in size and magnetic field for maintaining particle detection resolution. Options for the new detector magnet systems are being explored. Following the present largest detectors ATLAS and CMS, the study covers scaling up of the ATLAS magnet system layout based on using toroids for muon tracking and a solenoid for the inner detector. Also two dipole magnets are incorporated for covering the low angle forward directions. In a similar way the second option features a scaled-up CMS solenoid but also in combination with two dipole magnets. The outer dimensions of the magnet systems show a diameter of 20-30 m and an overall length of 40 to 50 m. The magnetic field in the bores of the large toroid and solenoid will go up to some 2.5 and 6 tesla, respectively, with peak magnetic fields in the 7-8 tesla range, still possible with NbTi technology. The magnetic stored energies are in the record range of 40-70 GJ.

Speaker: Prof. Herman H. J. Ten Kate (CERN - Physics Department)

Slides TenKate_-_FCC_Detector_Magnets_-_Invited_Oral_CEC-ICMC2015_(30June2015).pdf

4:30 PM Performance of the cold powered diodes and diode leads in the main magnets of the LHC

During quench tests in 2010 variations in resistance of an order of magnitude were found in the diode by-pass circuit of main LHC magnets. An investigation campaign was started to understand the source, the occurrence and the impact of the high resistances. Many tests were performed offline in the SM18 test facility with a focus on the contact resistance of the diode to heat sink contact and the diode wafer temperature. In 2014 the performance of the diodes and diode leads of the main dipole bypass systems in the LHC was assessed during the so-called CSCM test. In the test a current cycle similar to a magnet circuit discharge from 11 kA with a time constant of 100 s is performed. Resistances of up to 400 µΩ have been found in the diode leads at intermediate current, but in general the high resistances decrease at higher current levels and no signs of overheating of diodes have been seen and the bypass circuit passed the test. In this report the performance of the diodes and in particular the contact resistances in the diode lead are analysed with available data acquired over more than 10 years from acceptance test until the CSCM test in the LHC.

Speaker: Dr Gerard Willering (CERN)

Slides 2015-CECICMC-Diode_performance-V1.0.pdf 2015-CECICMC-Diode_performance-V1.0.pptx

4:45 PM Dimensional Changes of Nb3Sn Cables during Heat Treatment*

The LHC-Accelerator Research Program (LARP) has been designing and fabricating R&D magnets for the High Luminosity Upgrade (U.S.- Hi-Lumi) for over ten years. The magnets require keystoned Nb3Sn Rutherford cables in minimum unit lengths of up to 500 m. The cables are fabricated from wires with different diameter and filament layouts of RRP® fabricated by Oxford Superconducting Technology. During heat treatment the cable dimensions change: the cable typically becomes thicker, wider, and shorter, if not constrained. This paper compares the dimensions of cables in a reacted potted coils to those measured on cables reacted in tooling that leave the cable un-constrained. *This work was supported by the Director, Office of Science, High Energy Physics, U.S. Department of Energy under contract Nos. DE-AC02-05CH11231 and DE-AC02-98CH10886.*

Speaker: Ian PONG (L)

Slides ICMC_2015_C2OrF3_Pong_-_Dimensional_Changes_of_Nb3Sn_Cables_during_Heat_Treatment_v1.1.pdf ICMC_2015_C2OrF3_Pong_-_Dimensional_Changes_of_Nb3Sn_Cables_during_Heat_Treatment_v1.1.pptx

5:00 PM Design and manufacture of the large-bore 8T superconducting solenoid for the NAFASSY test facility

A wide bore superconducting solenoid is the core of the NAFASSY (NAtional FAcility for Superconducting SYstems) test facility, which is under construction at the University of Salerno. The NAFASSY laboratory is a joint program among University of Salerno, ENEA, CRdC and INFN under the financial support of the Italian Ministry for University and Research. The facility, hosted in a new building, includes a 250 W supercritical He refrigerator, a 20kA two quadrants (-20V, +25V) power converter for feeding the solenoid or INFN fast ramped accelerator magnets, and a 50kA/+12V power supply for the testing sample. The completion and the commissioning of the facility is foreseen within 2016. The NAFASSY magnet is a large-bore Nb3Sn solenoid, able to provide a peak field of 8 T close to the insert inner radius. Having a warm bore diameter of 1144 mm and a height of 1276 mm, the solenoid will allow to perform tests relevant for long size NbTi or medium-field Nb3Sn Cable-In-Conduit Conductors (CICCs), as well as small magnets, at variable temperature (ranging from 4.2 K to 10 K) in the presence of a transverse magnetic field. In fact, the warm bore makes the sample under test to be independent of the background solenoid. The design of the magnet is based on a rectangular CICC, cooled by forced flow supercritical He at 4.5 K and fed at a maximum current of 20 kA through a pair of high temperature superconductors current leads. The detailed design of the 8T solenoid, including the electro-magnetic, structural and thermo-hydraulic analysis, will be reported, as well as the production status.

Speaker: Dr Antonio della Corte (ENEA - C.R. Frascati, Italy)

slides.pdf

5:15 PM Testing of a sub-scale HTS coil for wind turbine generator

Large power direct drive superconducting generators for off-shore wind turbines show promise for competitive cost of energy and would enable the deployment of wind turbine outputting 10 MW or more. As part of an ARPA-e project, a 10 MW generator was optimized based on YBCO excitation coils. The rotor is using an iron core in order to reduce the amount of HTS required and lead to an acceptable cost of energy. A subscale HTS coil was fabricated using off-the-shelf YBCO tapes as a demonstrator. This paper deals with the testing of the HTS coil between 77 K and 25 K. The coil is 0.65 meter long and 0.32 meter wide. It is composed of about 100 m of YBCO tape from Superpower. The coil is conduction cooled using an AL325 cryocooler; the experimental setup will be described in detailed as well as the electromagnetic and thermal analysis of the coil. The experimental results consist in Ic measurements at different temperature and voltage monitoring of the 4 sections of the coil to identify and potential conductor motion or mechanical structure degradation.

Speaker: Philippe Masson (University of Houston)

Slides C2OrF-05-Masson.pdf C2OrF-05-Masson.pptx

5:30 PM Quench Characteristics of Conduction-cooled 6T NbTi Magnet System