Abstract
The vacuum mass spectrometer is a kind of vacuum gauge for partial pressure measurement. For many vacuum applications, the partial pressure for given gas is of more interest than the total pressure of the gases in a system. If precise measurement of the partial pressure is needed, the calibration of mass spectrometer is necessary. However, the sensitivity for one gas in a mixture was...
The Nitinol (acronyms for NiTi Naval Ordnance Laboratory) is quasi equiatomic alloy of Ni-Ti known for its properties of shape memory, superplasticity, strength and biocompatibility. It is the most widely used form memory alloy in the production of biomedical devices. However, the presence of Ni in metallic or oxidized form on its surface or the release of it from the core of the alloy is a...
Alumina ceramics vacuum chambers are used in half the area of the whole ring in the J-PARC RCS to reduce eddy current effects due to rapidly varying magnetic field. The cross sections of these chamber are race track and circular used in dipole magnets, in quadrupole magnets, respectively and the chambers which are installed in injection magnets have several kinds of cross section which are...
The new Advanced Rare Isotope Laboratory (ARIEL) is TRIUMF's flagship facility that will expand Canada's capabilities to produce and study isotopes for physics and medicine. Utilizing next-generation technology, it will showcase a made-in-Canada, high-power superconducting electron accelerator to produce exotic isotopes for research and development.
ARIEL will produce radioactive isotopes by...
Calibration and operation of total pressure gauges and residual gas analysers for UHV beamlines at CERN.
The vacuum systems of CERN amount to 120 km of beam lines; half of that length needs UHV to fulfil the particle beam requirements. Along the accelerators, dedicated pressure gauges and residual gas analysers are deployed for online gas density monitoring. The calibration of such...
"PETRA III is a third generation, 2.3 km long synchrotron radiation source. While initial studies for a conversion of PETRA III towards a diffraction-limited storage ring are ongoing, first ideas on the vacuum performance are assessed in this paper. Comparative simulations between preliminary magnetic lattice upgrades and MAX IV are performed using simplified geometries and ray-tracing,...
Primary absolute pressure standard of Russia in the range of 0,1-1000 Pa is a laser interferometric oil manometer. In the higher part of the range the oil's density uncertainty gives the main contribution to the standard’s uncertainty. The oil's density is measured at normal conditions (atmospheric pressure), but the real density value at the working pressure is less due to the liquid...
The Future Circular Collider electron-positron accelerator (FCC-ee) is one of the many proposals under study by an international collaboration under the framework of the Future Circular Collider study. The aim is to produce a conceptual design report (CDD) by end of 2019, to be used by CERN management and its governing bodies as an input to the next European Strategy for particle physics...
Electron cloud mitigation will be critical for the Future Circular Collider (FCC) and it has been specified that the wall material needs to have a Secondary Electron Yield (SEY) < 1. The baseline material for electron cloud mitigation will be Laser Ablated Surface Engineering (LASE) of Copper on the beam screen. The FCC will have a beam screen with T between 20 and 60 K therefore the...
Non Evaporable Getter (NEG) has been employed extensively in the particle accelerator especially where the conductance of the vessel is severely restricted and ultra-high vacuum condition is required. NEG coating will significantly reduce the rate of outgassing and at the same time provides active pumping surface for H2, CO and CO2. In addition, it has been proven that NEG coated surfaces have...
In recent years, the non-evaporable getter (NEG) thin film coating technology, have been developed for LHC project in 90s, is extensively used on world’s accelerator vacuum chambers, especially in ultralow emittance storage rings and in small gap insertion device vacuum chambers. The main advantages of using NEG coatings are distributed pumping speed, low thermal outgassing, low...
The ITER Tokamak, designed to study deuterium-tritium fusion reactions and to demonstrate its viability as a sustainable and clean energy source, is currently being built in South France, on Cadarache site. Its vacuum system, one of the largest and most complex vacuum systems ever to be built, requires several hundred of vacuum sensors for the pressure monitoring of its high vacuum...
The growing numbers of missions for exploration of deep space environment has put forward complicated challenges for the field of vacuum metrology. Some suggests that to use ‘shield’ for protection of the vacuum gauges from external environment, especially temperature which affect the vacuum manometer reading significantly. However, the shield leads to increased mass, volume, power consumption...
Copper is often used as thin film substrate in particle accelerators, in particular for non-evaporable getters and niobium. The native copper oxide, formed on the copper surface at room temperature in air, consists mainly of cuprous oxide Cu2O. This compound is very stable and can dissociate or sublimate only at high temperatures. However, baking copper under ultra-high vacuum at 250C-300C is...
Non-evaporable Getter (NEG) thin films have been widely used for ultrahigh vacuum applications, since the NEG coated vacuum chambers can function as a ‘local distributed pump’ after thermal activation. This is especially useful for conductance limited vacuum chambers, such as normally found at the particle accelerators. The NEG coated stainless-steel vacuum chambers have been used at the...
The vacuum chambers of the LHC’s arcs operate in a temperature range between 1.9 K, i.e. the temperature of the superconducting magnets, and 20 K. At such low temperatures, most of the residual gas species are efficiently adsorbed on the cold surface.
LHC’s beam emits synchrotron radiation inside its bending magnets and, consequently, electrons are extracted from the surrounding walls by...
In 2017, LHC overcame the target for integrated luminosity achieving the goal of 125 fb-1 since the start of its operation. All along this period LHC vacuum system successfully faced the challenge of the pressure instabilities generated by electron clouds. In this framework Electron Stimulated Desorption (ESD) studies revealed to be fundamental for dynamic pressure prediction and...
Considerable attention has been paid to elucidate the electronic properties of organic semiconductors in bulk and at interface for the basic understanding and the potential application to organic-based devices such as organic field-effect transistors, organic light emitting diodes, etc. The -conjugated hydrocarbons composed of fused benzene rings are typical organic semiconductors with high...
Vacuum system of the RAON heavy ion accelerator has been designed to meet local vacuum requirements based on the pressure rise due to the stimulated desorption by scattered ions interacting with residual gases. Main pumps of warm section, of which the target pressure is 5x10-9 mbar, between cryomodules will be of NEG type which has merits such as a large effective pumping speed if installed...
1.Introduction
The fabrication of g-C3N4 nanosheets is considered to be an effective method for improving its photocatalytic activity. Unfortunately, the time consuming multi-step synthesis and low yields of common approaches limit practical applications of both top-down and bottom-up synthesis methods.[1] Herein, we used a one-pot approach to obtain amine-functionalized ultrathin g-C3N4...
Highly-alloyed chrome-nickel stainless steel is the most important material in vacuum technology. Especially in high and ultra-high vacuum technology it is used for vacuum chambers and components. One of the main research focuses before 2005 [1] was the study of parasitic field emission (FE) of specially treated stainless-steel surfaces for applications in accelerator technology. The measured...
Screw vacuum pump, with a fully enclosed vacuum pumping process, integrates the latest achievements of mechanical, electronic control, thermodynamics and other disciplines. It has wide application prospects in raw materials chemical, chemical synthesis, drying, concentration and other fields. Dry gas seal is a new type of non-contact shaft seal on the basis of gas-lubricated bearing seal. The...
The Extra-Low Energy Anti-proton ring (ELENA) is a decelerator at CERN with the aim to slow down the antiprotons from the Antiproton Decelerator (AD) to a kinetic energy of 100 keV, improving the antimatter experiments trapping efficiency. ELENA operates in the Ultra High Vacuum (UHV) regime to assure a sufficiently long pbar lifetime and reduced beam blow-up. As the ring is under commission,...
Sputtering ion pump, a kind of vacuum acquisition equipment applied in the field of ultrahigh vacuum, has the characteristics of simple structure, zero noise, no vibration, no oil pollution and no cooling agent, which is playing a more important role with the increasing demand of ultra-high vacuum environment in advanced scientific equipment and national major projects. This paper analyzes the...
The EURAMET EMPIR project “16NRM5-ion gauge” aims to develop a standardised ionization gauge that is suitable as a transfer standard. In such a gauge the electron trajectories, kinetic energy and current inside the ionization volume needs to be well defined and stable. In the search for a most suitable design, CERN, amongst the other consortium partners, carried out a series of simulation on...
Liquids and vacuum are opposite concepts. We have developed a new technique for making possible the coexistence and the emergence of liquid solutions inside a vacuum chamber. We call this technique «Atomic Layer Injection», ALI [1] and it allows to deposit sub monolayers of biomolecules, as Adenosine triphosphate (ATP), or gold nanoparticles from a liquid solution at room temperature. With...
Cryopumping is one of effective methods to evacuate H$_2$ and has been used in various vacuum systems because of its cleanliness and high pumping speed. For development and utilization of cryopumps, it is indispensable to elucidate the physisorption characteristics of a cryosurface against H$_2$ in extremely high vacuum (XHV), where H$_2$ is the dominant residual gas. Several authors have...
Gas flow conductance of a tube can be measured with the pressure decay method. Here, a vacuum chamber of volume V is pumped through the tube, which allows for conductance C to be determined from the slope of the logarithm of the pressure decay curve $C=V×\text{d}(\text{ln}(p))/\text{d}t$, if upstream pressure p is measured with sufficient precision. In our case, estimated uncertainty of the...
With the rapidly development of science and technology in modern industry, the failure of mechanical parts caused by mechanical vibration become one of the main factors of affecting mechanical performance. Hard coatings, such as metallic and ceramic coatings, were reported the outstanding damping potential by the experience. Among them, Mg-Al alloy coating was widely used due to excellent...
Cosmic dust grains are believed to play an essential role in the emergency of chemical complexity in the universe. In particular, it may catalyze new chemical reactions with the circumstellar and interstellar gases. In addition, accretion of volatiles on dust grain surfaces leads to the formation of icy mantles, whose processing in the interstellar medium (ISM) also contributes to the large...
This work presents analytical and numerical results for modeling of general vacuum system using discrete and continuum physical-mathematical approach. In traditional vacuum technology, in other words, in discrete approach, the three main parts of the vacuum system – vacuum chamber, pumping line and vacuum pumps – are dealt in separated and watertight parts. This approach simplifies the...
One of the main advantages of NEG coating is providing required pressure in UHV/XHV range in vacuum chamber with restricted vacuum conductivity, i.e. vacuum chambers with high aspect ratio (length to characteristic cross section size). The most challenging for NEG coating production is depositing of the tubed with diameters smaller than 20 mm. We have developed and tested a deposition facility...
Laser Engineered Surface Structures (LESS) is a novel technology for reducing the Secondary Electron Yield (SEY) of metal surfaces, and has recently been investigated for mitigating the electron-cloud phenomenon in high-intensity particle accelerators such as the HL-LHC and the FCC at CERN.
Treatment with LESS increases the surface roughness, thus the outgassing of treated surfaces can be...
Heavy ion ring accelerators suffer from dynamic vacuum increase due to ion-induced desorption. Lost beam ions collide with the vacuum vessel, trigger the release of gas and the resulting pressure rise leads to more beam loss. This self-amplifying effect is a severe intensity limitation and affects the design and operation of next generation heavy ion accelerators.
A common mitigation of the...
Diamond Light Source is the UK’s national synchrotron light source. Carbon contamination of optics in the synchrotron’s associated beamlines by the disassociation of carbon from carbon monoxide and dioxide at optics surfaces under radiation can lead to a substantial drop of beam intensities and unwanted spectral features. Diamond Light Source has developed, and deployed on several beamlines,...
The electronic properties of organic semiconductors in bulk and at interface play an essential role in characteristic charge transport in soft matter, and eventually result in performance in organic-based devices such as organic field-effect transistors, organic thin film solar cells, organic light-emitting diodes, and single molecular junctions.1 Pentacene (C22H14) is regarded as a prototype...
With the increased beam energy and the upcoming high luminosity, electron cloud and synchrotron radiation could have an important impact on the LHC residual gas density and beam parameters. An innovative room temperature Vacuum Pilot Sector (VPS) is installed in a straight section of the LHC to investigate these phenomena in situ.
The Large Hadron Collider (LHC) is affected by electron cloud...
The AZO (aluminum-doped zinc oxide) thin film, produced by coating on the flexible substrate, has many advantages such as light quality, rich resource, flexible and mass production. This paper presents an effective method for the parameters optimization for the deposition process for AZO thin films, using the Taguchi method, combined with grey relational analysis, and an L-9 orthogonal array...
Vacuum chamber RF surface resistance may play a significant role in beam instabilities of charge particle accelerators. Several dedicated choked TE010-mode resonators with 2 and 3 chokes were designed and built in ASTeC for surface resistance measurements of planar samples.
In this paper we report our study on improving the accuracy of surface resistance measurements and possible sources of...
At present, non-vacuum accumulation leak detection method and vacuum leak detection method are widely used in the total leakage rate test of spacecrafts. But there are some problems of non-vacuum accumulation leak detection method, such as low leak detection sensitivity, long test period and so on. While the vacuum leak detection method has the problems of high construction cost and...
Amorphous silicon thin film solar cells have excellent photoelectric properties including simple preparation process, low production cost, easy to manufacture in large area. In this paper, we studied the influence of each layer parameters on performance of a-Si solar cells by wxAMPS simulation software such as the thickness, optical band gap, the doping concentration of the window layer and...
Elettra is a third generation synchrotron radiation light source in operation at Trieste (Italy). This light is produced by the interaction of high energy, high intensity electron beam with dedicated magnetic fields. The electron beam gains its high energy thanks to the electromagnetic field built and stored into the Radio Frequency (RF) cavities. The typical accelerating electric field of the...
The non-evaporable getter (NEG) coating has been used for years in many accelerators due to its advantages such as evenly distributed pumping speed, low thermal outgassing and low photon and electron stimulated desorption yields. Although quaternary Ti-Zr-Hf-V coating deposited from an allow wire has been found to have the lowest desorption yields, highest sticking probability and sorption...
The so-called thermal transpiration is a phenomenon well known to users of the thermostated capacitance diaphragm gauges (CDGs) at low absolute pressures below 100 Pa. It leads to a pressure difference between the internal chamber of the CDG with respect to the vacuum chamber to which it is connected. The associated correction ratio has been studied over several decades, for CDGs...
As the development of electronic technique and miniaturization of vacuum electronic devices, it has higher demands for their lifetime and reliability.In order to meet the sealing performance requirements, extra-high sensitive mass spectrometer leak detection method is developed. So the leak rate of 10-15Pa•m3 / s on the order of the standard leakage is demanded. Increasing the number of holes...
According to the requirement of vacuum leak detection container for small satellite, a set of vacuum leak detection container is developed. This paper discuss the design of model and the finite element analysis of different models. Through calculating the variation of the displacement X, Y, Z of different parts of the door and the cabinet, the stress distribution of different parts and the...
In order to realize a non-destructive and fast 2D profile monitor for an accelerator, we are now developing a dense gas sheet target in a vacuum, applying the beaming effect as used in the field of vacuum technology.
Test-particle Monte Carlo simulations revealed that the long rectangular channel with the very small ratio of the gap to the width is effectual to form the thin gas sheet.
For...
In superconductive linear accelerator, the performance and stability can be adversely impacted by gas adsorbed on cryogenic surfaces. The cryogenic devices usually work at liquid 4.2 K or 1.9 K, at such low temperature, the phenomena of gas adsorption on cryogenic surface will affect the gas migrating process along vacuum tubes obviously, so the gas migration process will be much different...
In order to test the leakage of the electric propulsion spacecraft after the xenon filling, it was studied which were the leak detection of methods and key technologies. A leak detection system has been developed by basing on the gas chromatography(GC). It was reliable which was verified by the experiments. The result proved that the leak detection system of the electric propulsion spacecraft...
The injector chain of LHC is being upgraded to achieve the beam quality required for the High-Luminosity LHC (5e34 cm^-2s^-1). To achieve that performance the injectors have to provide beams of double intensity and 2.5 times the present brightness.
The LHC Injectors Upgrade project (LIU) requires the connection of the new proton source (LINAC4) that will provide negative hydrogen ions at 160...
The LHC injectors Upgrade (LIU) project has the goal to prepare the injector chain to reliably deliver the beams required by the High Luminosity LHC (HL-LHC) era, aiming at doubling beam intensity while reducing the beam emittance. At the last stage of the injector chain, the Super Proton Synchrotron (SPS) will be extensively modified in the scope of LIU, starting in 2019. It will feature a...
CIADS is short for China Initiative Accelerator Driven System, consists of intense-beam proton accelerator,spallation target and subcritical core.The multistage differential pumping system is a part of the large and complex vacuum system of CIADS which is between intense-beam proton accelerator and spallation target. The working pressure of spallation target is 5.0E4Pa for He,however, the...
In this paper, an experimental steam ejector refrigeration system was built to measure the ejector performance at various operating conditions. The computational fluid dynamics (CFD) approach was also used to further analyse the experimental results where the internal flow behaviour cannot be fully accessed. The influence of operating pressure on the primary jet core variation and the axial...
The capacitance diaphragm gauges play important role as the precise secondary vacuum standard in the range from atmospheric pressure down to the absolute pressure at mPa level.
One of the important factor capable to influences pressure measurements due to its effect on pressure sensors and electronics is humidity level of the ambient air. The surrounding humidity forms the equilibrium water...
The European XFEL is a 3.4 km long underground facility that generates extremely intense X-ray flashes to be used by researchers from all over the world. It officially began operation in September 2017. In full operation it produces coherent femtosecond pulses with unprecedented brilliance in the energy range from 250 eV to 25 keV at MHz repetition rate. The facility comprises a linear...
The quest for high intensity proton circular accelerators calls for efficient electron cloud mitigation. Of particular interest is the electron cloud build-up in the steering dipole magnets necessary for the bending of particle trajectories in circular colliders. The electron cloud formation relates directly to the secondary electron yield of the accelerator’s vacuum chambers surrounding the...
A gas leak on orbit is a fatal fault for spacecraft, so a series of leak tests are carried out during the process of manufacturing and assembling. Helium leak testing method has much higher sensitivity than other methods. In order to gain high leak testing sensitivity, a spacecraft should undergo a helium leak test in large vacuum chamber. A vacuum leak testing system was built for the...
The Vacuum Measurement Lab at Korea Research Institute of Standards and Science (KRISS), Rep. of Korea, maintains primary standards as well as systems for calibration by comparison method. The KRISS primary standards can be used for the calibration purpose in the pressure range from ~ 10-7 Pa to 133 kPa.
It is mainly categorized into manometers, static (volume, series) expansion systems, and...
Ultrathin bilayers (BLs) of bismuth have been predicated to be a two-dimensional (2D) topological insulator. Here we report on the new route to manufacture the high quality Bi bilayers from 3D topological insulator, a top-down approach to prepare large-area and well-ordered Bi (111) BL with deliberate hydrogen etching on epitaxial Bi2Se3 films. With scanning tunneling microscopy (STM) and...
Few-atomic-layer Bi and Sb are 2D semiconductors and potentially also topological insulators useful in spintronics. On graphite and MoS2 with vapor deposition, we observed the self-assembly of several types of Sb and Bi ultrathin films. These nanostructures can be in either the rhombohedral or black phosphorus (BP) crystal structures. Systematic STM-based investigation reveals the crucial...
The electrical properties of oxide materials are strongly influenced by the presence of vacancies and other point defects. Whereas purely stoichiometric oxides are usually poor conductors, vacancies can significantly increase their electrical conductivity, being of n-type in the case of oxygen vacancies, like in ZnO, [1], or p-type in the case of cationic vacancies, like in NiO [2]. Many...
