Conveners
Vacuum Science & Technology: 1
- Karl Jousten (Physikalisch-Technische Bundesanstalt)
Vacuum Science & Technology: 1
- Karl Jousten (Physikalisch-Technische Bundesanstalt)
Vacuum Science & Technology: 2
- Janos Marki (Inficon)
Vacuum Science & Technology: 2
- Janos Marki (Inficon)
Vacuum Science & Technology: 3
- Martin Wüest
Vacuum Science & Technology: 3
- There are no conveners in this block
Vacuum Science & Technology: 4
- Irina Graur Martin (Aix Marseille University)
Vacuum Science & Technology: 4
- Irina Graur Martin (Aix Marseille University)
Vacuum Science & Technology: 5
- Jay Hendricks (NIST)
Vacuum Science & Technology: 6
- Marcy Stutzman (Jefferson Lab)
Vacuum Science & Technology: 6
- Marcy Stutzman (Jefferson Lab)
Presently, for high accuracy near-atmosphere vacuum measurements, capacitive diaphragm gauges (CDGs) are the norm. However, for a number of demanding applications involving high temperatures, strong electromagnetic fields or high-energy radiation, optical diaphragm gauges (ODGs, [1] & [2]) would be much better suited alternatives.
In these ODGs, the sensor head incorporates a Fabry-Pérot...
The New SI (which will very probably be adopted this autumn) will no longer be a mere set of the definitions of the units, but an organic system binding the units and the invariant constants of Nature. The approaching redefinition will become a complete turn to the system of units being interdependent by the defining constants and at the same time it will cause a dissolution of the border...
At NIST, new methods of pressure and vacuum realization that are based on quantum calculations are currently under development. This is exciting in that it fits with the current redefinition, that if a new technique relies upon a quantum property, measurement, calculation, or invariant of nature, then this technique can have served as a primary standard. Standards built this way are then...
Since the earliest days of neutral atom trapping it has been known that the background gas in the vacuum limits the lifetime of atoms in the trap. We are inverting this problem to create a quantum-based standard and sensor. Because the measured loss-rate of ultra-cold atoms from the trap depends on a fundamental atomic property (the loss-rate coefficient or thermalized cross section) such...
We describe the numerical simulation of an extractor gauge using SIMION 8.0 software. The detailed geometry was defined in SolidWorks and imported into SIMION as 5 separated electrodes. All dimensions defined by the manufacturer were strictly followed. Length distribution of calculated electron trajectories has been evaluated. This allowed determining the mean trajectory length inside the grid...
We assume that a hot cathode ion gauge can be made more stable by using an electron source for introducing an accelerated electron beam into the ionization volume in a straight path. By doing so, the electron trajectories, kinetic energy and current inside the ionization volume could be well defined and stable.The electron beam should have an energy of about 200 eV for stable ionizing the gas....
In 2019-2020, the LHC machine will be stopped and will enter a new phase of maintenance and consolidation called the long shutdown (LS2). During this period, all the LHC experiments will undergo significant upgrades and important modifications. One of the main objectives of the changes is to reduce the radiation dose to personnel following the ALARA (As Low As Reasonable Achievable) principle...
The European Spallation Source (ESS) is a neutron source based on a 2GeV-5MW linear accelerator. The goal of ESS is to be the brightest neutron facility and to enable novel science in many fields such as biology research, environmental technologies and fundamental physics. The ESS Linear Accelerator (LINAC) is under construction, Ion source and LEBT installation is started in Q1-2018.
The...
We have assembled a system using an array of NEG modules and a cryopump with Boron Nitride Nanotubes (BNNT) instead of the traditional charcoal. The BNNT has been mechanically attached to the cryosorption surfaces of a commerical cryopump, and the system fully baked to remove water with no adhesive present in the system. We report here on the pump speed of the BNNT cryopump, and characterize...
A microcavity array is a set of volumes in the micrometer range. A 3D microcavities array is a 3D arrangement of such small cavities. It may have volumes equally spaced in an ordered pattern or not. Good examples of these materials are foams, sponges and cork. Although the motivation for this work came from the need to understand the pressure evolution in cork cells when subjected to vacuum or...
Vacuum pumps and other components can be exposed to varying types and quantities of radiation. These include applications/apparatus in medical diagnostics and treatment, analytical instrumentation, sterilization techniques, space simulation as well as the established requirements in High Energy Physics.
This paper will present recent radiation tolerance measurements made by a DLA/ISO...
The trend in electron accelerators design consists in approaching the poles of the steering magnets close to the electron beam. This implies reducing the bore hosting the vacuum chamber and using very small diameter vacuum pipes [1]. The application of functional thin films as getters by physical vapor deposition in such small diameter chambers becomes then very difficult. The aim of this...
(abstract will follow)
Investigations performed on gas flows at a microscale have become of great interest for various applications that touch almost every industrial field, such as mass flow and temperature micro sensors, micro pumps, micro-systems for mixing or separation for local gas analysis, mass spectrometers, pressure gauges, dosing valves and micro heat exchangers. Among these applications the gas flow...
Numerous MEMS components such as acceleration sensors, gyroscope sensors, ultrasonic sensors or micro-resonators require vacuum packaging in order to reduce the gas friction of the mechanical moving parts. While these applications work already in fine vacuum, for field emission based electron or X-ray sources, high vacuum is required to avoid ion bombardment and arcing in order to achieve a...
Ion pumps are widely used in very sensitive applications such as Particle Accelerators and Electron Microscopes , where particles emitted from the vacuum pumps can heavily affect the performance of the machine or the resolution of the instrument .
Neutral and charged particle emission from ion pumps has been analyzed and its dependance on pressure, operating voltage and element geometry is...
The outgassing rate and gas uptake properties of materials is important for a variety of applications. One example is vacuum; vacuum chambers designed for UHV or XHV (ultra-high or extreme-high vacuum) applications often require outgassing rates on the order of 10-11 Pa L/cm2/s or better, and ultra-low outgassing rates are also required for any materials used within the UHV or XHV systems. ...
Sputter Ion Pumps (SIP) offer an appealing strategy to efficiently maintain ultra-high and extremely-high vacuum conditions in a vacuum chamber. The pumping speed, i.e. the volume flow of gas extracted from the vacuum in a specific period of time, can be determined according to various standards. However, recorded pumping speeds may vary severely, depending on the standard chosen and the...
Pressure is a key parameter for a large number of industrial processes. Amongst others, vacuum industry relies on accurate pressure measurement and control. Designing a single device being able to sense from very high vacuum to atmospheric pressure is a challenge to an interdisciplinary research community, leading to the development of a variety of pressure sensors using different operating...
We report on the realization of a novel methodology for refractometry — GAs MOdulation Refractometry (GAMOR) — that decreases the influence of drifts in Fabry Perot cavity refractometry. The instrumentation is based on a dual Fabry-Perot cavity (DFPC) refractometer in which one cavity is used as the measurement cavity while the other serves as the reference. The GAMOR methodology comprises a...
In the field of vacuum physics in industry as well as at research institutes the number of applications using optical signals for simple observation tasks, sample illumination or process monitoring increased dramatically in the last decades. As a result of the enhanced interest the demands on optical properties, the vacuum seals and the material properties of the vacuum optic components...
Aluminum is one of the preferable materials for reaching the UHV/XHV level. Comparable outgassing rates in the 1E-14 mbar*l/s/cm² regime using stainless steel components are only achievable by vacuum firing. Furthermore, stainless steel chambers for UHV/XHV applications are typically welded using different parts of tubes and CF weld flanges. After the welding and vacuum firing it is almost...
Vacuum materials require precise knowledge of their permeability P and diffusivity D, e.g. for sealing or outgassing. Agreement with the methods to measure P and D, mainly infusion/outgassing or membrane techinques1, is sometimes poor and material dependent2.
The paper reports an experimental apparatus for gas flux measurements suitable for membrane techniques. It...
Vacuum sealing devices with a small inner volume like micro-electro-mechanical system (MEMS) require a strict helium leak test to ensure the lifetime because the inner pressure rapidly increase even if a fine leak is occurred. However, it is difficult to measure the helium leak rate less than 10-11 Pa m3/s reliably because the range of commercially available helium standard leak is limited...
A pressure gauge with an integrated He-leak detector based on a novel ion source was presented to the vacuum community at the EVC-14 in 2016. The recent progress in the development of a vacuum gauge based on this ion source will be presented.
The fundamental idea of the vacuum gauge is the novel measuring principle: Instead of directly measuring the ion current, ions are accumulated inside...
The determination of the permeability of low porous media like the micro and nanoporous membrane is still a challenge up to now. The low permeable membranes have several applications in vacuum technology, filtering, separation process, protection from shock waves and flow control. It can combine high mass flow rate and a high level of rarefaction. This property makes it particularly suitable...
As an effective tool to acquire ultra-high vacuum (UHV), molecular pump is widely used in scientific research and advanced manufacturing, and the performance testing of molecular pump is of great importance to its quality evaluation and the design for UHV system. This presentation will not only give a thorough introduction of a novel wide-range testing apparatus of molecular pump developed by...
While planning vacuum experiments in particle accelerators and other research facilities, many technical conditions have to be considered. Especially to achieve vacuum in the UHV/XHV range, components like vacuum chambers need to fulfill well defined, vacuum-specific requirements. For that reason, it is important to specify grantable and binding quality characteristics when vacuum components...
Conventional residual gas analysers, such as quadrupole RGAs, have difficulty directly monitoring certain processes due to the high process pressures (typically above 1E-4 mbar) and the presence of volatile species such as hydrocarbons. These hydrocarbons often contaminate the RGA filaments, rendering the sensor unusable.
An alternative gas monitoring sensor that operates directly at...
The static expansion method is a well established method for realizing the pressure scale in medium and high vacuum by a fundamental method. The main component of uncertainty of the generated pressure in such a system is due to the temperature uncertainty of the vessels involved during an expansion. Stainless steel is a relative poor heat conductor so that considerable gradients of temperature...
The KATRIN neutrino experiment aims to measure the effective mass of electron anti-neutrinos with an unprecedented sensitivity of 0.2 eV/c$^2$ by measuring the energy spectrum of beta-electrons from tritium decays close to the endpoint of the spectrum. The decays take place in a high-intensity windowless gaseous tritium source (WGTS). The electrons are guided by strong magnetic fields through...
We present an algorithm that helps identifying components and contaminants in a residual gas spectrum. At first the possible weighted contribution to the measured spectrum for each reference out of a library is determined and ranked. A residual gas spectrum, in logarithmic scale, is then reconstructed by simulation based on partial pressures and fragmentation patterns of the most likely...
A large-scale cryopump (DN1250) used in large vacuum leak detecting system was designed and its performance experimentally investigated by Beijing Institute of Spacecraft Environment Engineering. In the cryopump, the first stage array (radiation shield and baffle) and the second stage cryopanel were cooled by four closed cycle helium refrigerators (two dual stage refrigerators and two single...
Dry scroll vacuum pump (DSVP) has been widely used in many industries with its inherent advantages of outstanding pumping capacity, low power consumption, low vibration and noise and oil free performance in the cavity, resulting in the increasing demand for DSVP. The huge fund has been invested to study DSVP by many research institutes and vacuum equipment manufacturers. However, it is...
The plume field in a vacuum facility for hall thruster ground testing is investigated in detail through a series of simulations using a direct simulation Monte Carlo (DSMC) code. The focus here is on the effects of finite background gas pressure in ground vacuum test facilities under different distribution of technical equipments such as the xenon pump, beam target or shroud. The results show...
Traditional dry pump measurement devices usually only perform single performance measurements under fixed conditions. This paper presents a performance measurement method with highly integrated, high precision and high degree of automation for vacuum dry pump, realizing not only the measurement of the original performance indicators, but also directly measurement main performance in the...
Heavy ion accelerators suffer from pressure increases during operation, triggered by ion-induced desorption. Lost beam ions impinge on surfaces of the vacuum system and gas is released what in turn leads to more beam loss and further pressure increase. This pressure instability is called dynamic vacuum and limits the intensity of the ion beam. A common mitigation technique is the installation...
Variational principles for magnetohydrodynamics (MHD) were introduced by previous authors both in Lagrangian and Eulerian form. In this paper we introduce simpler Eulerian variational principles from which all the relevant equations of non-barotropic MHD can be derived for certain field topologies. The variational principle is given in terms of five independent functions for non-stationary...
