No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Application of compact NEG-sputter ion pump combination in UHV system of HIAF
Abstract
HIAF-BRing, a new multi-purpose accelerator facility of the High Intensity Heavy-Ion Accelerator Facility project, requires an extremely high vacuum lower than 10⁻⁹ Pa to fulfill the requirements of radioactive beam physics and high energy density physics. Use of large speed Titanium sublimation pump (TSP) in combination with Sputter ion pumps (SIP) is not always feasible due to space limitations. A novel combination pump, based on Non Evaporable getter (NEG) and a 10 l/s SIP (NEXTorr® D 2000-10) has been evaluated as it provides large speed in a more compact design. The two combination pumps (TSP + SIP and NEXTorr D 2000-10) have been tested by dynamic flow method to measure the ultimate pressure, the pumping speed and the suitability for HIAF. Test results show that both combination pumps can be used in the pressure range of 10⁻¹⁰ Pa. The ultimate pressure of TSP + SIP combination pump is slightly lower than NEXTorr D 2000-10, but the latter one has much larger sorption capacities (H2: 210200 Pa l vs 265 Pa. l; CO: 430 Pa. l vs 24 Pa. l), which means it is applicable to a wider pressure range. At the same time, after twenty activation cycles, the initial pumping speed of NEXTorr D 2000-10 for H2 and CO decreased less than 10% as compared with the initial pumping speed of the first activation, which meets the actual vacuum system requirement of HIAF. A dedicated vacuum chamber with collimator and NEXTorr D 2000-10 has been designed and manufactured to stabilize the dynamic vacuum by decreasing the heavy ion induced gas desorption and increasing the gas pumping speed. The static and dynamic vacuum pressure evolution has been simulated to verify the feasibility of the NEXTorr D 2000-10 used in the HIAF-BRing.
... To achieve the ultimate pressure regime of 10 -11 Torr a titanium sublimation pumps are generally used in conjunction with a sputter ion pump, but this combination is not always feasible due to space limitations. The use of compact NEXTorr D2000-10 combination pump provide large speed in a more compact design and is applicable where large load of gases is generated and no more space available [8]. ...
... To achieve the ultimate pressure regime of 10 -11 Torr a large speed titanium sublimation pumps are generally used in combination with a sputter ion pump, but this combination is not always feasible due to large size. The compact NEXTorr D2000-10 combination pump is applicable where large load of gases is generated and no more space is available [8]. The pumping speed of oil diffusion pump and turbomolecular pump reaches maximum at ~10 -3 Torr and remain constant up to 10 -6 Torr. ...
The most common type of vacuum pumps and measuring gauges based on available literature are studied with emphasis on how new research and development will enable the new generation of vacuum technology specially in designing, its operational procedure and applications. The technologies were developed to meet the operational goal which include vacuum chamber structures, compatible materials, specialized vacuum pump and gauges. There are many areas where different vacuum condition is required for conducting experiments therefore modeling of pumping system is on demand. The basic understanding of how and when the particular pumping and measurement system can be applied most effectively and economically is essential. The poor choice of pumping and measurement system will interfere the scientific objectives and may leads to substantial maintenance demands and an unpleasant working environment. The development and fundamental investigation of innovative vacuum techniques for creation and measurement of vacuum used for various applications necessary for the research work to be done in future are presented.
Ce–Mg–Ni alloys have a high affinity for hydrogen, and are typical examples of compounds that form hydrides. These hydrides may be formed in medium vacuum by using a hydrogen getter. In this study, Ce23Mg4Ni7 ternary alloy was fabricated by vacuum induction melting. The hydrogen absorption kinetics of the alloy were tested using an automatic Sievers device, and its hydride microstructure was observed via a transmission electron microscopy (TEM). The results indicate that the ternary phase, Ce23Mg4Ni7, is the main phase of the alloy, and the alloy absorbed hydrogen to form a Ce23Mg4Ni7Hx hydride. Under a hydrogen pressure of 5000 Pa at 50 °C, the equilibrium pressure of the system can be reduced to less than 10 Pa. By the eighth time of backfilling to compensate for hydrogen, the equilibrium pressure is reduced to 1 × 10⁻² Pa. The Langmuir absorption equation was used to fit the hydrogen absorption results of the alloy, and it was shown that the saturated hydrogen absorption capacity of the alloy is 55.72 mL, and the absorption coefficient is 0.0078 at 50 °C.
During heavy ion operation, large pressure rises, up to a few orders of magnitude, were observed at CERN, GSI, and BNL. The dynamic pressure rises were triggered by lost beam ions that impacted onto the vacuum chamber walls and desorbed about 104 to 107 molecules per ion. The deterioration of the dynamic vacuum conditions can enhance charge-exchange beam losses and can lead to beam instabilities or even to beam abortion triggered by vacuum interlocks. Consequently, a dedicated measurement of heavy-ion induced molecular desorption in the GeV/u energy range is important for Large Hadron Collider (LHC) ion operation. In 2003, a desorption experiment was installed at the Super Proton Synchrotron to measure the beam-loss induced pressure rise of potential LHC collimator materials. Samples of bare graphite, sputter coated (Cu, TiZrV) graphite, and 316LN (low carbon with nitrogen) stainless steel were irradiated under grazing angle with 158 GeV/u indium ions. After a description of the new experimental setup, the results of the pressure rise measurements are presented, and the derived desorption yields are compared with data from other experiments.
The authors present here the description of the main features of MOLFLOW+, a new software package that allows the calculation of several physical quantities of interest to vacuum engineers and scientists, such as pressure profiles, effective pumping speeds, adsorption distributions, angle of incidence or effusion profiles, and more. MOLFLOW+ is a follow up to the code MOLFLOW, which has been developed by one of us since 1991, and used for the analysis and design of many vacuum systems and components. MOLFLOW+ makes use of modern trends such as OpenGL graphic interface, multicore processors, graphical processing units (GPUs), and runs under different operating systems. In addition to implementing the test-particle Monte Carlo (TPMC) algorithm, as done previously in MOLFLOW, MOLFLOW+ also implements an alternate algorithm, the angular coefficient (AC) method. This article goes into some details of the TPMC and AC methods as implemented in MOLFLOW+, shows results of benchmark runs and comparisons with published numerical and analytical data, and discusses the advantages and disadvantages of the two methods. CUDA is the compute unified device architecture, a C++-like development environment for a class of GPUs.
The vacuum-calibration apparatus is mainly composed of the extreme high-vacuum (XHV) system, ultrahigh vacuum system, and separated-flow system. The ultimate pressure of 7.9×10-10 Pa was obtained in the XHV calibration chamber by combining the magnetically levitated turbomolecular pump and nonevaporable getter pump (NEGP). The separated-flow method was used to extend the lower limit of vacuum-gauge calibration to 10-10 Pa . The uncertainty at lower limit was reduced when taking inert gases as test gases because NEGP has no pumping speed for inert gases. For this apparatus, the combined standard uncertainties were estimated to range from 1.5% at 10-4 Pa to 3.5% at 10-10 Pa .
The ion-induced desorption experiment, installed in the CERN Heavy Ion Accelerator LINAC 3, has been used to measure molecular desorption yields for 4.2 MeV/u lead ions impacting under grazing incidence on different accelerator-type vacuum chambers. Desorption yields for H2, CH4, CO, and CO2, which are of fundamental interest for future accelerator applications, are reported for different stainless steel surface treatments. In order to study the effect of the surface oxide layer on the gas desorption, gold-, silver-, palladium-, and getter-coated 316 LN stainless steel chambers and similarly prepared samples were tested for desorption at LINAC 3 and analysed for chemical composition by X-ray Photoemission Spectroscopy (XPS). The large effective desorption yield of 2 x 104 molecules/Pb53+ ion, previously measured for uncoated, vacuum fired stainless steel, was reduced after noble-metal coating by up to 2 orders of magnitude. In addition, pressure rise measurements, the effectiveness of beam scrubbing with lead ions and the consequence of a subsequent venting on the desorption yields of a beam-scrubbed vacuum chamber are described. Practical consequences for the vacuum system of the future Low Energy Ion Ring (LEIR) are discussed.
In preparation for the heavy ion program of the Large Hadron Collider (LHC) at CERN, accumulation and cooling tests with lead ion beams have been performed in the Low Energy Antiproton Ring (LEAR). These tests have revealed that due to the unexpected large outgassing of the vacuum system, the dynamic pressure of the ring could not be maintained low enough to reach the required beam intensities. To determine the actions necessary to lower the dynamic pressure rise, an experimental program has been initiated for measuring the molecular desorption yields of stainless steel vacuum chambers by the impact of 4.2 MeV/u lead ions with the charge states +27 and +53. The test chambers were exposed either at grazing or at perpendicular incidence. Different surface treatments (glow-discharges, non-evaporable getter coating) are reported in terms of the molecular desorption yields for H2, CH4, CO, Ar and CO2. Unexpected large values of molecular yields per incident ion up to 2 104 molecules/ion have been observed. The reduction of the ion-induced desorption yield due to continuous bombardment with lead ions (beam cleaning) has been investigated for five different stainless steel vacuum chambers. The implications of these results for the vacuum system of the future Low Energy Ion Ring (LEIR) and possible remedies to reduce the vacuum degradation are discussed.
The Spectrometer Ring (SRing) is an essential part of the High Intensity heavy-ion Accelerator Facility project (HIAF) in China. It is designed as a multi-functional experimental storage ring, which will be able to operate in three ion optical operation modes. The SRing will be used as a time-of-flight mass spectrometer for short-lived, especially neutron-rich nuclei. It will also be used to collect and cool Rare Isotope Beams (RIBs) or highly-charged stable ion beams for nuclear and atomic physics experiments. The design magnetic rigidity is in the range 1.5 to 15 Tm. The beam cooling system consists of stochastic cooling and electron cooling devices. With a help of an electron cooler, stored ions will be decelerated to a minimum energy of 30 MeV/u by RF cavities. The extraction system of the SRing will allow cooled ion beams to be extracted to an external target for further ion manipulations or reaction experiments. The general ion optics design and technical requirements of SRing subsystems are presented and discussed in this paper.
HIAF-BRing, a new multipurpose accelerator facility of the High Intensity heavy-ion Accelerator Facility project, requires an extremely high vacuum lower than 10⁻¹¹ mbar to fulfill the requirements of radioactive beam physics and high energy density physics. To achieve the required process pressure, the bench-marked codes of VAKTRAK and Molflow+ are used to simulate the pressure profiles of the BRing system. In order to ensure the accuracy of the implementation of VAKTRAK, the computational results are verified by measured pressure data and compared with a new simulation code BOLIDE on the current synchrotron CSRm. Since the verification of VAKTRAK has been done, the pressure profiles of the BRing are calculated with different parameters such as conductance, out-gassing rates and pumping speeds. According to the computational results, the optimal parameters are selected to achieve the required pressure for the BRing.
Absrracr Elettra is a third generation synchrotron light source which has been built especially for the use of high brilliance radiation from insertion devices and bending magnets. The vacuum system presents some pecularities which cannot be found in any existing machine. Carefully performed cleaning and outgassing procedures brought the base pressure to the 10-t' mbar range even for the unbaked vacuum chamber. A microprocessor controlled bakeout system developed in our laboratory was succesfully tested during commissioning. After in situ baking at the uniform temperature of 150 "C the specific outgassing rate of 2~10~'~ Torr.l.sec-1.cm-2 was obtained. The analysis of residual gas mixtures and bakeout monitoring were performed by multiplexing 6 quadrupole mass spectrometers. The control system for sputter-ion pumps (SIP) was developed in house. This enables to power 2 + 7 SIPS with only one power unit. There is a possibility of reading the absorbed current of each pump and to perform an automatic current to pressure conversion. This system was calibrated up to 5x10-" mbar for different SIP types modified with NEG modules. The Elettra vacuum system met all desired specifications after about 100 Ah of conditioning.
HIAF (High Intensity heavy ion Accelerator Facility), a new facility
planned in China for heavy ion related researches, consists of two ion
sources, a high intensity Heavy Ion Superconducting Linac (HISCL), a 45
Tm Accumulation and Booster Ring (ABR-45) and a multifunction storage
ring system. The key features of HIAF are unprecedented high pulse beam
intensity and versatile operation mode. The HIAF project aims to expand
nuclear and related researches into presently unreachable region and
give scientists possibilities to conduct cutting-edge researches in
these fields. The general description of the facility is given in this
article with a focus on the accelerator design.
The alternating gradient synchrotron (AGS) is a synchrotron for the acceleration of protons and heavy ions to tens of GeV amu−1 for fixed target physics research. The relativistic heavy ion collider (RHIC), with the AGS as its injector, allows the collision of heavy ion beams with several hundred GeV amu−1. The vacuum systems of the AGS-RHIC complex range from 10−6 torr in the ion sources to the ultrahigh vacuum of low 10−11 torr in the Booster and RHIC. The status of the machines will be described with emphasis on the following areas: the performance of the Booster ultrahigh vacuum system, the development of non-magnetic vacuum components for the muon storage ring, and progress in the construction of the RHIC vacuum systems.
The recently completed alternating‐gradient synchrotron booster is a synchrotron for the acceleration of both protons and heavy ions. To minimize the beam loss due to charge exchange of the partially stripped, low β(=v/c), very heavy ions with the residual gas molecules, ultrahigh vacuum of 10-11 Torr is required for the 200 m booster ring. An average pressure of mid 10-11 Torr has been achieved and maintained after initial in situ bakes and commissioning. In this article we describe: (1) design and layout of the vacuum systems; (2) material selection and vacuum processing; (3) personal computers/programmable logic controllers based bakeout system; (4) operation of vacuum instrumentation over long cable length; (5) results of bakeout and evaluation; and (6) experience gained during construction and commissioning.
HIRFL-CSR, a new accelerator project planned at the Heavy Ion Research Facility in Lanzhou (HIRFL), is a multipurpose cooling storage ring (CSR). To minimize the beam loss due to charge exchange of very heavy ions with the residual gas molecules, ultra-high vacuum of 3×10−9 Pa is required for the HIRFL-CSR facility, which is the lowest pressure in a large vacuum system in China up to now. In this article we describe: (1) design of the system; (2) vacuum chambers; (3) reduction of the outgassing rate; (4) vacuum equipment; (5) pressure distribution; (6) future programme
HIRFL-CSR, a new accelerator project planned at the Heavy Ion Research Facility in Lanzhou (HIRFL), has been started in December 1999. The average static pressure for the ultra-high vacuum system of HIRFL-CSR will be 3×10−9 Pa. To achieve this goal, much research and many experiments have been done. As a result, the first prototype of the vacuum system has been finished. The pressures near the pump and at the end of the chamber (about 4 m away from the pump) were 8×10−10 and 2.6×10−9 Pa, respectively. This paper describes the process of the design, manufacture and test on the prototype. It is focused on the chamber structure design, machining technology, calculation and testing for the main pumps, and design of the bake-out system. Future development of the vacuum system is also mentioned.
A test dome for pumping speed measurements on sputter ion pumps is described. Results of Monte Carlo computations are presented which give for this dome the correlation between the intrinsic pumping speed and the pressures as measured at the dome. In particular, the influence of gauge position on speed measurement has been investigated as well as the influence of the geometry of the pump under test. The pump geometry affects the angular distribution of the molecules re-entering the dome from the pump side. It is shown that this influence is in most cases negligible.
Collimation System Design and Dynamic Vacuum Simulation for the BRing
- P Li
P. Li, Collimation System Design and Dynamic Vacuum Simulation for the BRing.
HIAF Design Review Meeting. Lanzhou, (Apr 03th, 2017) http://hiaf.impcas.ac.cn/
download/list/7.html.
Pressure Profiles Calculation for the CSRm and Bring
- P Li
P. Li, et al., Pressure Profiles Calculation for the CSRm and Bring, MOPR008,
Proceedings of HB2016, Malmo, Sweden.
Vacuum pressure rise with intense ion beams in RHIC
- W Fischer
W. Fischer, et al., Vacuum pressure rise with intense ion beams in RHIC,
Proceedings of the 8 th European Particle Accelerator Conference, Paris, 2002, p.
1485.
Towards the high intensity limit in the FAIR project present status and future challenges
- P Spiller
P. Spiller, Towards the high intensity limit in the FAIR project present status and
future challenges, Proceedings of HB2010, Morschach, Switzerland, 2010, pp.
34-37.
Ion-stimulated gas desorption yields and their dependence on the surface preparation of stainless steel
- E Mahner
E. Mahner, et al., Ion-stimulated gas desorption yields and their dependence on the
surface preparation of stainless steel, Proceedings of the 8th European particle
Accelerator Conference, Paris, 2002, p. 2568.
The Ultra-high Vacuum System for the Low Energy Antiproton Ring (LEAR) Design. Cost and Performances
- M Brouet
M. Brouet, The Ultra-high Vacuum System for the Low Energy Antiproton Ring
(LEAR) Design. Cost and Performances. CERN/PS-ML/83-42.
Simulation of the long term beam intensity performance of the NEG-coated SIS18
- P Puppel
P. Puppel, et al., Simulation of the long term beam intensity performance of the
NEG-coated SIS18. Proceedings of HB2010,Morschach, Switzerland, 91-95.