07 Accelerator Technology Main Systems

T14 Vacuum Technology

Paper Title Page
MOZBG01 Vacuum Performances in the Most Recent Third Generation Synchrotron Light Sources 31
 
  • E. Al-Dmour
    ALBA, Bellaterra
 
  Several 3rd generation synchrotron light sources were built and commissioned during the last ten years. The vacuum system of these light sources was designed using different approaches, but with the same objectives which guarantee the lowest outgassing rate and the highest pumping speed that by the end will achieve the lowest influence in the circulated beam (longest life time, the lowest impedance and instabilities, etc). The performance of recently commissioned rings (DIAMOND, SOLEIL and the Australian Light Source) are presented, together with a comparison of the different approaches which have been used in the design of the vacuum system and the lessons for the design of new vacuum systems.  
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WEOBM04 LHC: The World's Largest Vacuum Systems being Commissioned at CERN 1959
 
  • J. M. Jimenez
    CERN, Geneva
 
  When it switches on in the spring of 2008, the 26.7 km Large Hadron Collider (LHC) at CERN, will have the world's largest vacuum system operating over a wide range of pressures and employing an impressive array of vacuum technologies. This system is composed by 54 km of UHV vacuum for the circulating beams and 24 km of insulation vacuum around the cryogenic magnets operated mainly at 1.9 K. Over the 54 km of UHV beam vacuum, 48 km of this must be at cryogenic temperature (1.9 K). The remaining 6 km of beam vacuum containing the insertions is at ambient temperature and uses non-evaporable getter (NEG) coatings – a vacuum technology that was born and industrialized at CERN. The pumping is completed using 600 ion pumps to remove noble gases and 1000 gauges are used to monitor the pressures. The cryogenic insulation vacuum, while technically less demanding, is impressive by its size - 24 km in length, 900 mm in diameter for a total volume of 640 m3. Once cooled at 1.9 K, the cryogenic pumping allows reaching pressure in the 10-6 mbar range. This paper described the entire vacuum system and the challenges of the design, manufacturing, installation and commissioning phases.  
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THPP137 Development of Vacuum Components for XFEL/SPring-8 3682
 
  • T. Bizen
    RIKEN/SPring-8, Hyogo
 
  Several new vacuum components have been developed for the XFEL/SPring-8 project. Vacuum waveguide flanges for C-band and S-band were successfully developed. These flanges provide both RF seal and vacuum seal. This seal mechanism can make vacuum seal even with a scratched gasket. A solid-lubricated clean bolt was developed for C-band and S-band flanges to avoid organic dust pollution that induce multipactor. New vacuum flange for accelerator beam line can use three types of gasket. A small RF contact for 28 mm inside diameter bellows was developed. This unfixed RF contact can move freely in all directions and displaced large.  
THPP138 Achievement and Evaluation of the Beam Vacuum Performance of the LHC Long Straight Sections 3685
 
  • G. Bregliozzi, V. Baglin, S. Blanchard, J. Hansen, J. M. Jimenez, K. Weiss
    CERN, Geneva
 
  The bake-out and activation of the 6 km Long Straight Sections (LSS) of the Large Hadron Collider (LHC) is in its final step. After bake-out and activation of the NEG coating, the average ultimate pressure, over more than one hundred vacuum sectors, is below 10-11 mbar. Therefore, the nominal requirement for the four experimental insertions is guaranteed. The nominal performances are also ensured for all the other insertions where collimators, RF cavities and beam dumping systems are present. The main difficulties encountered during the bake-out and activation of NEG coated chambers of the LSS vacuum sectors will be presented and discussed. In particular, the acceptance test and the limiting factors of the reached ultimate pressures will be addressed. Furthermore, the influence on the ultimate pressures of the beam vacuum elements (collimators, beam instrumentation, etc.) will be discussed. Finally, preliminary results obtained from a laboratory NEG pilot sector dedicated to the quality control of the LHC beam vacuum and to the evaluation of the NEG performance will be presented.  
THPP139 Stainless Steel Vacuum Chambers for the SSRF Storage Ring 3688
 
  • D. K. Jiang, Y. L. Chen, Y. Liu, Y. Lu, Y. M. Wen, L. Yin, Z. T. Zhao
    SINAP, Shanghai
  • G. D. Liu, Z. A. Zheng
    Shanghai Sanjin Vacuum Equipment Ltd. Company, Shanghai
 
  Stainless steel 316LN plate was adopted as main material for SSRF storage ring vacuum chambers and ante-chamber structure was used just as other 3rd light source. The analysis for the deformation of the chambers under atmospheric pressure and the thermal situation under synchrotron radiation were done with ANASYS program. Many problems on the structure design and fabrication technique were revealed and suitable solving methods were found in the process of development and manufacture of nine chamber prototypes. Deep draw die was used to form the chambers’ figuration. Wire cutting and CNC machining were used to manufacture the main components. The flatness tolerance, straightness tolerance and the deformation of the chambers under atmospheric pressure were all less than 1mm. After annealed in the vacuum furnace at 850℃, the magnetic permeability of welding seal was reduced from 2.5 to 1.02, the residual stress was deleted, and the vacuum performance was improved. Now SSRF vacuum system is being operated very well. The average pressure without beam is about 2.5×10-8 Pa and the average pressure with beam of 3GeV/100mA is about 8×10-7 Pa.  
THPP140 First Experience on NEG Coated Chambers at the Australian Synchrotron Light Source 3690
 
  • P. Manini, A. Conte, S. Raimondi
    SAES Getters S.p. A., Lainate
  • B. Mountford
    ASP, Clayton, Victoria
 
  The Australian Synchrotron, a 3 GeV third generation Light Source saw its first light in 2006. At full capacity it will house more than 30 photon beam lines providing state of the art facilities to support fundamental and applied research to the Australian scientific community. In the regional context, the Australian Synchrotron will also effectively complement the lower energy synchrotrons in Singapore (0,8 Gev) and Taiwan (1.5 GeV). The vacuum system of the storage ring, 216 m circumference, includes ion pumps and NEG cartridge pumps. Two NEG coated, ESRF style, aluminium Insertion Devices, each 2,5 m long, have been also installed in the storage ring to boost machine parameters and broaden the spectrum of wavelength available for experiments. Preliminary vacuum results obtained during conditioning and initial operation of the Insertion Devices are reported and compared to uncoated chambers. These results confirm the effectiveness of the NEG coating technology in reducing pressure build up inside conductance limited narrow chambers. Technological issues related to the chambers preparation, film deposition, quality control and characterization will be also discussed.  
THPP141 Test of a NEG Coated Copper Dipole Vacuum Chamber 3693
 
  • E. J. Wallén, M. Berglund, A. Hansson
    MAX-lab, Lund
  • R. Kersevan
    ESRF, Grenoble
 
  The paper reports about a test carried out at the 1.5 GeV storage ring MAX II where a standard dipole chamber made of stainless steel was replaced by a NEG coated chamber made of copper. The standard MAX II stainless steel dipole vacuum chamber is connected to an ion pump and a sublimation pump while the NEG-coated copper dipole vacuum chamber has no additional pumps. The NEG-coated dipole chamber made of copper has been demonstrated to work well with a stable vacuum level in the region where it is installed. The coating procedure for the bent dipole chamber copper tube is slightly more complicated than the coating procedure for a straight chamber of similar size due to its curvature and lack of line-of-sight. The procedure is also described in some detail. The main motivation for the interest in NEG-coated vacuum tubes is the reduced cost of the vacuum system and also the possibility to build more slender vacuum systems, thus simplifying and optimizing the design of accelerator magnet systems.  
THPP142 Vacuum Conditioning of the SOLEIL Storage Ring with Extensive Use of NEG Coating 3696
 
  • C. Herbeaux, N. Béchu, J.-M. Filhol
    SOLEIL, Gif-sur-Yvette
 
  The vacuum system of the SOLEIL storage ring is designed using a combination of standard pumps like Sputter Ion Pumps and Titanium Sublimation Pumps (TSP) and Non Evaporable Getter (NEG) coating. Following the ESRF results on low gap insertion device (ID) chambers, it was decided to use, in addition to the traditional pumps, NEG coating deposited by magnetron sputtering on extruded aluminium vessels. This has been applied in an extensive way to all the straight vessels of the storage ring that means quadrupole vessels and ID vessels, which represent about 56% of the circumference. The starting configuration of the SOLEIL vacuum system included all the NEG coated low gap ID chambers among which a 10.5 m long chamber. Conditioning of the vacuum system over an integrated beam dose of 500 A.h will be presented. The periodical re-activations of the TSP performed early 2007 improved significantly the conditioning rate. A comparison of the vacuum behaviour of two similar cells one with NEG coating and traditional pumping versus one with only NEG coating demonstrates the ability of the NEG coating to keep alone the pressure at low level.  
THPP143 Vacuum Design of the TPS Relates to the Beam Effects 3699
 
  • G.-Y. Hsiung, C. K. Chan, C.-C. Chang, H. P. Hsueh, Z.-D. Tsai
    NSRRC, Hsinchu
  • J.-R. Chen
    NTHU, Hsinchu
 
  The concept of the vacuum design for the 3 GeV Taiwan Photon Source (TPS) considers several points of view which relates to the beam effects. The vacuum design of the low outgassing rate and the effective pumping configurations to obtain the lowest average pressure in the electron storage ring is to obtain the longer beam life time and the least of the ion trapping effect and the consequent problem of beam ion instability. The inner structure of the beam ducts provides the lower impedance which reduces the problems of the collective beam instability and the heating dissipation and damage to the vacuum components. The thin wall of the beam ducts and the bellows are designed for the sextupoles that offers the function of fast feedback orbit correction of the beam. The final performance of the third generation light source with low emittance will rely on the original design of vacuum systems for the electron beam. The design philosophy of the vacuum systems for the TPS will be described.  
THPP144 The Vacuum System for SSRF Storage Ring 3702
 
  • D. K. Jiang, L. Chen, Y. L. Chen, W. Li, Y. Liu, Y. Lu, H. Zhang
    SINAP, Shanghai
 
  The vacuum system for SSRF was completed at the end of 2007 and has run for one month without any malfunction. The vacuum chamber for the storage ring made from stainless steel 316LN plate. About 180 absorbers and 80 RF bellows with a single finger structure are used for the storage ring. About 292 compound pumps (SIP+NEG) and 188 TSP are used. After the vacuum system in the straight section of a cell and all pumps in the bending section were baked, the ultimate pressure reached 2×10-8 Pa. Normally, the temperature raise on the chambers any where is less than 4℃ with current 100mA. The temperature raise of the cooling water for all absorbers is less than 3℃. The vacuum control and interlock system are on working order.  
THPP145 Machine Operation Issues Related to the Vacuum System of the ESRF 3705
 
  • R. Kersevan, M. Hahn, I. Parat, D. Schmied
    ESRF, Grenoble
 
  This paper deals with various operational issues related to the vacuum system of the ESRF storage ring. The impact on the vacuum pressure, beam lifetime, beam losses and other machine parameters after installation of new chambers, diagnostics, RF cavities and insertion devices, and vacuum leaks is discussed in some detail. Particular emphasis is given to the behaviour of the prototype of a 2m-long cryogenic in-vacuum undulator, a new RF cavity, and NEG-coated chambers. Lessons learned from the operation of these and other vacuum components will be extended to the proposed machine upgrade.  
THPP146 High-voltage Power Supply Distribution System 3708
 
  • M. Kobal, D. Golob, M. Plesko, A. Podborsek
    Cosylab, Ljubljana
  • T. Kusterle, M. Pelko
    JSI, Ljubljana
 
  High-voltage splitters enable connecting a larger number of ion-pumps to a single ion-pump controller. In particle accelerator facilities where relatively small pumps are used, using high-voltage splitters can significantly reduce costs and rack space. By using simple high-voltage splitters some functionality of the conrollers can be lost. The presented high-volage splitter is one of the most advanced devices on the market. It measures current going to every pump in the range 100 pA to 100 mA with an accuracy of 5%. Fully configurable tables are used to convert the measured current to the pressure at the pump. Current measurements are also used to monitor cable and ion-pump aging which results in linear increase of current with time. Hardware interlocks are used to disconnect individual pumps in case of poor vacuum to avoid pump damage. The limits can be set by the user, who can also set the number of active pumps. EPICS support was developed for the device with graphical user interfaces writen in EDM, java and WebCA. Since the presented device covers or exceeds a lot of the ion-pump controller functionality, simpler controlers can be used.  
THPP147 NEG Coated Chambers at SOLEIL: Technological Issues and Experimental Results 3711
 
  • P. Manini, A. Bonucci, A. Conte, S. Raimondi
    SAES Getters S.p. A., Lainate
  • N. Béchu, C. Herbeaux
    SOLEIL, Gif-sur-Yvette
 
  The SOLEIL accelerator complex includes a 100 MeV LINAC pre-injector, a full energy booster synchrotron and a 2.75 GeV electron storage ring with a 354-meter circumference, which provides synchrotron light to 24 photon beam lines. SOLEIL is the first synchrotron facility specifically designed to make extensive use of Non Evaporable Getter (NEG) coating technology to improve the vacuum, reduce bremsstralhung radiation and boost beam performances. In fact, NEG coating of the straight parts of the vacuum system covers more than 50% of the overall storage ring surface and includes 110 quadrupole and sextupole chambers as well as several conductance limited narrow insertion devices. Use of such a large amount of NEG coated chambers has posed several challenges in term of coating technology, chamber testing, installation and machine commissioning. We report in the present paper main technological issues related to the chambers preparation, film deposition, quality control and characterization. Chambers installation in the main ring, conditioning and activation procedures as well as preliminary vacuum performances will be also discussed.  
THPP148 Implementation of the SSRF Vacuum Control System 3714
 
  • H. F. Miao, W. Li, Y. J. Liu, L. R. Shen
    SINAP, Shanghai
 
  The Shanghai Synchrotron Radiation Facility (SSRF) is a third generation light source consisting of a 150MeV linac, a full energy booster and a 3.5GeV storage ring. The vacuum control system is a standard hierarchical control system based on EPICS. Serial device servers are used to connect most of vacuum devices such as gauge controllers, pump power supplies to the control network directly and integrated with EPICS using soft IOC. Ethernet based PLC systems are adopted for the valves control, temperature monitor, etc. The soft IOCs are running on the rack servers and the VLAN is used for separate to the other systems. An enhanced distributed archive engine stores runtime data to centre database that using native XML data type with XML schema for data storage. It is a high performance system and running well for daily operation now.  
THPP150 LANSCE Vacuum System Refurbishment Plan and Vacuum Alert System Improvements for Predictive Maintenance 3717
 
  • T. Tajima, M. J. Borden, A. Canabal, J. P. Chamberlin, S. Harrison, F. R. Olivas, M. A. Oothoudt
    LANL, Los Alamos, New Mexico
 
  The Los Alamos Neutron Science Center (LANSCE) accelerator, an 800-MeV H+/H- LINAC with a storage ring, has been operated over 30 years since early 1970s. A refurbishment project named LANSCE-R was approved and started in 2007. This paper describes our plan for vacuum system refurbishment as well as an update on the ongoing vacuum email alert system improvement project, which will eventually notify workers of the need for predictive maintenance of particular devices like ion pumps.  
THPP151 Feasibility Study for High Performance Vacuum Chamber 3720
 
  • Y. Tanimoto
    KEK, Ibaraki
 
  For longer beam lifetime, many synchrotron light sources employ ante-chamber type of beam ducts to reduce photon- and electron-stimulated desorption gases around stored beams. Still more reduction, however, can be expected if an X-ray transparent membrane, such as Beryllium thin film, is installed between the beam chamber and the ante-chamber because X-rays from stored beams pass through the membrane while gas molecules desorbed in the ante-chamber are shut out by the membrane. Similarly, photoelectrons and secondary electrons traveling from the ante-chamber to the beam chamber are also shut out by the membrane; this function is expected to mitigate beam-photoelectron instability in positron storage rings. Feasibility study for this type of vacuum chamber has been started at PF, and the result of the first-stage experiment will be presented.