Keyword: cryogenics
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MOPRI105 Heavy Ion Induced Desorption Measurements on Cryogenic Targets target, ion, vacuum, diagnostics 867
 
  • Ch. Maurer, D.H.H. Hoffmann
    TU Darmstadt, Darmstadt, Germany
  • L.H.J. Bozyk, H. Kollmus, Ch. Maurer, P.J. Spiller
    GSI, Darmstadt, Germany
  
  Funding: Bundesministerium für Bildung und Forschung FKZ 06DA7031
Heavy-ion impact induced gas desorption is the key process that drives beam intensity limiting dynamic vacuum losses. Minimizing this effect, by providing low desorption yield surfaces, is an important issue for maintaining a stable ultra high vacuum during operation with medium charge state heavy ions. For room temperature targets, investigation shows a scaling of the desorption yield with the beam's near-surface electronic energy loss, i.e. a decrease with increasing energy*,**. An optimized material for a room temperature ion-catcher has been found. But for the planned superconducting heavy-ion synchrotron SIS100 at the FAIR accelerator complex, the ion catcher system has to work in a cryogenic environment. Desorption measurements with the prototype cryocatcher for SIS100 showed an unexpected energy scaling***, which needs to be explained. Understanding this scaling might lead to a better suited choice of material, resulting in a lower desorption yield. An experimental setup for systematic examination of this scaling is presented. The cryogenic beam-induced desorption yield of several materials at different temperatures is examined.
* H. Kollmus et al., AIP Conf. Proc. 773, 207 (2005))
** E. Mahner et al., Phys. Rev. ST Accel. Beams 14, 050102 (2011)
*** L.H.J. Bozyk, H. Kollmus, P.J. Spiller, Proc. of IPAC 2012, p. 3239 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI105  
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TUPRO007 LS1 “First Long Shutdown of LHC and its Injector Chains” operation, radiation, electronics, shielding 1010
 
  • K. Foraz, S. Baird, M.B.M. Barberan Marin, M. Bernardini, J. Coupard, N. Gilbert, D. Hay, S. Mataguez, D.J. Mcfarlane
    CERN, Geneva, Switzerland
  
  The LHC and its injectors were stopped in February 2013, in order to maintain, consolidate and upgrade the different equipment of the accelerator chain, with the goal of achieving LHC operation at the design energy of 14 TeV in the centre-of-mass. Prior to the start of this Long Shutdown (LS1), a major effort of preparation was performed in order to optimize the schedule and the use of resources across the different machines, with the aim of resuming LHC physics in early 2015. The rest of the CERN complex will restart beam operation in the second half of 2014. This paper presents the schedule of LS1, describes the organizational set-up for the coordination of the works, the main activities, the different main milestones, which have been achieved so far, and the decisions taken in order to mitigate the issues encountered.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO007  
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TUPRO012 Optimisation and Implementation of the R2E Shielding and Relocation Mitigation Measures at the LHC during the LS1 radiation, civil-engineering, electronics, controls 1027
 
  • A.-L. Perrot, O. Andujar, M.B.M. Barberan Marin, M. Brugger, J.-P. Corso, K. Foraz, M. Jeckel, M. Lazzaroni, B. Lefort, B. Mikulec, Y. Muttoni
    CERN, Geneva, Switzerland
  
  In the framework of the Radiation to Electronics (R2E) project, important mitigation actions are being implemented in the LHC during the first Long Shutdown (LS1) to reduce the Single Event Error (SEE) occurrence in standard electronics present in much of the equipment installed in LHC underground areas. Recent simulations have motivated additional actions to be performed in Point 4, in addition to those already scheduled in Points 1, 5, 7 and 8. This paper presents the organisation process carried out during LS1 to optimise the implementation of the R2E mitigation activities. It reports the challenges linked to civil engineering and to safe room relocation in Points 5 and 7. It highlights the reactivity needed to face the new mitigation requirements to be implemented in Point 4 before the end of LS1. It presents the advancement status of the R2E mitigation activities in the different LHC points with the main concerns and impact with the overall LHC LS1 planning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO012  
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TUPRO015 Update on Predictions for Yearly Integrated Luminosity for HL-LHC based on Expected Machine Availability luminosity, operation, radiation, electronics 1036
 
  • A. Apollonio, M. Jonker, R. Schmidt, B. Todd, D. Wollmann, M. Zerlauth
    CERN, Geneva, Switzerland
  
  Machine availability is one of the key performance indicators to reach the ambitious goals for integrated luminosity in the post Long Shutdown 1 (LS1) era. Machine availability is even more important for the future High Luminosity LHC (HL-LHC) [1]. In this paper a Monte Carlo approach has been used to predict integrated luminosity as a function of LHC machine availability. The baseline model assumptions such as fault-time distributions and machine failure rate (number of fills with stable beams dumped after a failure / total number of fills with stable beams) were deduced from the observations during LHC operation in 2012. The predictions focus on operation after LS1 and its evolution towards HL-LHC. The extrapolation of relevant parameters impacting on machine availability is outlined and their corresponding impact on fault time distributions is discussed. Results for possible future operational scenarios are presented. Finally, a sensitivity analysis with relevant model parameters like fault time and machine failure rate is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO015  
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TUPRO085 Properties, Options and Limitations of PrFeB-magnets for Cryogenic Undulators undulator, permanent-magnet, induction, polarization 1238
 
  • F.-J. Börgermann, C. Brombacher, K. Üstüner
    Vacuumschmelze GmbH & Co. KG, Hanau, Germany
  
  The gap induction and thus the K-factor of permanent magnet undulators may be increased by cooling them to cryogenic temperatures. The use of NdFeB-magnets in cryogenic undulators, however, is limited to temperatures above 140 K due to the spin-reorientation transition (SRT) which leads to a reduction of the magnetization level. A further increase of the gap induction in undulators may be achieved by use of PrFeB-magnets at even lower temperatures, as this alloy does not show the SRT phenomenon. Although the effects are well known, up to now only a few undulator prototypes were built using this class of material since the coercivity of ternary PrFeB-magnets is not sufficient to minimize the risk of partial demagnetization when the undulator structure is kept at room temperature. This problem can be solved by applying actual technologies like grain-boundary diffusion in order to achieve coercivities exceeding 20 kOe at RT without sacrificing the high remanence Br of about 1.6 T at 77 K. We will provide actual data of the magnet performance achieved and show up the technological limitations in building PrFeB-based CPMU’s.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO085  
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TUPRI061 Power Loss Calculation in Separated and Common Beam Chambers of the LHC impedance, electron, coupling, simulation 1711
 
  • C. Zannini, G. Iadarola, G. Rumolo
    CERN, Geneva, Switzerland
  • G. Iadarola
    Naples University Federico II, Science and Technology Pole, Napoli, Italy
  
  The performance of 25 ns beams in the LHC is strongly limited by the electron cloud. To determine the amount electron cloud in the cold sections of the machine, it is very important to be able to disentangle the beam induced heating due to the beam coupling impedance from that attributable to electron cloud. This paper will focus on the calculation of the first contribution. First, the impedance model used for the calculation of the beam induced power loss is briefly discussed. Then, the methods for the calculation of the beam induced power loss in regions with one or two beams are also described. Finally, the calculated power loss is compared with the measured heat loads for both 25 and 50 ns beams in both the LHC arcs and in the inner triplets (ITs).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI061  
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WEPRO029 Developing of Advanced Magnet Structures for Cryogenic in Vacuum Permanent Magnet Undulators undulator, permanent-magnet, vacuum, electron 2004
 
  • C. Kuhn, J. Bahrdt, A. Gaupp, M. Scheer, B. Schulz
    HZB, Berlin, Germany
  
  Cryogenic in vacuum permanent magnet undulators with periods less than 10 mm and correspondingly narrow gaps require tighter geometric and magnetic tolerances and complex pole designs from different materials to achieve the needed high field strengths. We use new mechanic designs and manufacturing technologies for magnet and pole assembly. We develop new precise and UHV-compatible joining methods which are different from the current approaches which are based on mechanical clamping or gluing. . We examine the mechanical and magnetic properties by performing tests and discuss the results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO029  
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WEPRO047 A New Cooling System for Cryocooled Permanent Magnet Undulators at Diamond Light Source vacuum, undulator, operation, electron 2047
 
  • E.C. Longhi, A.G. Miller, E.C.M. Rial, A.J. Rose, J.C. Schouten, C.W. Thompson, A. Thomson, J.H. Williams
    DLS, Oxfordshire, United Kingdom
  • C. Monroe
    Monroe Brothers Ltd., Moreton-in-Marsh, United Kingdom
  
  Cryocooled permanent magnet undulators (CPMUs) using NdFeB magnets around 150K were first proposed by Hara*. These are cooled by using either GM cryocoolers or circulating sub-cooled liquid nitrogen. Due to the heat load from radiation and wakefield heating from the electron beam, temperature gradients can develop along the length of the magnet girders which could be as large as several degrees for the Diamond Light Source (DLS) storage ring operating parameters. Some grades of the magnetic material (NdxPr1-x)2Fe14B have remanence curves versus temperature which increase significantly for temperatures below 150K with peaks below 80K**. This means that the operating temperature of a CPMU using this material can be close to the boiling point of liquid nitrogen. The proposed cooling system for the new DLS CPMU is based on a thermosiphon allowing nitrogen to boil inside the cooling channels without a circulating pump. This has the advantage of absorbing large amounts (>250W) of heat with very small temperature gradients. We report here the results of a prototype magnet beam cooled with a thermosiphon producing a temperature gradient of less than 0.05K along a 2m beam at ~77K.
* T. Hara et al., Phys Rev Spec Top. Accelerator & Beam, Vol 7, 2004.
** J. Bahrdt et al., AIP Conf. Proc., SRI 2009, Melbourne Australia, vol. 1234, pp. 499-502, 2010. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO047  
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WEPME028 Systematic Measurement of the Pumping Capabilities of Cryogenic Surfaces radiation, vacuum, simulation, operation 2317
 
  • F. Chill, O.K. Kester
    IAP, Frankfurt am Main, Germany
  • L.H.J. Bozyk, O.K. Kester, P.J. Spiller
    GSI, Darmstadt, Germany
  
  The quality of the beam vacuum is crucial for the stable operation of synchrotrons with high intensity heavy ions. Cryogenic surfaces are capable of pumping residual gases by cryocondensation until the saturated vapor pressure (SVP) is reached. Even at LHe temperatures the SVP of hydrogen is too high. If the surface coverage is sufficiently low, residual gas can also be bound by cryosorption, yielding in acceptable low pressures. These pumping capabilities can be described by two parameters, both dependent on surface temperature and coverage: The sticking probability (SP), that is the chance of an impinging gas particle to be bound, and the mean sojourn time (MST) of a particle on the surface. To acquire these parameters, an experimental setup is currently built at GSI. It consists of a cryogenic chamber, cooled by a cold head and a warm part with vacuum diagnostics and gas inlet. It allows monitoring the pumping speed and also the equilibrium pressure of the cryogenic part from which the SP and the MST can be deducted. The results will be used to further improve the accuracy of the dynamic vacuum simulations in cryogenic areas of particle accelerators.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME028  
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WEPME029 Development of a Field Emitter-based Extractor Gauge for the Operation in Cryogenic Vacuum Environments vacuum, ion, cathode, operation 2320
 
  • M. Lotz, O.K. Kester, St. Wilfert
    GSI, Darmstadt, Germany
  
  This paper presents an investigation of a CNT emitter-based extractor gauge which is designed for pressure reading in cryogenic ultra-high vacuum systems. The results show that the modified gauge works well in both room temperature and cryogenic vacuum environments. Furthermore, it could be demonstrated that the modified gauge responds much more sensitive to small pressure fluctuations in cryogenic environments than the same gauge type having a hot-filament cathode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME029  
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WEPME038 Introduction to the Latest Version of the Test-particle Monte Carlo Code Molflow+ vacuum, simulation, injection, software 2348
 
  • M. Ady, R. Kersevan
    CERN, Geneva, Switzerland
  
  The Test-Particle Monte Carlo code Molflow+ is getting more and more attention from the scientific community needing detailed 3D calculations of vacuum in the molecular flow regime mainly, but not limited to, the particle accelerator field. Substantial changes, bug fixes, geometry-editing and modelling features, and computational speed improvements have been made to the code in the last couple of years. This paper will outline many of these new features, and show examples of applications to the design and analysis of vacuum systems at CERN and elsewhere.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME038  
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WEPME047 CERN Vacuum System Activities during the Long Shutdown 1: the LHC Beam Vacuum vacuum, experiment, electron, collimation 2375
 
  • V. Baglin, G. Bregliozzi, P. Chiggiato, J.M. Jimenez, G. Lanza
    CERN, Geneva, Switzerland
  
  After the Long Shutdown 1 (LS1) and the consolidation of the magnet bus bars, the CERN Large Hadron Collider (LHC) will operate with nominal beam parameters. Larger beam energy, beam intensities and luminosity are expected. Despite the very good performance of the beam vacuum system during the 2010-12 physics run (Run 1), some particular areas require attention for repair, consolidation and upgrade. Among the main activities, a large campaign aiming at the repair of the RF bridges of some vacuum modules is conducted. Moreover, consolidation of the cryogenic beam vacuum systems with burst disk for safety reasons is implemented. In addition, NEG cartridges, NEG coated inserts and new instruments for the vacuum system upgrade are installed. Besides these activities, repair, consolidation and upgrades of other beam equipment such as collimators, kickers and beam instrumentations are carried out. In this paper, the motivation and the description for such activities, together with the expected beam vacuum performance after LS1, are described in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME047  
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WEPME048 Preliminary Design of the HiLumi-LHC Triplet Area Beam Screen shielding, optics, vacuum, luminosity 2378
 
  • R. Kersevan, C. Garion, N. Kos
    CERN, Geneva, Switzerland
  
  The so-called beam screen (BS) is a proven solution for intercepting the thermal loads caused by the circulating beams in the cryogenically-cooled sections of the LHC and minimizing dynamic vacuum effects. The new triplet area foreseen for the HiLumi-LHC machine upgrade has the additional feature of needing internal tungsten shields to reduce the amount of collision debris which is deflected by the high-gradient triplet magnets towards the superconducting magnets' cold masses and coils. The very aggressive optics design, based on large beam separations, calls for a maximum of physical space to remain available to the counter rotating beams in the common BS. This places severe constraints to the fabrication and installation tolerances of the BS itself, in addition to affecting the design and routing of the cryogenic lines in the area. The latest version of the BS design will be shown and discussed, together with future plans for testing materials, fabrication procedures, and installation.
* The HiLumi LHC Design Study is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME048  
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WEPRI004 Operational Experience and Upgrades of the SOLEIL Storage Ring RF System cavity, operation, vacuum, SRF 2480
 
  • P. Marchand, J.P. Baete, R.C. Cuoq, H.D. Dias, M. Diop, J.L. Labelle, R. Lopes, M. Louvet, C.M. Monnot, L.S. Nadolski, S. Petit, F. Ribeiro, T. Ruan, R. Sreedharan, K. Tavakoli
    SOLEIL, Gif-sur-Yvette, France
  
  In the SOLEIL storage ring, two cryomodules provide to the electron beam an accelerating voltage of 3-4 MV and a power of 575 kW at 352 MHz. Each cryomodule contains a pair of superconducting cavities, cooled with liquid Helium at 4.5 K, which is supplied by a single 350 W cryogenic plant. The RF power is provided by four solid state amplifiers, each delivering up to 180 kW. The parasitic impedances of the high order modes (HOM) are strongly mitigated by means of four coaxial couplers, located on the central pipe connecting the two cavities. Eight years of operational experience with this system, as well as its upgrades, are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI004  
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WEPRI036 Fabrication Design of QWR and HWR Cryomodules cryomodule, vacuum, linac, cavity 2555
 
  • W.K. Kim, H. Kim, H.J. Kim, Y. Kim, M. Lee, G.-T. Park
    IBS, Daejeon, Republic of Korea
  
  The superconducting linac of RAON consists of five types of cryomodules. The cryomodules host QWR, HWR1, HWR2, SSR1, and SSR2 superconducting cavities. The cryomodules will be operated at 2K in order to test the performance of the superconducting cavities. The design of the cryomodule components is based on thermal shield to prevent incoming heat, two-phase pipe to supply superfluid helium, vacuum vessel for the formation of the internal vacuum, supporter parts for alignment and keeping structure, and magnetic shield to prevent external magnetic field. The detailed fabrication design of the cryomodules will be presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI036  
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WEPRI045 Key Design Features of Crab-Cavity Cryomodule for HiLumi LHC cavity, cryomodule, radiation, HOM 2580
 
  • S.M. Pattalwar, A.J. May, P.A. McIntosh, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt, B.D.S. Hall
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • O. Capatina
    CERN, Geneva, Switzerland
  • T.J. Jones, N. Templeton
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • T.H. Nicol
    Fermilab, Batavia, Illinois, USA
  
  A prototype Superconducting RF (SRF) cryomodule, comprising multiple compact crab cavities is foreseen to realise a local crab crossing scheme for the “Hi-Lumi LHC”, a project launched by CERN to increase the luminosity performance of LHC. A cryomodule with two cavities will be initially installed and tested on the SPS drive accelerator at CERN to evaluate performance with high-intensity proton beams. STFC in collaboration with, University of Lancaster, CERN and FNAL has developed a concept cryomodule that has overcome most of the critical challenges imposed by a series of boundary conditions arising from; the complexity of the cavity design, the requirement for multiple RF couplers, the close proximity to the second LHC beam pipe and the tight space constraints in the SPS tunnel. This paper highlights some of the key design features of the cryomodule with the results of the associated mechanical and thermal analysis.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI045  
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WEPRI046 Commissioning of the ERL Cryomodule on ALICE at Daresbury Laboratory cryomodule, linac, cavity, LLRF 2583
 
  • A.E. Wheelhouse, R.K. Buckley, S.R. Buckley, P.A. Corlett, L.S. Cowie, P. Goudket, A.R. Goulden, L. Ma, P.A. McIntosh, A.J. Moss, S.M. Pattalwar
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  The ERL cryomodule with two identical 7-cell, 1.3 GHz cavities developed as part of a international collaborative program has been installed in the linac stage on the ALICE (Accelerators and Lasers in Combined Experiments) facility at Daresbury Laboratory replacing the existing 9-cell cryomodule. The cavities have been cooled to 2 K and commissioning of the cryomodule is underway. This paper describes the conditioning and the characterisation tests performed on the two superconducting RF cavities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI046  
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WEPRI051 Results from RF Tests of the First US-built High-gradient Superconducting Cryomodule cavity, cryomodule, SRF, linear-collider 2598
 
  • A. Hocker, C.M. Baffes, K. Carlson, B. Chase, D.J. Crawford, E. Cullerton, D.R. Edstrom, E.R. Harms, T. Kubicki, M.J. Kucera, J.R. Leibfritz, J.N. Makara, D. McDowell, O.A. Nezhevenko, D.J. Nicklaus, H. Pfeffer, Y.M. Pischalnikov, P.S. Prieto, J. Reid, W. Schappert, P. Stabile, P. Varghese
    Fermilab, Batavia, Illinois, USA
  
  Funding: United States Department of Energy, Contract No. DE-AC02-07CH11359
Fermilab has built a cryomodule comprised of eight 1.3 GHz superconducting RF cavities for use in its Advanced Superconducting Test Accelerator (ASTA) facility. This cryomodule (RFCA002) was intended to achieve the International Linear Collider (ILC) “S1” goal of demonstrating an average accelerating gradient of 31.5 MV/m, and is the first of its kind built in the United States. The module has been cooled down and operated without beam at ASTA in order to assess its performance. The results from these tests are presented here. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI051  
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WEPRI066 Recent Progress in Nb3Sn SRF Cavity Development at Cornell cavity, niobium, SRF, accelerating-gradient 2641
 
  • S. Posen, D. Gonnella, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Nb3Sn coatings on niobium SRF cavities have the potential to significantly reduce cryogenic costs due to their extremely small surface resistance (Rs). In this paper, we present new results showing the repeatability of Cornell's fabrication process, which produces high Q0 cavities that reach medium fields with minimal Q-slope. We also show the results of attempts to smooth RF surfaces and reduce defects via material removal. However, both HF rinsing and centrifugal barrel polishing resulted in strong performance degradation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI066  
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WEPRI077 Cryogenic Test of a 750 MHz Superconducting RF Dipole Crabbing Cavity* cavity, radiation, simulation, electron 2672
 
  • A. Castilla, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • A. Castilla, J.R. Delayen, H. Park
    JLab, Newport News, Virginia, USA
  • A. Castilla
    DCI-UG, León, Mexico
  
  Funding: *Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. With resources of NERSC, under U.S. DOE contract No. DE-AC02-05CH11231.
A superconducting rf dipole cavity has been designed to address the challenges of a high repetition rate (750 MHz), high current for both electron/ion species (0.5/3 A per bunch), and large crossing angle (50 mrad) at the interaction points (IPs) crabbing system for the Medium Energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab. The cavity prototype built at Niowave, Inc. has been tested at the Jefferson Lab facilities. In this work we present a detailed analysis of the prototype cavity performance at 4 K and 2 K, corroborating the absence of hard multipacting barriers that could limit the desired transverse fields, along with the surface resistance (Rs) temperature dependency. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI077  
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WEPRI105 Preliminary Design of Cooling System for a PrFeB-based Cryogenic Permanent Magnet Undulator Prototype at IHEP vacuum, undulator, permanent-magnet, simulation 2743
 
  • Y.C. Zhang, S.P. Li, H.H. Lu, S.C. Sun, Y.F. Yang
    IHEP, Beijing, People's Republic of China
  
  A circulation cooling system is under progress for a 2-m-long PrFeB-based cryogenic permanent magnet undulator (CPMU) prototype at IHEP. Sub-cooled liquid nitrogen flows through each in-vacuum girder back and forth once. Refrigerant channels for both girders are parallel connected in vacuum chamber. Numerical simulation shows that the cooling system is able to cool down magnet array from 300 K to 83 K. Meanwhile, phase error increases about 0.1 degree.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI105  
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WEPRI107 Fundamental Thermal Analysis for Cryogenic System Design radiation, cavity, cryomodule, electron 2749
 
  • H. Kim, D. Jeon, W.K. Kim, G.-T. Park, I. Shin, J.H. Shin, S.W. Yoon
    IBS, Daejeon, Republic of Korea
  
  Non-uniform temperature distribution, surface roughness, and superfluid helium level change between 2K dewar and cryomodule are most important thermal analyses in designing cryogenic system. Effective temperature for non-uniform temperature distribution is defined. Thermal radiation property from surface roughness which is related to fractional dimension is investigated. Superfluid helium level change between 2K dewar and cryomodule is shown as a function of temperature difference. Our research can be useful thermal analyses for cryogenic system design.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI107  
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WEPRI108 Liquid Helium Technologies at Cryogenic Complex of the Heavy Ion Collider NICA superconducting-magnet, collider, booster, ion 2752
 
  • Iu.A. Mitrofanova, N.N. Agapov, N. Emelianov, H.G. Khodzhibagiyan, D. Nikiforov
    JINR, Dubna, Moscow Region, Russia
  • R. Herzog, A. Kade, J. Klier
    ILK Dresden, Dresden, Germany
  
  NICA (Nuclotron-based Ion Collider fAcility), presently under construction at JINR, will be, upon its completion, among the most advanced research instruments of the physics community. The facility is aimed at providing collider experiments with heavy ions up to uranium (gold at the beginning stage) with a centre of mass energy up to 11 GeV/u and an average luminosity up to 1027 cm-2 s−1. The NICA cryogenics includes a large number of technical ideas and solutions never used before. The most significant of these solutions are the fast cycling superconducting magnets, cooling by the two-phase helium flow, an unusually short period of time for cool down till the operating temperature, parallel connection of cooling channels of the magnets, «wet» turbo expanders, screw compressors with the outlet pressure of more than 25 bars and jet pumps for liquid helium. These technical solutions allow one to construct an efficient and reliable cryogenic system of the NICA complex.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI108  
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WEPRI109 The ESS Cryogenic System cryomodule, linac, target, neutron 2756
 
  • P. Arnold, J. Fydrych, W. Hees, J.M. Jurns, X. Wang, J.G. Weisend
    ESS, Lund, Sweden
  
  Cryogenic cooling is vital for large sections at ESS. The ESS cryogenic system comprises three separate helium refrigeration/liquefaction plants and an extensive cryodistribution system. Mainly there is a 2.0 GeV proton linac using superconducting RF cavities operating at 2 K. In addition to cooling the SRF cavities, cryogenics is also used for the cold hydrogen moderator surrounding the target. There is also a cryogenic installation associated with the site acceptance testing of the ESS cryomodules. ESS furthermore uses both liquid helium and liquid nitrogen in a number of the neutron instruments. The test stand cryoplant will as well provide liquid helium for neutron instrument sample environments and comprise a helium purification unit. Together with the gas management, helium recovery and a considerable cold and warm storage system, cryogenics form a substantial part of ESS. This paper describes the current conceptual design of the ESS cryogenic system including the expected heat loads and operating modes for the linac cryoplant. Challenges associated with the required high efficiency, reliability and turn-down capability will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI109  
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WEPRI110 The HNOSS Horizontal Cryostat and the Helium Liquefaction Plant at FREIA cavity, operation, vacuum, linac 2759
 
  • R. Santiago Kern, T.J.C. Ekelöf, K.J. Gajewski, L. Hermansson, R.J.M.Y. Ruber, V.G. Ziemann
    Uppsala University, Uppsala, Sweden
  • P. Bujard, N.R. Chevalier, T. Junquera, J.P. Thermeau
    Accelerators and Cryogenic Systems, Orsay, France
  
  A horizontal cryostat to test superconducting cavities and magnets at liquid helium temperatures is installed at FREIA (Facility for REsearch Instrumentation and Accelerator development) at Uppsala University, Sweden. The cryostat allows full testing of superconducting spoke and elliptical accelerating cavities without the need of a specialized cryomodule per cavity. Because horizontal cryostats are custom-built, their number in the accelerator world is very limited. The FREIA horizontal cryostat is one of a kind as it has been designed to be versatile: it is able to house either two ESS double-spoke, or two ESS/TESLA type elliptical cavities, or superconducting magnets or a combination of these with all the ancillary equipment (power couplers, tuners, etc) and test them at the same time, reducing installation time but requiring extra design effort and cryogens supply. In order to achieve this, a helium liquefier with a capacity of 140 l/h delivers liquid helium to the horizontal cryostat while the return gases are directed towards a recovery system, connected in closed loop with the liquefier.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI110  
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WEPRI111 Investigation of Moisture Contamination in the Cryogenic System at NSRRC operation, controls, cavity, storage-ring 2762
 
  • F. Z. Hsiao, S.-H. Chang, W.-S. Chiou, H.C. Li, T.F. Lin, C.P. Liu, H.H. Tsai
    NSRRC, Hsinchu, Taiwan
  
  In NSRRC the helium cryogenic plant began its normal operation in year 2002. Several events of moisture contamination forced the cryogenic plant to cease operation because the cooling performance degraded evidently. After long-term observation we found, through internal inspection of the helium gas buffer tank, maintenance of the compressor station, and warming the superconductive magnet, that moisture contamination occurred. This paper presents the effect of those conditions on the moisture contamination. The solution to decrease the moisture contamination is demonstrated here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI111  
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WEPRI113 Operation of SLRI Cryogenic System for a 6.5 T Superconducting Wavelength Shifter operation, synchrotron, insertion, controls 2765
 
  • S. Srichan, Ch. Dhammatong, P. Klysubun, V. Sooksrimuang, K. Takkrathoke, A. Tong-on
    SLRI, Nakhon Ratchasima, Thailand
  
  The cryogenic plant at Synchrotron Light Research Institute was designed to be used as the main liquid helium supply for a superconducting wavelength shifter, in order to generate high-energy X-rays from the relatively low-energy 1.2 GeV Siam Photon Source storage ring. The plant was installed and successfully commissioned in the year 2009. During the past three years since commissioning, the cryogenic system had been in operation to perform helium liquefaction without a superconducting magnet. Since the installation of a 6.5 T SWLS in September 2013, the cryogenic system has begun its operation with a full-time load. In this work, the first operation of the cryogenic system with a superconducting insertion device is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI113  
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THOBB02 Superconducting Cavity Cryomodule Designs for the Next Generation of CW Linacs: Challenges and Options cavity, cryomodule, vacuum, operation 2831
 
  • T.H. Nicol, Y.O. Orlov, T.J. Peterson, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  Funding: Supported by FRA under DOE Contract DE-AC02-07CH11359
The designs of nearly all superconducting RF (SRF) linacs over the last several years, with one notable exception being CEBAF at Jefferson Lab, have assumed pulsed beam operation with relatively low duty factors. These include the XFEL at DESY, the ILC, the original configuration for Project X at Fermilab, as well as several others. Recently proposed projects, on the other hand, including the LCLS-II at SLAC, the newly configured low and medium energy sections for Project X, and FRIB at Michigan State, to name a few, assume continuous wave or CW operation on quite a large scale with ambitious gradients and cavity performance requirements. This has implications in the cavity design as well as in many parts of the overall cryomodule due to higher dynamic heat loads in the cavities themselves and higher heat loads in the input and high-order-mode (HOM) couplers. Piping internal to the cryomodule, the effectiveness of thermal intercepts, the size of integrated heat exchangers, and many other aspects of the overall design are also affected. This paper will describe some of these design considerations as we move toward the next generation of accelerator projects. 		 
slides icon Slides THOBB02 [8.388 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THOBB02  
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THPPA00 EPS-AG Prize d) Presentation electron, operation, simulation, synchrotron 2837
 
  • J.F. Esteban Müller
    EPFL, Lausanne, Switzerland
  • J.F. Esteban Müller
    CERN, Geneva, Switzerland
  
  EPS-AG Prize d) Presentation. The Prize d) winner will present the work for which the prize is awarded, on the basis of the judging by the EPS-AG Prizes Selectin Committee.  
slides icon Slides THPPA00 [3.432 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPPA00  
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THPRO077 The New FREIA Laboratory for Accelerator Development cryomodule, controls, FEL, linac 3059
 
  • R.J.M.Y. Ruber, A.K. Bhattacharyya, T.J.C. Ekelöf, K. Fransson, K.J. Gajewski, V.A. Goryashko, L. Hermansson, M. Jacewicz, T. Lofnes, M. Olvegård, R. Santiago Kern, R. Wedberg, R.A. Yogi, V.G. Ziemann
    Uppsala University, Uppsala, Sweden
  • D.S. Dancila, A. Rydberg
    Uppsala University, Department of Engineering Sciences, Uppsala, Sweden
  
  The FREIA laboratory is a Facility for REsearch Instrumentation and Accelerator Development at Uppsala University, Sweden constructed recently to develop and test accelerator components. Initially it will develop the RF system for the spoke cavities of the ESS linac and test prototype spoke cavities at nominal RF power. For this purpose we installed a helium liquefaction plant, a versatile horizontal test cryostat and two 352 MHz RF power stations, one based on two tetrodes and the other on solid state technology. Beyond these developments FREIA will house a neutron generator and plans for a THz FEL are under discussion. FREIA is embedded in the Ångström physics, chemistry and engineering campus at Uppsala in close proximity to mechanical workshops, clean room with electron microscopes, tandem accelerator and the biomedical center.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO077  
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THPME039 Requirements for ESS Superconducting Radio Frequency Linac linac, cryomodule, SRF, cavity 3311
 
  • C. Darve, M. Eshraqi, D.P. McGinnis, S. Molloy, E. Tanke
    ESS, Lund, Sweden
  
  The European Spallation Source (ESS) is a pan-European project. It will be built by at least 17 European countries, with Sweden and Denmark as host nations. The Superconducting Radio-Frequency (SRF) linac is composed of one section of spoke cavity cryomodules (352.21 MHz) and two sections of elliptical cavity cryomodules (704.42 MHz). These cryomodules contain niobium SRF cavities operating at 2 K. Following a redesign of its accelerator, SRF linac design shall comply with a new set of requirement, like an increase of the beam current from 50 mA to 62.5 mA and an increase of the peak electrical surface field from 40 MV/m to 45 MV/m. Requirements and the main disciplines needed to construct this portion of the linac are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME039  
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THPME103 Beam Current Monitors for FAIR synchrotron, ion, operation, proton 3483
 
  • M. Schwickert, H. Bräuning, F. Kurian, H. Reeg, A. Reiter
    GSI, Darmstadt, Germany
  • R. Geithner, W. Vodel
    HIJ, Jena, Germany
  • R. Neubert
    FSU Jena, Jena, Germany
  
  The FAIR (Facility for Antiproton and Ion Research) accelerator facility presently under construction at GSI will supply a wide range of beam intensities for physics experiments. Design beam intensities range from 2.5·1013 protons/cycle to be delivered to the pBar-target and separator for production of antiprotons, to beams of e.g. 109 ions/s in the case of slowly extracted beams. The large intensity range demands for dedicated beam current monitors for precise, non-destructive beam intensity measurements in the synchrotrons, transport lines and storage rings of the FAIR facility. This report describes GSI developments of purpose-built beam current monitors for the SIS100 synchrotron and high-energy beam transport lines (HEBT) of FAIR. Prototype measurements with a SQUID-based Cryogenic Current Comparator and a resonant beam charge transformer are presented, and possibilities for further upgrades are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME103  
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THPME122 A SQUID-based Beam Current Monitor for FAIR pick-up, electronics, niobium, ion 3524
 
  • R. Geithner, T. Stöhlker, W. Vodel
    HIJ, Jena, Germany
  • R. Geithner, R. Neubert, P. Seidel
    FSU Jena, Jena, Germany
  • F. Kurian, H. Reeg, M. Schwickert
    GSI, Darmstadt, Germany
  • T. Stöhlker
    IOQ, Jena, Germany
  
  A Cryogenic Current Comparator (CCC) was developed for the upcoming FAIR-Project, providing a non-destructive online monitoring of the beam current in the nA-range. The CCC was optimized for a lowest possible noise-limited current resolution together with a high system bandwidth. Therefore, the low temperature properties of ferromagnetic core materials used in the pick-up coil were investigated and different SQUID-systems were tested. In this contribution we present results of the completed Cryogenic Current Comparator for FAIR working in a laboratory environment, regarding the improvements in resolution and bandwidth due to the use of suitable ferromagnetic core materials and optimized SQUID-system components.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME122  
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THPME174 High-accuracy Diagnostic Tool for Electron Cloud Observation in the LHC based on Synchronous Phase Measurements electron, operation, simulation, synchrotron 3677
 
  • J.F. Esteban Müller, P. Baudrenghien, T. Mastoridis, E.N. Shaposhnikova, D. Valuch
    CERN, Geneva, Switzerland
  
  Electron cloud effects such as heat load in the cryogenic system, pressure rise and beam instabilities are among the main limitations for the LHC operation with 25 ns spaced bunches. A new observation tool was developed to monitor the e-cloud activity and has been successfully used in the LHC during Run 1 (2010-2012). The power loss of each bunch due to the e-cloud can be estimated using very precise bunch-by-bunch measurement of the synchronous phase shift. In order to achieve the required accuracy, corrections for reflection in the cables and some systematic errors need to be applied followed by a post-processing of the measurements. Results show clearly the e-cloud build-up along the bunch trains and its evolution during each LHC fill as well as from fill to fill. Measurements during the 2012 LHC scrubbing run reveal a progressive reduction in the e-cloud activity and therefore a decrease in the secondary electron yield (SEY). The total beam power loss can be computed as a sum of the contributions from all bunches and compared with the heat load deposited in the cryogenic system. The plan to use this method in the LHC operation is also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME174  
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THPRI106 Specialized Technical Services at ESS cryomodule, vacuum, target, neutron 4028
 
  • J.G. Weisend, P. Arnold, J. Fydrych, W. Hees, G. Hulla, F. Jensen, J.M. Jurns, P. Ladd, G. Lanfranco, H. Spoelstra, X. Wang
    ESS, Lund, Sweden
  
  The European Spallation Source (ESS), a world class lab for neutron science currently under construction in Lund, Sweden requires a number of technical services that extend across the various project areas (accelerator, target and neutron science). These services include: cryogenics, vacuum and technical electrical and cooling systems. This effort constitutes more than 70 million Euros of construction cost. Rather than have separate support groups in each of the project areas, ESS has created a Specialized Technical Services group within the Accelerator Division to provide these services. This approach permits standardization, development of synergies and improved communication. The STS group also provides cryomodule testing and accelerator infrastructure and installation to the accelerator project. This paper describes the scope of work, current design status and future plans for Specialized Technical services at ESS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI106  
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THPRI113 Spallation Neutron Source Cryogenic Test Facility Horizontal Test Apparatus Operation cavity, plasma, operation, SRF 4043
 
  • B. DeGraff, B.S. Hannah, T.S. Neustadt, J. Saunders
    ORNL RAD, Oak Ridge, Tennessee, USA
  • R. Afanador, M. Doleans, M.P. Howell, S.-H. Kim, C.J. McMahan
    ORNL, Oak Ridge, Tennessee, USA
  
  Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
The Spallation Neutron Source (SNS) has built Superconducting Radio Frequency (SRF) processing and testing facilities to support improvement programs and future upgrades. The Cryogenic Test Facility (CTF) system is capable of delivering liquid helium at 4.5K to different test apparatus in support of SRF testing. This paper describes the final stages of fabrication, commissioning and the initial operation of the Horizontal Test Apparatus (HTA). The HTA allows for cold testing of single jacketed medium-beta or high-beta SRF cavities. Heat loads, capacities, and other performance data collected during operation will be presented. Cavity testing lifecycle for plasma processing research and development will be discussed. System changes to allow for 2K helium operation in the HTA will also be addressed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI113  
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THPRI114 Apparatus and Technique for Measuring Low RF Resistivity of Tube Coatings at Cryogenic Temperatures vacuum, electron, cavity, network 4046
 
  • A. Hershcovitch, M. Blaskiewicz, J.M. Brennan, J. Brodowski, W. Fischer, R. Than, J.E. Tuozzolo
    BNL, Upton, Long Island, New York, USA
  • A.X. Custer, A.A. Dingus, M.Y. Erickson, N.Z. Jamshidi, H.J. Poole
    PVI, Oxnard, California, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
An in-situ technique for coating stainless steel vacuum tubes with Cu was developed to mitigate the problems of wall resistivity that leads to unacceptable ohmic heating of superconducting magnets cold bore and electron cloud generation in RHIC that can limit future machine luminosity enhancement. Room temperature RF resistivity of 10 μm Cu coated stainless steel RHIC beam tube has conductivity close to copper tubing. Before coating the RHIC beam pipe with copper, it is imperative to test the Cu coating’s conductivity at cryogenic. A folded quarter wave resonator structure has been designed and built for insertion in a cryogenic system to measure RF resistivity of copper coated RHIC tubing at liquid helium temperatures. The design is based on making the resonator structure out of a superconducting material such that the copper coating is the most lossy material. RHIC tubing samples prepared with different magnetron sputtering deposition modes are to be optimized by iterative processes. Additionally, this device can also be used for the development of better, cheaper SRF cavities and electron guns. The apparatus and its design details will be presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI114  
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