Keyword: cryogenics
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MOXGB3 LHC Commissioning at Higher Energy operation, dipole, injection, hardware 6
 
  • P. Collier, F. Bordry, J. Wenninger
    CERN, Geneva, Switzerland
  
  The LHC has just come to the end of its first Long Shutdown (LS1) and preparations are underway to prepare for Run 2 data taking at 13 TeV centre of mass energy. After briefly recalling the major work undertaken during the 2-year long LS1, details will be given of the cool-down and hardware commissioning phase where each individual superconducting circuit is individually qualified for operation at nominal current. For the main dipole circuits this phase was completed with a quench training campaign in order to operate reliably at the required field. In parallel to the training campaign a rigorous cold checkout has been used to qualify the machine as an ensemble and to establish the conditions necessary for beam operation. The details of this phase will be given together with associated dry runs and beam injection tests. Finally, the latest news will be presented concerning the beam commissioning of the machine in preparation for first physics operation, which will hopefully begin in June.  
slides icon Slides MOXGB3 [8.452 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOXGB3  
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MOBD1 Preliminary Design of the High-Luminosity LHC Beam Screen with Shielding vacuum, shielding, luminosity, impedance 60
 
  • C. Garion, V. Baglin, R. Kersevan
    CERN, Geneva, Switzerland
  
  A new beam screen is needed in the High-Luminosity LHC (HL-LHC) final focusing magnets. Such an essential vacuum component, while operating in the range 40-60 K, has to ensure the vacuum performance and to prevent the beam-induced heating from reaching the cold bore which is at 1.9 K. In addition, they have to shield the cold mass from physics debris coming from the nearby beam collision points. To such purpose, energy absorbers made of tungsten alloy are installed onto the beam screen in the vacuum system. In this contribution, the proposed mechanical design is shown; it covers different thermomechanical aspects such as the behaviour during a magnet quench and the heat transfer from the tungsten absorbers to the cooling tubes. Assembly and manufacturing tolerances are also considered to evaluate the impact on the aperture. Results obtained with a short prototype assembly test are discussed.  
slides icon Slides MOBD1 [3.089 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOBD1  
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MOPHA052 Optimization of ILC Cryomodule Design Using Explosion Welding Technology cryomodule, niobium, neutron, cavity 913
 
  • A. Basti
    University of Pisa and INFN, Pisa, Italy
  • F. Bedeschi
    INFN-Pisa, Pisa, Italy
  • Ju. Boudagov, B.M. Sabirov, G. Shirkov, Yu.V. Taran
    JINR, Dubna, Moscow Region, Russia
  • A. Bryzgalin, L. Dobrushin, S. Illarionov, E. Pekar
    PWI, Kiev, Ukraine
  • P. Fabbricatore
    INFN Genova, Genova, Italy
  
  Optimization of ILC cryomodule design using explosion welding technology. B.Sabirov, J.Budagov, G.Shirkov - JINR, Dubna, Russia A.Basti, F.Bedeschi, P.Fabbricatore - INFN, Pisa/Genova, Italy A.Bryzgalin, L.Dobrushin, S.Illarionov, E.Pekar - EWI, Kiev, Ukraine JINR activity in the ILC Project is the development, in association with INFN, of techniques to simplify and make cheaper the construction of the ILC cryomodules. In the current ILC TDR design both the helium vessel shell and the connected pipes are made of expensive titanium, one of the few metals that can be welded to niobium by the electron beam technique. We describe the construction and performance of transition elements, obtained by explosion welding, that can couple the niobium cavity with a stainless steel helium vessel. Several designs for these transitions have been produced and studied showing varying levels of reliability. Based on this experience a new design, including a minimal titanium intermediate layer, has been built. Preliminary tests yield impressive results, indicating a very strong resistance of the bon  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA052  
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TUPWA071 Improvements of the Laser System for RF-Gun at SuperKEKB Injector laser, electron, operation, gun 1598
 
  • R. Zhang, T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou
    KEK, Ibaraki, Japan
  
  For realizing higher charge and low emittance electron and positron beams in SuperKEKB, we have been making improvements in laser system for RF-gun. The difficulty in controlling thermomechanical distortions has been one of the most important factors for preserving high laser conversion efficiency of infrared-to-ultraviolet and operating at higher repetition rate. We demonstrated that efficient removal of waste heat can be realized by adopting Yb:YAG and copper bonding composite via Au-Sn solder. On the other hand, we proposed the novel design of the cascade laser configuration. Base on this, we can improve the quantum efficiency by utilizing other Yb ions doped crystals as active medium which are pumped by 1035 nm Yb:YAG laser. Excellent thermal management and high charge beams have been achieved by improvements of these two aspects. Additionally, in order to employ high duty ratio pump system and realize laser operation at high repetition rate, we investigated the laser operation in cryogenic environment. A perspective towards the next step experiment is also presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA071  
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WEPWA014 Low Temperature Properties of 20 K Cooled Test Cavity for C-band 2.6-cell Photocathode RF Gun cavity, experiment, gun, resonance 2519
 
  • T. Tanaka, M. Inagaki, K. Nakao, K. Nogami, T. Sakai
    LEBRA, Funabashi, Japan
  • M.K. Fukuda, T. Takatomi, J. Urakawa, M. Yoshida
    KEK, Ibaraki, Japan
  • D. Satoh
    TIT, Tokyo, Japan
  • T.S. Shintomi
    Nihon University, Tokyo, Japan
  
  Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
A cryogenic C-band 2.6-cell photocathode RF gun, which operates at 20 K, is under development at Nihon University for future possibility of use in a compact linac-driven X-ray source. The cavity material is 6N8 high purity copper, the RRR of which being expected to be higher than 3000. A 2.6-cell pi-mode test cavity was fabricated for investigation of the properties under low temperature of 20 K*. Ultraprecision machining and diffusion bonding of the cavity were carried out in KEK. The operating frequency of the RF gun cavity is 5712 MHz. The machining dimensions of the test cavity were determined by taking into account the contraction of copper from room temperature to 20 K by approximately 0.33 %. The resonant frequency observed at around 21 K was 5711.761 MHz, which is 185 kHz higher than the expected value that was deduced from the resonant frequency obtained at 23.5 degree C in vacuum and the linear expansion coefficient data for OFC copper by NIST**. The unloaded Q-value of 64500 obtained at 21 K is in agreement with the SUPERFISH calculation when the surface resistance of the RRR=3000 copper was specified with taking the anomalous skin effect into account.
* T. Tanaka et al., Proceedings of IPAC2014, 658-660, http://accelconf.web.cern.ch/AccelConf
/IPAC2014/papers/mopri030.pdf
** http://cryogenics.nist.gov/MPropsMAY/OFHC%20Copper/OFHCCopperrev.htm 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA014  
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WEPMA005 Particularities of the ARIEL e-Linac Cryogenic System cryomodule, linac, radiation, TRIUMF 2750
 
  • I.V. Bylinskii, G.W. Hodgson, D. Kishi, S.R. Koscielniak, A. Koveshnikov, R.E. Laxdal, R.R. Nagimov, D. Yosifov
    TRIUMF, Vancouver, Canada
  
  Funding: Canada Foundation for Innovation, British Columbia Knowledge Development Fund, and National Research Council Canada.
The Advanced Rare IsotopE Laboratory (ARIEL) is a major expansion of the Isotope Separation and Acceleration (ISAC) facility at TRIUMF [1]. A key part of the ARIEL project is a 10 mA 50 MeV continuous-wave superconducting radiofrequency (SRF) electron linear accelerator (e-linac). The 1.3 GHz SRF cavities are cooled by liquid helium (LHe) at 2 K [2]. The 4 K 2 K LHe transition is achieved onboard of each cryomodule by the cryoinsert containing counterflow heat exchanger augmented with JT valve [3]. Air Liquide LHe cryoplant provides 4 K LHe to cryomodules. After successful commissioning of the cryoplant, 2 K sub-atmospheric (SA) system and cryomodules, the ultimate integration test confirmed stable operation of two cryomodules comprising two 9 cell SRF cavities. Particularities of this cryogenic system include conservative design of the oil removal system, original design heat exchanger in the SA pumping system, hermetic SA pumps, inline full SA flow purifier, multipurpose recovery/purification compressor, modular LHe distribution system, top-loaded design cryomodules, and overall radiation resistant design. The paper presents details of these features as well as integration tests results. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA005  
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WEPMA019 Status of the Super-FRS Magnet Devlopment for Fair dipole, quadrupole, status, octupole 2792
 
  • H. Müller, E.S. Fischer, H. Leibrock, P. Schnizer, M. Winkler
    GSI, Darmstadt, Germany
  • J.-E. Munoz-Garcia, L. Quettier
    CEA/IRFU, Gif-sur-Yvette, France
  • L. Serio
    CERN, Geneva, Switzerland
  
  The Super FRS is a two-stage in flight separator to be built next to the site of GSI, Darmstadt, Germany as part of FAIR (Facility for Anti-proton and Ion Research). Its purpose is to create and separate rare isotope beams and to enable the mass measurement also for very short lived nuclei. Due to its three branches a wide variety of experiments can be carried out in frame of the NUSTAR collaboration. Due to the large acceptance needed, the magnets of the Super-FRS have to have a large aperture and therefore only a superconducting solution is feasible. A superferric design with superconducting coils was chosen in which the magnetic field is shaped by an iron yoke. We will present the actual design status of the dipole- and multipole magnets as well as the status of the development of the dedicated test facility at CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA019  
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WEPMA037 Manufacturing and First Test Results of Euclid SRF Conical Half-wave Resonator cavity, niobium, vacuum, SRF 2841
 
  • E.N. Zaplatin
    FZJ, Jülich, Germany
  • C.H. Boulware, T.L. Grimm, A. Rogacki
    Niowave, Inc., Lansing, Michigan, USA
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302.
Euclid TechLabs has developed a superconducting conical half-wave resonator (162.5 MHz β=v/c=0.11) for the high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory. The main objective of this project is to provide a resonator design with high mechanical stability based on an idea of the balancing cavity frequency shifts caused by external loads. A unique cavity side-tuning option has been successfully implemented. Niowave, Inc. proposed a complete cavity production procedure including preparation of technical drawings, processing steps and resonator high-gradient tests. During manufacturing a series of cavity and helium vessel modifications to simplify their manufacturing were proposed. Following standard buffered chemical polish surface treatment and high-pressure rinse, a vertical test was carried out at Niowave’s facilities. Here we present the status of the project and the first high-gradient results. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA037  
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WEPMN051 Design of a Superconducting Gantry Cryostat quadrupole, dipole, proton, vacuum 3043
 
  • C. Bonțoiu, I. Martel, J. Sanchez-Segovia
    University of Huelva, Huelva, Spain
  • R. Berjillos, J.P.B. Perez
    TTI, Santander, Spain
  
  The University of Huelva in collaboration with the Andalusian Foundation for Health Research (FABIS) and the TTI Company is currently involved in developing and assembling a prototype for a compact superconducting proton gantry with the goal to generate a business case within the narrow niche of hadron therapy. This article presents the current status of the engineering design for the cryostat and beam steering system. An account for the mechanical deformations due to magnetic forces and weight is also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN051  
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WEPMN065 Progress at the FREIA Laboratory cavity, linac, controls, EPICS 3072
 
  • M. Olvegård, A.K. Bhattacharyya, T.J.C. Ekelöf, J. Eriksson, K. Fransson, K.J. Gajewski, V.A. Goryashko, L. Hermansson, M. Holz, M. Jacewicz, M. Jobs, Å. Jönsson, H. Li, T. Lofnes, H. Nicander, R.J.M.Y. Ruber, R. Santiago Kern, R. Wedberg, V.G. Ziemann
    Uppsala University, Uppsala, Sweden
  • D.S. Dancila, A. Rydberg
    Uppsala University, Department of Engineering Sciences, Uppsala, Sweden
  • R.A. Yogi
    ESS, Lund, Sweden
  
  The FREIA Facility for Research Instrumentation and Accelerator Development at Uppsala University, Sweden, has reached the stage where the testing of superconducting cavities for the European Spallation Source (ESS) is starting. The new helium liquefaction plant has been commissioned and now supplies a custom-made, versatile horizontal cryostat, HNOSS, with liquid helium at up to 140 l/h. The cryostat has been designed and built to house up to two accelerating cavities, or, later on, other superconducting equipment such as magnets or crab cavities. A prototype cavity for the spoke section of the ESS linac will arrive mid 2015 for high-power testing in the horizontal cryostat. Two tetrode-based commercial RF power stations will deliver 400 kW peak power each, at 352 MHz, to the cavity through an RF distribution line developed at FREIA. In addition, significant progress has been made with in-house development of solid state amplifier modules and power combiners for future use in particle accelerators. We report here on these and other ongoing activities at the FREIA laboratory.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN065  
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WEPHA004 Present Quality Assurance for the LHC Beam Vacuum System and its Future Improvement vacuum, controls, operation, status 3103
 
  • J. Sestak, V. Baglin, G. Bregliozzi, P. Chiggiato
    CERN, Geneva, Switzerland
  
  During the Long Shutdown 1 (LS1), the LHC beam vacuum system was upgraded to minimize dynamic vacuum effects like stimulated desorption and beam-induced electron multipacting. A quality assurance plan was mandatory due to the demanding vacuum performance and the limited access to the equipment during the following operation period. Laboratory assessment tests and underground interventions were performed following well-defined and approved procedures. All vacuum related activities were documented and written reports stored in dedicated databases. Quality controls were performed to find mechanical, cabling and equipment functionality non-conformities. Possible issues were identified, classified and tracked in a non-conformity database for future corrective actions. This contribution give an overview of the quality assurance policy followed during the LS1 and the non-conformities reported after quality control. Possible future improvements are also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA004  
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WEPHA006 Recommissioning of the COLDEX Experiment at CERN electron, vacuum, controls, experiment 3109
 
  • R. Salemme, V. Baglin, F. Bellorini, G. Bregliozzi, K. Brodzinski, P. Chiggiato, P. Costa Pinto, P. Gomes, A. Gutierrez, V. Inglese, B. Jenninger, R. Kersevan, E. Michel, M. Pezzetti, B. Rio, A. Sapountzis
    CERN, Geneva, Switzerland
  
  COLDEX (Cold bore Experiment), installed in the Super Proton Synchrotron (SPS) at CERN, is a test vacuum sector used in 2001-2004 to validate the Large Hadron Collider (LHC) cryogenic vacuum system with LHC type proton beams. Its cryostat houses a 2.2 m long copper perforated beam screen surrounded by a stainless steel cold bore, both individually temperature controlled down to 5 and 3 K, respectively. In the framework of the development for the High Luminosity upgrade of the LHC (HL-LHC), COLDEX has been re-commissioned in 2014. The objective of this re-commissioning is the validation of the performance of amorphous carbon coatings at cryogenic temperature with LHC type beams. The existing COLDEX beam screen has been dismounted and carbon coated, while a complete overhaul of the vacuum, cryogenic and control systems has been carried out. This contribution describes the phases of re-commissioning and reviews the current experimental set-up. An overview of the possible measurements with COLDEX, in view of its HL-LHC experimental program, is also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA006  
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WEPHA007 Amorphous Carbon Coatings at Cryogenic Temperatures with LHC Type Beams: First Results with the COLDEX Experiment electron, vacuum, simulation, experiment 3112
 
  • R. Salemme, V. Baglin, G. Bregliozzi, P. Chiggiato, R. Kersevan
    CERN, Geneva, Switzerland
  
  Extrapolations of electron cloud data from the Large Hadron Collider (LHC) Run 1 to the High Luminosity upgrade (HL-LHC) beam parameters predict an intolerable increase of heat load on the beam screens of the inner triplets. Amorphous carbon (a-C) coating of the beam screen surface is proposed to reduce electron cloud production, thereby minimising its dissipated power. To validate this solution, the COLDEX experiment has been re-commissioned. Such equipment mimics the performance of the LHC cold bore and beam screen cryogenic vacuum system in presence of LHC beams in the Super Proton Synchrotron (SPS). The main objective of the study is the performance evaluation of a-C coatings while operating the beam screen in the 10 to 60 K temperature range and cold bore below 3 K. This paper reviews the status of COLDEX and the results obtained during its first experimental runs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA007  
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WEPHA017 Qualification of the Bypass Continuity of the Main Dipole Magnet Circuits of the LHC dipole, operation, controls, experiment 3141
 
  • S. Rowan, B. Auchmann, K. Brodzinski, Z. Charifoulline, B.I. Panev, F. Rodriguez-Mateos, I. Romera, R. Schmidt, A.P. Siemko, J. Steckert, H. Thiesen, A.P. Verweij, G.P. Willering
    CERN, Geneva, Switzerland
  • H. Pfeffer
    Fermilab, Batavia, Illinois, USA
  
  The copper-stabilizer continuity measurement (CSCM) was devised in order to attain complete electrical qualification of all busbar joints, lyres, and the magnet bypass connections in the 13~kA circuits of the LHC. A CSCM is carried out at 20 K, i.e., just above the critical temperature, with resistive magnets. The circuit is then subject to an incremental series of controlled powering cycles, ultimately mimicking the decay from nominal current in the event of a magnet quench. A type test to prove the validity of such a procedure was carried out with success in April 2013, leading to the scheduling of a CSCM on all main dipole circuits up to and including 11.1 kA, i.e., the current equivalent of 6.5 TeV operation. This paper details the procedure, with respect to the type test, as well as the results and analyses of the LHC-wide qualification campaign.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA017  
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WEPHA032 Study on the LN2 Consumption of the Beamline Ln2 Transfer System for TPS Project* controls, operation, vacuum, superconducting-RF 3182
 
  • H.C. Li, W.S. Chan, S.-H. Chang, W.-S. Chiou, F. Z. Hsiao, W.R. Liao, T.F. Lin, H.H. Tsai
    NSRRC, Hsinchu, Taiwan
  
  One system to transfer liquid nitrogen (LN2) will be installed at TPS in 2015 for beamline. This system includes two transfer lines (length 600 m), eight keep-full devices and 26 branch lines with 26 control valves for 24 straight sections of beam lines. The required consumption of LN2 for each beam line is 30 L/h. An archive system was developed to monitor and to calculate the consumption of LN2 for each beam line. This consumption was calculated based on the pressure difference and the flow coefficient (Kv) of the control valve. This paper presents the configuration of the LN2 supply system at NSRRC and a test bench of the calculation of LN2 consumption. A simple test result is presented and discussed.
Cryogenics 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA032  
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WEPHA052 Test Cavity and Cryostat for SRF Thin Film Evaluation cavity, vacuum, niobium, SRF 3232
 
  • O.B. Malyshev, P. Goudket, L. Gurran, D.O. Malyshev, S.M. Pattalwar, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt, L. Gurran
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • P. Goudket, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • T.J. Jones, E.S. Jordan
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  
  In developing superconducting coatings for SRF cavities, the coated samples are tested using various techniques such as resistance measurements, AC and DC magnetometry which provide information about the superconducting properties of the films such as RRR, Hc1, Hc2 and vortex dynamics. However, these results do not allow the prediction of the superconducting properties at RF frequencies. A dedicated RF cavity was designed to evaluate surface resistive losses on a flat sample. The cavity contains two parts: a half-elliptical cell made of bulk Nb and a flat Nb disc. The two parts can be thermally and electrically isolated via a vacuum gap, whereas the electromagnetic fields are constrained through the use of RF chokes. Both parts are conduction cooled hence the system is cryogen free. The flat disk can be replaced with a sample, such as a Cu disc coated with Nb film. The RF test provide the cavity Q-factor and thermometrical measurements of the losses on the sample. The design advantages are that the sample disc can be easily installed and replaced; installing a new sample requires no brazing/welding/vacuum or RF seal, so the sample preparation is simple and inexpensive.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA052  
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WEPTY021 Origin of Trapped Flux Caused by Quench in Superconducting Niobium Cavities cavity, superconductivity, niobium, cryomodule 3309
 
  • M. Checchin, A. Grassellino, M. Martinello, O.S. Melnychuk, A. Romanenko, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
  • M. Checchin, M. Martinello
    Illinois Institute of Technology, Chicago, Illlinois, USA
  
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
In this study we prove that the mechanism at the basis of quality factor degradation due to quench involves the entrapment of ambient magnetic field. The cavity quench in the absence of magnetic field does not introduce any extra losses, and a clear trend between the external field and the extra losses introduced by the quench was observed. It is demonstrated that the quality factor can be totally recovered by quenching in zero applied magnetic field. A dependence of the amount of quality factor degradation on the orientation of the magnetic field with respect to the cavity was also found. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY021  
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WEPTY031 Estimation of Cryogenic Heat Loads in Cryomodule due to Thermal Radiation niobium, radiation, cryomodule, cavity 3338
 
  • A. Saini, V.A. Lebedev, N. Solyak, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  Cryogenic system is one of major cost drivers in high intensity superconducting (SC) continuous wave (CW) accelerators. Thermal radiations coming through the warm-ends of cryomodule and room temperature parts of the power coupler result in additional cryogenic heat loads. Excessive heat load in 2K environment may degrade overall performance of the cavity. In this paper we present studies performed to estimate additional heat load at 2K due to thermal radiation in 650 MHz cavity cryomodule in high energy section of PIP-II SC linac.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY031  
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WEPTY035 Design and Test of the Compact Tuner for Narrow Bandwidth SRF Cavities cavity, operation, SRF, vacuum 3352
 
  • Y.M. Pischalnikov, E. Borissov, I.V. Gonin, J.P. Holzbauer, T.N. Khabiboulline, W. Schappert, S.J. Smith, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  
  Funding: Fermi Research Alliance, LLC under Contract N. DE-AC02-07CH11359 with U.S. Department of Energy.
The design of the compact tuner for 1.3 GHz 9-cell elliptical cavity will be presented. This compact tuner is designed for future accelerators that will operate in CW and pulsed RF-power modes. The major design features include highly reliable active components (electromechanical actuators and piezo-actuators) and the ability to replace tuner active components through designated ports in the cryomodule vacuum vessel. Results of tuner testing with cold cavity will also be presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY035  
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WEPTY061 Progress on the Cryogenic and Current Tests of the MSU Cyclotron Gas Stopper Superconducting Magnet cyclotron, ion, vacuum, dipole 3415
 
  • M.A. Green, G. Bollen, S. Chouhan, A.F. Zeller
    FRIB, East Lansing, Michigan, USA
  • J. DeKamp, C. Magsig, D.J. Morrissey, J. Ottarson, S. Schwarz
    NSCL, East Lansing, Michigan, USA
  
  Funding: This work reported in this paper was supported in part by an NSF grant PHY-0958726
The Michigan State University (MSU) cyclotron gas stopper magnet is a warm iron superconducting cyclotron dipole. The desired field shape is obtained by the pole iron profile. Each coil of the two halves is in a separate cryostat and connected in series through a warm electrical connection. The entire system is mounted on a high voltage platform, and is cooled using six two-stage 4.2 K pulse tube coolers. This paper presents the progress on the magnet fabrication, cooling, and current testing. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY061  
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WEPTY064 Thermal-mechanical Analysis of the FRIB Nuclear Fragment Separator Dipole Magnet radiation, dipole, quadrupole, target 3425
 
  • S.A. Kahn, A. Dudas, G. Flanagan
    Muons, Inc, Illinois, USA
  • R.C. Gupta
    BNL, Upton, Long Island, New York, USA
  
  Funding: This work was supported by the U.S. Department of Energy under Grant DE-SC-0006273
Dipole magnets in the fragment separator region of the Facility for Rare Isotope Beams (FRIB) are critical elements used to select the desired isotopes. These magnets are subjected to high radiation and heat loads. High temperature superconductors (HTS), which have been shown to be radiation resistant and can operate at 40 K where heat removal is substantially more efficient than 4.5 K where conventional superconductors such as NbTi and Nb3Sn operate, are proposed for the coils. The magnet coils carry large current and will be subjected to large Lorentz forces that must be constrained to avoid distortions of the coils. It is desirable to minimize the use of organic materials in the fabrication of this magnet because of the radiation environment. This paper will describe an approach to support the coils to minimize coil deformation and cryogenic heat loss. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY064  
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WEPTY071 Time Resolved Cryogenic Cooling Analysis of the Cornell Injector Cryomodule HOM, simulation, operation, impedance 3443
 
  • R.G. Eichhorn, S.R. Markham, P. Quigley, E.N. Smith
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Managing parallel cryogenic flows has become a key challenge in designing efficient and smart cryo-modules for particle accelerators. In analyzing the heating dynamics of the cornell high current injector module a power-full computational tool has been set-up allowing time resolved analysis and optimization. We will describe the computational methods and data sets we have used, report the results and compare them to measured data from the module being in good agreement. Mitigation strategies developed on basis of this model have helped pushing the operational limitations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY071  
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WEPTY078 High Q0 at Medium Fields in Nb3Sn SRF Cavities at 4.2 K cavity, niobium, SRF, operation 3467
 
  • S. Posen, D.L. Hall, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • Th. Proslier
    ANL, Argonne, Illinois, USA
  
  Nb3Sn has proven itself to be a very promising alternative SRF material. With twice the critical temperature of niobium cavities, 1.3 GHz Nb3Sn cavities can achieve quality factors on the order of 1010 even at 4.2 K, significantly reducing cryogenic infrastructure and operational costs. In addition, its large predicted superheating field may allow for maximum accelerating gradients up to twice that of niobium for high energy applications. In this work, we report on new cavity results from the Cornell Nb3Sn SRF program demonstrating a significant improvement in the maximum field achieved with high Q0 in a Nb3Sn cavity. At 4.2 K, accelerating gradients above 16 MV/m were obtained with Q0 of 8x109, showing the potential of this material for future applications. In addition to this result, current limitations are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY078  
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WEPWI012 First Attempt of At-cavity X-ray Detection in a CEBAF Cryomodule for Field Emission Monitoring cavity, cryomodule, electron, ion 3515
 
  • R.L. Geng, E. Daly, M.A. Drury, A.D. Palczewski
    JLab, Newport News, Virginia, USA
  
  We report on the first result of at-cavity X-ray detection in a CEBAF cryomodule for field emission monitoring. In the 8-cavity cryomodule F100, two silicon diodes were installed near the end flange of each cavity. Each cavity was individually tested during the cryomodule test in JLab’s cryomodule test facility. The behaviors of these at-cavity cryogenic X-ray detectors were compared with those of the standard “in air” Geiger-Muller tubes. Our initial experiments establish correlation between X-ray response of near diodes and the field emission source cavity in the 8-cavity string. For two out of these eight cavities, we also carried out at-cavity X-ray detection experiment during their vertical testing. The aim is to track field emission behavior uniquely from vertical cavity testing to horizontal cavity testing in the cryomodule.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI012  
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WEPWI032 Mechanical Properties of Niobium Cavities cavity, niobium, SRF, electron 3554
 
  • G. Ciovati, P. Dhakal, J. Matalevich, G.R. Myneni
    JLab, Newport News, Virginia, USA
  
  Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
The mechanical stability of bulk Nb cavity is an important aspect to be considered in relation to cavity material, geometry and treatments. Mechanical properties of Nb are typically obtained from uniaxial tensile tests of small samples. In this contribution we report the results of measurements of the resonant frequency and local strain along the contour of single-cell cavities made of ingot and fine-grain Nb of different purity subjected to increasing uniform differential pressure, up to 6 atm. Measurements have been done on cavities subjected to different heat treatments. Good agreement between finite element analysis simulations and experimental data in the elastic regime was obtained with a single set of values of Young’s modulus and Poisson’s ratio. The experimental results indicate that the yield strength of medium-purity ingot Nb cavities is higher than that of fine-grain, high-purity Nb. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI032  
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WEPWI038 Temperature Mapping of Nitrogen-doped Niobium Superconducting Radiofrequency Cavities cavity, niobium, SRF, radio-frequency 3575
 
  • J. Makita
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, P. Dhakal
    JLab, Newport News, Virginia, USA
  
  It was recently shown that diffusing nitrogen on the inner surface of superconducting radiofrequency (SRF) cavities at high temperature can improve the quality factor of the niobium cavity. However, a reduction of the quench field is also typically found. To better understand the location of rf losses and quench, we used a thermometry system to map the temperature of the outer surface of ingot Nb cavities after nitrogen doping and electropolishing. Surface temperature of the cavities was recorded while increasing the rf power and also during the quenching. The results of thermal mapping showed no precursor heating on the cavities and quenching to be ignited near the equator where the surface magnetic field is maximum. Hot-spots at the equator area during multipacting were also detected by thermal mapping.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI038  
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WEPWI045 Status of Superconducting Traveling Wave Cavity for High Gradient Linac cavity, accelerating-gradient, vacuum, feedback 3591
 
  • R.A. Kostin, P.V. Avrakhov, A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • T.N. Khabiboulline, Y.M. Pischalnikov, N. Solyak, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  The use of a travelling wave (TW) accelerating structure with a small phase advance per cell instead of standing wave may provide a significant increase of accelerating gradient in a superconducting linear accelerator. The TW section achieves an accelerating gradient 1.2-1.4 times larger than TESLA-shaped standing wave cavities for the same surface electric and magnetic fields. The final stage of a 3-cell superconducting travelling wave cavity development is presented. This cavity will be tested in travelling wave regime at cryogenic temperature.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI045  
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WEPWI058 The NSLS-II RF Cryogenic System cavity, controls, PLC, operation 3624
 
  • J. Rose, T. Dilgen, W.K. Gash, J. Gosman, J. Papu, R. Sikora
    BNL, Upton, Long Island, New York, USA
  • Y. Jia
    Linde BOC Process Plants LLC, Tulsa, Oklahoma, USA
  • C.M. Monroe
    Monroe Brothers Ltd., Moreton-in-Marsh, United Kingdom
  • V. Ravindranath
    SLAC, Menlo Park, California, USA
  • H. Wilhelm
    Linde Kryotechnik AG, Pfungen, Switzerland
  
  Funding: Work supported by DOE contract DE-SC0012704
The National Synchrotron Light Source II is a 3 GeV X-ray user facility commissioned in 2014. A new helium refrigerator system has been installed and commissioned to support the superconducting RF cavities in the storage ring. Special care was taken to provide very stable helium and LN2 pressures and flow rates to minimize microphonics and thermal effects at the cavities. Details of the system design along with commissioning and early operations data will be presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI058  
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WEPWI060 Cryogenic Test of Double Quarter Wave Crab Cavity for the LHC High Luminosity Upgrade cavity, luminosity, radiation, higher-order-mode 3630
 
  • B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, C. Cullen, L.R. Hammons, C. Marques, J. Skaritka, S. Verdú-Andrés, Q. Wu
    BNL, Upton, Long Island, New York, USA
  • L. Alberty, R. Calaga, O. Capatina
    CERN, Geneva, Switzerland
  • S.A. Belomestnykh, I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  • Z. Li
    SLAC, Menlo Park, California, USA
  
  Funding: Work partly supported by US LARP, by US DOE under contract No. DE-AC02-05CH11231 and through BSA under contract No. DE-AC02-98CH10886. Research supported by EU FP7 HiLumi LHC - Grant Agreement 284404.
A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×109. We report the test results of this design. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI060  
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THPF009 Pumping Properties of Cryogenic Surfaces in SIS100 vacuum, simulation, operation, background 3696
 
  • L.H.J. Bozyk, O.K. Kester, P.J. Spiller
    GSI, Darmstadt, Germany
  • F. Chill, O.K. Kester
    IAP, Frankfurt am Main, Germany
  
  Funding: Work supported by Hic4Fair and BMBF (FKZ:05P12RDRBK).
The synchrotron SIS100 of the planned FAIR facility will provide heavy ion beams of highest intensities. The required low charge states are subject to enhanced charge exchange processes in collisions with residual gas molecules. Therefore, highest vacuum quality is crucial for a reliable operation and minimal beam loss. The generation of the required low gas densities relies on the pumping capabilities of the cryogenic beam pipe walls. Most typical gas components in ultra high vacuum are bound by cryocondensation at LHe temperatures, resulting in ultimate low pressures with almost infinite pumping capacity. Hydrogen can not be crycondensated to acceptable low pressures. But if the surface coverage is sufficiently low, it can get bound by cryoadsorption. The pumping capabilities of cryogenic walls for Hydrogen have been investigated for SIS100-like conditions. The measurement results have been used in dynamic vacuum simulations at heavy ion operation. The simulation results are presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF009  
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THPF010 Simulation and Experimental Investigation of Heavy Ion Induced Desorption from Cryogenic Targets target, simulation, ion, experiment 3699
 
  • 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. Here, new experimental results will be presented along with insights gained from gas dynamics simulations.
* 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-IPAC2015-THPF010  
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THPF015 Status of the FAIR Heavy Ion Synchrotron Project SIS100 quadrupole, dipole, ion, injection 3715
 
  • P.J. Spiller, U. Blell, L.H.J. Bozyk, J. Ceballos Velasco, T. Eisel, E.S. Fischer, O.K. Kester, H.G. König, H. Kollmus, V. Kornilov, P. Kowina, J.P. Meier, A. Mierau, C. Mühle, C. Omet, D. Ondreka, N. Pyka, H.R. Ramakers, P. Rottländer, C. Roux, P. Schnizer, St. Wilfert
    GSI, Darmstadt, Germany
  
  The procurements of major technical components for the heavy ion synchrotron SIS100 are progressing. Especially the production of the long lead items, the main superconducting dipole and quadrupole magnets and the main Rf systems could be started. The system layout for the injection system and the specifications for all injection devices has been completed. In parallel, the Digital Mock-Up (DMU) and design for major extraction components has been developed. Certain technical challenges observed during the acceptance tests of First of Series (FOS) components and risks and their mitigation will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF015  
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THPF069 The Early Results of the Vertical Test for β=0.12 HWR at RISP cavity, coupling, vacuum, niobium 3839
 
  • G.-T. Park, H.J. Cha, H.C. Jung, H. Kim, W.K. Kim, Y.J.K. Kim
    IBS, Daejeon, Republic of Korea
  
  At RISP, we are planning to perform the vertical test of the β=0.12 half wave resonator. We report our progress on the preparation of the test including the cryogenic system, the RF system, the control and data acquisition system, and the radiation shields. We had the first few occaaisions of the cool down and various measurements at a low gradient. Out preliminary result on the Q0-Eacc excitation curve will be given.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF069  
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