Keyword: SRF
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MOXGB2 Commissioning and Operation of 12 GeV CEBAF linac, operation, cryomodule, cavity 1
 
  • A. Freyberger
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
The Continuous Electron Beam Accelerator Facility (CEBAF) located at the Thomas Jefferson National Accelerator Laboratory (JLab) has been recently upgraded to deliver continuous electron beams to the experimental users at a maximum energy of 12 GeV, three times the original design energy of 4 GeV. This paper will present an overview of the upgrade, referred to as the 12GeV upgrade, and highlights from recent beam commissioning results. 		 
slides icon Slides MOXGB2 [4.359 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOXGB2  
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MOBB2 Fabrication of TESLA-shape 9-cell Cavities at KEK for Studies on Mass-Production in Collaboration with Industries cavity, cryomodule, status, controls 31
 
  • T. Saeki, H. Hayano
    KEK, Ibaraki, Japan
  
  The construction of the new Center-of-Innovation (COI) buiding started at KEK from 2014 for the studies of mass-production of Superconducting-RF accelerators in collaboration with industries. The COI buiding is sitting next to the existing KEK-STF building and will include various Superconducting-RF facilities like clean-room for cavity-string assembly, cryomodule-assembly facility, cryogenic system, vertical-test facility, cryomodule-test facility, input-coupler processing facility, cavity Electro-Polishing (EP) facility, and control-room/office-rooms in the dimension of 80 m x 30 m. The purpose of this new SRF facilities is to establish a close collaboration between SRF researchers and industries in order to prepare for the upcoming large-scale future SRF project, like ILC. This article reports the fabricaion of four TESLA-shape 9-cell cavities for the commisioning of these new facilities. Details of the fabrication of these four cavities will be presented.  
slides icon Slides MOBB2 [3.983 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOBB2  
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MOPWA032 Aspects of SRF Cavity Optimization for BESSY-VSR Upgrade cavity, HOM, higher-order-mode, storage-ring 171
 
  • T. Galek, K. Brackebusch, T. Flisgen, J. Heller, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • B.D. Isbarn, B. Riemann, M. Sommer, T. Weis
    DELTA, Dortmund, Germany
  
  Funding: Work supported by Federal Ministry for Research and Education BMBF under contract 05K13HR1.
In this work we present a preliminary study of a long chain of cavities and some aspects involved in the optimization procedure. It is important to numerically model and optimize the SRF cavities with respect to external quality factors of the most dangerous higher order modes. BESSY-VSR is an upgrade scheme for the existing BESSY II storage ring aiming to simultaneously support variable electron pulse lengths. Currently, BESSY II supports long 15 ps bunches in the standard user optics configuration and short 1.5 ps bunches in a so-called low-α optics mode. In order to develop BESSY II into a variable electron pulse length storage ring, additional two sets of SRF higher-harmonic cavities will be installed. The present RF acceleration system operates at 0.5 GHz and the additional 3rd harmonic and 3rd sub-harmonic cavities will operate at 1.5 GHz and 1.75 GHz, respectively. These cavities are essential to produce short 1.5 ps bunches with a design current of up to 0.8 mA per bunch. The total current in the storage ring is limited by the higher order mode damping capabilities of the SRF cavities. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA032  
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MOPMN002 Advances in Parallel Finite Element Code Suite ACE3P cavity, simulation, radiation, electron 702
 
  • C.-K. Ng, L. Ge, C. Ko, O. Kononenko, Z. Li, L. Xiao
    SLAC, Menlo Park, California, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
  
  Funding: Work supported by the US DOE under contract DE-AC02-76SF00515.
New capabilities in SLAC's parallel finite element electromagnetics simulation suite ACE3P are reported. These include integrated electromagnetic (Omega3P), thermal and mechanical (TEM3P) modules for multi-physics modeling, an interface to particle-material interaction codes for calculation of radiation effects due to dark current generation (Track3P), and coupled electromagnetic (ACE3P) and beam dynamics (IMPACT) simulation. Results from these applications are presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN002  
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MOPHA024 A Novel Transverse Deflecting Cavity for Slice Diagnostics at BERLinPro cavity, polarization, emittance, low-level-rf 827
 
  • A. Ferrarotto, B. Riemann, T. Weis
    DELTA, Dortmund, Germany
  • H.-W. Glock, T. Kamps, J. Völker
    HZB, Berlin, Germany
  
  Funding: Work supported by BMBF under contract no. 05K10PEA
BERLinPro is an energy-recovery linac project to be realized at the Helmholtz-Zentrum Berlin (HZB) for an electron beam with 1mm mrad normalized emittance and 100 mA average current. The initial beam parameters are determined by the performance of the electron source, an SRF photo-electron injector. The development auf this SRF photon-electron injector is a main task of BERLinPro. Especially the beam emittance is basically defined by the SRF photogun. For beam diagnostics time dependent effects from the RF curvature and space charge must be taken into account and a sophisticated slice diagnostics is required. To perform this type of diagnostics a transverse deflecting cavity has been designed, characterized and is presently under construction.. This single cell cavity operates in a TM110-like mode at 1.3 GHz optimized for high transverse shuntimpedance of appr. 3.2 MOhm by a concentration of fields near the beam axis. The cavity has a novel geometry that allows for an operation with both polarizations of the TM110-Mode. The layout of the deflecting cavity will be presented together with the results of the low RF characterization. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA024  
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MOPTY013 Control System for DC-SRF Photo-Injector at Peking University controls, laser, LLRF, cryomodule 962
 
  • L.W. Feng, J.K. Hao, S. Huang, L. Lin, K.X. Liu, S.W. Quan, F. Wang, B.C. Zhang
    PKU, Beijing, People's Republic of China
  
  A control system has been designed and constructed to full-fill the operation requirement of the DC-SRF photo injector developed at Peking University. The system includes FPGA based low level radio frequency (LLRF) control system, PLC based machine protection system, VME based magnet power control, and PC based EPICS IOC. All these systems were integrated to support the stable operation of the DC-SRF photo injector and has shown their robustness. The LLRF system was optimized and tuned for 2K CW/Pulse operation and the stability of amplitude and phase achieves 0.1% and 0.1° respectively.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY013  
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MOPTY014 An Experimental Study of Higher-Order Modes Excited by High Repetition Rate Electron Beam in an SRF Cavity HOM, electron, cavity, experiment 965
 
  • Y. Gao, J.E. Chen, L.W. Feng, J.K. Hao, S. Huang, L. Lin, K.X. Liu, X. Luo, S.W. Quan, F. Wang, Zh.W. Wang
    PKU, Beijing, People's Republic of China
  
  Funding: National Natural Science Foundation of China (No. 11275014)
Higher-order modes (HOMs) excited by electron beam traversing a superconducting rf (SRF) cavity contain lots of information and can be used for intra-cavity electron beam diagnostics. Unlike single bunch, multiple bunches would excite HOMs with a much complicated spectrum. In this paper, we present our recent research on HOMs excited by a high repetition rate electron beam in an SRF cavity. Especially, we focus on the integer multiple frequency peaks in the HOM spectrum, which are determined by the nearest eigen HOM peaks. The experiments were carried out on the DC-SRF photoinjector, which was operated at MHz repetition rate. The results agree well with theoretic analysis. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY014  
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MOPWI025 Phase and Amplitude Tuning Algorithms for the FRIB Superconducting Cavities cavity, linac, acceleration, simulation 1207
 
  • Y. Zhang, P. Chu, Z.Q. He
    FRIB, East Lansing, Michigan, USA
  
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
FRIB driver linac will deliver all heavy ion beams up to uranium with energy above 200 MeV/u, and maximum beam power on target 400 kW for nuclear physics research. Phase and amplitude tuning of the FRIB superconducting cavities – totally about 330 of them, are important to the linac beam commissioning at low power and normal operation at high power. Because relatively low beam energy and high acceleration gradient, beam velocity changes significantly in the cavity RF gaps and the beam bunch cannot preserve perfectly in the further downstream beam diagnostics systems, beam longitudinal tuning algorithms are studied for different FRIB cavities and at different beam energy, which include the acceleration cavities as well as the re-buncher cavities. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI025  
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TUPWA018 Progress Report of the Berlin Energy Recovery Project BERLinPro gun, booster, cavity, electron 1438
 
  • M. Abo-Bakr, W. Anders, K.B. Bürkmann-Gehrlein, A. Burrill, A.B. Büchel, P. Echevarria, A. Frahm, H.-W. Glock, A. Jankowiak, C. Kalus, T. Kamps, G. Klemz, J. Knobloch, J. Kolbe, J. Kühn, O. Kugeler, B.C. Kuske, P. Kuske, A.N. Matveenko, A. Meseck, R. Müller, A. Neumann, N. Ohm, K. Ott, E. Panofski, F. Pflocksch, D. Pflückhahn, J. Rahn, J. Rudolph, M. Schmeißer, O. Schüler, J. Völker
    HZB, Berlin, Germany
  
  Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association
The Helmholtz Zentrum Berlin is constructing the Energy Recovery Linac Project BERLinPro on its site in Berlin Adlershof. The project is intended to expand the required accelerator physics and technology knowledge mandatory for the design, construction and operation of future synchrotron light sources. The project goal is the generation of a high current (100 mA), high brilliance (norm. emittance below 1 mm mrad) cw electron beamat 2~ps rms bunch duration or below. The planning phase of the project is completed and the design phase of most of the components is finished. Many of them have already been ordered. After some delay the construction of the building has started in February 2015. The status of the various subprojects as well as a summary of current and future activities will be given. Major project milestones and details of the project time line will be finally introduced. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA018  
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TUPWA023 A Step Closer to the CW High Brilliant Beam with the ELBE SRF-Gun-II gun, cavity, cathode, electron 1456
 
  • R. Xiang, A. Arnold, P.N. Lu, P. Michel, P. Murcek, J. Teichert, H. Vennekate
    HZDR, Dresden, Germany
  
  In order to achieve the CW electron beam with a high average current up to 1 mA and a very low emittance of 1 μm, an improved superconducting photo-injector (ELBE SRF-Gun-II) has been installed and commissioned at HZDR since 2014. This new gun replaces the first 3.5-cell SRF gun (SRF-Gun-I) at the SC Linac ELBE. The RF performance of the niobium cavity has been evaluated, the beam parameters for low charge bunches have been measured, and the first beam has been guided into the ELBE beam line. The results agree with the simulation very well. The photocathode transfer system has been installed for the first high current beam test planned in 2015. However, the unexpected strong degradation on the cavity and also on the photocathode was found soon after the first photocathode exchange. In this contribution the results of the SRF-Gun-II commissioning and the latest experiment will be presented in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA023  
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TUPMA047 Multipacting-free Quarter-wavelength Choke Joint Design for BNL SRF cathode, gun, cavity, electron 1935
 
  • W. Xu, S.A. Belomestnykh, I. Ben-Zvi, C.J. Liaw, G.T. McIntyre, K.S. Smith, R. Than, J.E. Tuozzolo, E. Wang, D. Weiss, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  
  The BNL SRF gun cavity was operated well at CW mode up to 2 MV. However, the performance suffered due to multipacting in the quarter-wavelength choke-joint. A new multipacting-free cathode stalk was designed and will be conditioned. This paper will describes RF and thermal design of new cathode stalk and conditioning results.
This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA047  
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TUPMA049 First Beam Commissioning at BNL ERL SRF Gun cathode, gun, electron, cavity 1941
 
  • W. Xu, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, S. Deonarine, D.M. Gassner, H. Hahn, L.R. Hammons, T. Hayes, J.P. Jamilkowski, P. K. Kankiya, D. Kayran, N. Laloudakis, R.F. Lambiase, V. Litvinenko, L. Masi, G.T. McIntyre, K. Mernick, T.A. Miller, G. Narayan, D. Phillips, V. Ptitsyn, T. Rao, T. Seda, F. Severino, B. Sheehy, K.S. Smith, A.N. Steszyn, T.N. Tallerico, R. Than, J.E. Tuozzolo, E. Wang, D. Weiss, M. Wilinski, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, V. Ptitsyn
    Stony Brook University, Stony Brook, USA
  
  Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
The 704 MHz superconducting RF gun successfully generated the first photoemission beam on Nov. 17 2014. This paper will report the latest results of SRF beam commissioning, including the SRF cavity performance, cathode QE measurements, and beam parameter measurements. The beam commissioning setup is described in the paper as well. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA049  
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TUPHA006 NSLS-II Storage Ring Insertion Device and Front-End Commissioning emittance, injection, storage-ring, insertion 1974
 
  • G.M. Wang, C. Amundsen, G. Bassi, J. Bengtsson, A. Blednykh, E.B. Blum, W.X. Cheng, J. Choi, O.V. Chubar, T.M. Corwin, M.A. Davidsaver, L. Doom, W. Guo, D.A. Harder, P. He, Y. Hidaka, Y. Hu, P. Ilinski, C.A. Kitegi, S.L. Kramer, Y. Li, M. Musardo, D. Padrazo, B. Podobedov, K. Qian, R.S. Rainer, J. Rank, S. Seletskiy, T.V. Shaftan, S.K. Sharma, O. Singh, V. Smalyuk, R.M. Smith, T. Summers, T. Tanabe, F.J. Willeke, L. Yang, X. Yang, L.-H. Yu
    BNL, Upton, Long Island, New York, USA
  
  The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source at Brookhaven National Laboratory. In the spring 2014, the storage ring was commissioning up to 50 mA without insertion device. In the fall, the project beamlines, includes seven insertion devices on six ID ports were commissioned within two and a half months. These beamlines consist of IXS, HXN, CSX-1, CSX-2, CHX, SRX, and XPD-1, from the radiation sources elliptically polarizing undulator (EPU), damping wiggler (DW) and in vacuum undulator (IVU) to cover the VUV through the very hard x-ray range. In this paper, a number of commissioning and operation experiences are discussed here, such as injection, lifetime, ID residual field and compensation, source point stability, beam alignment and tools for control, monitor and beam protection.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPHA006  
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WEPMA010 First Test Results of the BERLinPro 2-cell Booster Cavities cavity, booster, cryomodule, linac 2765
 
  • A. Burrill, W. Anders, A. Frahm, J. Knobloch, A. Neumann
    HZB, Berlin, Germany
  • G. Ciovati, W.A. Clemens, P. Kneisel, L. Turlington
    JLab, Newport News, Virginia, USA
  
  The BERLinPro Energy Recovery Linac (ERL) is currently being built at Helmholtz-Zentrum Berlin in order to study the physics of operating a high current, a 100 mA, 50 MeV ERL utilizing all SRF cavity technology. This machine will utilize three unique SRF cryomodules for the photoinjector, booster and linac cryomodules respectively. The focus of this paper will be on the cavities contained within the booster cryomodule. Here there will be three 2-cell SRF cavities, based on the original design by Cornell University, but optimized to meet the needs of the project. All of the cavity fabrication, processing and testing was carried out at Jefferson Laboratory where 4 cavities were produced and the 3 cavities with the best RF performance were fitted with helium vessels for installation in the cryomodule. This paper will report on the test results of the cavities as measured in the vertical testing dewar at JLab after fabrication and again after outfitting with the helium vessels.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA010  
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WEPMA011 First Horizontal Test Results of the HZB SRF Photoinjector for BERLinPro cavity, operation, cryomodule, gun 2768
 
  • A. Burrill, W. Anders, A. Frahm, J. Knobloch, A. Neumann
    HZB, Berlin, Germany
  • G. Ciovati, W.A. Clemens, P. Kneisel, L. Turlington
    JLab, Newport News, Virginia, USA
  
  The BERLinPro project, a small superconducting RF (SRF) c.w. energy recovery linac (ERL) is being built at Helmholtz-Zentrum Berlin in order to develop the technology required for operation of a high current, 100 mA, 50 MeV ERL. The electron source for the accelerator is a 1.4 cell SRF photoinjector fitted with a multi-alkali photocathode. As part of the HZB photoinjector development program three different SRF photoinjectors will be fabricated and tested. The photoinjector described herein is the second cavity that has been fabricated, and the first photoinjector designed for use with a multi-alkali photocathode. The photoinjector has been built and tested at JLab and subsequently shipped to HZB for testing in the horizontal test cryostat HoBiCaT prior to installation in the photoinjector cryomodule. This cryomodule will be used to measure the photocathode operation in a dedicated experiment called GunLab, the precursor to installation in the BERLinPro hall. This paper will report on the final results of the cavity installed in the helium vessel in the vertical testing dewar at Jefferson Lab as well as the first horizontal test in HoBiCaT  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA011  
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WEPMA013 Hom Damping Optimization Design Studies for BESSY VSR Cavities damping, HOM, cavity, impedance 2774
 
  • A.V. Vélez, H.-W. Glock, J. Knobloch, A. Neumann
    HZB, Berlin, Germany
  
  The BESSY VSR project is a future upgrade of the 3rd generation BESSY II light source. By using the same "standard" user optics, simultaneously long (ca. 15ps) and short (ca. 1.5ps) bunches will be stored. Thus, superconducting higher harmonic cavities of the fundamental 500 MHz at two frequencies need to be installed in the BESSY II storage ring. This work describes the optimizations studies for the Waveguide-based HOM dampers and the adjustable fundamental power coupler for the 1.5 GHz first SRF cavity prototype.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA013  
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WEPMA035 Low- and High-Beta SRF Elliptical Cavity Stiffening cavity, simulation, resonance, proton 2835
 
  • E.N. Zaplatin
    FZJ, Jülich, Germany
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  Elliptical SRF cavities are the main accelerating structures in many accelerators worldwide. Different types of external loads on the resonator walls predetermine the main working conditions of the SC cavities. The most important of them are very high electromagnetic fields that result in strong Lorentz forces and the pressure on cavity walls from the helium tank that also deforms the cavity shape. Also mechanical eigen resonances of cavities are the main source of the microphonics. To withstand any kind of external loads on the resonator walls different schemes of the cavity stiffening were applied. In the paper we report the basic investigations of the cavity stiffening using FNAL 650 MHz β=0.92 and 0.61 as an example. The single-cell investigation results were used as the reference to develop the ultimate scheme of the helium vessel structure to ensure the best resonator stability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA035  
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WEPMA036 Double-Cell Notch Filter for SRF Gun Investigations gun, cathode, cavity, simulation 2838
 
  • E.N. Zaplatin
    FZJ, Jülich, Germany
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • J. Knobloch, A. Neumann
    HZB, Berlin, Germany
  • V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  Some projects of SRF guns apply the design where the cathode can be easily and quickly removed. One of the disadvantages of this design is the RF power leakage from the accelerating gun cavity cells to the cathode housing that results in the excessive cathode heating. To minimize the RF power leak different kinds of choke filters are used to protect the cathode structure. These choke filters represent resonant circuits with a zero input impedance and installed at the entrance of the cathode structure that shunt the cathode housing. Still, since the choke filter frequency shift under working conditions is bigger than its bandwidth a filter tuning during assembly only in the warm stage seems insufficient and requires also fine-tuning during operation. To eliminate the problems of the choke filter fine-tuning and hence ensure its stability during operation, a combination of the resonance choke elements can be implemented. In the paper we demonstrate advantages of the double-cell notch filter using BERLinPro SRF gun cavity as an example with its simple design modifications.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA036  
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WEPMA037 Manufacturing and First Test Results of Euclid SRF Conical Half-wave Resonator cavity, niobium, vacuum, cryogenics 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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WEPMA041 1.3 GHz SRF Cryomodules for the Mainz Energy-recovering Superconducting Accelerator MESA cryomodule, linac, lattice, controls 2853
 
  • F. Schlander, K. Aulenbacher, R.G. Heine, D. Simon, T. Stengler
    IKP, Mainz, Germany
  
  Funding: Work supported by the German Federal Ministery of Education and Research (BMBF) and German Research Foundation (DFG) under the Cluster of Excellence "PRISMA"
The Mainz Energy-recovering Superconducting Accelerator MESA requires superconducting RF systems that provide sufficient energy of 50 MeV per turn to an electron beam. The ordering process of two Rossendorf-type cryomodules, containing two 9-cell 1.3 GHz XFEL-like cavities each, is in progress. Besides an overview of the adaptations required for the multipass and high current beam operation of the cryomodules, details about challenges regarding the installation of the cryomodules on the premises of the Institut für Kernphysik at Universität Mainz are given. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA041  
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WEPMA046 Studies on Innovative Production methods of HOM Coupler for SRF 9-cell Cavity HOM, cavity, controls, target 2869
 
  • K. Nohara, N. Kawabata, K. Miyajima, M. Shinohara
    SPS, Funabashi-shi, Japan
  • H. Hayano, S. Kato, T. Saeki, A. Yamamoto, M. Yamanaka
    KEK, Ibaraki, Japan
  
  Pure Nb as the material of SRF cavity bears hard workability in general. This is why both the inner and outer conductors of HOM coupler for 9-cell cavity have been conventionally produced by full machining, backward extrusion accompanied with annealing and so on. However, in the mass production of 9-cell cavities in ILC, further cost reduction is required. We produced both the inner and outer conductors of HOM coupler for 9-cell cavity in the advanced press forming methods aiming at cost reduction. Press forming of a pure Nb sheet for the outer conductor of HOM coupler was performed with fewer processes free from intermediate annealing and primary machining. For the inner conductor of HOM coupler, water jet cutting and press cold-forging of a plate was performed. The above advanced press forming methods showed favored results, leading to a possibility of simple mass-production of components and cost reduction. The vertical test on a 9-cell cavity with the press formed HOM couplers achieved 36 MV/m that is beyond ILC qualification. The R＆D works are ongoing for further improvement.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA046  
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WEPMA051 Superconducting Solenoid Package Prototyping for FRIB SRF Linac solenoid, dipole, operation, linac 2886
 
  • K. Hosoyama, K. Akai, S. Yamaguchi
    KEK, Ibaraki, Japan
  • E.E. Burkhardt, K. Saito, Y. Yamazaki
    FRIB, East Lansing, Michigan, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Coopertive Agreement DESC000661.
FRIB is an under constructing machine in USA for nuclear physics, which has intensity front SRF linacs to accelerate ion beam from proton to uranium up to 200 MeV/u. FRIB has large users community, so the machine has to be operated very reliably and stably. Superconducting solenoid and steering dipoles as a package is mounted in the cryomodule nearby SRF cavities to focus beam strongly and space effectively. This produces an issue interacting between the fringe field from the solenoid and the SRF cavity, which makes potential performance degradation on SRF cavity. NbTi superconducting wire is utilized for the solenoid package. The high field design like 9T is very critical operation due to the SC characteristics of the wire. The solenoid package has to be designed very carefully. In this paper will report the prototyping of 25 cm 8T solenoid package for FRIB cryomodule, which includes design, fabrication, and cold test.
* This work has been done under the collaboration between KEK and MSU. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA051  
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WEPMA060 The Development of Cavity Frequency Tracking Type RF Control System for SRF-TEM cavity, LLRF, acceleration, electron 2914
 
  • N. Higashi
    The University of Tokyo, Graduate School of Science, Tokyo, Japan
  • A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, M. Nishiwaki, H. Sakai, M. Sawabe, K. Ueno, M. Yamamoto
    KEK, Ibaraki, Japan
  • M. Kuriki
    HU/AdSM, Higashi-Hiroshima, Japan
  • S. Yamashita
    ICEPP, Tokyo, Japan
  
  Superconducting accelerating cavities used in high-energy accelerators can generate high electric fields of several 10 MV/m by supplying radio frequency waves (RF) with frequencies matched with resonant frequencies of the cavities. Generally, frequencies of input RFs are fixed, and resonant frequencies of cavities that are fluctuated by Lorentz force detuning and Microphonics are corrected by feedbacks of cavity frequency tuners and input RF power. Now, we aim to develop the cavity frequency tracking type RF control system where the frequency of input RF is not fixed and consistently modulated to match the varying resonant frequency of the cavity. In KEK (Tsukuba, Japan), we are developing SRF-TEM that is a new type of transmission electron microscope using special-shaped superconducting cavity. By applying our new RF control system to the SRF-TEM, it is expected to obtain stable accelerating fields so that we can acquire good spatial resolution. In this presentation, we will explain the required stabilities of accelerating fields for SRF-TEM and the feasibility of SRF-TEM in the case of applying the cavity frequency tracking type RF control system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA060  
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WEPMN013 Development of DC-SRF Injector at Peking University cavity, laser, electron, cathode 2944
 
  • J.K. Hao, J.E. Chen, P.L. Fan, L.W. Feng, S. Huang, L. Lin, K.X. Liu, S.W. Quan, F. Wang, Zh.W. Wang, X.D. Wen, H.M. Xie, K. Zhao, F. Zhu
    PKU, Beijing, People's Republic of China
  
  DC-SRF electron injector, which combines a DC Pierce gun and a 3.5 cell 1.3 GHz superconductor cavity in a cryomodule, has been developed at Peking University. Based on the improvements of beam line, LLRF system and 2K cryogenic system, stable operation of the DC-SRF injector has been carried out recently. Electron beams with 3.4 MeV energy and the currents of ~1mA in a macro-pulse mode was obtained. As the first application of this DC-SRF injector, THz radiation produced with a 10 period undulator was also detected. The description of the experiment process and results will be presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN013  
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WEPMN024 Exploration of Multi-fold Symmetry Element-loaded Superconducting Radio Frequency Structure for Reliable Acceleration of Low- & Medium-Beta Ion Species cavity, acceleration, RF-structure, ion 2978
 
  • S.C. Huang
    IMP/CAS, Lanzhou, People's Republic of China
  • R.L. Geng
    JLab, Newport News, Virginia, USA
  
  Reliable acceleration of low- to medium-beta proton or heavy ion species is needed for future high current superconducting radio frequency accelerators. Due to the high-Q nature of a superconducting RF resonator, it is sensitive to many factors such as loading variation (from either the accelerated beam or from parasitic field emitted electrons), mechanical vibration, and liquid helium bath pressure fluctuation etc. To increase the stability against those factors, a mechanically strong and stable RF structure is desirable. Guided by this consideration, multi-fold symmetry element-loaded superconducting radio frequency structures, cylindrical tanks with multiple (n>=3) rod-shaped radial elements, are being explored. The top goal of its optimization is to improve mechanical stability. A natural consequence of this structure is a lowered ratio of the peak surface electromagnetic field to the acceleration gradient as compared to the traditional spoke cavity. A disadvantage of this new structure is an increased size for a fixed resonant frequency and optimal beta. This paper describes the optimization of EM design and preliminary mechanical analysis for such structures.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN024  
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WEPMN042 400 mA Beam Store with Superconducting RF Cavities at PLS-II cavity, vacuum, operation, cryomodule 3021
 
  • Y.U. Sohn, M.-H. Chun, T. Ha, M.S. Hong, Y.D. Joo, H.-S. Kang, H.-G. Kim, K.R. Kim, T.-Y. Lee, C.D. Park, H.J. Park, I.S. Park, S. Shin, I.H. Yu, J.C. Yun
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  Funding: Minister of Science, ICT and Future Planning
Three superconducting RF cavities were commissioned with electron beam in way of one by one during the last 3 years, and now PLS-II is in user service on the way of beam current to 400mA, the target of PLS-II. The cavities and cryomodules were prepared with SRF standard technology and procedures, then vertical test, windows conditioning, cryogenic test in each cryomodule, horizontal power test, conditioning, and commissioning without and with beam at PLS-II tunnel by collaboration with industries. All the cavities showed stable performances as good as not-observing any RF instability from cavities, couplers and windows up to 400 mA beam store, but observing several cavity quenches and minor vacuum bursts by abrupt power with control and human errors. The initial beam current for user run were recorded as 150 mA with one cavity, 280 mA with two cavities and 320 mA with three cavities. The 400 mA beam was also achieved with two cavities by decay mode and also with three cavities by top-up mode. The stabilities of RF amplitude and phase are good enough not to induce beam instabilities. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN042  
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WEPHA052 Test Cavity and Cryostat for SRF Thin Film Evaluation cavity, vacuum, niobium, cryogenics 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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WEPHA058 Superconducting Coatings Synthesized by CVD/PECVD for SRF Cavities niobium, superconductivity, plasma, accelerating-gradient 3246
 
  • P. Pizzol, P. Chalker, T. Heil
    The University of Liverpool, Liverpool, United Kingdom
  • A.N. Hannah, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G.B.G. Stenning
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  Funding: STFC
Bulk niobium cavities are widely employed in particle accelerators to create high accelerating gradient despite their high material and operation cost. In order to reduce this cost, thin layer of niobium are deposited on a copper cavity, which has lower material cost with higher availability and more importantly higher thermal conductivity. The coating of superconducting cavities currently is synthesized by physical vapour deposition (PVD) method which suffers from lack of conformity. By using chemical vapour deposition (CVD) and plasma enhanced chemical vapour deposition (PECVD) it is possible to deposit thin Nb layers uniformly with density very close to bulk material. This project explores the use of PECVD / CVD techniques to deposit metallic niobium on copper using NbCl5 as precursor and hydrogen as a coreagent. The samples obtained were then characterized via SEM, TEM, SAD, XRD, XPS, and EDX as well as assessing their superconductivity characteristics (RRR and Tc) All the samples deposited are superconductive and polycrystalline; the sample obtained with CVD measured RRR=31 and Tc=7.9 K, while the sample obtained with PECVD exhibited RRR=9 and Tc= 9.4 K. In both cases the films grew in a (100) preferred orientation. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA058  
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WEPHA059 Physical Vapour Deposition of Thin Films for Use in Superconducting RF Cavities superconductivity, plasma, power-supply, radio-frequency 3249
 
  • S. Wilde, B. Chesca
    Loughborough University, Loughborough, Leicestershire, United Kingdom
  • A.N. Hannah, D.O. Malyshev, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G.B.G. Stenning
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  The production of superconducting coatings for radio frequency cavities is a rapidly developing field that should ultimately lead to acceleration gradients greater than those obtained by bulk Nb RF cavities. Optimizing superconducting properties of Nb thin-films is therefore essential. Nb films were deposited by magnetron sputtering in pulsed DC mode onto Si (100) and MgO (100) substrates and also by high impulse magnetron sputtering (HiPIMS) onto Si (100), MgO (100) and polycrystalline Cu. The films were characterised using scanning electron microscopy, x-ray diffraction and DC SQUID magnetometry.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA059  
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WEPTY008 Superconducting Harmonic Cavity for the Advanced Photon Source Upgrade cavity, HOM, photon, cryomodule 3267
 
  • M.P. Kelly, A. Barcikowski, J. Carwardine, Z.A. Conway, D. Horan, S.H. Kim, P.N. Ostroumov, G.J. Waldschmidt
    ANL, Argonne, Illinois, USA
  • J. Rathke, T. Schultheiss
    AES, Medford, New York, USA
  
  A new bunch lengthening cryomodule using a single-cell ‘higher-harmonic’ superconducting cavity (HHC) based on the TESLA shape and operating at the 4th harmonic (1408 MHz) of the main RF is under development at Argonne. The system will be used to improve the Touschek lifetime and increase the single-bunch current limit in the upgraded multibend achromat lattice of the Advanced Photon Source electron storage ring. The 4 K cryomodule will fit within one half of a straight section, ~2.5 meters, of the ring. The system will use a pair of moveable 20 kW (each) CW RF power couplers to adjust the loaded Q and extract power from the beam. This will provide the flexibility to adjust the impedance presented to the beam and run at various beam currents. Higher-order modes (HOMs) induced by the circulating electron beam will be extracted along the beam axis and damped using a pair of room temperature beam line absorbers. Engineering designs and the prototyping status for the cavity, power couplers and HOM absorbers are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY008  
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WEPTY010 Electropolishing for Low-Beta and Quasi-Waveguide SRF Cavities cavity, cathode, niobium, controls 3273
 
  • T. Reid, Z.A. Conway, S.M. Gerbick, M. Kedzie, M.P. Kelly, P.N. Ostroumov
    ANL, Argonne, Illinois, USA
  
  Argonne National Laboratory (ANL) has extended high quality electropolishing techniques based on those developed for the International Linear Collider to several more complex superconducting RF cavities. These include the co-axial TEM-mode quarter-wave and half-wave cavities as well as a 2.8 GHz quasi-waveguide structure intended for beam bunch rotation. This system is an improved version of the one developed for 1.3 GHz 9-cell cavities and includes easy provision for direct water cooling using the helium jacket. The performance of these SRF cavities both in terms of RF fields and losses equals or exceeds that of most 9-cell elliptical cavities built and tested today.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY010  
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WEPTY022 Modifications of Superconducting Properties of Niobium Caused by Nitrogen Doping Recipes for High Q Cavities niobium, cavity, superconductivity, vacuum 3312
 
  • A. Vostrikov, M. Checchin, A. Grassellino, A. Romanenko
    Fermilab, Batavia, Illinois, USA
  • Y.K. Kim, A. Vostrikov
    University of Chicago, Chicago, Illinois, USA
  
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Discovery at Fermilab of a drastic effect of nitrogen doping leading to unprecedented high Q values in niobium cavities * motivated a strong interest in revealing the physics underlying the effect. In this contribution we present new results obtained by DC magnetometry, AC susceptibility, resistivity and thermal properties measurements on nitrogen doped samples prepared by different recipes/doping levels, which shed light on the possible origin of the effect.
* A. Grassellino et al, 2013 Supercond. Sci. Technol. 26 102001 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY022  
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WEPTY034 T-map Studies on Gradient-limiting Mechanism in Nitrogen Doped Cavities cavity, niobium, superconductivity, factory 3348
 
  • M. Martinello, M. Checchin, A. Grassellino, A. Romanenko
    Fermilab, Batavia, Illinois, USA
  
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Nitrogen doping * results in ultra-high quality factors in SRF niobium cavities but currently achievable gradients in doped cavities are, on average, somewhat lower than in EP/120C baked cavities. The origin of this difference is explored in the reported work by detailed temperature mapping studies on several single cell nitrogen doped cavities.
* A. Grassellino et al, 2013 Supercond. Sci. Technol. 26 102001 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY034  
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WEPTY035 Design and Test of the Compact Tuner for Narrow Bandwidth SRF Cavities cavity, cryogenics, operation, 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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WEPTY066 T-Maps Taken During Cool-down of an SRF cavity: a Tool to Understand Flux Trapping cavity, superconductivity, data-analysis, operation 3431
 
  • R.G. Eichhorn, F. Furuta, G.M. Ge
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  During the past years the impact of cool-down procedures on the flux trapping properties of superconducting cavities have been under investigation. We have measured temperature distributions of a multi-cell cavity using a T-map set-up to understand the transition to superconductivity in detail. We will report how the spatial disorder is affected by the cool-down speed and relate our findings to data on flux pinning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY066  
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WEPTY068 Asymmetric Thermo-currents Diminishing SRF Cavity Performance cavity, niobium, simulation, superconducting-cavity 3437
 
  • R.G. Eichhorn, J. May-Mann
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Over the past years it became evident that the quality factor of a superconducting cavity is not only determined by its surface preparation procedure, but is also influenced by the way the cavity is cooled down. In this paper we will present results from numerical field calculations of magnetic fields produced by thermo-currents, driven by temperature gradients and material transitions. We will show how they can impact the quality factor of a cavity by producing a magnetic field at the RF surface of the cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY068  
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WEPTY072 Update on Nitrogen-doped 9-cell Cavity Performance in the Cornell Horizontal Test Cryomodule cavity, cryomodule, linac, operation 3446
 
  • D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, D.L. Hall, Y. He, K.M.V. Ho, G.H. Hoffstaetter, M. Liepe, J.T. Maniscalco, T.I. O'Connel, S. Posen, P. Quigley, J. Sears, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • A. Grassellino, C.J. Grimm, O.S. Melnychuk, A. Romanenko
    Fermilab, Batavia, Illinois, USA
  
  Funding: U.S. Department of Energy
The Linac Coherent Light Source-II (LCLS-II) is a new x-ray source that is planned to be constructed in the existing SLAC tunnel. To meet the quality factor specifications (2.7x 1010 at 2.0 K and 16 MV/m), nitrogen-doping has been proposed as a preparation method for the SRF cavities. In order to demonstrate the feasibility of these goals, four 9-cell cavity tests have been completed in the Cornell Horizontal Test Cryomodule (HTC), which serves as a test bench for the full LCLS-II cryomodule. Here we report on the most recent two cavity tests in the HTC: one cavity nitrogen-doped at Cornell and tested with high Q input coupler and then again tested with high power LCLS-II input coupler. Transition to test in horizontal cryomodule resulted in no degradation in Q0 from vertical test. Additionally, increased dissipated power due to the high power input coupler was small and in good agreement with simulations. These results represent a crucial step on the way to demonstrating technical readiness for LCLS-II. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY072  
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WEPTY073 Update on Nitrogen Doping: Quench Studies and Sample Analysis cavity, niobium, vacuum, radiation 3450
 
  • D. Gonnella, F. Furuta, G.M. Ge, J.J. Kaufman, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: U.S. Department of Energy, NSF
Recently, nitrogen-doping of niobium has emerged as a promising preparation method for SRF cavities to reach higher intrinsic quality factors than can be reached with typical cavity preparation. Nitrogen-doped cavities prepared at Cornell have shown quality factors higher than 4x1010 at 2.0 K and 16 MV/m. While Q results have been very exciting, a reduced quench field currently limits nitrogen-doped cavities with quench typically occurring between 15 and 25 MV/m. Here we report on recent results from Cornell on single-cell and 9-cell cavities, focusing on new preparations and maximum and critical fields. First we discuss results from over-doping niobium with nitrgoen, baking nitrogen-doped cavities at 120C, and doping with Argon. For a subset of these cavities we show results from quench studies that have been completed using temperature mapping. Finally, we present the first measurements of the higher critical field, Hc2, for nitrogen-doped niobium samples. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY073  
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WEPTY075 Hc2 Measurements of Nb3Sn and Nitrogen-doped Niobium using Physical Property Measurement System niobium, controls, superconductivity, radio-frequency 3458
 
  • J.T. Maniscalco, D. Gonnella, D.L. Hall, M. Liepe, S. Posen
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  The measurement of the upper critical field of a type-2 superconductor, Hc2, is an important step in determining its superconducting properties, and therefore its suitability as a material in SRF cavities. However, measuring Hc2 directly can be challenging, as performing electrical measurements causes changes in the very properties one seeks to measure. We present a method for extracting Hc2 from resistivity measurements made near the transition temperature for varied applied fields and excitation currents. We also present results of these measurements made on Nb3Sn and nitrogen-doped niobium.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY075  
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WEPTY076 RF Performance Studies of Thin-Film Superconductors Using a Sample Host Cavity cavity, niobium, operation, background 3462
 
  • J.T. Maniscalco, D.L. Hall, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Thin-film superconductors have the potential for reduced cost and for improved SRF performance over traditional bulk niobium superconducting cavities. Materials such as Nb3Sn, multilayer NbN/MgO, and thin-film Nb are currently under investigation for cost reduction or possible improvements in RF losses and accelerating gradients. Due to the complex geometries of traditional RF cavities, it is preferable to use a sample host cavity to study flat samples of the novel materials. The Cornell sample host cavity has been commissioned and has now reached peak magnetic surface fields of 100 mT. We present updates on the recent performance of the cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY076  
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WEPTY077 On Quench Propagation, Quench Detection, and Second Sound in SRF Cavities niobium, cavity, simulation, radio-frequency 3464
 
  • S.R. Markham, R.G. Eichhorn
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  The detection of a second sound wave, excited by a quench, has become a valuable tool in diagnosing hot spots and performance limitations of superconducting cavities. Several years ago, Cornell developed an oscillating super-leak transducer (OST) for these waves that nowadays are used world-wide. In a usual set-up, several OSTs surround the cavity, and the quench location is determined by triangulation of the different OST signals. Convenient as the method is there is a small remaining mystery: taking the well-known velocity of the second sound wave, the quench seems to come from a place slightly above the cavity’s outer surface. We will present a model based on numerical quench propagation simulations and analytic geometrical calculations that help explain the discrepancy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY077  
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WEPTY078 High Q0 at Medium Fields in Nb3Sn SRF Cavities at 4.2 K cavity, niobium, cryogenics, 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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WEPTY082 High Gradient Testing of the Five-cell Superconducting RF Module with a PBG Coupler Cell cavity, HOM, linac, coupling 3471
 
  • S. Arsenyev, W.B. Haynes, D.Y. Shchegolkov, E.I. Simakov, T. Tajima
    LANL, Los Alamos, New Mexico, USA
  • C.H. Boulware, T.L. Grimm, A. Rogacki
    Niowave, Inc., Lansing, Michigan, USA
  
  We report results of high-gradient testing of the first 5- cell superconducting radio frequency (SRF) module with a photonic band gap cell (PBG). Higher order mode (HOM) damping is vital for preserving the quality of high-current electron beams in novel SRF accelerators. Because HOMs are not confined by the PBG array, they can be effectively damped in order to raise the current threshold for beam instabilities. The PBG design increases the real-estate gradient of the linac because both HOM damping and the fundamental power coupling can be done through the PBG cell instead of via the beam pipe at the ends of the cavity. A superconducting multi-cell cavity with a PBG damping cell is therefore an attractive option for high-current linacs. The first-ever SRF multi-cell cavity incorporating a PBG cell was designed a LANL and built at Niowave Inc. The cavity was tuned to a desired gradient profile and underwent surface treatment at Niowave. A vertical test (VTS) was then performed at LANL, demonstrating an abnormally low cavity quality factor in the accelerating mode of 1.6*106. Future tests are proposed to determine the source of the losses and resolve the problem.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY082  
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WEPWI007 TTF3 Power Coupler Thermal Analysis for LCLS-II CW Operation simulation, operation, cavity, resonance 3503
 
  • L. Xiao, C. Adolphsen, Z. Li, C.D. Nantista, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  • I.V. Gonin, N. Solyak
    Fermilab, Batavia, Illinois, USA
  
  The TESLA 9-cell SRF cavity design has been adopted for use in the LCLS-II SRF Linac. Its TTF3 coaxial Fundamental Power Coupler (FPC), developed for pulsed operation in the European XFEL and ILC, requires modest changes to make it suitable for LCLS-II CW operation, in which it must be able to handle up to 7 kW of average power with the maximum temperature rise not to exceed 150 C. In order to improve TTF3 FPC cooling, an increased copper plating thickness will be used on the inner and outer conductor stainless steel RF surfaces. Fully 3D FPC thermal analysis with copper plating was performed using the SLAC developed parallel finite element code suite ACE3P with integrated electromagnetic, thermal and mechanical multi-physics simulation capabilities. In this paper, we present TTF3 FPC thermal analysis simulation results obtained using ACE3P as well as a comparison with measurement results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI007  
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WEPWI009 Nitrogen Doping Study in Ingot Niobium Cavities cavity, niobium, accelerating-gradient, radio-frequency 3506
 
  • P. Dhakal, G. Ciovati, P. Kneisel, G.R. Myneni
    JLab, Newport News, Virginia, USA
  • J. Makita
    ODU, Norfolk, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
Thermal diffusion of nitrogen in superconducting radio frequency cavities at temperatures around 800C has resulted in the increase in quality factor with a low-field Q-rise. However, the maximum accelerating gradients of these doped cavities often reduces below the values achieved by standard treatments. In this contribution, we present the results of the nitrogen diffusion into ingot niobium cavities subjected to successive material removal from the inner cavity surface by electropolishing in an effort to explore the underlying cause for the gradient degradation. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI009  
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WEPWI011 Commissioning Results of Nb3Sn Cavity Vapor Diffusion Deposition System at JLab cavity, niobium, vacuum, network 3512
 
  • G.V. Eremeev, W.A. Clemens, K. Macha, H. Park, R.S. Williams
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Nb3Sn as a BCS superconductors with a superconducting critical temperature higher than that of niobium offers potential benefit in lower surface resistance at the same temperature and frequency for SRF cavities. A Nb3Sn vapor diffusion deposition system was built and commissioned at Jefferson Lab. As the part of the commissioning a single cell 1.5 GHz CEBAF-shaped cavity was coated in the built system. The cavity exhibited the superconducting transition at about 17.9 K. The low field quality factor was about 5x109 at 4 K and 7x109 at 2 K dropping with field to about 109 at both temperatures at about 8 MV/m. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI011  
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WEPWI013 New Results of Development on High Efficiency High Gradient Superconducting RF Cavities cavity, linac, niobium, photon 3518
 
  • R.L. Geng
    JLab, Newport News, Virginia, USA
  • C. Adolphsen, Z. Li
    SLAC, Menlo Park, California, USA
  • J.K. Hao, K.X. Liu
    PKU, Beijing, People's Republic of China
  • H.Y. Zhao
    Ningxia Orient Tantalum Industry Co., Ltd., Dawukou District, Shizuishan city, People's Republic of China
  
  We report on the latest results of development on high efficiency high gradient superconducting radio frequency (SRF) cavities. Several 1-cell cavities made of large-grain niobium (Nb) were built, processed and tested. Two of these cavities are of the Low Surface Field (LSF) shape. Series of tests were carried out following controlled thermal cycling. Experiments toward zero-field cooling were carried out. The best experimentally achieved results are Eacc = 41 MV/m at Q0 = 6.5×1010 at 1.4 K by a 1-cell 1.3 GHz large-grain Nb TTF shape cavity and Eacc = 49 MV/m at Q0 = 1.5×1010 at 1.8 K by a 1-cell 1.5 GHz large-grain Nb CEBAF upgrade low-loss shape cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI013  
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WEPWI016 Investigation of Differential Surface Removal due to Electropolishing at JLab cavity, simulation, cathode, radio-frequency 3525
 
  • F. Marhauser, J. Follkie, C.E. Reece
    JLab, Newport News, Virginia, USA
  
  Surface chemistry carried out for Superconducting Radio Frequency (SRF) cavities such as Buffered Chemical Polishing (BCP) and Electropolishing (EP) aims to uniformly remove the internal surface of a cavity along the entire structure and within each cell from equator to iris in order to obtain an equally etched surface. A uniform removal however is not readily achievable due to the complex fluid flow and varying temperatures of the acid mixture, which can lead to differential etching. This needs to be considered when envisaging a certain surface damage removal throughout the interior. The process-specific differential etching influences the target frequency set at the manufacturing stage as well as the field flatness and length of the as-built cavity. We report on analyses of JLab's present EP system using experimental data for six nine-cell cavities that have been processed recently in the frame of the LCLS-II high-Q development plan. In conjunction with numerical simulations, the differential etching and the impact on field flatness is assessed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI016  
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WEPWI019 Quench Studies of Six High Temperature Nitrogen Doped 9 Cell Cavities for Use in the LCLS-II Baseline Prototype Cryo-module at Jefferson Laboratory cavity, cryomodule, niobium, injection 3528
 
  • A.D. Palczewski, G.V. Eremeev, R.L. Geng, C.E. Reece
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Jefferson Lab (JLab) processed six nine-cell cavities as part of a small-scale production for LCLS-II cavity processing development utilizing the promising nitrogen-doping process. [1] Various nitrogen-doping recipes have been scrutinized to optimize process parameters with the aim to guarantee an unloaded quality factor (Q 0) of 2.7·1010 at an accelerating field (Eacc) of 16 MV/m at 2.0 K in the cryomodule. During the R&D phase the characteristic Q0 vs. Eacc performance curve of the cavities has been measured in JLab’s vertical test area at 2 K. The findings showed the characteristic rise of the Q0 with Eacc as expected from nitrogen-doping. Initially, five cavities achieved an average Q0 of 3.3·1010 at the limiting Eacc averaging to 16.8 MV/m, while one cavity experienced an early quench accompanied by an unusual Q 0 vs. Eacc curve. The project accounts for a cavity performance loss from the vertical dewar test (with or without the helium vessel) to the horizontal performance in a cryomodule, such that these results leave no save margin to the cryomodule specification. Consequently, a refinement of the nitrogen-doping has been initiated to guarantee an average quench field above 20 MV/m without impeding the Q 0. This paper covers the refinement work performed for each cavity, which depends on the initial results, as well as a quench analysis carried out before and after the rework during the vertical RF tests as far as applicable. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI019  
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WEPWI021 An Analysis of the Temperature and Field Dependence of the RF Surface Resistance of Nitrogen-Doped Niobium SRF Cavities with Respect to Existing Theoretical Models cavity, niobium, site, superconductivity 3532
 
  • C.E. Reece, A.D. Palczewski
    JLab, Newport News, Virginia, USA
  • B. P. Xiao
    BNL, Upton, Long Island, New York, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177
Recent progress with the reduction of rf surface resistance (Rs) of niobium SRF cavities via the use of high temperature surface doping by nitrogen has opened a new regime for energy efficient accelerator applications. For particular doping conditions one observes dramatic decreases in Rs with increasing surface magnetic fields. The observed variations as a function of temperature may be analyzed in the context of recent theoretical treatments in hopes of gaining insight into the underlying beneficial mechanism of the nitrogen treatment. Systematic data sets of Q0 vs. Eacc vs. temperature acquired during the high Q0 R&D work of the past year will be compared with theoretical model predictions. *
* B. P. Xiao et al., Physica C: Superconductivity 490 (0), 26-31 (2013) and
A. Gurevich, PRL 113 (8), 087001 (2014) 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI021  
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WEPWI022 RF System Requirements for a Medium-Energy Electron-Ion Collider (MEIC) at JLab ion, electron, collider, booster 3536
 
  • R.A. Rimmer, J. Guo, J. Henry, H. Wang, S. Wang
    JLab, Newport News, Virginia, USA
  • Y.L. Huang
    IMP/CAS, Lanzhou, People's Republic of China
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
JLab is studying options for a medium energy electron-ion collider that could fit on the JLab site and use CEBAF as a full-energy electron injector. A new ion source, linac and booster would be required, together with collider storage rings for the ions and electrons. In order to achieve the maximum luminosity these will be high current storage rings with many bunches. We present the high level RF system requirements for the storage rings, ion booster ring and high-energy ion beam cooling system, and describe the technology options under consideration to meet them. We also present options for staging that might reduce the initial capital cost while providing a smooth upgrade path to a higher final energy. The technologies under consideration may also be useful for other proposed storage ring colliders or ultimate light sources. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI022  
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WEPWI028 Simulation Study Using an Injection Phase-locked Magnetron as an Alternative Source for SRF Accelerators controls, injection, klystron, cavity 3544
 
  • H. Wang, T. E. Plawski, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  
  As a drop-in replacement for the CEBAF CW klystron system, a 1497 MHz, CW type high efficiency magnetron using injection phase lock and amplitude variation is attractive. Amplitude control using magnetic field trimming and anode voltage modulation has been studied using analytical models and MATLAB/Simulink simulations. Since the 1497 MHz magnetron has not been built yet, previously measured characteristics of a 2.45GHz cooker magnetron are used as reference. The results of linear responses to the amplitude and phase control of a superconducting RF (SRF) cavity, and the expected overall benefit for the current CEBAF and future MEIC RF systems are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI028  
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WEPWI032 Mechanical Properties of Niobium Cavities cavity, niobium, electron, cryogenics 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, radio-frequency, cryogenics 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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WEPWI040 Experiment and Results on Plasma Etching of SRF Cavities cavity, plasma, niobium, ion 3581
 
  • J. Upadhyay, J.J. Peshl, S. Popović, L. Vušković
    ODU, Norfolk, Virginia, USA
  • D.S. Im
    Old Dominion University, Norfolk, Virginia, USA
  • H.L. Phillips, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  
  The inner surfaces of SRF cavities are currently chemically treated (etched or electro polished) to achieve the state of the art RF performance. We designed an apparatus and developed a method for plasma etching of the inner surface for SRF cavities. The process parameters (pressure, power, gas concentration, diameter and shape of the inner electrode, temperature and positive dc bias at inner electrode) are optimized for cylindrical geometry. The etch rate non-uniformity has been overcome by simultaneous translation of the gas point-of-entry and the inner electrode during the processing. A single cell SRF cavity has been centrifugally barrel polished, chemically etched and RF tested to establish a baseline performance. This cavity is plasma etched and RF tested afterwards. The effect of plasma etching on the RF performance of this cavity will be presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI040  
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WEPWI044 High-Power Magnetron Transmitter for the Electron Collider Ring of the MEIC Facility controls, cavity, electron, injection 3587
 
  • G.M. Kazakevich
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • B.E. Chase, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • Y.S. Derbenev
    JLab, Newport News, Virginia, USA
  
  Operation of the 3-12 GeV electron collider 8-shape ring of the MEIC facility causes a Synchrotron Radiation (SR) of electrons in arcs with energy loss of ~20 kW/m at beam current of ~3 A. The total SR loss up to 2 MW per a revolution is presumed to compensate by Superconducting RF (SRF) accelerating cavities. To minimize the beam emittance, each individual SRF cavity is proposed to feed by an individual and independent RF source allowing a wide-band control in phase and power. Most efficient and less expensive in capital and maintenance costs the high-power transmitters based on magnetrons, injection-locked by phase-modulated signals, controlled in wide-band are proposed as the RF sources. The magnetron RF sources utilizing 2-cascade magnetrons allowing a wide-band phase and power control by the injection-locking phase-modulated signals were experimentally modelled by 2.45 GHz, CW, 1 kW magnetrons. Results of the modelling and adequacy of the transmitters for the SRF cavities are discussed in the presented article.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI044  
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WEPWI046 Demonstration of Coaxial Coupling Scheme at 26 MV/m for 1.3 GHz TESLA-type SRF Cavities cavity, coupling, niobium, acceleration 3594
 
  • Y. Xie, A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • T.N. Khabiboulline, A. Lunin, V. Poloubotko, A.M. Rowe, N. Solyak, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • J. Rathke
    AES, Medford, New York, USA
  
  Funding: Work sponsored by DOE SBIR Grant DE-SC0002479.
We will report the first successful rf test of a detachable coaxial coupler by Euclid Techlabs and Fermilab SRF development department. The coaxial coupling method has vast advantages compared with ordinary welded-on couplers. It totally eliminates coupler kicks and it is detachable and easy to clean. We reached 26 MV/m (no hard quench limit) with a quarter-wave detachable coaxial coupler. This is also a demonstration of the highest field gradient ever reached with a superconducting joint. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI046  
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WEPWI049 Commissioning of the 112 MHz SRF Gun and 500 MHz Bunching Cavities for the CeC PoP Linac gun, bunching, experiment, electron 3597
 
  • S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, V. Litvinenko, G. Narayan, P. Orfin, I. Pinayev, T. Rao, J. Skaritka, K.S. Smith, R. Than, J.E. Tuozzolo, E. Wang, Q. Wu, B. P. Xiao, W. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, T. Xin
    Stony Brook University, Stony Brook, USA
  • P.A. McIntosh, A.J. Moss, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The Coherent electron Cooling Proof-of-Principle (CeC PoP) experiment at BNL includes a short electron linac. During Phase I a 112 MHz superconducting RF photoemission gun and two 500 MHz normal conducting bunching cavities were installed and commissioned. The paper describes the Phase I linac layout and presents commissioning results for the cavities and associated RF, cryogenic and other sub-systems. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI049  
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WEPWI050 SRF and RF Systems for LEReC Linac cavity, gun, electron, booster 3600
 
  • S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, A.V. Fedotov, G.T. McIntyre, S. Polizzo, K.S. Smith, R. Than, J.E. Tuozzolo, Q. Wu, B. P. Xiao, W. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  • V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The Low Energy RHIC electron Cooling (LEReC) is under development at BNL to improve RHIC luminosity at low energies. It will consist of a short electron linac and two cooling sections, one for blue and one for yellow beams. For the first stage of the project, LEReC-1, we will to install a 704 MHz superconducting RF cavity and two normal conducting cavities operating at 704 MHz and 2.1 GHz. The SRF cavity will boost the electron beam energy up to 2 MeV. The warm cavities will be used to correct the energy spread introduced in the SRF cavity. The paper describes layouts of the SRF and RF systems, their parameters and status. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI050  
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WEPWI051 Update on the CeC POP 704 MHz 5-Cell Cavity Cryomodule Design and Fabrication cavity, cryomodule, electron, linac 3603
 
  • J.C. Brutus, S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, I. Pinayev, J. Skaritka, L. Snydstrup, R. Than, J.E. Tuozzolo, W. Xu
    BNL, Upton, Long Island, New York, USA
  • S.M. Gerbick, M.P. Kelly, T. Reid
    ANL, Argonne, USA
  • T.L. Grimm, R. Jecks, J.A. Yancey
    Niowave, Inc., Lansing, Michigan, USA
  • Y. Huang
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
A 5-cell SRF cavity operating at 704 MHz will be used for the Coherent Electron Cooling Proof of Principle (CeC PoP) system currently under development for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The CeC PoP experiment will demonstrate the ability of relativistic electrons to cool a single bunch of heavy ions in RHIC. The cavity will accelerate 2 MeV electrons from a 112 MHz SRF gun up to 22 MeV. Novel mechanical designs, including the helium vessel, vacuum vessel, tuner mechanism, and FPC are presented. This paper provides an overview of the design, the project status and schedule of the 704 MHz 5-cell SRF for the CeC PoP experiment.
. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI051  
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THPF033 The First Operation of 56 MHz SRF Cavity in RHIC cavity, HOM, operation, cryomodule 3767
 
  • Q. Wu, S.A. Belomestnykh, I. Ben-Zvi, M. Blaskiewicz, L. DeSanto, D. Goldberg, M. Harvey, T. Hayes, G.T. McIntyre, K. Mernick, P. Orfin, S.K. Seberg, F. Severino, K.S. Smith, R. Than, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A 56 MHz superconducting RF cavity has been designed, fabricated and installed in the Relativistic Heavy Ion Collider (RHIC). The cavity operated at 4.4 K with a “quiet helium source” to isolate the cavity from environmental acoustic noise. The cavity is a beam driven quarter wave resonator. It is detuned and damped during injection and acceleration cycles and is brought to operation only at store energy. For a first test operation, the cavity voltage was stabilized at 300 kV with full beam current. Within both Au + Au and asymmetrical Au + He3 collisions, luminosity improvement was detected from direct measurement, and the hourglass effect was reduced. One higher order mode (HOM) coupler was installed on the cavity. We report in this paper on our measurement of a broadband HOM spectrum excited by the Au beam. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF033  
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THPF055 Status of the Superconducting Cavity Development at IHEP for the CADS Linac cavity, linac, operation, proton 3824
 
  • F.S. He, J.P. Dai, J. Dai, X. Huang, L.H. Li, Z.Q. Li, Q. Ma, Z.H. Mi, B. Ni, W.M. Pan, X.H. Peng, T. Qi, P. Sha, G.W. Wang, Q.Y. Wang, Z. Xue, X.Y. Zhang, G.Y. Zhao
    IHEP, Beijing, People's Republic of China
  • H. Huang, H.Y. Lin
    Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
  
  IHEP (Institute of High Energy Physics) is developing a CW 10MeV proton injector and part of the 25MeV main linac for the CADS project. 14 SRF (superconducting radio frequency) spoke-012 cavities for the injector, as well as 6 SRF spoke-021 cavities for the main linac are to be beam commissioned before middle of 2016; meanwhile, VT (vertical test) of two more types of prototype cavities are to be finished with 2015, for the future phases of the project. In this paper, the VT statistics of 10 spoke012 cavities, 4 spoke021 cavities, and a 5-cell β0.82 elliptical cavity are reported; the cavity performance during beam commissioning of the TCM (test cryomodule) is reported as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF055  
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THPF128 Accelerator Physics and Technology Research Toward Future Multi-MW Proton Accelerators proton, target, electron, experiment 4019
 
  • V.D. Shiltsev, P. Hurh, A. Romanenko, A. Valishev, R.M. Zwaska
    Fermilab, Batavia, Illinois, USA
  
  Funding: Fermi Research Alliance, LLC operates Fermilab under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
Recent P5 report indicated the accelerator-based neutrino and rare decay physics research as a centrepiece of the US domestic HEP program. Operation, upgrade and development of the accelerators for the near-term and longer-term particle physics program at the Intensity Frontier face formidable challenges. Here we discuss accelerator physics and technology research toward future multi-MW proton accelerators. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF128  
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THPF135 Optimization of Orbits, SRF Acceleration, and Focusing Lattice for a Strong-Focusing Cyclotron cavity, cyclotron, dipole, focusing 4038
 
  • K.E. Melconian, S. Assadi, J. Gerity, J.N. Kellams, P.M. McIntyre, A. Sattarov
    Texas A&M University, College Station, Texas, USA
  • N. Pogue
    PSI, Villigen, Villigen, Switzerland
  
  The strong-focusing cyclotron is a high-current proton/ion accelerator in which superconducting rf cavities are used to provide enough energy gain per turn to fully separate orbits, and arc-shaped beam transport channels are located in the sector dipole aperture to provide strong focusing of all orbits. An optimization method has been devised by which the orbit separations can be adjusted to provide sufficient separation while maintaining isochronicity on all orbits. The transport optics of the FD lattice is also optimized to provide stable transport and to lock the betatron tunes to a favorable value over the full range of acceleration.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF135  
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