Keyword: SRF
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MOPMY002 Simulation and Experimental Studies of a 2.45GHz Magnetron Source for an SRF Cavity with Field Amplitude and Phase Controls controls, cavity, LLRF, injection 514
 
  • H. Wang, T. E. Plawski, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • A. Dudas, M.L. Neubauer
    Muons, Inc, Illinois, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and NP STTR Grant DE-SC0013203.
Phase lock to an SRF cavity by using injection signal through output waveguide of a magnetron has been demonstrated [1, 3]. Amplitude control using magnetic field trimming and anode voltage modulation has been studied using MATLAB/Simulink simulations [2]. Based on these, we are planning to use an FPGA based digital LLRF system, which allows applying various types of control algorithms in order to achieve the required accelerating field stability. Since the 1497 MHz magnetron is still in the design stage, the proof of principle measurements of a commercial 2450 MHz magnetron are carried out to characterize the anode I-V curve, output power (the tube electronic efficiency), frequency dependence on the anode current (frequency pushing) and the Rieke diagram (frequency pulling by the reactive load). Based on early Simulink simulation, experimental data and extension of the Adler equation governing injection phase stability by Chen's model, the specification of the new LLRF control chassis for both 2450 and 1497MHz systems are presented in this paper. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY002  
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MOPMY009 HOM Consideration of 704 MHz and 2.1 GHz Cavities for LEReC Linac cavity, HOM, booster, electron 528
 
  • B. P. Xiao, I. Ben-Zvi, M. Blaskiewicz, J.M. Brennan, J.C. Brutus, A.V. Fedotov, H. Hahn, G.T. McIntyre, C. Pai, K.S. Smith, J.E. Tuozzolo, Q. Wu, T. Xin, W. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh
    Fermilab, Batavia, Illinois, 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 supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 and by National Energy Research Scientific Computing Center under contract No. DE-AC02-05CH11231 by US DOE.
To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energy RHIC electron Cooler (LEReC) is currently under development at BNL. The Linac of LEReC is designed to deliver 2 MV to 5 MV electron beam, with rms dp/p less than 5·10-4. The HOM in this Linac is carefully studied to ensure this specification. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY009  
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MOPMY032 Design and Upgrade the Safety System for the SRF Electronic System at the Taiwan Photon Source cryogenics, vacuum, storage-ring, PLC 567
 
  • F.-T. Chung, F.-Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, M.-C. Lin, Z.K. Liu, C.H. Lo, C.L. Tsai, M.H. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
  
  This paper presents some new designs and upgrades of a SRF interlock and electronic system. Based on the experience from Taiwan Light Source (TLS) that uses one Cornell-type superconducting cavity made by ACCEL in the storage-ring RF system [1], in the new TPS SRF system [3] home-made LLRF and SRF electronics [4] are constructed for two KEKB-type superconducting cavities [2] that are installed in the storage ring of circumference 518 m. For reliable operation of the TPS SRF system, enhanced safety functions of the system were added to improve the original SRF system in TLS. The improved functions can provide both the operators and the RF systems with a safer environment and clearer messages for trouble-shooting and malfunction status indications.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY032  
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MOPOR032 Using of the MENT Method for Reconstruction of 2D Particle Distributions in IFMIF Accelerators linac, emittance, simulation, HOM 668
 
  • P.A.P. Nghiem, N. Chauvin, L. Ducrot, M. Valette
    CEA/DSM/IRFU, France
  
  Beam particles are characterized by their coordinates in real spaces or phase spaces that are at least two-dimensional. It is often necessary to reconstruct such a 2D-distribution from the knowledge of only its projections on some axes, either for making use of tomography measurement results or for setting up an input beam for transport simulations. In this article, the use of the MENT (Maximum Entropy) reconstruction method is reported for the IFMIF accelerators where high intensity beam distributions are far from Gaussian ones.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR032  
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MOPOY057 The Linear IFMIF Prototype Accelerator (LIPAC) Design Development under the European-Japanese Collaboration rfq, linac, vacuum, cryomodule 985
 
  • P. Cara, R. Heidinger
    Fusion for Energy, Garching, Germany
  • N. Bazin, S. Chel, R. Gobin, J. Marroncle, B. Renard
    CEA/DSM/IRFU, France
  • B. Brañas Lasala, D. Jiménez-Rey, J. Mollá, P. Méndez, I. Podadera
    CIEMAT, Madrid, Spain
  • A. Facco, E. Fagotti, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • A. Kasugai, S. Keishi, S. O'hira
    JAEA, Aomori, Japan
  • J. Knaster, A. Marqueta, Y. Okumura
    IFMIF/EVEDA, Rokkasho, Japan
  • K. Sakamoto
    QST, Aomori, Japan
  
  The IFMIF aims to provide an accelerator-based, D-Li neutron source to produce high energy neutrons at sufficient intensity. Part of the BA agreement (Japan-EURATOM), the goal of the IFMIF/EVEDA project is to work on the engineering design of IFMIF and to validate the main technological challenges which includes a 125mA CW D+ accelerator up to 9 MeV mainly designed and manufactured in Europe. The components are in an advanced stage of manufacturing. The first components which allow the production of a 140 mA-100 keV deuteron beam have been delivered, installed and under commissioning at Rokkasho. The second phase (100 keV to 5 MeV) will end by March 2017. The third phase (short pulse) and forth phase (cw) will be the integrated commissioning of the LIPAc up to 9 MeV. The duration of the project has been recently extended up to end 2019 to allow the commissioning and operation of the whole accelerator (1MW). The aim of this paper is to give an overview of the LIPAc, currently under commissioning in Japan, to outline the engineering design and the development of the key components, as well as the expected outcomes of the engineering work, associated with the experimental program.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY057  
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TUPMY014 Muon Acceleration Concepts for Future Neutrino Factory linac, acceleration, focusing, cryomodule 1574
 
  • S.A. Bogacz
    JLab, Newport News, Virgina, USA
  
  Funding: Work supported by the Muon Accelerator Program
Here, we summarize current state of concept for muon acceleration aimed at future Neutrino Factory. The main thrust of these studies was to reduce the overall cost while maintaining performance through exploring interplay between complexity of the cooling systems and the acceptance of the accelerator complex. To ensure adequate survival of the short-lived muons, acceleration must occur at high average gradient. The need for large transverse and longitudinal acceptances drives the design of the acceleration system to initially low RF frequency, e.g. 325 MHz, and then increased to 650 MHz, as the transverse size shrinks with increasing energy. High-gradient normal conducting RF cavities at these frequencies require extremely high peak-power RF sources. Hence superconducting RF (SRF) cavities are chosen. Here, we considered two cost effective schemes for accelerating muon beams for a stagable Neutrino Factory: Exploration of the so-called 'dual-use' linac concept, where the same linac structure is used for acceleration of both H− and muons and alternatively, the SRF efficient design based on multi-pass (4.5) 'dogbone' RLA, extendable to multi-pass FFAG-like arcs. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY014  
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TUPOW034 Status Report of the Berlin Energy Recovery Linac Project BERLinPro gun, cavity, linac, vacuum 1827
 
  • M. Abo-Bakr, W. Anders, K.B. Bürkmann-Gehrlein, A.B. Büchel, P. Echevarria, A. Frahm, H.-W. Glock, F. Glöckner, F. Göbel, B.D.S. Hall, S. Heling, H.-G. Hoberg, A. Jankowiak, C. Kalus, T. Kamps, G. Klemz, J. Knobloch, J. Kolbe, G. Kourkafas, J. Kühn, B.C. Kuske, P. Kuske, J. Kuszynski, D. Malyutin, A.N. Matveenko, M. McAteer, A. Meseck, C.J. Metzger-Kraus, R. Müller, A. Neumann, N. Ohm, K. Ott, E. Panofski, F. Pflocksch, J. Rahn, J. Rudolph, M. Schmeißer, O. Schüler, M. Schuster, J. Ullrich, A. Ushakov, J. Völker
    HZB, Berlin, Germany
  
  Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association
The Helmholtz Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro at the Berlin Adlershof site. 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 beam. We report on the project progress: since spring 2015 the building is under construction, ready for occupancy in January 2017. The planning phase for the first project stage is completed for the warm machine parts, the SRF gun and partly for the SRF booster. Most of the components have been ordered and are in fabrication with some already delivered. An update of the status of the various subprojects as well as a summary of future activities will be given. Project milestones and details of the timeline will be reviewed. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW034  
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TUPOY055 Study on Electro-polishing of Nb Surface by Periodic Reverse Current Method with Sodium Hydroxide Solution experiment, cavity, operation, cathode 2020
 
  • J. Taguchi, A. Namekawa
    Nomura Plating Co, Ltd., Osaka, Japan
  • H. Hayano, T. Saeki
    KEK, Ibaraki, Japan
  • C.E. Reece, H. Tian
    JLab, Newport News, Virginia, USA
  
  Electropolishing is one of the best methods of Nb surface finishing of the superconducting cavity to obtain high accelerating gradient. Mixed solution of hydrofluoric acid and sulfuric acid is generally used in the electropolishing of Nb. But this solution is very dangerous and because the corrosion of the metal occurs by hydrofluoric acid, all equipment must be made of high density polyethylene or fluorocarbon resin. This causes the expensive cost of electropolishing instrument. In addition, this solution produces sulfur compound on the Nb surface in the electropolishing reaction. This sulfur compound can be field emission sources on the inner surface of cavity and degrades acceleration performance. In this poster, we report noble electropolishing method using periodic reverse current and sodium hydroxide solution. The reaction produces no sulfur content and the equipment is less expensive because the instrument can be made of usual plastic material. As the result of experiments with Nb-coupon samples, we found that the surface roughness is equivalent to the conventional electropolishing method.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY055  
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WEIB03 Technology Transfer and Research Projects TRIUMF, cryomodule, detector, linac 2109
 
  • R.E. Laxdal
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  
  The funding scenario seems to improve based on the capability of a laboratory to generate technology that can be transferred to industry, in particular if the technology is of public interest. New research projects may benefit if the technology transfer is considered as an integral part of the project itself. The drawback could be that revenue generated by a successful technology transfer may give the impression that research projects only provide societal benefit by direct transfer through closed protocols. This paper provides an overview of different technology transfer projects worldwide and how different laboratories are dealing with the issue.  
slides icon Slides WEIB03 [28.369 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEIB03  
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WEPMB012 Production and Investigation of Superconducting 9-Cell Cavity Made of Large Grain Nb in KEK cavity, accelerating-gradient, electron, niobium 2141
 
  • T. Dohmae, H. Inoue, K. Umemori, Y. Watanabe, M. Yamanaka
    KEK, Ibaraki, Japan
  
  For CW operation of superconducting cavity, reduction of heat load at cavity surface is one of important topics, since generated heat load is much higher than that of pulse wave. Using Large Grain (LG) Nb for superconducting cavity has possibility to reach higher Q0 than using Fine Grain Nb, which reduces heat load to 2K Helium. KEK Cavity Fabrication Facility(CFF) group had successfully produced superconducting 1-cell cavity made of LG Nb in 2013, and reached high Q0 at the vertical test (maximum field of 45 MV/m). Then, KEK CFF group started producing first superconducting 9-cell LG cavity in 2015, which will be completed in the end of December 2015. Whole processes of producing this cavity from sliced Nb are done in KEK. In this report, process flow and strategies of producing 9-cell cavity and results of vertical test will be presented in detail.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB012  
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WEPMB014 Cavity Performance of the Prototype KEK Superconducting RF Gun cathode, cavity, target, gun 2148
 
  • T. Konomi, E. Kako, E. Kako, Y. Kobayashi, Y. Kobayashi, K. Umemori, K. Umemori, S. Yamaguchi
    KEK, Ibaraki, Japan
  • R. Matsuda
    Mitsubishi Heavy Industries Ltd. (MHI), Takasago, Japan
  • T. Yanagisawa
    MHI, Hiroshima, Japan
  
  A superconducting RF (SRF) gun can generate a high current and high energy beam. It has a possibility to achieve requirement from high performance ERL and high repetition FEL. Target values of the L-band KEK SRF gun are that beam repetition is 1.3 GHz, beam current is 100 mA, beam energy is 2 MeV, emittance is 1 mm mrad or less. The number of cell is 1.5. Accelerating energy of 2 MeV corresponds to 42 MV/m of maximum surface field. The photocathode is designed to be illuminated by excitation laser from backside. The SRF gun cavity consists of the 1.5 cell accelerating cavity, cathode plug and choke filter for protecting the heating of cathode plug. To evaluate these parts individually, these parts are added step by step. High gradient test of the accelerating cell without cathode plug and choke filter was done. The surface peak electric field reached 66 MV/m, and this meet the target value 42 MV/m sufficiently. Next high gradient test will be done after adding the choke filter. The choke filter is designed to be simple to wash choke cell easier. In this conference, we will report the design, fabrication and high gradient performance of the SRF gun cavity with choke filter.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB014  
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WEPMB015 Construction and 2K Cooling Test of Horizontal Test Cryostat at KEK cavity, operation, cryomodule, HOM 2151
 
  • K. Umemori, K. Hara, E. Kako, Y. Kobayashi, Y. Kondo, H. Nakai, H. Sakai, S. Yamaguchi
    KEK, Ibaraki, Japan
  
  A horizontal test cryostat was designed and constructed at AR East building on KEK. Main purposes of test stand are improvement of module assembly technique and effective development of module components. Diameter of vacuum chamber is 1 m and its length is 3 m, which is enough to realize performance test of L-band 9-cell cavity with full assembly, including input couplers, HOM dampers/couplers and frequency tuners. On the sides, several ports are prepared to access to components, such as coupler and tuners. A cold box is placed on the top of the chamber. Liquid He is filled in a 4K-pod and 2K He is supplied through a J-T valve. A He pumping system is prepared. Inside of the chamber was covered with 80K shield, which is cooled by Liquid nitrogen. A cavity is supported on 5K table, which is also used as 5K thermal anchors. After cooling down to 80K using liquid Nitrogen, 4K He was stored and pumped down to 2K. The cooling test was successful. In this presentation, details of design and construction of the horizontal test cryostat is described and results of the cooling tests are shown. High power tests will be realized in near future.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB015  
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WEPMB016 Vertical Test Results of Nitrogen Doped SRF Cavities at KEK cavity, vacuum, monitoring, operation 2154
 
  • K. Umemori, H. Inoue, E. Kako, T. Konomi, T. Kubo, H. Sakai, H. Shimizu, M. Yamanaka
    KEK, Ibaraki, Japan
  • H. Hara, K. Sennyu, T. Yanagisawa
    MHI-MS, Kobe, Japan
  
  Recently Nitrogen doping(N-doping) technique was proposed and drastic improvements of Q-values were reported. Since high-Q operation of SRF cavities are very attractive for CW machine, we started investigation on performance of Nitrogen doped SRF cavities. Nitrogen doping systems were prepared on two vacuum furnaces, which have been used for annealing of SRF cavities. Two fine grain single cell cavities have been used for the study. After 800 degree, 3 hours annealing, N-doping were carried out under several Pa of Nitrogen pressure and followed by post annealing. Three kind of different conditions, pressure and duration time, were attempted. After applying EP-2, cavity performances were evaluated by vertical tests. Against our expectations, we observed lower Q-values, at every measurements, than those measured without N-doping. In this presentation, we describe details about N-doping system and parameters and results obtained by vertical tests. Some discussions are also given against our results.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB016  
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WEPMB021 Construction of Measurement System for Superconducting Characteristics on Thin-film Samples at KEK cavity, solenoid, operation, experiment 2167
 
  • T. Saeki, H. Hayano, T. Kubo
    KEK, Ibaraki, Japan
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • H. Oikawa
    Utsunomiya University, Utsunomiya, Japan
  
  We set up a measurement system for superconducting characteristics on thin-film samples at KEK. The system includes small-sized and middle-sized cryostats, where critical temperature, critical magnetic field, Residual Resistiviy Ratio (RRR), Superconducting RF (SRF) resistivity can be measured on thin-film samples. A small-sized cryostat has a compact refrigerator to cool down samples for the measurements of critical temperature and RRR. On the other had, we can cool down various setups with a middle-sized cryostat by using liquid helium. A thin-film sample is set into a mushroom cavity and the SRF characteristics of the thin-film sample can be measured. In another setup, a sample is set with a small coil and the third harmonic measurement is done on the sample around the critical temperature. Finally, a thin-film sample is set into the bore-center of superconducting magnet and the magnetization of sample is measured with external magnetic field around the critical temperature. This article presents the details of the system and some measurements of samples by the system.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB021  
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WEPMB023 Hydroforming SRF Three-cell Cavity from Seamless Niobium Tube cavity, niobium, accelerating-gradient, superconductivity 2170
 
  • M. Yamanaka, T. Dohmae, H. Inoue, G.-T. Park, K. Umemori
    KEK, Ibaraki, Japan
  • A. Hocker
    Fermilab, Batavia, Illinois, USA
  • T. Tajima
    LANL, Los Alamos, New Mexico, USA
  
  We are developing the manufacturing method for superconducting radio frequency (SRF) cavities by using a hydroforming instead of using conventional electron beam welding. We expect higher reliability and reduced cost with hydroforming. For successful hydroforming, high-purity seamless niobium tubes with good formability as well as advancing the hydroforming technique are necessary. Using a seamless niobium tube from ATI Wah Chang, we were able to successfully hydroform a 1.3 GHz three-cell TESLA-like cavity and obtained an Eacc of 32 MV/m. A barrel polishing process was omitted after the hydroforming. The vertical test was carried out with very rough inside surface. We got amazing and interesting result.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB023  
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WEPMB026 MHI-MS's Production Activities of Superconducting Cavity cavity, electron, gun, superconducting-RF 2180
 
  • H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa
    MHI-MS, Kobe, Japan
  • E. Kako, T. Konomi, H. Nakai, K. Umemori
    KEK, Ibaraki, Japan
  
  Mitsubishi Heavy Industries Mechatronics Systems, Ltd. (MHI-MS), a subsidiary of MHI, took over MHI's accelerator business on October 1, 2015, and has been developing the business since that time. MHI-MS has developed manufacturing process of superconducting cavities continuously. In this presentation, recent progress will be reported.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB026  
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WEPMB031 Post Processing of Spoke Type Superconducting Cavities at Institute of High Energy Physics cavity, linac, proton, target 2191
 
  • J. Dai, J.P. Dai, F.S. He, X. Huang, L.H. Li, Z.Q. Li, H.Y. Lin, Z.C. Liu, B. Ni, W.M. Pan, P. Sha, G.W. Wang, Q.Y. Wang, Z. Xue, X.Y. Zhang, G.Y. Zhao
    IHEP, Beijing, People's Republic of China
  
  Funding: Work supported by Chinese Academy of Science strategic Priority Research Program-Future Advanced Nuclear Fission Energy.
After upgrading the post-processing system, several superconducting cavities were RF tested at Institute of High Energy Physics (IHEP) in China recently. The test results of 14 spoke 012 cavities and 6 spoke 021 cavities which used at China ADS injector I and linac all exceeds our design objective. Moreover, a spoke 040, a 650MHz elliptical cavity and a 325MHz HWR cavity are also vertical tested and the test results are all significantly surpass our design value. The post processing of these cavities including Buffered Chemical Polishing (BCP), high temperature heat treatment and High Pressure water Rinsing (HPR) is presented here.
daijin@pku.edu.cn 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB031  
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WEPMB032 Fabrication and Testing Status of IHEP03 cavity, superconducting-RF, niobium, status 2194
 
  • T.X. Zhao, J. Gao, S. Jin, Z.Q. Li, Y.L. Liu, Z.C. Liu, Y. Wang, J.Y. Zhai, H.J. Zheng
    IHEP, Beijing, People's Republic of China
  • M. Asano, E. Kako
    KEK, Ibaraki, Japan
  • H. Yu, H. Yuan
    BIAM, Beijing, People's Republic of China
  
  After the successful development of the IHEP01 and IHEP02 1.3GHz 9cell superconducting cavity, we developed a 1.3GHz Tesla-Like 9cell superconducting cavities in collaboration with KEK. The cavity was made by niobium material produced in OTIC, Ningxia, China. After completeing welding, leakage check, BCP, HPR, we sent the cavity to KEK and used the standard procedures of ILC cavity for processing. These include electron polishing, vacuum furnace outgassing, tuning for field flatness and frequency, light EP, baking and vertical test. We target to have a high Q0 cavity for this experiment. In this paper, we will report the experimental status of the IHEP03 cavity.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB032  
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WEPMB034 Analysis of Niobium Quality Control for SRF Cavity cavity, niobium, controls, radio-frequency 2197
 
  • M.J. Joung
    IBS, Daejeon, Republic of Korea
  
  Funding: the Ministry of Science, ICT and Future Planning (MSIP) and the National Research Foundation (NRF) of the Republic of Korea under Contract 2013M7A1A1075764.
Clean and smooth surface is important to get low sur-face resistance for superconducting material. SRF (Super-conducting Radio Frequency) cavity made of niobium which is superconducting material and also one of the rare metal. The procedure of niobium quality control was set up to get high performance SRF cavity. The procedure consists of three parts; certificates check, Nb specification verification, and surface inspection and measurements of thickness, roughness, flatness. Three important properties which are RRR value, chemical composition and me-chanical properties were verified to conform Nb specifica-tion. The range of thickness, roughness and flatness for niobium as SRF cavity raw material were obtained by measurement. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB034  
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WEPMB035 SRF Cavities for RAON cavity, TRIUMF, factory, accelerating-gradient 2200
 
  • H.C. Jung, J. Joo, J. Lee
    IBS, Daejeon, Republic of Korea
  • R.E. Laxdal, Z.Y. Yao
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  
  SRF cavities of superconducting linear accelerators in RAON are developed and tested at 2K/4K. 1st Quarter Wave Resonator (QWR) and Half Wave Resonator (HWR) are fabricated by a domestic vender and tested in the TRIUMF's facility. The measured Q factors are above the required values at the operating gradients. And the predicted multipacting phenomena are observed in the test and easily conditioned. The Q factors decreased after a slow cooldown and enhanced at 4K tests by a low temperature baking. Based on these tests, modified bare cavities are newly developed, jacketed and will be tested with tuners and power couplers.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB035  
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WEPMB036 High Pressure Rinsing for Niobium Superconducting Cavity cavity, niobium, target, operation 2202
 
  • Y. Jung, M.J. Joung, M. Lee
    IBS, Daejeon, Republic of Korea
  • J. Lee, J. Seo
    Vitzrotech Co., Ltd., Ansan City, Kyunggi-Do, Republic of Korea
  
  Niobium superconducting cavity is treated with high pressure rinsing to clean the inner surface of the cavity. Either organic or inorganic residues on the inner surface of the cavity can cause serious problems during the cavity operation. A thermal quenching - superconducting material loses its superconductivity - is a typical phenomenon brought out by harmful defects by increasing critical temperature. We have performed high pressure rinsing experiments to check out a prototype HPR machine. HPR experiments were performed with a simplified cavity structure, and analyzed as a function of the pressure, the distance from a nozzle, and the sizes of defects on the niobium surface. In this presentation, we will discuss the performance of the prototype HPR machine.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB036  
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WEPMB052 System Integration and Beam Commissioning of the 500-MHz RF Systems for Taiwan Photon Source cavity, operation, vacuum, storage-ring 2234
 
  • Ch. Wang, L.-H. Chang, M.H. Chang, C.-T. Chen, L.J. Chen, F.-T. Chung, M.-C. Lin, Z.K. Liu, C.H. Lo, G.-H. Luo, C.L. Tsai, H.H. Tsai, M.H. Tsai, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
  
  The accelerator complex of the Taiwan Photon Source (TPS) consists of two 500-MHz RF systems: one RF system with two KEKB-type single-cell SRF modules is operated for the 3-GeV storage ring of circumference 518 m, and the other with one five-cell Petra cavity at room temperature is for the concentric full-energy booster synchrotron. This report overviews the installation, system integration, commissioning, and initial operation of the 500-MHz RF systems for the TPS with emphasis on our solution to approach the highly reliable SRF operation at its maximum design beam current of 500-mA. Lessons learned during the project are reviewed.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB052  
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WEPMB056 CVD Deposition of Nb Based Materials for SRF Cavities niobium, lattice, superconductivity, accelerating-gradient 2241
 
  • P. Pizzol, P. Chalker, T. Heil
    The University of Liverpool, Liverpool, United Kingdom
  • 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
  
  Bulk niobium cavities are widely employed in particle accelerators to create high accelerating gradient despite their high material and operation cost. Advancements in technology have taken bulk niobium close to its theoretical operational limits, pushing the research to explore novel materials, such as niobium based alloys. Nitrides of niobium offer such an alternative, exhibiting a higher Tc compared to bulk niobium. Replacing then the niobium with a material with better thermal conductivity, such as copper, coated with thin films of nitrides in a multilayer S-I-S would lead to improved performance at reduced cost. Physical vapour deposition (PVD) is currently used to produce these coatings, but it suffers from lack of conformity. This issue can be resolved by using chemical vapour deposition (CVD), which is able to produce high quality coatings over surfaces with a high aspect ratio. This project explores the use of CVD techniques to deposit NbN thin films starting from their chlorinated precursors. The samples obtained are characterized via SEM, FIB, XRD, and EDX.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB056  
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WEPMB057 First Results of Magnetic Field Penetration Measurements on Multilayer S-I-S Structures cavity, niobium, target, experiment 2245
 
  • O.B. Malyshev, K.D. Dumbell, L. Gurran, N. Pattalwar, S.M. Pattalwar, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • A.V. Gurevich
    ODU, Norfolk, Virginia, USA
  • L. Gurran
    Lancaster University, Lancaster, United Kingdom
  • L. Gurran
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  The performance of superconducting RF cavities made of bulk Nb is limited by a breakdown field of Bp=~200 mT, close to the superheating field for Nb. A potentially promising solution to enhance the breakdown field of the SRF cavities beyond the intrinsic limits of Nb is a multilayer coating suggested in [1]. In the simplest case, such a multilayer may be a superconductor-insulator-superconductor (S-I-S) coating, for example, bulk niobium (S) coated with a thin film of insulator (I) followed by a thin layer of another superconductor (S) which could be e.g. dirty niobium [2]. Here we report the first results of our measurements of field penetration in Nb thin films and Nb-AlN-Nb multilayer samples at 4.2 K using the magnetic field penetration facility designed, built and tested in ASTeC.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB057  
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WEPMR002 Ultimate Gradient Limitation in Niobium Superconducting Accelerating Cavities simulation, factory, niobium, cryogenics 2254
 
  • M. Checchin, A. Grassellino, M. Martinello, S. Posen, A. Romanenko
    Fermilab, Batavia, Illinois, USA
  • M. Checchin, M. Martinello
    Illinois Institute of Technology, Chicago, Illlinois, USA
  • J. Zasadzinski
    IIT, Chicago, Illinois, USA
  
  Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The present study is addressed to the theoretical description of the ultimate gradient limitation in SRF cavities. Our intent is to exploit experimental data to confirm models which provide feed-backs on how to improve the current state-of-art. New theoretical insight on the cavities limiting factor can be suitable to improve the quench field of N-doped cavities, and therefore to take advantage of high Q0 at high gradients. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR002  
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WEPMR004 Cryomdoule Test Stand Reduced-Magnetic Support Design at Fermilab cryomodule, cavity, vacuum, linac 2262
 
  • M.W. McGee, S.K. Chandrasekaran, A.C. Crawford, E.R. Harms, J.R. Leibfritz, G. Wu
    Fermilab, Batavia, Illinois, USA
  
  Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy
In a partnership with SLAC National Accelerator Laboratory (SLAC) and Jefferson Lab, Fermilab will assemble and test 17 of the 35 total 1.3 GHz cryomodules for the Linac Coherent Light Source II (LCLS-II) Project. These devices will be tested at Fermilab's Cryomodule Test Facility (CMTF) within the Cryomodule Test Stand (CMTS-1) cave. The problem of magnetic pollution became one of major issues during design stage of the LCLS-II cryomodule as the average quality factor of the accelerating cavities is specified to be 2.7 x 1010. One of the possible ways to mitigate the effect of stray magnetic fields and to keep it below the goal of 5 mGauss involves the application of low permeable materials. Initial permeability and magnetic measurement studies regarding the use of 316L stainless steel material indicated that cold work (machining) and heat affected zones from welding would be acceptable. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR004  
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WEPMR014 RF Design of a High Average Beam-Power SRF Electron Source electron, cavity, laser, free-electron-laser 2289
 
  • N. Sipahi, S. Biedron, S.V. Milton
    CSU, Fort Collins, Colorado, USA
  • I.V. Gonin, R.D. Kephart, T.N. Khabiboulline, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  There is a significant interest in developing high-average power electron sources, particularly in the area of electron sources integrated with Superconducting Radio Frequency (SRF) systems. For these systems, the electron gun and cathode parts are critical components for stable intensity and high-average powers. In this initial design study, we will present the design of a 9-cell accelerator cavity having a frequency of 1.3 GHz and the corresponding field optimization studies.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR014  
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WEPMR015 Surface Topography Techniques at Cornell University: Optical Inspection and Surface Replica cavity, laser, controls, GUI 2292
 
  • G.M. Ge, F. Furuta, D. Gonnella, D.L. Hall, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Surface imperfections significantly limit the performance of superconducting radio frequency (SRF) cavities. The development of surface topography techniques aims to locate the surface flaws in an SRF cavity and profile their geometry details. This effort plays an important role of quality control in cavity productions as well as provides contour information of the defects for understanding quench mechanisms. The surface topography techniques at Cornell University include an optical inspection system and surface replica technique. In this paper, we present the details of the techniques and show features found in the SRF cavities at Cornell.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR015  
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WEPMR016 Vertical Electropolishing Studies at Cornell with KEK and Marui cathode, cavity, target, niobium 2295
 
  • F. Furuta, G.M. Ge, T. Gruber, J.J. Kaufman, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • H. Hayano, S. Kato, T. Saeki
    KEK, Ibaraki, Japan
  
  Cornell's SRF group has developed Vertical Electro-Polishing (VEP) and applied on 1.3GHz Niobium SRF cavities as the primary surface treatment. High-Q and high voltage performances of VEP'ed SRF cavities had been successfully demonstrated at Cornell. In 2014, new VEP R&D collaboration has started between Cornell, KEK, and Marui Galvanizing Co. Ltd. (MGI). MGI and KEK has developed their original VEP cathode named 'i-cathode Ninja'® which has four retractable wing-shape parts per cell for single-/9-cell cavities. We will report the results of VEP process using 'i-cathode Ninja'® on single cell cavity at Cornell.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR016  
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WEPMR019 Development of Plasma Cleaning at Cornell University plasma, cavity, experiment, superconductivity 2302
 
  • G.M. Ge, F. Furuta, M. Liepe, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Cornell University is developing the plasma cleaning technology as an alternative cleaning technique for SRF cavity surface preparation. In experiments, we successfully ignited the plasma in a single-cell SRF cavity. However the experiments were limited by the peak electric-fields in the RF coupler. In this paper, we show the analysis of the limitation and propose a new design of the coupler which can eliminate the limitation.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR019  
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WEPMR022 ERL Main Linac Cryomodule Cavity Performance and Effect of Thermal Cycling cavity, cryomodule, linac, target 2312
 
  • F. Furuta, J. Dobbins, R.G. Eichhorn, G.M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Cornell has designed, fabricated, and tested a high current (100 mA) CW SRF prototype cryomodule for the future energy-recovery linac (ERL) based synchrotron-light facility at Cornell . It houses six 7-cell SRF cavities with individual HOM absorbers and one magnet/ BPM section. Cavities are targeted to operate with high Qo of 2.0·1010 at 16.2 MV/m, 1.8 K in continuous wave (CW) mode. We will report the RF test results of 7-cell cavities in this cryomodule after initial cooldown and several thermal cycles with different cooldown method.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR022  
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WEPMR023 Surface Analysis Studies of Nb3Sn Thin Films cavity, niobium, radio-frequency, electron 2316
 
  • D.L. Hall, J.J. Kaufman, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  A recent study to optimise the coating of thin-film Nb3Sn cavities has resulted in coating procedures that can fabricate 1.3 GHz cavities capable of reproducibly achieving fields of >16 MV/m with record high Qs >1010 at 4.2 K. However, the performance of these next generation SRF cavities is as yet well below the theoretical maximum performance expected of Nb3Sn, thus giving ample room for further advancements. Current measurements strongly suggest that the current limits are due to local defects and irregularities in the coated surface. In this paper we analyse, using methods including SEM/EDS, TEM, XRD and EBSD, the surface of both sample coupons and cavity cut-outs, with a view to identifying and understanding the origin of surface non-uniformities that would lead to increased surface resistance and cavity quench.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR023  
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WEPMR024 RF Measurements on High Performance Nb3Sn Cavities cavity, niobium, radio-frequency, accelerating-gradient 2320
 
  • D.L. Hall, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  A single-cell 1.3 GHz ILC-shape thin-film Nb3Sn-on-Nb cavity recently achieved accelerating gradients of >16 MV/m with a record Q0 of approx. 2·1010 at 4.2 K, exceeding the power efficiency seen in the current most efficient niobium cavities. A concurrent study of the coating process has resulted in a coating procedure that is capable of replicating this performance in other single-cell cavities. In this paper we demonstrate the RF performance and behaviour of these next generation SRF cavities, with an emphasis on both the impact from both external magnetic fields and the cavity cool down procedure on cavity performance.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR024  
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WEPMR025 Improved N-Doping Protocols for SRF Cavities simulation, cavity, niobium, radio-frequency 2323
 
  • D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, T. Gruber, G.H. Hoffstaetter, J.J. Kaufman, P.N. Koufalis, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: NSF, DOE
Nitrogen-doping has been shown to consistently produce better quality factors in SRF cavities than is achievable with standard preparation techniques. Unfortunately, nitrogen-doping typically brings with it lower quench fields and higher sensitivities of residual resistance to trapped magnetic flux. Here we present work to understand these effects in hopes of mitigating them while maintaining the high Q desired by future projects. Using a nitrogen diffusion simulation, material parameters of nitrogen-doped cavities can be predicted prior to doping. These simulations results are consistent with SIMS data taken from samples treated with cavities. The nature of doping's effect on quench field has also been studied using CW and pulsed measurements. These results have allowed us to better understand the nature of nitrogen-doping and its effect on cavity performance. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR025  
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WEPMR026 RF Losses from Trapped Flux in SRF Cavities cavity, vacuum, site, niobium 2327
 
  • D. Gonnella, J.J. Kaufman, P.N. Koufalis, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: NSF
Previous measurements at Cornell have shown that the sensitivity of residual resistance to trapped magnetic field in SRF cavities is heavily dependent on the mean free path of the RF penetration layer of the niobium. Here we report on a systematic study of ten cavity preparations with different mean free paths and the effect of these preparations on sensitivity to trapped magnetic flux. In the clean limit, longer mean free path leads to a lower sensitivity to trapped magnetic flux while in the dirty limit the opposite is true, shorter mean free path leads to lower sensitivity. These results are also shown to be in good agreement with theoretical predictions of RF losses due to oscillations of vortex lines. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR026  
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WEPMR027 Dependence of Surface Resistance on N-Doping Level niobium, cavity, linac, radio-frequency 2331
 
  • D. Gonnella, F. Furuta, G.M. Ge, J.J. Kaufman, P.N. Koufalis, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: NSF, DOE
Nitrogen-doping has become a standard tool for reaching high quality factors in SRF cavities in the medium field region at 2 K. This high Q has been shown to be a result of lowering of the temperature dependent BCS resistance. Here we show that this lowering of the BCS resistance is due to interstitial nitrogen in the niobium lowering the mean free path. The BCS resistance extracted from experimental data is shown to be consistent with theoretical predictions from BCS theory; that there is an optimal doping of which the mean free path is lowered to about half the intrinsic coherence length. These results provide insight into understanding the mechanisms behind nitrogen-doping and allow us to more accurately predict doping parameters to reach optimal cavity performance. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR027  
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WEPMR028 Studies on the Field Dependence of the BCS Surface Resistance cavity, experiment, niobium, radio-frequency 2335
 
  • J.T. Maniscalco, D. Gonnella, G.H. Hoffstaetter, P.N. Koufalis, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Experiments have shown that the temperature-dependent portion of the RF surface resistance of SRF materials also exhibits a dependence on the magnitude of the surface field, manifested as a "Q-slope" or "anti-Q-slope" in the medium field region. Recent theoretical work proposes an explanation of the anti-Q-slope in dirty-limit superconductors. In this report, we compare theoretical predictions with the results of systematic experimental studies on the RF field dependence of the surface resistance using 1.3 GHz niobium SRF cavities with a wide range of mean free paths. We find very good agreement between theory and experiment in the dirty limit, with some divergence as the cavities approach the clean limit.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR028  
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WEPMR029 New Material Studies in the Cornell Sample Host Cavity cavity, niobium, superconducting-RF, vacuum 2338
 
  • J.T. Maniscalco, D.L. Hall, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • O.B. Malyshev, R. Valizadeh, S. Wilde
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • S. Wilde
    Loughborough University, Loughborough, Leicestershire, United Kingdom
  
  Cornell has developed a TE mode sample host microwave cavity in order to study large, flat samples of novel SRF materials. In recent calibration tests, the cavity was shown to reach peak magnetic fields on the sample plate of >100 mT and a quality factor Q0 greater than 1010, making it a powerful system to study the performance of superconductors at high RF fields with nOhms sensitivity. In this report we present results of measurements of two samples of thin-film Nb deposited on Cu using HiPIMS at 500 C and at 800 C.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR029  
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WEPMR030 Pulsed Field Limits in SRF Cavities cavity, niobium, klystron, factory 2341
 
  • J.T. Maniscalco, D. Gonnella, D.L. Hall, P.N. Koufalis, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  High-power pulsed (HPP) measurements of SRF cavities offer several different avenues of experimentation from standard continuous wave (CW) measurements by probing higher fields and reducing thermal effects. In this paper we report upon recent measurements of N-doped Nb and Nb3Sn cavities, investigating the limitations of the superheating field, flux entry field, and other maximum fields. We also investigate the potential of these materials for operation in a pulsed accelerator, which would partially or fully mitigate the effects of defects (i.e. thermal quenches).  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR030  
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WEPMR033 Observation of Stable Low Surface Resistance in Large-Grain Niobium SRF Cavities cavity, niobium, vacuum, site 2344
 
  • R.L. Geng
    JLab, Newport News, Virginia, USA
  • S.C. 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.
Low surface resistance, or high unloaded quality factor (Q0), superconducting radio frequency (SRF) cavities are being pursued actively nowadays as their application in large-scale CW SRF accelerators can save capital and operational cost in cryogenics. There are different options in realization of such cavities. One of them is the large-grain (LG) niobium cavity. In this contribution, we present new experimental results in evaluation of LG niobium cavities cooled down in the presence of an external magnetic field. High Q0 values are achieved even with an ambient magnetic field of up to 100 mG. More over, it is observed that these high Q0 values are super-robust against repeated quench, literally not affected at all after the cavity being deliberately quenched for hundreds of times in the presence of an ambient magnetic field of up to 200 mG. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR033  
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WEPMR037 Wakefield Analysis of the 56 MHz SRF Cavity cavity, impedance, HOM, wakefield 2354
 
  • Q. Wu, Y. Hao
    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.
The 56 MHz SRF cavity is a superconducting quarter-wave resonator installed in the common section of RHIC. Both beams share the cavity in an interwoven pattern over the entire store. The wake field excited in the cavity is the superposition of the two opposing bunches. This paper will discuss the wake field excited by both beams, and the higher order mode power as a result of the excited field. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR037  
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WEPMR038 Frequency Tuning for a DQW Crab Cavity cavity, operation, simulation, insertion 2357
 
  • S. Verdú-Andrés, I. Ben-Zvi, J. Skaritka, Q. Wu, B. P. Xiao
    BNL, Upton, Long Island, New York, USA
  • K. Artoos, R. Calaga, O. Capatina, R. Leuxe, C. Zanoni
    CERN, Geneva, Switzerland
  • I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  
  Funding: Work supported by US DOE via BSA LLC contract No.DE-AC02-98CH10886, the US LARP program, US DOE contract No. DE-AC02-05CH1123 (NERSC resources) and by HiLumi project.
The nominal operating frequency for the HL-LHC crab cavities is 400.79 MHz within a bandwidth of ±60kHz. Attaining the required cavity tune implies a good understanding of all the processes that influence the cavity frequency from the moment when the cavity parts are being fabricated until the cavity is installed and under operation. Different tuning options will be available for the DQW crab cavity of LHC. This paper details the different steps in the cavity fabrication and preparation that may introduce a shift in the cavity frequency and introduces the different tuning methods foreseen to bring the cavity frequency to meet the specifications. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR038  
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WEPMR040 HOM Absorber Study by Photon Diffraction Model HOM, photon, cavity, damping 2360
 
  • C. Xu, I. Ben-Zvi, V. Ptitsyn, P. Takas, W. Xu
    BNL, Upton, Long Island, New York, USA
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • B. P. Xiao
    SBU, Stony Brook, New York, USA
  
  Photon diffraction model (PDM) is one of the most promising candidates to study High Order Mode (HOM) power absorption on absorbing materials for high current SRF cavities. Because at very high frequency (>10GHz), the wavelengths of HOMs are much smaller compared with accelerators dimension, the phase of those HOM will be negligible. Meanwhile, Finite Element Method (FEM) cannot lend a high resolution on evaluation the HOM field patterns due to limited meshing capability. This PDM model utilizes Monte Carlo simulation to trace the ray diffusive reflection in a cavity. This method can directly estimate the power absorption on the cavity and absorber wall. This method will help design the HOM damper setup for eRHIC HOM damper. In this report, we evaluate HOM absorption on the cavity wall with different absorber setup and give a possible solution for power damping scheme for high frequency HOMs.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR040  
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WEPMR041 RF and Mechanical Design of 647 MHz 5-Cell BNL4 Cavity for eRHIC ERL cavity, electron, HOM, linac 2364
 
  • W. Xu, I. Ben-Zvi, H. Hahn, G.T. McIntyre, C. Pai, R. Porqueddu, K.S. Smith, J.L. Tuozzolo, J.E. Tuozzolo, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  
  Funding: This work is supported by LDRD program of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
A 647 MHz 5-cell cavity has been designed for the envisioned EIC at BNL which is configured as an eRHIC ERL with a FFAG lattice to achieve the necessary e-p luminosity. The cavity was optimized to allow propagation of all HOMs out of the cavity for high BBU threshold current and low HOM power (loss factor). eRHIC will collide the electron beam over a wide energy range with protons from 40 GeV to 250 GeV, which requires the cavity to tune up to 170 kHz at 2 K. This poses a true challenge to the mechanical design of the SRF cavity. This paper will present the RF and mechanical designs of the 647 MHz 5-cell cavity, and status of the cavity fabrication will be addressed as well. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR041  
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WEPMR042 Ridge Waveguide HOM Damping Scheme for High Current SRF Cavity HOM, cavity, linac, damping 2367
 
  • W. Xu, I. Ben-Zvi, Y. Gao, H. Hahn, G.T. McIntyre, R. Porqueddu, V. Ptitsyn, K.S. Smith, R. Than, J.L. Tuozzolo, C. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  
  Funding: This work is supported by LDRD program of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
HOM damping is a challenge for high-current SRF linacs possibly generating HOM power at a level of 10 KW per cavity. A rectangular waveguide used as a natural high pass filter is a good option as high power, large spectrum HOM damper. However, its size is too big, causing a big challenge for the cooling and cryogenic system. A reliable, compact HOM damping scheme using a ridged waveguide is being developed to damp high power (> 10 kW), large spectrum HOMs ( up to 40 GHz) that may be generated in the 647 MHz 5-cell eRHIC ERL SRF linac. The size of a ridged waveguide is less than a quarter of the regular waveguide, which alleviates the thermal issue. This paper presents the design of a ridged waveguide and estimated HOM damping results using a ridged waveguide. The thermal or cooling design of the ridged waveguide will also be addressed. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR042  
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WEPMR045 Engineering Issues of the Medium Energy Beam Transport Line and SRF Linac for the LIPAc linac, alignment, vacuum, solenoid 2377
 
  • D. Gex, H. Dzitko, A. Lo Bue, G. Phillips, L. Semeraro, J.M. Zarzalejos
    F4E, Germany
  • N. Bazin, G. Devanz, P. Hardy
    CEA/IRFU, Gif-sur-Yvette, France
  • J. Castellanos, J.M. García, D. Jiménez-Rey, D. López, L.M. Martínez, I. Podadera
    CIEMAT, Madrid, Spain
  • O. Nomen
    IREC, Sant Adria del Besos, Spain
  • F. Scantamburlo
    IFMIF/EVEDA, Rokkasho, Japan
  
  The International Fusion Materials Irradiation Facility (IFMIF) aims to provide an accelerator-based, D-Li neutron source to produce high energy neutrons at sufficient intensity and irradiation volume for DEMO materials qualification. Part of the Broader Approach (BA) agreement between Japan and EURATOM, the goal of the IFMIF/EVEDA project is to work on the engineering design of IFMIF and to validate the main technological challenges which, among a wide diversity of hardware includes the LIPAC (Linear IFMIF Prototype Accelerator), a 125 mA CW deuteron accelerator up to 9 MeV mainly designed and manufactured in Europe. The aim of this paper is to address the engineering issues of the MEBT and SRF linac related to assembly and Integration at LIPAc facility, focusing in the seismic analysis of the beamlines to ensure the robustness of the equipment and the alignment activities with the cutting edge technology performed in Europe before sending the components to Rokkasho. These activities are essential before starting the installation process of the MEBT in the first half of 2016, and to initiate the assembly and integration of the SRF Linac cryomodule in the next phase.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR045  
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WEPMW008 Possible Beam Parameters in Double RF Operation of the CERN LHC operation, emittance, damping, synchrotron 2430
 
  • E.N. Shaposhnikova, J. F. Esteban Müller
    CERN, Geneva, Switzerland
  
  The LHC operates using a 400 MHz SC RF system. A 200 MHz NC RF system was foreseen in the LHC Design Report to improve beam capture and the bare resonators were manufactured, but never installed. Later the second harmonic RF system was proposed to cure longitudinal beam instabilities in the absence of a dedicated wideband feedback system in the LHC. For nominal intensities the longitudinal beam stability is ensured by controlled emittance blow-up during the acceleration ramp. Recently slow growing instabilities were observed at the end of long fills at 6.5 TeV as bunches shrink due to synchrotron radiation damping. For High Luminosity LHC twice higher intensities should be kept stable with new equipment installed in the ring. Additional motivations for a second RF system in the LHC have also been considered. Operation with an extra RF system is limited by the required RF configuration (phase between the two RF systems) and longitudinal beam stability. In this work requirements for the double RF systems are analyzed together with a possible range of longitudinal beam parameters.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW008  
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WEPOW009 The Bessy Vsr Project for Short X-Ray Pulse Production operation, optics, storage-ring, radiation 2833
 
  • A. Jankowiak, W. Anders, T. Atkinson, H. Ehmler, A. Föhlisch, P. Goslawski, K. Holldack, J. Knobloch, P. Kuske, D. Malyutin, A.N. Matveenko, R. Müller, A. Neumann, K. Ott, M. Ries, M. Ruprecht, A. Schälicke, A.V. Vélez, G. Wüstefeld
    HZB, Berlin, Germany
  • A. Burrill
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of the Helmholtz Association
HZB has started the innovative project, BESSY VSR, to upgrade the 1.7 GeV synchrotron radiation source BESSY II. Its goal is to provide both 1.7 ps and 15 ps long, intense X-ray pulses simultaneously at all beam lines. These pulses are generated by enhanced longitudinal bunch focusing using superconducting 5-cell cavities operating at 1.5 GHz and 1.75 GHz. The resulting beating of the voltages creates alternating long and short buckets that can be custom filled. As a first major step, prototype superconducting cavities, initially only cooled to 4.4 K and thus operating at reduced voltage, will be installed into the BESSY II storage ring. Physical and technical aspects of this proposal where recently studied* and the results and project status are presented.
* A. Jankowiak, J. Knobloch for the BESSY VSR team, Technical Design Study BESSY VSR, doi:10.5442/R0001, Helmholtz-Zentrum Berlin (Germany), June 2015. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW009  
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WEPOY023 Beam Dynamics Studies for Coherent Electron Cooling Experiment electron, emittance, linac, cavity 3032
 
  • Y.H. Wu, D. Kayran, V. Litvinenko, I. Pinayev
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron Cooling (CeC)* is a proposed advanced beam cooling method that has the potential to reduce the ion beam emittance in significantly shorter time compared to existing cooling methods. The newly constructed linear electron accelerator for the CeC experiment can generate electron beams with the required beam parameters for effective cooling. In this paper, we show simulation studies for the CEC linac by using the PARMELA** and ELEGANT*** beam dynamics tracking codes.
* V.N.Litvinenko and Y.S.Derbenev, PRL 102, 114801 (2009)
** Lloyd M.Young, Parmela manual, Los Alamos National Laboratory
*** M. Borland, Elegant, Argonne National Laboratory (2000) 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY023  
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THYB01 Performance of Superconducting Cavities for the European XFEL cryomodule, cavity, operation, vacuum 3186
 
  • D. Reschke
    DESY, Hamburg, Germany
  
  The superconducting accelerator of the European XFEL consists of the injector part and the main linac. The injector includes one 1.3 GHz accelerator module and one 3.9 GHz third harmonic module, while the main linac consists of 100 accelerator modules, each housing eight 1.3 GHz TESLA-type cavities, operated at an average design gradient of 23.6 MV/m. The fabrication and surface treatment by industry as well as the vertical and cryomodule RF tests of the required 808 superconducting 1.3GHz cavities are analysed and presented.  
slides icon Slides THYB01 [3.227 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THYB01  
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THOBB02 Impurity Doping of Superconducting Radio Frequency Cavities cavity, niobium, vacuum, radio-frequency 3195
 
  • P.N. Koufalis, F. Furuta, G.M. Ge, D. Gonnella, J.J. Kaufman, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: NSF PHYS-1416318
Impurity doping of bulk-niobium superconducting radio frequency (SRF) cavities is a relatively new field of study and the underlying physics is not yet fully understood. Previous studies have shown an increase in the intrinsic quality factor and the corresponding decrease of the temperature-dependent component of the surface resistance of nitrogen-doped cavities with increasing accelerating field.* Here we investigate the effects of alternative inert dopants on the surface resistance and thus the intrinsic quality factor of SRF cavities in pursuit of the optimal dopant and doping level.
A. Grassellino et al., Nitrogen and Argon Doping of Niobium for Superconducting Radio Frequency Cavities. Supercond. Sci. Technol., 26(102001), 2013 		 
slides icon Slides THOBB02 [4.048 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOBB02  
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THOBB03 Root Causes of Field Emitters in SRF Cavities Placed in CEBAF Tunnel cavity, cryomodule, vacuum, operation 3198
 
  • R.L. Geng
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
It has been suspected that appearance of new field emitters can occur in SRF cavities after their placement in accelerator tunnel for long term beam operation. This apparently has been the case for CEBAF. However, no physical evidence has been shown in the past. In this contribution, we will report on the recent results concerning the root cause of field emitters in SRF cavities placed in CEBAF tunnel. We will discuss these results in the context of high-reliability and low-cryogenic-loss operation of CEBAF. 		 
slides icon Slides THOBB03 [3.768 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOBB03  
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THPMB051 Development of Intelligent Alarm Message System at TPS status, vacuum, radiation, operation 3363
 
  • C.C. Liang, C.H. Chang, C.H. Chen, J. Chen, J.Y. Chen, Y.-S. Cheng, M.-S. Chiu, S. Fann, C.S. Huang, C.-C. Kuo, T.Y. Lee, Y.C. Lin, Y.-C. Liu, H.-J. Tsai, F.H. Tseng, I.C. Yang, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
  
  The traditional alarm systems usually set up/low limit for various signals. When the acquired values exceed the limits, the alarm system would be activated. The proposed system in this article can focus on various possible events with many kinds of signals for response judgments. During alarm calling period, data can also be announced and recorded. The system can also monitor various events according to different time shifts. Integrating LabVIEW, mobile phone, AT-command and Bluetooth communication, the system can handle factory broadcast, sending E-mail and SMS message. The above sound and words messages can be set directly at the home-made software interface. The new intelligent alarm system can eliminate the procedure made by man with the added event recording, system stability improvement and debugging function in wider application fields.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB051  
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THPOW003 Highlights on Metallic Photocathodes Used in SRF Gun gun, cathode, laser, emittance 3928
 
  • R. Xiang, A. Arnold, P.N. Lu, P. Michel, P. Murcek, J. Teichert, H. Vennekate
    HZDR, Dresden, Germany
  • P.N. Lu, H. Vennekate
    TU Dresden, Dresden, Germany
  
  For the accelerator-based light sources and the electron colliders, the development of photoinjectors has become a key technology. Especially for the superconducting radio frequency cavity based injector (SRF Gun), the searching for better photocathodes is always a principal technical challenge. To use metallic photocathodes for ELBE SRF Gun is the primary choice to prevent cavity contamination. In this contribution, we will report the investigation of Magnesium (Mg) in ELBE SRF gun, including laser cleaning treatment and the measurement on quantum efficiency, Schottky effect, dark current and damage threshold.
The work is supported by the European Community under the FP7 programme (EuCARD-2 and LA3NET) and by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW003  
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THPOW058 Drive Laser System for the DC-SRF Photoinjector at Peking University laser, electron, optics, operation 4076
 
  • F.M. Liu, L.W. Feng, S. Huang, L. Lin, K.X. Liu, S.Y. Si, Zh.W. Wang, G. Zhao
    PKU, Beijing, People's Republic of China
  
  The DC-SRF photoinjector, developed at Peking University, uses Cs2Te as the photocathode and accordingly 266 nm laser is used as the drive laser. A drive laser sys-tem，which includes a 1064 nm laser oscillator, a four-stage amplifier, and second and fourth harmonic genera-tors, has been designed and applied successfully. To avoid the high average current electron beam from hitting the vacuum tube and causing safety problems, a laser pulse selector with an EO modulator has been designed and included into the laser drive system to reduce the repetition rate of electron pulses during the DC-SRF photoinjector commissioning. It can adjust the repetition rate of laser pulses from 81.25 kHz to 81.25 MHz. In this paper, we introduce the drive laser system and describe the laser pulse selector in detail.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW058  
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THPOY035 Machine Protection and Safe Operation of LIPAc Linear Accelerator operation, rfq, linac, vacuum 4178
 
  • A. Marqueta, J. Knaster, K. Nishiyama
    IFMIF/EVEDA, Rokkasho, Japan
  • P.-Y. Beauvais, H. Dzitko
    F4E, Germany
  • P. Cara
    Fusion for Energy, Garching, Germany
  • H. Kobayashi
    KEK, Ibaraki, Japan
  • I. Podadera
    CIEMAT, Madrid, Spain
  
  A Li(d, xn) fusion relevant neutron source with a broad peak at 14 MeV is indispensable to characterize and qualify suitable structural materials for the plasma facing components in future fusion reactors. LIPAc (Linear IFMIF Prototype Accelerator), presently under its installation and commissioning phase in Rokkasho, will validate the concept of a 40 MeV deuteron accelerator with its 125 mA CW and 9 MeV deuteron beam for a total beam average power of 1.125 MW. The Machine Protection System (MPS) of LIPAc provides the essential interlock function of stopping the beam in case of excessive beam loss or other hazardous situations. However, approaching LIPAc beam commissioning Phase B (including RFQ powered by total 1.6 MW RF power) a risk analysis has been performed on all major technical systems to identify the sources of risk, apply the necessary countermeasures and enhance accelerator availability, avoiding unnecessary beam stop triggers and allowing a fast beam recovery whenever possible. The overall strategy for the machine protection at LIPAc is presented in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY035  
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