Keyword: multipactoring
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MOP026 A Cross-Lab Qualification of Modified 120°C Baked Cavities cavity, shielding, factory, niobium 90
 
  • M. Wenskat, D. Reschke, J. Schaffran, L. Steder, M. Wiencek
    DESY, Hamburg, Germany
  • D. Bafia, A. Grassellino, O.S. Melnychuk
    Fermilab, Batavia, Illinois, USA
  • A.D. Palczewski
    JLab, Newport News, Virginia, USA
  • M. Wiencek
    IFJ-PAN, Kraków, Poland
 
  Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program and by the BMBF under the research grant 05H18GURB1.
Within a global effort to understand and standardize the nitrogen-infusion and the low T bake procedure, one large grain and two fine grain single-cell cavity were treated and tested at FNAL and then send to other labs including DESY and JLab for further studies.
 
poster icon Poster MOP026 [0.813 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP026  
About • paper received ※ 20 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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MOP073 The Study of High Power Couplers for CIADS status, operation, experiment, simulation 241
 
  • Z.Q. Lin, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, C.L. Li, Y.M. Li, M. Lu, F. Pan, T. Tan, R.X. Wang, Z. Xue, Z.Q. Yang, S.X. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  High power couplers with high operation reliability are needed for the superconducting cavities used in the Linac of CiADS project at IMP. This paper will report two works on high power coupler. The DC bias structure of the coupler was optimized to suppress the multipacting effect, where the series resistors were introduced to the wire of the DC bias to reduce the field propagating along the DC bias’s wire. For the purpose of significantly decreasing the power needed to condition the coupler, we designed a new RF conditioning scheme, in which the coupler served as a standing wave resonator, and the positions of the crests and troughs of the wave were tunable. The details of the design mentioned above will be depicted.  
poster icon Poster MOP073 [14.677 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP073  
About • paper received ※ 25 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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MOP076 Fundamental Power Coupler Design for a 325 MHz Balloon SSR Cavity cavity, vacuum, simulation, cryogenics 252
 
  • R.E. Laxdal, Y. Ma, B. Matheson, B.S. Waraich, Z.Y. Yao, V. Zvyagintsev
    TRIUMF, Vancouver, Canada
 
  TRIUMF has designed, fabricated and tested the first balloon variant of the single spoke resonator at 325 MHz and β=0.3. TRIUMF has also designed a 6 kW fundamental power coupler as part of the development. The design of the coupler will be presented.  
poster icon Poster MOP076 [1.282 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP076  
About • paper received ※ 24 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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MOP077 Ceramic Study on RF Windows for Power Coupler, Waveguide, and Klystron in Particle Accelerator electron, GUI, klystron, operation 255
 
  • Y. Yamamoto, S. Michizono
    KEK, Ibaraki, Japan
 
  R&Ds on different types of ceramic used in power coupler, waveguide, and klystron for particle accelerators are under progress in Center of Innovation (COI) at KEK, and at some outside companies. There are five important parameters on the properties of ceramics; that is, relative permittivity, dielectric loss tangent, surface and volume resistivity, and secondary electron emission coefficient. For measurements of these parameters, eight kinds of ceramic samples supplied from five vendors have been measured using three different measurement systems since 2017. In this report, the recent results for these studies will be presented in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP077  
About • paper received ※ 22 June 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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MOP080 Latest Progress in Designs and Testings of PIP-II Power Couplers cavity, rfq, vacuum, cryogenics 263
 
  • S. Kazakov, B.M. Hanna, O.V. Pronitchev, N. Solyak
    Fermilab, Batavia, Illinois, USA
 
  Proton Improvement Plan – II (PIP-II) project is under go in Fermi National Laboratory. Main part of the project is 800 MeV proton superconducting accelerator which includes 116 superconducting cavities of 5 different types and three 162.5, 325 and 650 MHz frequencies. Key elements of accelerator which determine a reliable operation are main couplers for superconducting cavities. This paper describes the latest progress in design and testing of main couplers for PIP-II projects.  
poster icon Poster MOP080 [0.881 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP080  
About • paper received ※ 18 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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TUFUB7 Measurement of Surface Resistance Properties with Coaxial Resonators - Review cavity, experiment, ECR, SRF 374
 
  • H. Park, S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
 
  Achieving ever decreasing surface resistance at higher field in superconducting RF accelerating structures is one of most outstanding developments in modern accelerators. The BCS theory has been used widely to estimate the surface resistance and to direct the technology. However, recent research results show that the behavior of the surface resistance further deviates from the BCS theory. So far the study on surface resistance was performed usually with cavities of single frequency which limited the study of frequency dependent surface resistance. The Center for Accelerator Science at Old Dominion University has designed and built several half wave coaxial cavities to study the frequency, temperature, and RF field dependence of surface resistance. TRIUMF in Canada also joined this line of research using such multi frequency quarter wave and half wave coaxial cavities. This type of multi mode cavity will allow us to systematically study the parameters affecting surface resistance on the same cavity surface. In this paper, we review the results ODU and TRIUMF collected so far and proper analysis methods.  
slides icon Slides TUFUB7 [3.551 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUFUB7  
About • paper received ※ 01 July 2019       paper accepted ※ 12 July 2019       issue date ※ 14 August 2019  
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TUP051 Progress Towards Commissioning the Cornell DC Field Dependence Cavity cavity, niobium, SRF, solenoid 543
 
  • J.T. Maniscalco, T. Gruber, A.T. Holic, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  The Cornell DC Field Dependence Cavity is a new coaxial test resonator designed to study the impact of strong (up to 200 mT or more) DC surface magnetic fields on the superconducting surface resistance, providing physical insight into the root of the ‘‘anti-Q-slope’’ and probing critical fields. In this report we report progress in the commissioning of this new apparatus, including finalized design elements and results of prototype tests.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP051  
About • paper received ※ 25 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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TUP066 New Design of SSR2 Spoke Cavity for PIP II SRF Linac cavity, quadrupole, linac, HOM 600
 
  • P. Berrutti, I.V. Gonin, T.N. Khabiboulline, M. Parise, D. Passarelli, G.V. Romanov, F. Ruiu, A.I. Sukhanov, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
 
  Funding: US Department of Energy
Superconducting SSR2 spoke cavities provide acceleration of the H in PIP II SRF linac from 35 to 185 MeV. The RF and mechanical design of the SSR2 cavities has been completed and satisfies the technical requirements. However, our resent results of the high RF power tests of fully dressed SSR1 cavities show considerably strong multipacting (MP), which took significant time to process. On the other hand, the new results of the tests of balloon cavity showed significant mitigation of MP. In this paper we present the results of the improved design of the SSR2 cavity, based on the balloon cavity concept. The electromagnetic design is presented, including RF parameter optimization, MP simulations, field asymmetry analysis, High Order Mode (HOM) calculations. Mechanical analysis of the dressed cavity is presented also, which includes Lorentz Force Detuning optimization, and reduction of the cavity resonance frequency sensitivity versus He pressure fluctuations. The design completely satisfies the PIP II technical requirements.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP066  
About • paper received ※ 21 June 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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WETEB8 The Fundamental Power Coupler for CEPC Booster Cavity vacuum, cavity, booster, simulation 789
 
  • T.M. Huang, F. Bing, R. Guo, H.Y. Lin, Q. Ma, W.M. Pan, J.Y. Zhai, Z. Zhang
    IHEP, Beijing, People’s Republic of China
 
  Funding: Supported by National natural Science Foundation of China ( 11475203)
96 Tesla type 1.3GHz 9-cell superconducting cavities, housed in eight 12m-long cryomodules, will be adopted for CEPC booster. Each cavity equips with one variable coupling, double-window fundamental power coupler (FPC). The FPC will operate at RF power up to 20 kW at quasi-CW mode. A variable coupling from 4·106 to 107 is required to meet different operation modes of Higgs, W and Z. A new coupler that employs a 50 Ω coaxial line with bellow structures, a cylindrical warm window, a coaxial planar cold window and a coupling adjusting actuator has been designed. Then two prototypes have been fabricated and high power tested up to CW 70 kW successfully. In this paper, the design, fabrication and high power test of the prototype FPCs will be presented.
 
slides icon Slides WETEB8 [9.971 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEB8  
About • paper received ※ 23 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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THFUB1 Nb3Sn at Fermilab: Exploring Performance cavity, SRF, niobium, superconductivity 818
 
  • S. Posen, J. Lee, O.S. Melnychuk, Y.M. Pischalnikov, D.A. Sergatskov, B. Tennis
    Fermilab, Batavia, Illinois, USA
  • J. Lee, D.N. Seidman
    NU, Evanston, Illinois, USA
 
  Fermilab’s Nb3Sn coating program produced its first 1.3 GHz single cell cavities in early 2017 and since then has explored the performance of Nb3Sn on a wide variety of cavity substrates and performed microscopic studies down to atomic resolution. Results to present in this talk include a study of frequency dependence from 650 MHz to 1.3 GHz of BCS resistance, residual resistance, and magnetic flux sensitivity. We show microscopic studies performed in collaboration with Northwestern University’s Materials Science and Engineering Department of limitation mechanisms in Nb3Sn, including thin film regions and tin segregation at grain boundaries, discussing correlations with RF performance and mechanisms for the formation of these features during growth. Finally, we present results of the first 1.3 GHz 9-cell cavity coated with Nb3Sn.  
slides icon Slides THFUB1 [27.194 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THFUB1  
About • paper received ※ 29 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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THP090 Characterization of SSR1 Cavities for PIP-II Linac cavity, radiation, cryomodule, linac 1120
 
  • A.I. Sukhanov, F.G. Garcia, B.M. Hanna, S. Kazakov, Y.M. Pischalnikov, O.V. Prokofiev, W. Schappert, I. Terechkine, V.P. Yakovlev, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  • C. Contreras-Martinez
    FRIB, East Lansing, Michigan, USA
  • S. Samani
    Queen Mary University of London, London, United Kingdom
 
  A cryomodule of 325 MHz Single Spoke Resonator type 1 (SSR1) superconducting RF cavities is being built at Fermilab for the PIP-II project. Twelve SSR1 cavities were manufactured in industry in USA (10 cavities) and India (2 cavities) and delivered to Fermilab. In this paper we present results of characterization of fully integrated jacketed cavities with high power coupler and tuner at the Fermilab Spoke Test Cryostat (STC).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP090  
About • paper received ※ 23 June 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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