FRCAA —  Cavities 1   (05-Jul-19   08:00—10:00)
Chair: A. Facco, INFN/LNL, Legnaro (PD), Italy
Paper Title Page
Overview of SRF Deflecting and Crabbing Cavities  
  • S.U. De Silva
    ODU, Norfolk, Virginia, USA
  Developments over the past few years on novel superconducting deflecting and crabbing cavities have introduced advanced rf geometries with improved performance, in comparison to the typical squashed elliptical cavities operating in TM110 type mode. These new structures are compact geometries operating in either TEM type or TE11-like mode. One of the key applications of such cavities is the use of crabbing systems for circular colliders in increasing the luminosity. Crabbing systems are an essential component in future colliders with intense beams and proposed electron-ion colliders. High luminosity upgrade of LHC is planned to implement crabbing systems at two interaction points. Recently, a two-cavity cryomodule with double quarter wave crabbing cavity was installed in SPS at CERN and successfully tested with the proton beam. We present the details of different superconducting deflecting and crabbing cavities and their applications, as well as the recent results of the crabbing systems test at SPS.  
slides icon Slides FRCAA1 [14.149 MB]  
Balloon Single Spoke Resonator - A New Variant for Reduced Multipacting  
  • Z.Y. Yao, R.E. Laxdalpresenter
    TRIUMF, Vancouver, Canada
  Spoke resonators have been widely proposed and optimized for various applications. Good performance has been demonstrated by many cavity tests. Accompanying the great progress, the adverse impact of strong multipacting (MP) is also noted, consistent with modern 3D simulations. This paper will discuss MP behaviors in the single spoke resonator (SSR). In particular a phenomenological theory is developed to highlight the details of the geometry that affect MP. The analysis leads to an optimized geometry of a single spoke resonator defined here as the ’balloon’ geometry. TRIUMF has designed, fabricated and tested the first balloon SSR at 325 MHz and β=0.3. Cold tests proved the principle of the balloon concept, the elimination of MP barriers around the operational gradient. This paper will also report the details of the mechanical and RF design, the fabrication steps and recent cold test results.  
slides icon Slides FRCAA2 [19.831 MB]  
FRCAA3 Industrial Cavity Production: Lessons Learned to Push the Boundaries of Nitrogen-Doping -1
  • D. Gonnella, S. Aderhold, A. Burrill, M.C. Ross
    SLAC, Menlo Park, California, USA
  • E. Daly, G.K. Davis, F. Marhauser, A.D. Palczewski, K.M. Wilson
    JLab, Newport News, Virginia, USA
  • A. Grassellino, C.J. Grimm, T.N. Khabiboulline, O.S. Melnychuk, S. Posen, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
  Funding: Work supported by US DOE Contract DE-AC02-76SF00515.
Nitrogen doping has been proven now in several labs to enhance Q0 values of 1.3 GHz cavities in the gradient domain favored by CW operation. The choice of doping for the LCLS-II project has given the community a wealth of statistics and experience on the challenge of transferring the doping technology to industry. Overall, industry-produced nitrogen-doped cavities have shown excellent performance, however some technical issues have arisen. This talk focuses on lessons learned from the production of over 300 nitrogen-doped cavities for LCLS-II and how issues were mitigated to further improve performance. Finally, I will discuss pushing the boundaries of nitrogen-doping further by exploring different doping regimes in order to maintain excellent Q0 performance, while reaching higher quench fields.
slides icon Slides FRCAA3 [16.880 MB]  
FRCAA4 Progress in SRF CH-Cavities for the HELIAC CW Linac at GSI -1
  • M. Miski-Oglu, K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, J. List, S. Yaramyshev
    HIM, Mainz, Germany
  • K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, A. Rubin, A. Schnase, S. Yaramyshev
    GSI, Darmstadt, Germany
  • K. Aulenbacher, F.D. Dziuba, J. List
    KPH, Mainz, Germany
  • M. Basten, M. Busch, T. Conrad, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
  • S. Lauber
    IKP, Mainz, Germany
  The machine beam commissioning is a major milestone of the R&D for the superconducting heavy ion continuous wave linear accelerator HELIAC of Helmholtz Institute Mainz (HIM) and GSI developed in collaboration with IAP Goethe-University Frankfurt. During successful beam commissioning of the superconducting 15-gap Crossbar H-mode cavity at GSI Helmholtzzentrum für Schwerionenforschung heavy ions up to the design beam energy have been accelerated. The design acceleration gain of 3.5 MeV has been reached with full transmission for heavy ion beams of up to 1.5 particle mueA. We present fabrication experience and results of off-line and on-line cavity performance. The next step is the procurement and commissioning of so called ’Advanced Demonstrator’ - the first of series cryomodule for the entire accelerator HELIAC. Results of further Demonstrator beam tests, as well as the status of the Advanced demonstrator project will be reported.  
slides icon Slides FRCAA4 [9.864 MB]  
SRF Activities and Progress at IHEP  
  • F.S. He, F. Bing, J. Dai, C. Dong, T.M. Huang, S. Jin, D.B. Li, Z.Q. Li, H.Y. Lin, B.Q. Liu, Z.C. Liu, Q. Ma, F. Meng, Z.H. Mi, W.M. Pan, P. Sha, Q.Y. Wang, L.G. Xiao, F.Y. Yang, J.Y. Zhai, P. Zhang, X.Y. Zhang, H.J. Zheng, Q. Zhou
    IHEP, Beijing, People’s Republic of China
  There are several active SRF projects at IHEP, including HEPS, CEPC, CSNS upgrade, SHINE and PAPS SRF facility. Four cryomodules with 166.6 MHz β=1 QWR cavities are proposed for HEPS, while each cavity will providing 1.2 MV and 145 kW to the electron beam. The vertical and horizotal tests of the proof-of-principle cavities were recently conducted. 650 MHz 2-cell cavities and 1.3 GHz 9-cell cavities were proposed for the CEPC, and high Q technology is adopted by the project. Infrastructures are developed for the high Q study, while R&D on single-cell cavities are under-way. Efforts on learning mass-production of cavities and cavity-string were also made for both CEPC and SHINE projects. SRF linac from 80 MeV to over 300 MeV were adopted for the upgrade of CSNS, with 325 MHz Double-spoke cavities at β=0.50 and 650 MHz-5cell elliptical cavities at β=0.65. The PAPS SRF facility is biased on mass production for large SRF projects, i.e. aiming at assembly and testing of 200-400 cavities & couplers and 20 cryomodules per year. The equipment installation and commissioning is on going. The activities and progress of these SRF projects with be addressed in this presentation.  
slides icon Slides FRCAA5 [13.318 MB]  
FRCAA6 Investigation on 1, 3 and 9-Cell SRF Elliptical Cavities made of Large Grain Niobium -1
  • T. Dohmae, H. Inoue, T. Kubo, H. Shimizu, K. Umemori, Y. Watanabe, M. Yamanaka
    KEK, Ibaraki, Japan
  Large grain (LG) niobium is directly sliced from niobium ingot. LG niobium sheet has larger crystal size than that of fine grain (FG) niobium which is forged and rolled, and normally used as the SRF cavity materials. It is expected that higher Q-value can be achieved using LG niobium sheet. And, effective reduction in material cost can be also achieved by LG niobium since forge and rolling process are skipped. On the other hand, there are some difficulties in fabrication since it has large deformation due to strong anisotropy. Cavity fabrication facility in KEK has been fabricated 1, 3 and 9-cell elliptical cavities made by LG niobium and RF tested in vertical cryostat. In this talk, the fabrication process and test results from these cavities will be presented.  
slides icon Slides FRCAA6 [5.819 MB]