Author: Ao, H.
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TUPAL022 Low-Reflection RF Window for ACS Cavity in J-PARC Linac 1051
  • J. Tamura, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-mura, Japan
  • H. Ao
    FRIB, East Lansing, USA
  • F. Naito, M. Otani
    KEK, Ibaraki, Japan
  • Y. Nemoto
    Nippon Advanced Technology Co., Ltd., Tokai, Japan
  In the Japan Proton Accelerator Research Complex (J-PARC) linac, the Annular-ring Coupled Structure (ACS) cavities have been stably operating. To maintain this operation availability, we manufactured three backups of the pillbox-type RF windows for the ACS cavities in fiscal year 2015 and 2017. It is desirable to minimize the RF reflection of the RF window to prevent standing waves from exciting between the cavity and the RF window, and not to significantly change the optimized coupling factor between the cavity and the waveguide. To realize the minimization, the relative permittivities of the ceramic disks of the RF windows were evaluated by measuring the resonant frequencies of the pillbox cavity containing the ceramic disk. On the basis of the evaluated relative permittivities, the pillbox-part lengths of the RF windows were determined. The measured Voltage Standing Wave Ratios (VSWRs) of the manufactured RF windows are just about 1.08 and these are applicable for the practical use.  
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TUPAL037 Installation Progress on FRIB β=0.041 Cryomodules Toward Beam Commissioning 1087
  • H. Ao, B. Bird, N.K. Bultman, F. Casagrande, C. Compton, K.D. Davidson, K. Elliott, V. Ganni, A. Ganshyn, P.E. Gibson, I. Grender, W. Hartung, L. Hodges, K. Holland, A. Hussain, M. Ikegami, S. Jones, P. Knudsen, S.M. Lidia, I.M. Malloch, E.S. Metzgar, S.J. Miller, D.G. Morris, P.N. Ostroumov, J.T. Popielarski, L. Popielarski, M.A. Reaume, T. Russo, K. Saito, M. Shuptar, S. Stanley, S. Stark, D.R. Victory, J. Wei, J.D. Wenstrom, M. Xu, T. Xu, Y. Xu, Y. Yamazaki, Q. Zhao, S. Zhao
    FRIB, East Lansing, USA
  • A. Facco
    INFN/LNL, Legnaro (PD), Italy
  • R.E. Laxdal
    TRIUMF, Vancouver, Canada
  • M. Wiseman
    JLab, Newport News, Virginia, USA
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
The Facility for Rare Isotope Beams (FRIB) driver linac is to accelerate all the stable ion beams from proton to uranium beyond 200 MeV/u with beam powers up to 400 kW, which will be the first large-scale, CW SRF ion linac. The beam commissioning of the front end (from the ion source to the RFQ) already began and is in progress. The Accelerator Readiness Review (ARR) for beam through the first three β=0.041 cryomodules is scheduled for May 2018. The next step is the beam commissioning through the 12 SRF cavities housed in these 3 cryomodules with 6 superconducting solenoid magnets. The cryomodules and the adjacent warm diagnostics boxes in between have been already installed and aligned in the tunnel. This paper describes the installation progress of the β=0.041 cryomodules and plans for ARR02.
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