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Morozumi, Y.

Paper Title Page
WEPMS042 Optimization of the Low-Loss SRF Cavity for the ILC 2439
  • Z. Li, L. Ge, K. Ko, L. Lee, C.-K. Ng, G. L. Schussman, L. Xiao
    SLAC, Menlo Park, California
  • T. Higo, Y. Morozumi, K. Saito
    KEK, Ibaraki
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • J. S. Sekutowicz
    DESY, Hamburg
  Funding: Work supported by DOE contract DE-AC02-76SF00515.

The Low-Loss shape cavity design has been proposed as a possible alternative to the baseline TESLA cavity design for the ILC. The advantages of this design over the TESLA cavity are its lower cryogenic loss, and higher achievable gradient due to lower surface fields. High gradient prototypes for such designs have been tested at KEK (ICHIRO) and JLab (LL). However, issues related to HOM damping and multipacting (MP) still need to be addressed. Preliminary numerical studies of the prototype cavities have shown unacceptable damping for some higher-order dipole modes if the typical TESLA HOM couplers are directly adapted to the design. The resulting wakefield will dilute the beam emittance thus reduces the machine luminosity. Furthermore, high gradient tests on a 9-cell prototype at KEK have experienced MP barriers although a single LL cell had achieved a high gradient. From simulations, MP activities are found to occur in the end-groups of the cavity. In this paper, we will present the optimization results of the end-groups for the Low-Loss shape for effective HOM damping and alleviation of multipacting. Comparisons of simulation results with measurements will also be presented.

THOAKI03 Revision of Accelerating and Damping Structures for KEK STF 45 MV/m Accelerator Modules 2575
  • Y. Morozumi, F. Furuta, T. Higo, T. Saeki, K. Saito
    KEK, Ibaraki
  KEK is constructing its superconducting RF test facility and installing 1.3 GHz superconducting accelerator structures. Learning from experience with our first 45MV/m 9-cell structures, we have revised accelerating structures as well as higher order mode dampers for improved performance. Problems found in the earlier structures are discussed and solutions are presented. New experimental results will be also reported.  
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