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Ge, L.

Paper Title Page
TPPP028 Simulation of HOM Leakage in the PEP-II Bellows 2050
 
  • C.-K. Ng, N.T. Folwell, L. Ge, J. Langton, L. Lee, A. Novokhatski
    SLAC, Menlo Park, California
 
  Funding: Work supported by U.S. DOE contract, DE-AC02-76SF00515.

An important factor that limits the PEP-II from operating at higher currents is higher-order-mode (HOM) heating of the bellows. One source of HOM heating is the formation of trapped modes at the bellows as a result of geometry variation in the vacuum chamber, for example, the masking near the central vertex chamber. Another source comes from HOMs generated upstream that leak through the gaps between the bellows fingers. Modeling the fine details of the bellows and the surrounding geometry requires the resolution and accuracy only possible with a large number of mesh points on an unstructured grid. We use the parallel finite element eigensolver Omega3P for trapped mode calculations, and the S-matrix solver S3P for transmission analysis. The damping of the HOMs by the use of absorbers inside the bellows will be investigated.

 
TPPT056 Design of a Low Loss SRF Cavity for the ILC 3342
 
  • J.S. Sekutowicz
    DESY, Hamburg
  • L. Ge, K. Ko, L. Lee, Z. Li, C.-K. Ng, G.L. Schussman, L. Xiao
    SLAC, Menlo Park, California
  • I.G. Gonin, T.K. Khabiboulline, N. Solyak
    Fermilab, Batavia, Illinois
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • Y. Morozumi, K. Saito
    KEK, Ibaraki
 
  An international team comprising DESY, KEK, JLAB, FNAL and SLAC is collaborating on the design, fabrication and test of a low loss, 1.3 GHz 9-cell SRF structure as a potential improvement for the ILC main linac. The advantages of this structure over the TTF structure include lower cryogenic loss, shorter rise time, and less stored energy. Among the issues to be addressed in this design are HOM damping, Lorentz force detuning and multipacting. We will report on HOM damping calculations using the parallel finite element eigenmode solver Omega3P and the progress made towards an optimized design. Studies on multipacting and estimates of the Lorentz force detuning will also be presented.