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Rusnak, B.

Paper Title Page
WEPMS017 High-Power Coupler Component Test Stand Status and Results 2367
  • B. Rusnak
    LLNL, Livermore, California
  • C. Adolphsen, G. B. Bowden, L. Ge, R. K. Jobe, Z. Li, B. D. McKee, C. D. Nantista, J. Tice, F. Wang
    SLAC, Menlo Park, California
  • R. Swent
    Stanford University, Stanford, Califormia
  Funding: This work was performed under the auspices of the U. S. DOE by the University of California, LLNL under Contract No. W-7405-Eng-48. SLAC Work supported under Contract No. W-7405-Eng-48.

Fundamental power couplers for superconducting accelerator applications like the ILC are complicated RF transmission line assemblies due to their having to simultaneously accommodate demanding RF power, cryogenic, and cleanliness constraints. When these couplers are RF conditioned, the observed response is an aggregate of all the parts of the coupler and the specific features that dominate the conditioning response are unknown. To better understand and characterize RF conditioning phenomena toward improving performance and reducing conditioning time, a high-power coupler component test stand has been built at SLAC. Operating at 1.3 GHz, this test stand was designed to measure the conditioning behavior of select components of the TTFIII coupler independently, including outer-conductor bellows, diameter changes, copper plating and surface preparations, and cold window geometries and coatings. A description of the test stand, the measurement approach, and a summary of the results obtained are presented.

WEPMS041 Multipacting Simulations of TTF-III Coupler Components 2436
  • L. Ge, C. Adolphsen, K. Ko, L. Lee, Z. Li, C.-K. Ng, G. L. Schussman, F. Wang
    SLAC, Menlo Park, California
  • B. Rusnak
    LLNL, Livermore, California
  Funding: This work was supported by US DOE contract No. DE-AC02-76SF00515. This work was performed under the auspices of the US DOE by the University of California, LLNL under Contract No. W-7405-Eng-48.

The TTF-III coupler adopted for the ILC baseline cavity design has shown a tendency to have long initial high power processing times. A possible cause for the long processing times is believed to be multipacting in various regions of the coupler. To understand performance limitations during high power processing, SLAC has built a flexible high-power coupler test stand. The plan is to test individual sections of the coupler, which includes the cold and warm coaxes, the cold and warm bellows, and the cold window, using the test stand to identify problematic regions. To provide insights for the high power test, detailed numerical simulations of multipacting for these sections will be performed using the 3D multipacting code Track3P. The simulation results will be compared with measurement data.

THPMS016 A Large-Format Imaging Optics System for Fast Neutron Radiography 3029
  • B. Rusnak, P. Fitsos, M. Hall, M. Jong, R. Souza
    LLNL, Livermore, California
  Funding: This work was performed under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

As part of the ongoing development of fast neutron imaging technology for national secu-rity applications at LLNL, a large-format imaging optics system has been designed and built. The system will be used to acquire radiographic images of heavily-shielded low-Z objects irradiated by ~ 10 MeV neutrons and is expected to have an ultimate spatial resolution ~ 1 mm (FWHM). It is comprised of a 65 cm x 65 cm plastic scintillator (e.g. BC-408), an aluminized front-surface turning mirror and a fast (~ f/1.25) optical lens coupled to a CCD camera body with a cryo-cooled, back-illuminated 4096 x 4096 (15 micron) pixel sensor. The lens and camera were developed and purchased from vendors and system integration was done at LLNL. A description of the overall system and its initial performance characteristics shall be presented.