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Shaw, R.W.

Paper Title Page
TUO2B03 SNS Injection Foil Experience 334
  • M.A. Plum, S.M. Cousineau, J. Galambos, S.-H. Kim, P. Ladd, Y. Polsky, R.W. Shaw
    ORNL, Oak Ridge, Tennessee
  • C.F. Luck, C.C. Peters
    ORNL RAD, Oak Ridge, Tennessee
  • R.J. Macek
    LANL, Los Alamos, New Mexico
  • D. Raparia
    BNL, Upton, Long Island, New York

The Spallation Neutron Source comprises a 1 GeV, 1.4 MW linear accelerator followed by an accumulator ring and a liquid mercury target. To manage the beam loss caused by the H0 excited states created during the H− charge exchange injection into the accumulator ring, the stripper foil is located inside one of the chicane dipoles. This has some interesting consequences that were not fully appreciated until the beam power reached about 840 kW. One consequence was sudden failure of the stripper foil system due to convoy electrons stripped from the incoming H− beam, which circled around to strike the foil bracket and cause bracket failure. Another consequence is that convoy electrons can reflect back up from the electron catcher and contribute to foil and bracket failure. An additional contributor to foil system failure is vacuum breakdown due to the charge developed on the foil by secondary electron emission. In this paper we will detail these and other interesting failure mechanisms, and describe the improvements we have made to mitigate them.


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