• M.A. Plum, 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 diamond stripper foils in use at the Spallation Neutron Source worked successfully with no failures until May 3, 2009, when we started experiencing a rash of foil failures after increasing the beam power to ~840 kW. The main contributions to foil failure are thought to be 1) convoy electrons, stripped from the incoming H− beam, that strike the foil bracket and may also reflect back from the electron catcher, and 2) vacuum breakdown from the charge developed on the foil by secondary electron emission. In this paper we will detail these and other failure mechanisms, and describe the improvements we have made to mitigate them.