SNS stripper foil development program

When the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) becomes fully operational it will be the world's highest intensity neutron spallation source. The charge-exchange injection section in the accumulator ring, which strips the injected H− beam to H+, requires a stripper foil 260 μg/cm2 thick, 12 mm wide, a height of at least 20 mm, and support from just the top edge. The foil will get very hot due to the 1.4 MW, 1 GeV, 60 Hz H− beam that passes through the foil, in addition to the 7–10 foil traversals each circulating proton makes through the foil. The planned upgrade to 3 MW beam power presents an even greater challenge. To meet this challenge a diamond foil development program has been underway at ORNL since 2001. Both microcrystalline and nanocrystalline foils have been developed and tested. In this paper we will discuss the SNS injection process, stripper foil requirements, and results from the diamond foil development and testing program.