Thermo-mechanical response of the halo intercepts interacting with the SNS proton beam

The integral part of the primary collimator of the SNS accumulator ring is a halo intercept assembly in the form of movable scraper blades that allow the interception of the halo protons in four planes. In order to achieve large Coulomb scattering of the halo protons and energy losses of less than 1%, platinum was chosen as the material of choice while its thickness was optimized to satisfy the energy loss requirements. This paper outlines the adopted design of the scraper assembly and presents the thermal response of the system that intercepts the beam halo as well as the subsequent thermal stress analysis and the issues associated with the performance of the scraper. Specifically, the current design incorporates a highly conducting material (copper) in the blade structure interfacing with the platinum scraper and is responsible for conducting the deposited energy away from the beam interception region. The mechanical performance and durability of such system, especially of the special bonding between the dissimilar materials, is the primary focus of this effort