New design of a collimator system at the PSI proton accelerator

PSI is gradually upgrading the 590 MeV proton beam intensity from the present 2.2 mA towards 3 mA, which poses a significant challenge to the reliable operation of the accelerator facility. Of particular concern is the collimator system which is exposed to the strongly divergent beam from a muon production target. It shapes an optimal beam profile for low-loss beam transport to the neutron spallation source SINQ. The current collimator system absorbs about 14 % of the proton beam power. Consequently, the maximum temperature of the collimator system exceeds 400 C at 2.2 mA, which is close to the limit set for safe operation. In this paper, we present a new collimator system design which could withstand the proton beam intensity of 3 mA, while fulfilling the intended functionality. Advanced multiphysics simulation technology is used for the geometric and material optimizations, to achieve the lowest possible actual to yield stress ratio at 3 mA. A sensitivity study is performed on the correlation between the beam misalignments and the reliability of the accelerator components in the proton downstream region.