Scattering effect in proton beam windows at spallation targets

TL;DR

This study investigates the scattering effects caused by proton beam windows in spallation targets, highlighting their impact on beam loss and distribution through simulation analyses of different materials and structures.

Contribution

It provides the first detailed simulation analysis of scattering effects in PBWs, considering various materials and configurations for the CSNS spallation source.

Findings

Scattering effects significantly influence beam loss and distribution.

Different PBW materials and structures affect scattering outcomes.

Simulations demonstrate the importance of considering scattering in PBW design.

Abstract

Proton beam window (PBW) is a boundary wall between a high vacuum area in the proton beam line and the helium atmosphere in a helium vessel at a high beam power target. The thermal and mechanical problems of the PBW have been studied in other spallation neutron sources; however, the scattering effect in PBW is seldom reported in literature but it may pose serious problems for the target design if not well treated. This paper will report the simulation studies of the scattering effect in PBW. Different materials and different structures of PBW are discussed. Taking CSNS as an example, a thin single-layer aluminum alloy PBW with edge cooling has been chosen for CSNS-I and CSNS-II, and a sandwiched aluminum alloy PBW has been chosen for CSNS-III. Simulations results of the scattering effect in the presence of beam uniformization at target by using non-linear magnets at the different CSNS PBWs are presented. The simulations show that the scattering effect at PBW is very important in the beam loss and the beam distribution at the target.