Scattering effect in proton beam windows at spallation targets

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.Comment: 8 pages, 6 figures, 6 tables. Appears in High Power Laser and Particle Beams 201

Thermal analysis and optimization of proton beam window for the CSNS

“…The results show that the energy deposition per proton on A5083 is one third of that on Inconel718. Besides, the scattering effect of A5083 is better than that of In-conel718 [8]. These are the two main reasons for the CSNS to choose A5083 as the PBW material.…”

“…The scattering effect has been simulated, which recommended a thin window, the results are shown in Fig. 4 [8]. However, thin window will enhance the machining difficulty.…”