Design of the input power coupler for Boron Neutron Capture Therapy Drift Tube Linac

Abstract

An accelerator-based Boron Neutron Capture Therapy (BNCT) facility has been built at the campus of China Spallation Neutron Source (CSNS). To upgrade it, a Drift Tube Linac (DTL) is designed to provide a 40 mA, 25% duty factor, 10.1 MeV beam for the target. Two opposing power couplers are employed to deliver forward peak power up to 640 kW for the beam and DTL cavity. A new coaxial power coupler with a single Tristan type window is designed to meet the power and coupling coefficient requirements. In this paper, the detailed RF optimization process of the coupler is described. According to the RF simulation results, the multipacting (MP) phenomenon at critical locations is simulated by the CST PS (Particle Studio). Simulations of thermal and mechanical are also carried out, the cooling design to provide a large margin for RF heating is performed based on the simulation results.