Design of N₂ + He two-stage stripper for CSR1

Charge stripper ring 1 (CSR1) is a circumferential ring with a stripper installed inside to improve the charge conversion efficiency, which is considered to be constructed as a future project. A two-stage stripper combing N 2 and He is being considered for the stripper in CSR1. Evaluating the circumferential charge state, required gas thickness, and charge distribution after charge exchange is essential in designing the N 2 + He two-stage stripper. In this study, the ionization and electron capture cross-sections for charge exchange in a gas target were calculated, and the equilibrium charge state and charge state evolution in the gas were evaluated. Circumferential calculations considering only the charge state were also performed to estimate the extraction yield of the designed charge state.