Simulation Results of Loss Distribution of U³⁶⁺ due to Charge-exchange Process

During heavy ion accelerator operation, the charge exchange effect between ions and residual gas molecules is the key factor to influence beam lifetime. The charge exchange process has ions lost on the wall and leads to a dynamical vacuum change, which will seriously affect the accelerator operation and reduce the extraction beam intensity. The Institute of Modern Physics' future project, called High Intensity heavy ion Accelerator Facility (HIAF), will be built in Huizhou city, Guangdong Province, China. The Booster Ring (BRing) will provide 2×11 ppp ²³⁸U³⁵⁺ for nuclear physics experiments. This article studies the track of particle U³⁶⁺ before impacting on the wall, which is the reference particle U³⁵⁺ losing one electron, and gets the U³⁶⁺ loss distribution along the BRing. The simulation result shows that U³⁶⁺ will be influenced seriously by dispersion elements, and will be lost in the drift sections after the dipoles. Collimators made out of materials with low desorption will be installed in the particles lost positions. The collimator efficiency after optimization can be larger than 95%. It also shows BRing average pressure change and beam intensity change between collimators on and off. The result points out that the BRing average pressure change will be less than 10% with collimators on, which makes BRing operate stably.