Optimizing the RF cavity parameters at CSNS-II with Particle Swarm Optimization

Objective This study is aimed at optimizing the parameters of a dual-harmonic RF systemwhich will be used in CSNS-II to have a larger bunching factor and less particle losing to decrease the space charge effect.Methods By studying the synchrotron equation of motion in a double RF system,some features of the bunch are quantized.The normalized bucket area should be constant,the injection condition should be satisfied,and larger bunching factor is preferred during the cycle period.With these ideas,three objective functions are proposed.Particle swarm optimization(PSO)method is employed to search the optimal solution.Results There is less particle loss in the simulation with the optimized parameters.The growth rate of the transverse emittance is smaller after the optimization.The bunch can keep a larger bunching factor which is very useful to decrease the space charge force.Conclusion The parameters of the dual-harmonic RF system are optimized with swarm optimization method.This study provides a general method to optimize the similar system,especially for an accelerator.