Numerical study the influences of charge exchange ions on optical system ion beam

Based on particle-in-cell (PIC) and Monte Carlo collision (MCC) method, a two-dimensional numerical model was adopted to investigate the distribution and kinetic characteristics of the charge exchange (CEX) ions in the optical system of ion thruster. The simulation results show that, the screen grid current is increased by 1.42 percent when the CEX ions are considered. On the other hand, the accelerator grid current increases from zero to 1.41 percent of the main beam current. It is indicated from the simulation results that the CEX ions originated in the far downstream region of the optics are the main reason of the accelerator grid current and the erosion on the downstream face of the accelerator grid.