Three-dimensional numerical study on motion laws of ions in ion thruster optics

With the particle-in-cell(PIC) method adopted, a three-dimensional numerical model was developed to study the motion behaviors of beam ions and charge exchange(CEX) ions in the ion thruster optics. Based on the geometric and physical parameters designated, the electric potential in calculation domain, the trajectories and velocities phase space distributions of the beam and CEX ions, and the grid currents were obtained with simulation. The CEX ions produced at the downstream of the acceleration grid will be accelerated by electric field and then impinge on the downstream surface of the acceleration grid, which would be the main reason for acceleration grid erosion. On the other hand, the CEX ions produced between the screen grid and the acceleration grid would impinge on the inner wall of the acceleration grid aperture, which enlarges of the acceleration grid aperture gradually.