Start-up process of ion optics in ion thrusters

In this study, a particle-in-cell model of ion optics was established to simulate the changing trend of an ion beam shape over time during an ion optic start-up. This model was established to study the effect of ion beam shape change on the accel grid during ion optical start-up and to discuss the start-up strategy of ion optics. The results show that the ions at the edge of the beam have a radial velocity component toward the centerline of the ion optics owing to the electric field; this causes the ion beam to shrink gradually toward the centerline over time. Furthermore, the accel grid can be prevented from being bombarded by ions by design at the operating voltage. However, the grid may still be bombarded by ions during the low-voltage start-up process, thereby affecting its life. Thus, the ion dynamics must be considered during the start-up process.