Abstract: Accelerator voltage directly affects the electron back streaming and acceleration grid sputter erosion. Therefore, how to obtain the best values of accelerator voltage is important for an ion thruster. The semi-empirical analysis method combined with the numerical simulation was used to analyze the equilibrium evolution of the beam current extracted from the LIPS-300 ion thruster grid and the grid lifetime was calculated. By using the numerical model, the sputter erosion rate that CEX sputtered on the surface of the acceleration grid was obtained. Then applying this erosion rate to the theoretical model, the lifetime of the LIPS-300 ion thruster was estimated and the failure modes for the five different accelerator voltages were analyzed. The results show that the change of the accelerator voltage would not affect the performance of the LIPS-300 ion thruster gird. For the LIPS-300 ion thruster, the downstream of the acceleration grid would be more vulnerable to CEX sputtering erosion. While the accelerator voltage is changed from -220V to -190V, the key failure modes of the LIPS-300 ion thruster gid is electron back streaming failure. By comparing the lifetime of the grid for the five different accelerator voltages, the best voltage is -220V and the corresponding lifetime is 16170.4h.

Key words: Ion thruster, Accelerator voltage, Lifetime, Theoretical analysis, Simulation