Traceability and suppression of performance degradation of a miniature microwave ion thruster

Microwave ion thrusters have the potential to be applied in space gravitational wave detection missions by their easy miniaturization and high ionization efficiency at low gas pressure. However, the ionization and acceleration processes can be affected by various degradation factors, which in turn reduce the thrust range and lifetime. Therefore, to ensure the long-term stable operation of the miniature microwave ion thruster, the first long-duration discharge test was conducted in this paper to trace the discharge degradation factors. It is found that the discharge channel, antenna, and filler contamination greatly impact the performance. Discharge channel contamination cannot be avoided, but it can be treated as a pretreatment. Since it is a deceleration process, its effect on discharge performance diminishes rapidly with discharge time. Further, the antenna and filler structure were revised and the second long-duration discharge test was carried out. Performance degradation caused by antenna and filler contamination is substantially suppressed. However, the revision of the antenna leads to a reduction in thrust in high thrust mode.