Active protection against abnormal discharges in ion thruster grids based on staged voltage reduction

Ion thrusters are widely utilized in deep space missions due to their high efficiency and long operational life. However, the grid assemblies within these systems are susceptible to long term degradation caused by high energy ion sputtering and deterioration of dielectric insulation, which can lead to unexpected electrical breakdowns and pose serious risks to propulsion system stability and reliability. To mitigate these risks, this study presents a staged voltage reduction protection circuit with microsecond level response capability. The circuit is built on a dual Buck converter topology and incorporates a three level protection strategy that dynamically adjusts voltage reduction and shutdown timing based on the severity of the discharge event. Simulation results indicate that, with optimized duty cycle settings and response delay parameters, the circuit can suppress discharge energy by more than 70% under both moderate and severe fault conditions. Experimental tests further demonstrate the module’s ability to respond rapidly to high current disturbances, with measured waveforms clearly exhibiting staged voltage reduction and circuit disconnection behavior. The protection system achieves an action delay of ∼30 ms, reflecting excellent real time protection performance. Overall, this work offers a practical and effective solution for active protection against abnormal discharges in ion thruster systems and provides a solid foundation for future engineering applications, with strong potential for integration into advanced aerospace propulsion platforms.