Discharge voltage characteristic in ablative pulsed plasma thrusters

Ablative Pulsed Plasma Thruster (APPT), as the earliest electric thruster, has been applied in engineering applications over 50 years. The voltage characteristic, as the most direct parameter, is mostly measured in all APPT experiments to measure the performances. However, almost all researchers applied the capacitor voltages instead of the electrode voltages to estimate the performances (i.e., propellant utilization efficiency, plasma flow between electrodes). Due to the real-time variation of the plasma impedance, there were some deviations in these estimations. In this study, voltage characteristics of the accelerated electrodes were analyzed experimentally and theoretically: in the single discharge process, the trends of phase delay and amplitude difference between electrode voltage and capacitor voltage are related with the variations of the resistance and inductances of the plasma bulk; as the APPT discharge voltage increases, the phase delay and amplitude difference between electrode voltage and capacitor voltage increase in the whole trend, the estimated deviations become larger. This study provides a reference for the numerical model analysis in ablative pulsed plasma thrusters.