Electrode material selection and plasma-surface interactions in a coaxial pulsed plasma thruster

This study presents the development and extended operational testing of a Coaxial Pulsed Plasma Thruster (CPPT) specifically designed for small satellite propulsion applications. The annular ignition system demonstrated highly stable performance over 38,000 firing cycles, while the thruster itself underwent over 100,000 discharge cycles at a capacitor discharge energy of 18.4 J, achieving a maximum thrust efficiency of 37%. Fast Faraday Cup diagnostics revealed that the plasma plume was primarily confined between −30° and 0°, and high-speed imaging confirmed that the plume direction varied with ignition location. Thrust measurements using a hanging pendulum thrust stand indicated impulse bits of 181 μN·s or 134 μN·s, depending on the discharge waveform characteristics. Experimental analysis showed that using 304 stainless steel as both the cathode and ignition electrode material enabled reliable ignition under vacuum conditions. Although visible metallic powder deposition was observed on the surface of the polytetrafluoroethylene (PTFE) propellant, it did not significantly degrade thruster performance, as evidenced by sustained arc discharge stability and minimal electrode erosion. Overall, the CPPT exhibited low ablation rates and high operational efficiency, highlighting its strong potential as a long-lifetime, low-power propulsion system for microsatellites and other space missions.