Modeling and Simulation on the Ionization Process of the Coaxial Pulsed Plasma Thruster

Coaxial pulsed plasma thruster (CPPT) is a kind of electric thrust device. Because of their advantages of simple structure, high reliability and low working power, CPPTs have been widely used on micro-satellites in recent years. Ionization rate is a parameter to measure the propellant utilization efficiency of CPPT. However, the ionization mechanism in the discharge area of a CPPT and the specific influence of different factors such as electrode size on the ionization rate remains unclear. Firstly, we did experiment using prototypes with different electrode diameter and different initial voltage. In the experiment, for each prototype, the ablated mass is measured, the resistance and inductance of the circuit is calculated from the voltage and current curve, and the ionization rate is calculated from the specific impulse and plume speed. Then, we built a model of the ionization process of CPPTs, and did simulation with ablated mass, resistance and inductance of the circuit got in the previous experiment. It is concluded that, while the other parameters are unchanged, the ionization rate will decrease when the initial voltage increases, and will increase when the diameter of the electrode (inner electrode or outer electrode) increases. Finally, the conclusions were compared and shown to be consistent with the ionization rate obtained in the experiment.