Experimental and numerical study of an electrothermal pulsed plasma thruster for small satellites

A pulsed plasma thruster (PPT) with a propellant feeding mechanism was designed using two poly tetrafluoroethylene (PTFE) bars as propellants. The PPT was mounted on a thrust stand with a 1-m-long perpendicular pendulum which was developed for precise measurements of impulse bits. Initial thrust performance showed thrust-to-power ratio of 43–48 μN/W, specific impulse of 470–500 s and thrust efficiency of 10–12% with energy of 4.5–14.6 J. Ten thousand shots achieved a total impulse of approximately 3.6 Ns, and the PTFE bars were consumed approximately 2 mm in length. However, uneven receding of the PTFE surface was observed. In order to investigate physical phenomena in a whole system, an unsteady numerical simulation of initial discharge, generation of plasma, heat transfer to the PTFE, heat conduction inside the PTFE, ablation from the PTFE surface and acceleration of plasma was performed. The calculated results were used to explain the physical phenomena in the cavity, especially ablated mass of the PTFE.