Propellant Utilization Efficiency in a Pulsed Plasma Thruster

Abstract

In a pulsed plasma thruster discharge, the propellant utilization efficiency is commonly seen as the weak point for its thrust performance, and for its low thrust efficiency respectively. However, the value depends strongly on operational settings and the design of the pulsed plasma thruster itself. To access this efficiency to understand further the influence of parameters, a method combining experimental and modeling efforts is proposed within this paper. By using various optical methods, including high-speed camera imaging, emission spectroscopy, and Mach–Zehnder interferometry, the plasma bulk velocity for different energy configurations of the SPPT-68 ADD SIMP-LEX is derived. Together with the total ablated mass and an improved slug model, the ratio of mass accelerated in the discharge process is computed and, thus, the propellant utilization efficiency is derived. Velocities in the range of 25 to were measured, leading to propellant utilization efficiencies of about 40 to 60% depending on the voltage and capacitance used in the pulsed plasma thruster.