A Pulsed Plasma Thruster Using Dimethyl Ether as Propellant

Abstract

The pulsed plasma thruster (PPT), has attracted attention again as a micro thruster because of its compactness, lightweight and comparatively low power consumption. On the other hand, for a conventional Teflon PPT, propellant utilization efficiency is relatively low among electric propulsion device because the propellant originated from late-time ablation produces negligible thrust. The liquid propellant PPT (LP-PPT), where water or ethanol was fed with an injector, was proposed to overcome the difficulties. Thrust measurement has shown that LP-PPT provided higher specific impulses than the conventional PPT. However, water requires temperature management for propellant storage owing to relatively high freezing point. Moreover, even if ethanol, which has sufficiently low freezing point, was used as propellant, pressurant is necessary as well as water because the vapor pressures are deficient for self-pressurization. In this study, we have proposed to use dimethyl ether (DME) as propellant. DME, which has a freezing point of 131 K at 1 atm and a vapor pressure of 6 atm at 298 K, is storable in tanks as a liquid and requires no feeding pressurant. We have designed a DME pulsed plasma thruster to evaluate the performance. Thrust measurement yielded a specific impulse of 430 s for coaxial type at a capacitor stored energy of 13 J.