Impulse Bit Measurements from Metal Plasma Thruster

Abstract

A torsional thrust stand, calibrated for impulse bits in the range of , was used to measure impulse bits from a metal plasma thruster. Impulse data were obtained on roughly 1400 shots, with metal plasma thruster targets of molybdenum, niobium, palladium, aluminum, and carbon. Model predictions (based on a simple circuit model and published plasma parameters) were validated by data from the calibrated torsional thrust stand. Over a typical 50-shot firing sequence, the impulse bits measured showed a coefficient of variation of approximately 5%. This implies that individual impulse bits of about can be imparted to a satellite with variation about the mean in a total impulse burst of . For a 20 kg satellite, this would result in a velocity increment of just , enabling very precise attitude control and fine positioning control of nano- and microsatellites. The metal plasma thruster uses solid metal propellant and hence requires no liquids, gases, flow valves, or flow controls and has no moving parts. Total impulse approximately provides orbit raising and drag compensation capability.