Initial Development of the Microcavity Discharge Thruster

Proof-of-concept efforts to demonstrate the propulsion capabilities of microcavity plasma discharges through design and fabrication of a Microcavity Discharge (MCD) thruster are discussed. The primary goal is to design and fabricate a MCD thruster and to demonstrate that the MCD thruster can ultimately achieve performance levels of 1 mN per cavity, a thrust efficiency exceeding 60%, and an Isp of 160 seconds. Because the MCD thruster has low specific mass and is scalable over a large number of cavities, a successful performance demonstration would ultimately result in an advanced propulsion system useful for primary (orbit transfer, maneuvering) and secondary (attitude, position and acceleration control) applications for a wide range of satellites. Research at the University of Illinois (Optical Physics and Engineering, Electric Propulsion labs) and the University of Texas at Austin (Computational Plasma Research Lab) is described. Microcavity electrode arrays with integral micronozzles on each cavity are fabricated and are driven at 20 – 150 kHz at a power level of up to 0.25 W per cavity. Thruster and mass flow measurements are made with cold flow to determine nozzle performance. Heating measurements are made to determine stagnation temperature and heat loss. Computational modeling provides a simulation-based understanding of the plasma physics in the microcavity and supports the experimental measurements. A detailed first-principles computational model provides time-accurate solutions of the multi-species, multi-temperature, self-consistent plasma governing equations for discharge physics, coupled to the compressible Navier-Stokes equations for the bulk fluid flow through the MCD thruster.