Skip to content

Air Force SBIR Phase I: Pulsed Plasmoid Propulsion System for Agile and Resilient Spacecraft

Eagle Harbor Technology, Inc. (EHT) and the Professor Ben Jorns at the Plasmadynamics & Electric Propulsion Laboratory at the University of Michigan (UM) partnered to advance the state of the art Rotating Magnetic Field-Field Reversed Configuration thruster (RMF-FRC). This technology takes inspiration from fusion energy science. The RMF created plasmoids are accelerated out of the thruster at high speed. Despite twenty years of research, there had not been a demonstration of continuous operation in a flight like environment or published thrust stand measurement of performance prior to this work.

Rotating Magnetic Field-Field Reversed Configuration (RMF-FRC) operation. Left: Plasma fluxes into volume with biased magnetic field. Middle: RMF antenna generates azimuthal current in plasma giving rise to field reversal. Right: Lorentz force interaction with background magnetic field.

Using previously developed EHT Full-Bridge Modules, EHT built a solid-state power system to drive the RMF coils for the UM thruster. EHT has used a similar power systems to drive an Electrode-less Plasma Source and High Power Helicon Experiment for pulse durations up to 1 ms. In this SBIR, EHT developed a new version that can operate continuously at up to 4 kW average power while still driving peak currents of 2 kA at 500 kHz.

The EHT power system was integrated with the UM RMF-FRC thruster mounted on an inverted-pendulum thrust stand in the Large Vacuum Test Facility at the University of Michigan. UM characterized the thruster performance with thrust stand measurements, high-speed imaging, and current and voltage telemetry. The thruster performance was mapped for xenon flow rates ranging from 10-200 sccm, peak antenna currents from 1.5 to 2 kA at 500 kHz, and multiple magnetic field strengths. The coupling efficiency of the antenna to the plasma was found to be greater than 50% with active specific impulses (per shot) exceeding 1000 s and active efficiencies approaching 5%.

Long-exposure (10 s) images of the thruster plume operating on xenon. The antenna current was 1.95 kA in all cases.

The parametric trends in performance with operating condition suggest that the performance would continue to improve with antenna current and pulse frequency. This provides a clear path forward for achieving even more marked improvements in operation. Based on the UM thrust stand results, EHT and UM are proposing to continue this work and increase the average and peak power capabilities of the RMF-FRC thruster and associated power system.