Thrust Stand Measurements of an RMF-FRC Thruster with Continuous Power System

Eagle Harbor Technologies, Inc. (EHT) developed a continuously-operating repetitively-pulsed power system for the University of Michigan (UM) Rotating Magnetic Field (RMF) – Field-Reversed Configuration (FRC) Thruster. EHT leveraged a previously designed resonant full bridge in single-burst mode to develop a continuously-operating repetitively-pulsed system at 4 kW of average power. The EHT solid-state power system can drive peak currents of ±2 kA at 500 kHz in the inductive RMF coils. UM integrated the power system with the thruster and conducted performance measurements in their Large Vacuum Test Facility. With the EHT power system they demonstrated parametrical control of the thruster performance (thrust, specific impulse, and efficiency) by varying the plasma input energy, neutral flow rate, and applied magnetic field. The new EHT power system and UM thruster upgrades improved the coupling efficiencies from ~3% to more than 50% and active specific impulses approaching 1000 s, while allowing for a direct thrust measurement. This is the first direct performance measurement of a continuously operating RMF–FRC Thruster using a standard inverted-pendulum thrust stand in space-like conditions.