Implementation and initial validation of a 100-kW class nested-channel Hall thruster
The X3 is a 100-kW class nested-channel Hall thruster developed by the Plasmady- namics and Electric Propulsion Laboratory at the University of Michigan in collaboration with the Air Force Research Laboratory and NASA. The cathode, magnetic circuit, boron nitride channel rings, and anodes all required specific design considerations during thruster development. Thermal modeling was used to properly account for thermal growth in ma- terial selection and component design. A number of facility upgrades were required at the University of Michigan to facilitate operation of the X3. These upgrades included a modified propellant feed system, a redesigned power and telemetry breakout box, and nu- merous updates to thruster handling equipment. The X3 was tested on xenon propellant at two current densities, 37% and 73% of the nominal design value. It was operated to a maximum steady-state discharge power of 60.8 kW. The tests presented here served as an initial validation of thruster operation. Thruster behavior was monitored with telemetry, photography and high-speed current probes. The photography showed a uniform plume throughout testing. At constant current density, reductions in necessary mass flow rate of 18% and 26% were observed in the three-channel operating configuration as compared to the superposition of each channel running individually. The high-speed current probes showed that the thruster was stable at all operating points and that the channels influence each other when more than one is operating simultaneously. Additionally, the ratio of peak-to-peak AC-coupled discharge current oscillations to mean discharge current did not exceed 51% for any operating points reported here, and did not exceed 17% at the higher current density.
