Development and Initial Performance Testing of a Low-Power Magnetically Shielded Hall Thruster with an Internally-Mounted Hollow Cathode IEPC-2017-64

A new development model MaSMi Hall thruster, which utilizes a compact internally-mounted hollow cathode, was designed, fabricated, and tested. The low-current cathode demonstrated stable current-voltage characteristics and thermal performance over the current range of the MaSMi-DM. While the cathode uses a standard sheathed heater, heaterless cathode ignition testing revealed a predictable start-up behavior and provided insight into the system-level architecture required for reliable heaterless ignitions. A new anode gas feed design used in the MaSMi-DM demonstrated a maximum peak-to-peak pressure variation of 3.2% and 2.6% at propellant flow rates of 1 mg/s and 3 mg/s, respectively. Initial testing of the MaSMi-DM has now started, with preliminary results at 300 V and 500 W in a non-optimized operating condition demonstrating 41% total efficiency with a total specific impulse of 1320 s. Visual observations of the plasma discharge, carboncoated discharge channel walls post-operation, and the results from the plasma simulations provide strong evidence of magnetic shielding. High-speed diagnostics recorded normal breathing mode oscillation behavior in the 20-50 kHz range and captured additional modes at >200 kHz, possibly associated with azimuthal discharge plasma spokes or the cathode.

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