Operation of a Hollow Cathode Neutralizer for Sub-100-W Hall and Ion Thrusters

We explore the operation of the Rafael heaterless hollow cathode (RHHC) at low discharge current levels corresponding to sub-100-W Hall and ion thrusters operation. We present experimental results of the cathode operating at discharge current levels of 0.2-0.5 A and mass flow rates of 0.2 and 0.25 mg/s. For each operational condition, potential measurements near the cathode region, in the cathode plume, and on the anode were conducted. We show that the cathode may operate in a self-sustained mode at discharge current levels down to 0.35 A. We show that the cathode coupling potential increases as the discharge current is decreased and may reach values of 40 V at the lowest discharge current. Accordingly, the cathode coupling power is estimated to account for up to 14 W of the anode power supply power. We show that when the RHHC cathode is coupled with a hypothetical very low-power Hall thruster, the estimated cathode power intake would be 10%-23% of the overall thruster power. Finally, using external cathode body temperature measurements, we assess the radiated power from the cathode surface to be lower than 1 W. Overall, we demonstrate that the RHHC cathode is suitable for operation with very low-power Hall and ion thrusters for discharge power under 100 W.