Cathode magnetic shielding for improved coupling in a 50 W-class cusped-field Hall thruster

Cathode–thruster coupling can introduce significant energy loss in low-power cusped-field Hall thrusters because the external cusped magnetic field impedes electron transport from the hollow cathode to the plume and discharge channel. This study investigates cathode-position effects and cathode magnetic shielding in a 50 W-class cusped-field Hall thruster. Three cathode configurations were first tested: parallel, 45° inclined, and perpendicular to the thruster axis. The perpendicular configuration provided the highest measured performance, but its proximity to the channel exit may increase erosion risk and complicate engineering integration. A magnetic shield was therefore installed around the parallel cathode to reduce the local magnetic field and improve cathode–thruster coupling. Magnetic-field simulation showed that the magnetic field at the cathode orifice decreased from approximately 250 G to below 50 G. Compared with the normal cathode, the magnetically shielded cathode reduced the magnitude of the cathode-to-ground voltage, improved voltage utilization, and enabled self-sustaining cathode operation without keeper power during performance measurement. At a total thruster power of (Formula presented) W, the measured thrust was (Formula presented) mN, the total specific impulse was (Formula presented) s, and the total efficiency was (Formula presented) under the present ground-test conditions. These results indicate that cathode magnetic shielding can effectively improve cathode–thruster coupling and the measured performance of the tested low-power cusped-field Hall thruster under the present ground-test conditions.