Development of a lanthanum hexaboride hollow cathode for a magnetic octupole thruster

Electric propulsion has undergone significant advancements, leading to increased usage in satellite constellation management and orbital transfer vehicles. This study describes the design and development of a lanthanum hexaboride (LaB6) hollow cathode for the Magnetic Octupole Plasma Thruster (MOPT), a novel electric propulsion concept for future space missions. Its operational characteristics are also provided. To gain insights into the coupling behavior between the cathode plume and the octupole magnetic field, the hollow cathode was operated with and without an octupole magnet over a range of discharge currents and flow rates. The results indicate that the discharge voltage was anti-correlated with the discharge current and flow rate. Notably, the octupole magnetic field observed reduced discharge voltage oscillations in both high- and low-discharge-current regimes. Nonetheless, the existence of the magnetic field was associated with the amplification of ionization-like instabilities in the high-flow-rate regime. Finally, the paper also delves into the plasma behavior under the influence of the octupole magnetic field, signifying an advancement in developing LaB6 hollow cathodes for their potential use in space-based MOPT applications.