Thrust and Efficiency Characterization of a Low-Power Applied-Field Magnetoplasmadynamic Thruster With a Superconducting Magnet

Superconducting magnets can become an enabling technology, offering new potential for applied-field magnetoplasmadynamic thrusters (AF-MPDTs). This study investigates the role of high, Tesla-level magnetic fields (up to 1 T) in AF-MPDTs operating in the low-power regime. More specifically, the AF-MPDT is operated with a lanthanum-hexaboride hollow cathode using argon flow rates below 2 mg/s, and anode discharge currents below 10 A. The reported results aim to characterize thruster performance in relation to both anode voltage and thrust. The thruster delivers up to 27.8 mN of thrust, with a peak thrust efficiency of 22% and a thrust-to-power ratio of 32 mN/kW. The highest reported discharge power was 1.73 kW. In the low-field regime (< 250 mT) the magnetic field increases thrust and thruster performance. Thrust is seen to increase linearly reaching a maximum at 500 mT–750 mT, depending on the combination of anode discharge current and argon flow rate. The ability of the thruster to convert swirl energy into axial acceleration is shown to decrease with increasing field, limiting performance in the high-field regime. In addition, it has been shown that the applied magnetic field can be used as an efficient mechanism for thrust modulation.