Discharge characteristics of a low-power applied-field magnetoplasmadynamic thruster in a Tesla-level magnetic field

Abstract High magnetic fields, efficiently generated by superconducting magnets, can enhance and modulate the thrust of applied-field magnetoplasmadynamic thrusters (AF-MPDTs). However, the extent to which high fields can impact performance is unknown due to the scarcity of tests conducted at Tesla-level fields. This paper presents the discharge characteristics of a kW-class thruster (maximum 1.6 kW) operating under a high magnetic flux density, reaching 1.25 T, with argon propellant flow rates of 2 and 4 mg/s. The results show that the discharge voltage at all fields scales linearly with the back electromotive voltage, indicating consistent creation of useful voltage in the investigated regime. A similar trend is observed for the anode voltage fall, which increases with the magnetic fields in the high-field regime and decrease with the mass flow rate. The temperatures monitored at the anode showed a maximum increase of 29.1 K at 750 mT during 15 A discharge. The temperature measurements were used to quantify the anode’s thermal efficiency. The highest thermal efficiency of the anode, 66%, was registered at 750 mT and showed minimal variation for both 10 A and 15 A at higher fields. For low-current discharges, the anode’s efficiency followed the linear trend up to high fields indicating the potential of using high fields (< 250 mT) to improve the performance of low-power (< 10 A) AF-MPDTs.