Effects of applied magnetic fields on the performance of magnetoplasmadynamic thrusters

Since the performance of MPD thrusters is highly dependent on the applied magnetic field, we experimentally investigated the effects of magnetic field geometry. Thrust, specific impulse, and ion energy distribution were measured under various operating conditions. The results indicate that the magnetic field configuration of permanent magnets with a magnetic null point may limit effective ion acceleration, leading to reduced thrust while the permanent magnet produces a stronger applied magnetic field ( B _A : 0.175 T) than the electromagnet ( B _A : 0.016–0.065 T). For the electromagnet configuration, thrust increased more significantly with discharge current at a lower flow rate (500 sccm) and a higher electromagnetic coil current (40 A). When the discharge current was increased to 300 A under the aforementioned conditions, the maximum thrust of 436 mN and the specific impulse of 2935 s were obtained. From these observations, the current-voltage (I–V) characteristics, which are strongly influenced by the magnetic field, appear to be closely linked to the thruster performance, as evidenced by the measured thrust and ion energy distributions. The findings highlight the dominant influence of the magnetic field geometry on the thruster performance, along with the contributions of the discharge current and the argon flow rate.