抄録
Temporal plasma-fluid behavior and performance of a pulsed MPD thruster are numerically examined for respective propellants of Ar and He under some current waveforms, each of which has a finite rise time and approaches asymptotically to a maximum current value. The current rise time and the mass flow rate are varied in the range of 1--20μs and 0.4--1.2g/s respectively. The maximum discharge current is set to the critical current. After an ignition, a shock wave is produced and propagates toward the downstream region. Under the condition of a constant discharge time, the specific impulse and the thrust efficiency are improved with shortening a current rise time mainly due to the increase in the impulse bit with regard to electromagnetic thrust. Using He propellant, the ratio of the magnetic thrust to the total thrust is increased from 50% (Ar) to 89% (He), which results in the higher specific impulse of He (≈2,500s) than that of Ar (≈800s).
