Onset of the magnetized arc and its effect on the momentum of a low-power two-stage pulsed magneto-plasma-dynamic thruster.

A new type of plasma accelerator-a low-power (<30W), miniature (cm-sized), two-stage pulsed magneto-plasma-dynamic thruster-has been proposed. Being magnetized by an axially symmetric dc magnetic field of ∼200 mT, the vacuum arc discharge demonstrates a threshold behavior: Parameters such as thrust and the thrust-to-power ratio rapidly jump after a certain dc voltage (∼30 V) is applied on the accelerating electrode. We show that such an effect improves the thrust (from ∼2 to ∼210 µN), efficiency (from ∼1% to 50%), and thrust-to-power ratio (from ∼0.5 to ∼18 µN/W).