Microwave-excited microplasma thruster: a numerical and experimental study of the plasma generation and micronozzle flow

A microplasma thruster of the electrothermal type has been developed using azimuthally symmetric microwave-excited microplasmas. The plasma source was ~2 mm in diameter and ~10 mm long, and operated at around atmospheric pressures; the micronozzle was a converging–diverging type, having a throat ~0.2 mm in diameter and ~1 mm long. Numerical and experimental results with Ar demonstrated that this miniature electrothermal thruster gives a thrust of >1 mN, a specific impulse of ~100 s and a thrust efficiency of ~10% at a microwave power of <10 W.