PLASMA EXPANSION AND SHOCK WAVE PROPAGATION IN A MICROWAVE-BEAMING THRUSTER

摘要

An experiment on microwave beaming propulsion under reduced pressure has been conducted. 170GHz millimeter-wave of up to 0.5MW was provided by a gyrotron. Although measured impulsive thrust has a weak dependency on ambient pressure, propagation velocity of plasma front observed using a high-speed framing camera was increased with the decrease in ambient pressure. Plasma-front propagation velocity was predicted based on photo-ionization in a pre-shock region. The predicted propagation velocity dependency on pressure showed a good agreement with measured one.