Plasma Generation at Atmospheric Pressure Using a High-Power Microwave Beam and Its Application to Rocket Propulsion

摘要

Experiments on microwave plasma generation and its application to microwave beamed energy propulsion were conducted using a 1-MW-class, 170-GHz gyrotron. The microwave beam was focused using a parabola reflector and plasma was initiated near the focal point in the ambient air. Plasma propagated upstream in the microwave beam channel while absorbing microwaves. Its propagation velocity was supersonic when the microwave power density was greater than 75 kW/cm{sup}2. The propulsive impulse was measured using a cone-cylinder-shaped thruster model. As a result, the maximum momentum coupling coefficient was obtained at a certain plasma propagation distance. In addition, a larger momentum coupling coefficient was obtained when plasma was propagated at a supersonic velocity. This is because supersonic plasma propagation forms a strong shock wave, resulting in an efficient pressure increase.