Open-front approach of a microwave rocket sustained by a resonant magnetic field

Shock-wave propagation around a microwave-rocket nozzle was numerically reproduced using a computational fluid dynamics code when an electron cyclotron resonance condition was satisfied by irradiating 25 GHz microwaves onto the rocket nozzle under an external magnetic field. The pulse-duration and nozzle-shape dependence for the thrust performance of the microwave rocket was evaluated by changing the normalized heating length and the normalized nozzle radius. The open-front approach usinga butterfly valve was newly proposed to improve the thrust performance by eliminating the negative thrust and removing the stagnation region during the gas-refilling process. The thruster only received the positive pressure of the shock wave by eliminating the contribution of the negative pressure using the open-front approach, which improved the thrust performance. In addition to the thrust improvement, the gas-refilling performance was also improved because the ambient gas flowed from the open front to the nozzle inside without forming the stagnation region. The improvement of the thrust performance and the gas-refilling performance can improve the payload transportation efficiency and further reduce the cost of launch using beamed-energy propulsion.