Beam Focusing Performance of Microwave-Driven In-Tube Accelerator

Numerical simulation and experiment of a microwave beaming propulsion system, microwave-driven in-tube accelerator (MITA), was conducted. In MITA system, the vehicle is placed in the waveguide, and the microwave beam is irradiated into the front side of the vehicle. The beam is reflected by the front mirror of the vehicle and the waveguide and then focused at the vehicle's rear side. The focused beam causes breakdown of the atmosphere, and the generated plasma induces the shock wave through a gas heating process. In the numerical simulation, 28 GHz microwave beam was irradiated into the two-dimensional axisymmetric model of MITA to investigate microwave propagation and thrust performance. It showed a better performance at beam focusing and thrust generation, when larger size of waveguide and vehicle was used. In the experiment, 28 GHz low-power microwave beam was irradiated into the MITA model to investigate the beam focusing process of MITA. Microwave beam was successfully focused at the rear side of the vehicle, and it showed a large power density at the focal point. The larger size model showed a better beam focusing performance.