Abstract:Microwave plasma has the advantages of high energy density, high ionization rate and high temperature, and high-density plasma has good reflectivity to electromagnetic waves, which can be used as a microwave plasma switch. A two-dimensional model of microwave plasma has been established using the finite element simulation method, coupling the Boltzmann equation with the plasma fluid equation. The electron density evolution process of the plasma switch of the gas discharge tube inside the waveguide has been simulated, giving the electron distribution and the variation of the electron density with time inside the plasma switch. It describes the triggering principle and the process of the plasma switch. The simulation results show that the plasma is first generated on the side of the gas discharge tube away from the incident port, then fills up the whole discharge tube, and finally a high-density plasma accumulates on the surface of the tube close to the incident port to form a reflection of the microwaves inside the tube. The model also gives the electron density distribution and microwave reflection coefficients inside the plasma switch at different microwave incident powers and different air pressures. The simulation results show that the plasma switch has the best reflectivity and response speed at an air pressure of 400 Pa. The reflection coefficient reaches 0.8 at 10 kW incident power, and the plasma switch is more prone to self-breakdown at this air pressure.