Analysis based on global model of nitrogen plasma produced by pulsed microwave at low pressure

Abstract

This paper analyzes certain evolution processes in nitrogen plasmas discharged using pulsed microwaves at low pressure. Comparing the results obtained from the global model incorporating diffusion and the microwave transmission method, the temporal variation of the electron density is analyzed. With a discharge pressure of 300 Pa, the results obtained from experiments and the global model calculation show that when the discharge begins the electron density in the plasma rises quickly, to a level above the critical density corresponding to the discharge microwave frequency, but falls slowly when the discharge microwave pulse is turned off. The results from the global model also show that the electron temperature increases rapidly to a peak, then decays after the electron density reaches the critical density, and finally decreases quickly to room temperature when the discharge microwave pulse is turned off. In the global model, the electron density increases because the high electron temperature induces a high ionization rate. The decay of the electron density mainly comes from diffusion effect.

Space and time evolution of high-power microwave breakdown on the atmosphere side of the dielectric surface

“…The high electric field inherent to the HPM causes frequently the dielectric surface flashover phenomena on the atmospheric side, where the thin plasma layer forms and hinders obviously the transmission of the HPM. [10][11][12] Therefore, it is very important to study and understand the fundamental process. Some experimental and theoretical investigations involving the HPM breakdown on the atmosphere side of the dielectric surface have been reported.…”