Numerical study of microwave dielectric surface breakdown at atmospheric condition

Summary form only given. On the vacuum side, the microwave breakdown caused by secondary electron emission on the dielectric interface was extensively investigated with Particle-in-Cell method. In this paper, microwave air breakdown at dielectric surface is investigated by numerical solution of fluid-based plasma equations coupled with the Maxwell equations. The governing equations and parameters of air breakdown are the same as those in our previous paper. The thickness and the relative dielectric constant of the dielectric layer are chosen as 6.5 mm and 2.7, which are same as those in Ref.[3]. The results of 5mm and 20mm thick plasma regions are compared in the one-dimension model. It is found that the electron number density in the upstream region for 20mm is larger than that for 5mm. In the two-dimension model, as is shown in the Fig. 1, it is found for TE10 mode that the plasmoid firstly grows in the middle of waveguide until its density becomes large enough to diffract the incident field, then the plasma region moves along the surface to both sides. The plasma region cannot reach the wall of waveguide, where the electric field is smaller than the breakdown threshold.