Simulation of the reignition of a discharge behind a dielectric layer in air at atmospheric pressure

This paper presents simulations of an air plasma discharge at atmospheric pressure in a point-to-plane configuration with a dielectric layer in the path of the discharge. First, the dielectric layer is placed on the cathode plane and we study the influence of the permittivity and thickness of the dielectric on the positive streamer discharge dynamics and the dielectric surface charging. We show that the velocity of the surface discharge on the dielectric surface depends on the capacitance of the dielectric layer and decreases as this capacitance increases. Conversely, the amount of positive surface charge deposited by the positive surface discharge on the dielectric surface is not directly related to the value of the capacitance of the dielectric layer. However, the amount of surface charge deposited increases as the capacitance of the dielectric layer increases. Second, the dielectric layer is placed in the air gap as an obstacle for the propagation of the first streamer discharge ignited at the point electrode. In this case, after the impact on the dielectric, the first discharge spreads along the upper dielectric surface and we show that, depending on the location of the dielectric layer, its permittivity, its thickness and its opacity to radiation, a second discharge may reignite or not below the dielectric layer. During the discharge dynamics, positive charges are deposited on the upper surface of the dielectric and negative charges are deposited on its bottom surface. For all conditions studied in this work, we show that surface charge deposition on both faces of the dielectric layer has a small influence on the discharge reignition below the dielectric layer. Finally, with two closely spaced dielectric layers in the path of the discharge, a series of spreading/reignition for each dielectric layer is observed.