Simulations of Nonthermal Electrical Discharges in Air Over Solid Insulating Barrier

The propagation of streamer discharges in air in strongly divergent electric fields and their interaction with solid dielectric barrier inserted between the energized electrodes are analyzed by means of computer simulations. The model used is based on a hydrodynamic approximation of the transport of charge carriers in both media (electrons and ions in air, and electrons and holes in solid) coupled with Poisson's equation for the electric field and accounts for charge injection and accumulation on gas-solid interfaces. The model is solved numerically utilizing customized finite-element formulation employing streamline upwind Petrov-Galerking method for stabilizing solution of drift-diffusion equations for fluxes of charged species. The results of the simulations performed for conditions of earlier reported experimental studies are presented and discussed. It is shown that streamer discharges may develop in different modes depending upon particular conditions and are capable of propagating along solid surfaces in the direction transverse to the applied field. In the latter case, their progress is fully controlled by space and surface charges accumulated within discharge plasma and on gas-solid interfaces. The developed calculation method creates a base for considering more complicated and practically oriented tasks.