Particle Simulation of Positive Streamer Discharges on Surface of DC Transmission Conductors With Coating Materials

Streamer discharges occurring on bare and coated conductors are investigated, respectively, by means of 2-D particle-in-cell (PIC)/Monte Carlo collision simulations. The evolutions of streamer discharges and the involved electric fields, electron densities, and propagation velocities have been demonstrated. The electron energy probability functions (EEPFs) reveal the nonequilibrium properties of streamer plasmas. Moreover, the effects of relative permittivity, the thickness of coating layers, and the presence of protrusions upon the formation of streamer discharges have been studied. It is shown that streamer discharges can be inhibited effectively by the application of coating materials, which have the largest effect on the initial stage of the discharge. The electron density, electric field strength, and propagation velocity of the streamers can be reduced significantly. The results provide insights into fundamental physics governing the streamer discharge and may find promising applications in the protection of direct current transmission lines.