Gas flow influence on streamer-to-leader transition in surface barrier discharge in air at atmospheric pressure

The experimental results on study of a sinusoidal surface barrier discharge (SBD) in airflow at different velocities are presented. Influence of gas flow velocity and its orientation on plasma structure of SBD is established and the conditions providing transition of SBD from the streamer mode to the mode with surface leaders (SL) are found out as well. It is shown the formation of the SL in SBD happens owing to thermal effects associated with a local gas heating in both the bright current spots disposed at the sharp edge of high-voltage electrode and thin current channels (streamers) originated from these spots. It was revealed that gas flow with a high velocity directed against the propagation of surface streamers leads to destruction of the bright anode spots and elimination of the SL (but not the streamers) on a barrier surface. However the gas flow with the same velocity but opposite direction leads to regular disposition of the bright current spots at the edge of high-voltage electrode and regular spatial structure of the thin current channels (streamers and leaders) originated from the current spots. It was found out that gas flow of any orientation leads to diminishing the gas temperature in the plasma channels compared to that in SBD in gas at rest. (paper)