CCD imaging of dielectric barrier discharges in air: Plasma self organization

Dielectric barrier discharges at atmospheric pressure are widely used for industrial applications. Here, the authors studied the streamers ignition and development in a surface discharge on one hand, and a point to plane discharge on the other hand. In both setups, the discharge is driven by a 50 Hz sinusoidal power supply, so the streamers ignitions are random. Measurements are made by electrical diagnostics and CCD imaging in dry air. In both cases, pictures show simultaneous ignitions of several filaments in a very short duration (40 ns). In the point to plane discharge, the plasma filaments spread over the surface in complex, branching patterns (Lichtenberg figures) whereas in the surface discharge they are all adjacent and parallel. The electrical and morphological properties of both discharges are compared and discussed.