Rotating Concentric Spot-Ring Pattern in a Dielectric Barrier Discharge System

The rotating concentric spot-ring pattern in a dielectric barrier discharge is investigated in different time scales. From a series of frames with 2-ms exposure taken by a high-speed video camera, it is found that the two rings rotate with different rotating periods and the rotating direction of the inner ring changes with time. The instantaneous image with 10-μs exposure shows the appearance of the surface discharge besides the volume discharge. The change of the orientation of the surface discharge leads to the size of the spot in outer ring changing with rotation.