LAUSR

We perform a systematic numerical investigation of the nanosecond-pulsed surface dielectric-barrier-discharge evolution under different electrode polarities. For both positive and negative electrode polarities, two discharge strokes take place corresponding to the leading edge and the trailing edge of the nanosecond voltage pulse. During the first discharge stroke, the positive streamer propagates along the dielectric surface accompanying a thin plasma sheath layer, while the negative streamer stays attached to the dielectric surface. The resultant propagation velocity of the positive streamer is found to be faster than that of the negative streamer. During the second discharge stroke, a plasma sheath layer forms between the negative streamer and the dielectric surface due to the electrons drifting away from the near-surface region, while the sheath layer between the positive streamer and the dielectric surface fades away due to the electrons drifting toward the dielectric surface. For both positive and negative electrode polarities, it is revealed that a strong downstream body force is generated when the plasma sheath layer exists, due to the high net charge density and strong electric field in the near-surface sheath layer.