LAUSR

The effect of flowing air on dielectric barrier discharge excited by alternating voltage was investigated by high-speed video analysis and electrical measurements. The discharge was still in filamentary mode in flowing air, and the space-time distribution of filaments was changed by airflow. With the increase in airflow velocity, the space-time distribution of discharge filaments shown in top view images went through four phases, that is, spot-like distribution, line-like distribution, cotton-like distribution, and stripe-like distribution. Accordingly, the motion and morphology of discharge filaments shown in side view images also presented four phases: remaining still and straight between adjacent cycles, moving and bending downstream, almost remaining still and straight between adjacent cycles, and moving and bending downstream again. Different motions of filaments were considered to be the reason for the changed distribution of filaments in flowing air. In addition, the intensity of discharge in flowing air was enhanced by increasing the gas gap and discharge frequency. At high discharge current, larger airflow velocity was needed to reach phase transition. The changed distribution of micro-discharge remnants in flowing air can be responsible for the phase transition. Micro-discharge remnants redistributed during the time interval of adjacent half-cycle discharges, under the action of various forces, such as electric field force, drag force, repulsive force, electrostatic coupling force, and trap binding force. The changed position of micro-discharge remnants led to the complex motions of discharge filaments and further resulted in the changed space-time distribution of filaments.