Application of the Gray-Level Standard Deviation in the Analysis of the Uniformity of DBD Caused by the Rotary Electrode

As the uniform dielectric barrier discharges (DBDs) consisted by a large number of microdischarges in a long timescale may meet the needs of industrial application, the evaluation of the uniformity of DBDs used in the industry is different from that in the laboratory. In this paper, a digital image processing method presented in our previous paper is used to describe the uniformity of DBDs caused by the rotary plate electrode in a long timescale. Whether or not the electrode is rotated, with an increase in time, the gray-level standard deviation Std of the discharge image gradually decreases and reaches its stable value at last. The electrode rotation results in reducing the time constant required to reach a steady state for the gray-level distribution. With an increase in rotary speed, Std gradually decreases and reaches its stable values at last. This means that the electrode rotation improves the uniformity of the discharge. The reason produced the aforementioned phenomena should come from the relative motion of the accumulated charge on the dielectric surface and microdischarge remnants in the volume.