Influence of a Rotating Electrode on the Uniformity of an Atmospheric Pressure Air Filamentary Barrier Discharge

Abstract

The uniform dielectric barrier discharges (DBD) consisting of numerous microdischarges in a long time‐scale may also meet the needs of industrial applications. In contrast to the glow DBDs, their uniformity is significantly influenced by the spatial distribution of microdischarges. In this paper, the streamers distribution in DBDs with rotating electrodes and the effects of the rotational speed on the discharge uniformity are investigated using a flow simulation and the SD of image gray levels, respectively. The simulation results show that the neutral gas flow caused by the electrode rotation has a great effect on the shape and length of the streamers. This has mainly contributed to the discharge remnant in the volume traveled by the neutral gas, which affects the discharge distribution. The SD of gray levels sharply decreases with an increase of the rotational speed, which indicates that the discharge uniformity can be effectively improved by the electrode rotation. When the rotational speed is over 3 000 rpm, the SD keeps almost constant, even with an increase of the applied voltage and frequency. It has similar characteristic as a uniform discharge.

Effect of rotating a dielectric barrier on discharge energy and uniformity in an atmospheric pressure air DBD

“…It is worth pointing out that the enhancement of the macroscopic uniformity of microdischarges is due to the superposition of microdischarge channels with different discharge cycles. The discharge images of a rotating dielectric barrier DBD show a similar uniform distribution to that of a rotating metal electrode DBD [31]. However, the former requires fewer cycles of microdischarge superposition (100 cycles in this work and 700 cycles in the paper [31]), indicating that rotating a dielectric barrier is more effective in improving the microdischarge uniformity.…”

“…Additionally, the introduction of airflow can influence the distribution of residual space particles and therefore change the location of subsequent discharges [29,30]. Moreover, it has been proved that rotating metal electrodes can cause rotating airflow, which improves the discharge energy and uniformity by affecting the spatial distribution of discharge residues [31][32][33]. Considering that surface charges can move with a dielectric barrier [34,35], rotating a dielectric plate instead of a metal one can not only shift discharge remnants by inducing airflow, but also alter the position of surface charges, which can further affect the plasma properties.…”

Effect of airflow on the discharge uniformity at different cycles in the repetitive unipolar nanosecond‐pulsed dielectric barrier discharge

“…To reveal the variation of discharge uniformity as a function of discharge cycle, we further present the standard deviation of the image gray levels in Figure 9. The formula for the calculation of the standard deviation of the image gray levels is as follows [ 56 ] : $$$\mathrm{SD}=\sqrt{\frac{1}{(M\times N)(M\times N-1)}\left[(M\times N)\sum _{x-0}^{M-1}\sum _{y-0}^{N-1}u{(x,y)}^{2}-{\left(\sum _{x-0}^{M-1}\sum _{y-0}^{N-2}u(x,y)\right)}^{2}\right]},$$$where M and N are the number of pixels in the horizontal and vertical directions of the image, respectively. u ( x , y ) is the distribution of the image gray levels.…”

“…To reveal the variation of discharge uniformity as a function of discharge cycle, we further present the standard deviation of the image gray levels in Figure 9. The formula for the calculation of the standard deviation of the image gray levels is as follows [56] :…”

Distribution and evolution of surface charges in nanosecond pulsed dielectric barrier discharge under the quiescent air and airflow

“…In digital image processing technology, the SD of image gray levels is a measure of the image contrast, a larger image gray level SD represents a higher contrast, corresponding to a higher surface charge density. The SD of image gray levels is calculated according to the following formula [50]:…”