LAUSR

The primary aims of this paper are to provide a better understanding of surface dielectric barrier discharge based on annular geometry and to investigate the effect of segmented grounding electrodes on their electrical and optical properties. To this end, four grounding electrode conditions are considered: 10-segment, 20-segment, and 30-segment ones as the experimental conditions, and an unsegmented (termed 0-segment) one as the control. A great number of current pulses with lower amplitudes are observed under the segmented conditions compared to the 0-segment condition. In the former case, the current pulse number and the peak value are observed to be inversely and directly proportional to the number of segments, respectively. However, the average currents corresponding to the various segmentations are observed to be nearly identical, and each of them is lower than that under the 0-segment condition. Secondly, the discharge uniformity under the 30-segment condition is observed to be better than under the 0-segment condition, because even though the discharge is usually concentrated at covered regions, it spreads spanwise to the adjacent uncovered regions as the number of segments is increased. Consequently, the airflow induced by spanwise-spread plasma extends the effective range of plasma action. Moreover, the Lissajous figures corresponding to the four conditions are ascertained to be approximately parallelogram-shaped. However, the slopes of the discharge phases are dependent on the voltage, as the variations of equivalent capacitance in dark and discharge phases are distinct. A higher amount of power is consumed under the 30-segment condition than under the 0-segment condition, although the maximum transported charge is much lower in the former case. Finally, in the quasi-sinusoidal external electric field distribution induced by the segmented grounding electrode, a slightly lower-than-average electric fields avoid the creation of obvious separated channels, while a moderate peak-to-peak difference of electric field improves the electric field distortions caused by existing micro-discharges. This phenomenon serves as a satisfactory explanation of the differences between the discharge channel developments and the plasma distributions under different conditions. Based on the obtained results, we conclude that the performance of discharge plasma can be improved by arranging the electrodes optimally.