Study on the effect of floating extra dielectric plate on air dielectric barrier discharge

The addition of a floating extra dielectric plate to the gas gap of a conventional parallel plate dielectric barrier discharge (DBD) has been reported as an effective method to increase the volume and effective area of the action of homogeneous atmospheric pressure nonequilibrium plasma. However, the discharge mechanism is still not clear. In this paper, we introduced a floating additional dielectric plate into the gas gap of a conventional dielectric barrier discharge (DBD). We studied the dynamic process of the discharge after the addition of the floating dielectric plate and measured the temporal resolution of the electric field in the gas gap under these conditions. We have investigated the effect of the floating extra dielectric plate on the discharge uniformity and the change of discharge mode with the plate position as well as different pulse repetition frequencies (PRFs). The results indicate that the addition of the floating extra dielectric plate significantly improves plasma uniformity. The study found that the floating extra dielectric plate not only improves discharge uniformity across all PRF conditions but also causes the discharges in different gas gaps to operate in distinct modes when the upper and lower gaps have unequal widths. Furthermore, the plasma consistently forms preferentially in the gas gap near the high-voltage electrode. Using the E-FISH technique, we measured the time-resolved curves of the electric field in each gas gap. The problem of the discharge order of the gas gap was explained from the perspective of residual charge distribution in combination with the electric field.