Evolution Processes of Nanosecond Pulsed Dielectric Barrier Discharge by Spatiotemporal Resolved Spectra in Needle-Plate Electrode Configuration

Abstract

As an effective method to optimize the ionization efficiency, [1] high voltage nanosecond pulsed discharge (NPD) has become an emerging technology for the production of nonthermal plasma at atmospheric pressure. Besides the unique advantages in the applications, the gas rapid breakdown mechanism, the discharge mode transition, and the physicochemical processes in NPD are also very significance for the fast pulse voltage. In our work, high resolution temporal-spatial spectra and images are employed to investigate the rapid breakdown mechanism and dynamical evolution process of high-voltage nanosecond pulsed dielectric barrier discharge under needle-plate electrode configuration at atmospheric air. Evolution dynamic processes in a discharge pulse are observed by one-shot ICCD images. There are three main stages in NPD are distinguished, which are the streamer breakdown from needle tip to plate electrode, the regime transition from streamer to diffuse, and the propagation of surface discharge on the plate electrode surface. The temporal-spatial distributions of the emission intensities of N2 (C³∏u→ B³∏g) and N2⁺ (B²∑u⁺→ X²∑g⁺) are investigated and the reduced electric field (E/N) can be calculated by the intensity ratio from the first negative systems of nitrogen ion and second positive systems of nitrogen molecular. It is found the spectra of N2⁺ (B²∑u⁺→ X²∑g⁺) are mainly emitted from the region near the needle tip in the initial period of the breakdown process. The electrical field is maximum on the edge of the needle electrode at the initial time, and decreases with the increase of distance from the needle. After the volume discharge is extinguished at 35–40 ns, an obvious increase of the electrical field near the surface of the dielectric plate appears, which drives the surface discharge propagating to the periphery along the dielectric plate.