A Simple Model for the Effects of External Ultraviolet Irradiation on Surface Dielectric Barrier Discharges

This study describes the development of a simple model to reproduce the effects of external ultraviolet (UV) irradiation on the discharge process of a surface dielectric barrier discharge (DBD). The effects of UV irradiation on microdischarge behaviors have long been observed experimentally, and various theories have been proposed to explain these phenomena. In this study, assuming that the UV irradiation causes the desorption of electrons weakly adsorbed on dielectric surfaces, we develop a model that incorporates the electron flux at the plasma-surface interface as a key parameter. The model is developed for a fluid-based plasma simulation to investigate the spatiotemporal evolution of charged particles and electric field during the formation of streamer structures in surface DBDs under atmospheric-pressure air conditions. The results show that as the electron desorption flux from the dielectric surface increases, the streamer formation occurs earlier. However, once the flux exceeds a certain threshold and the electric field shielding becomes non-negligible due to the negative ions which are formed through the attachment of desorbed electrons to neutral particles, the streamer formation is delayed instead. This trend disappears when the streamer initiation point becomes closer to the voltage-applied electrode as the voltage rise rate increases, suggesting that the spatiotemporal scale of streamer formation is one of the key factors on the sensitivity to the UV irradiation.