Simulation on atmospheric pressure barrier discharge with varying relative position between two wavy dielectric surfaces

As a popular approach to producing atmospheric pressure non-thermal plasma, dielectric barrier discharge (DBD) has been extensively used in various application fields. In this paper, DBD with wavy dielectric layers is numerically simulated in atmospheric pressure helium mixed with trace nitrogen based on a fluid model. With varying relative position (phase difference (Δφ)) of the wavy surfaces, there is a positive discharge and a negative discharge per voltage cycle, each of which consists of a pulse stage and a hump stage. For the pulse stage, maximal current increases with increasing Δφ. Results show that DBD with the wavy surfaces appears as discrete micro-discharges (MDs), which are self-organized to different patterns with varying Δφ. The MDs are vertical and uniformly-spaced with Δφ = 0, which are self-organized in pairs with Δφ = π/4. These MD pairs are merged into some bright wide MDs with Δφ = π/2. In addition, narrow MDs appear between tilted wide MDs with Δφ = 3π/4. With Δφ = π, the pattern is composed of wide and narrow MDs, which are vertical and appear alternately. To elucidate the formation mechanism of the patterns with different Δφ, temporal evolutions of electron density and electric field are investigated for the positive discharge. Moreover, surface charge on the wavy dielectric layers has also been compared with different Δφ.