Electrical and optical characteristics of surface DBD in pure N2 and N2-NO mixtures

Summary form only given. Atmospheric-pressure, non-equilibrium plasmas produced by dielectric barrier discharge (DBD) are very attractive for various industrial applications (pollution control, sterilization, ozone generation, and surface modification) because of their low-cost, high operation speed and ability to operate without vacuum systems. The DBD can be easily produced either in volume or on surface by applying appropriate high voltage to electrodes separated by dielectric barrier(s). In this work we report on time resolved spectroscopic and electrical characteristics of Masuda type surface DBD fed by N₂ and N₂-NO mixtures. The DBD electrode consists of a alumina plate (0.62 mm thick) with 18 parallel nickel stripes (0.035 mm thick, 1 mm wide, 3 mm distance) as the discharge electrode and square-like induction electrode on the backside. The DBD was powered by modulated AC (5 kHz, up to 7 kV peak-to-peak) high voltage. The power density delivered to the discharge volume was controlled by combining appropriately the AC modulation/HV amplitude with the gas flow rate. Electrical measurements were performed using a fast digitizing oscilloscope. Optical measurements were performed by means fast photomultipliers which detected surface-averaged optical emission collected through the optical fibers, quartz optics and interfacial filters. We have registered emissions of four different electronic systems: N₂ ⁺(B²Sigma_u ⁺rarrX²Sigma_g ⁺) (1. NG) )first negativeN₂ ⁺(C³Pi_urarrB³Pi_g) second positive (2.PG), N₂ ⁺(C´´⁵Pi_urarrA´⁵Sigma_g ⁺) Herman infrared (HIR), NO-gamma(A²Sigma⁺rarrX²Pi). Finally, the O₃, NO/NO_x and N₂O analyzers were used to monitor stable dis- harge products. Temporal evolutions of observed emission systems induced by the discharge prove that observed emissions are produced by a) energetic discharge electrons through direct electron impact excitation/ionization of N₂ molecule (in the case N₂ 2.PG and N₂ ⁺ 1.NG bands), and b) N₂(A) metastable species through N₂(A)+N₂(A) energy pooling and N₂(A)+NO resonant energy transfer processes (in the case of N₂ HIR and NO-gamma bands). The energy efficiency of the NO conversion in the case of the N₂-NO mixture evidences the deNO_x process driven by nitrogen atoms produced close to the surface of the discharge electrode.