Computational investigation on dynamics of atmospheric pressure air discharge excited by a twin needle-plate electrode configuration

The large-scale low temperature plasma produced by atmospheric pressure discharge utilizing an array needle-plate electrode design has promising future applications in a variety of industries. Improving the scale and uniformity of plasma requires a thorough investigation of the interactions between needle discharges. For that purpose, a two-dimensional (2D) computational analysis of the interaction of two concurrently propagating air discharges created by a twin needle-plate electrode design is presented in the paper. Investigations are also conducted on the effect of needle spacing, pulsed peak voltage, and pulse polarity. Immediately after ignition, two identical discharges move in the same direction toward the plane electrode. The propagation route is a curve with tight needle-to-needle spacing, which is ascribed to competition between electrostatic repulsion and photoionization-induced attraction. Larger needle spacing, higher peak voltage, or negative polarity all can increase the plasma area on the plate electrode. Additionally, reducing the distance between needles or raising the pulsed peak voltage is an effective way to improve the spatial homogeneity of the discharge array. Positive voltage pulses cause a more homogeneous discharge than negative voltage pulses.