Pattern formation in dielectric barrier discharge in air

Summary form only given. Formations of regular pattern by filaments in dielectric barrier discharge have been studied in past two decades. Many regular patterns, such as hexagon, stripe, square, spiral, concentric-ring patterns, have been observed in inertia gas, nitrogen or the mixture of inertia gas and other gas. However there is no report about the observation of regular pattern in dielectric barrier discharge in air. Here we'll report experimental observation of hexagon, square and super hexagon patterns in dielectric barrier discharge in air near atmospheric pressure by using water electrodes. Hexagon pattern appears when the gas pressure is in the range of 0.1-1 atm. Whereas square and superhexagon patterns exist in small parameter ranges of gas pressure and gas gap width. The spatiotemporal dynamics differs from that in dielectric barrier discharge in Ar although the bifurcation scenario from hexagon to square, then to superhexagon is similar to that in Ar discharge. The optical emission spectrum is used to measure the vibration temperature of the discharge