Square Pattern In Dielectric Barrier Streamer Discharge In Ar/Air

The square pattern has been obtained for the first time in dielectric barrier Ar/Air discharge at atmospheric pressure by using the double water electrodes and its spatio-temporal dynamics is measured by optical method. The phase diagram of pattern types as a function of air concentration and applied voltage by fixing other parameters is given. Through the square pattern dynamics measurement, it is found that the square pattern is an interleaving of two square patterns, Filaments in each pattern discharge almost at the same time. The sequence of two patterns presence is changed alternately, that is, one pattern will appear at the second pulse of total pattern in this half cycle if it appears at first pulse in last half cycle. The stability of square pattern was studied by considering the interaction among the wall charges. The discharge moments of individual filament alternate from long one to short in the square pattern, which can been explained by using the breakdown and quench model through considering the wall discharge accumulated on the dielectric layers.In addition, the temporal characteristic of discharge in filament mode in Ar and the variation of discharge with the applied voltage are investigated .For example, the number of the current pulses and the charges transferring in half cycle increase with the applied voltage. The results show that the final discharge in the last half cycle decided the first breakdown in this half cycle by analyzing the sequence among three current pulses in a half cycle.