Spatio-temporal breakdown in surface DBDs: evidence of collective effect

This paper presents an experimental investigation of the plasma ignition in a dielectric barrier surface discharge in air at atmospheric pressure. CCD pictures of the discharge are compared with electrical measurements. A detailed study of the current peaks during the positive half period of the applied voltage has been performed. CCD pictures of single discharges events have been taken. They show synchronous breakdowns of plasma filaments, corresponding to current intensities of several amperes. It is shown that each plasma filament transfers a current of about 40 mA. The influence of adsorbed electrons on the synchronization of the plasma filaments is discussed. The length of the filaments increases during the half period and can be plotted as a linear function of the difference between applied and ignition voltages. The differences between the discharges of positive and negative half periods are presented. The discharges of the negative half period consist of diffuse spots of shorter lengths and are characterized by low currents (several milliamperes), and individual breakdowns.