Experimental study of streamers in pure N\u3csub\u3e2\u3c/sub\u3e and N\u3csub\u3e2\u3c/sub\u3e/O\u3csub\u3e2\u3c/sub\u3e mixtures and a ≈13 cm gap

Empirical data on streamer formation and propagation in near-atmospheric pressure N2 and N2/O2mixtures are presented. The data were obtained primarily from high-speed, high-sensitivity shutter and streak photography of streamers produced in a ≈13 cm gap. The streamer propagation velocity as a function of applied voltage, polarity, total pressure, and O2 concentration are provided. In addition, information on streamer bifurcation, and streamer shape and size is included. The breakdown process has two phases: a fast phase featuring the propagation of streamers, and much slower phase involving the heating of the gas to form the spark channel. Also we found that the addition of O2 significantly alters the streamer characteristics and behavior, indicating that photoionization processes play an important role