Streamer, glow, arc and spark mode of atmospheric pressure pin-pin discharge

Pin-pin discharge between bare electrodes is one of the most classic and simplest discharge generated under atmospheric air, and it has widely applications depending on its various discharge modes, such as streamer discharge in ozone generation, glow discharge in elemental analysis, and spark discharge in nitrogen fixation. In this study, we controlled the pin-pin discharge transiting from streamer mode, to glow mode and arc mode, by matching a group of resistor and capacitor under the excitation of AC high- voltage. Besides, the spark mode of pin-pin discharge was also generated under the excitation of nanosecond pulse. The breakdown and evolution process of discharge were investigated by ICCD and streak camera. It is found that discharge mode of glow, arc or spark are all transformation from the initial streamer. The fast breakdown of initial streamer discharge is about 1.25 ns, and there is a bright cathode spot existed before the discharge transition. Last but not least, the electron density, excitation temperature, vibrational temperature, rotational temperature are diagnosed to understand the characteristics of various discharge modes.