The development of positive and negative streamers in a point-to-plane gap filled with air and nitrogen at various pressures (50–200 kPa) and voltages (8–25 kV) was studied. A four-channel intensified charge-coupled device (ICCD) and a streak-camera were used. Electrical parameters were measured with high resolution (10 GHz). An original method of measuring a displacement current caused by a streamer was applied. As was expected, positive streamer branches in nitrogen at low voltages and/or elevated pressures while a large-diameter streamer is formed in air. However, at high voltages or negative polarity, the large-diameter streamer is formed both in nitrogen and air in the entire pressure range. It was found that runaway electrons (REs) are generated in the very first picoseconds of gas ionisation near the pointed cathode. It was assumed that REs can be generated near the pointed anode and produce bremsstrahlung radiation due to a sharply inhomogeneous distribution of electrical potential. It was found that in the final stage of negative streamer development in air and nitrogen, the gas between the streamer front and the opposite electrode is ionised almost simultaneously in the entire volume when the streamer diameter is almost equal to the interelectrode gap.

中文翻译：

---

失控电子产生条件下，在急剧不均匀电场中的空气和氮气中的正负流光

研究了在不同压力（50-200 kPa）和电压（8-25 kV）下充满空气和氮气的点对面间隙中正负流光的发展。使用四通道增强电荷耦合器件（ICCD）和条纹相机。以高分辨率 (10 GHz) 测量电气参数。采用了测量流光引起的位移电流的独创方法。正如预期的那样，在低电压和/或高压下，正流光在氮气中分支，而在空气中形成大直径流光。然而，在高电压或负极性下，在整个压力范围内的氮气和空气中都会形成大直径流光。研究发现，在尖阴极附近气体电离的最初几皮秒内会产生失控电子（RE）。假设RE可以在尖头阳极附近产生，并由于电位的急剧不均匀分布而产生轫致辐射。研究发现，在空气和氮气中负流注发展的最后阶段，当流注直径几乎等于电极间间隙时，流注前部和相对电极之间的气体在整个体积中几乎同时电离。