Abstract

The results of investigations of a spark discharge in air in the gap between the tip (anode) and a 1.5‑mm-long plane are presented. It is shown that, after breakdown, the discharge develops in the form of a beam of individual microchannels that close the discharge gap, then, after 20–30 ns, a continuous outer boundary of the channel forms and its radial expansion begins. The electron concentration at this moment reaches its maximum value at the level of 2 × 10¹⁹ cm^—3. It was found that, starting from 60 ns, a cylindrical shock wave departs from the channel boundary. With time, the difference in the radii of the shock wave and the channel increases, resulting in the formation of a radial structure in the form of a highly conductive internal channel, separated from the shock wave by an intermediate shell. A computational and theoretical model is proposed to describe the dynamics of the spark channel expansion from the moment of the formation of a solid outer boundary, and a satisfactory agreement between the calculations and experimental data is obtained.

中文翻译：

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径向扩展阶段“尖端（阳极）-平面”几何形状中空气中微结构火花通道的动力学研究

摘要

给出了在尖端（阳极）和1.5毫米长的平面之间的间隙中空气中的火花放电的研究结果。结果表明，击穿后，放电以单个微通道束的形式发展，该束微通道关闭了放电间隙，然后在20–30 ns后，形成了通道的连续外部边界，并开始了径向扩展。此时的电子浓度在2×10 ¹⁹ cm ^-3的水平达​​到最大值。发现从60 ns开始，圆柱形冲击波从通道边界偏离。随着时间的流逝，冲击波和通道的半径之差增加，导致形成具有高导电性的内部通道形式的径向结构，该径向结构通过中间壳体与冲击波分开。提出了一个计算和理论模型来描述从形成固体外边界时刻起火花通道膨胀的动力学，并且在计算和实验数据之间获得了令人满意的一致性。