The object of this study is the investigation of spark discharges ignited by unipolar positive rectangular HV pulses with 200ps rise time and (15±2)kV amplitude with 3ns duration (FWHM) in synthetic air in a 1.2mm pin-to-pin gap (tungsten electrodes) at atmospheric pressure. The discharge development was recorded by synchronised iCCD and streak camera measurements in single-shot operation revealing a two-stage propagation mode. The discharge started with a fast initial breakdown across the entire gap (~10mm/ns) during the HV slope followed by a much slower (~0.1mm/ns) propagation originating from both electrodes towards the gap centre. The combination of high-resolution diagnostics with numerical modelling indicated that the initial breakdown phase is caused by the rapid increase of electric field strength during the steep HV slope, which leads to the simultaneous fast propagation of a positive and a negative streamer.

中文翻译：

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由具有亚纳秒上升时间的高压脉冲驱动的短间隙火花放电中的双传播模式

本研究的目的是研究由上升时间为 200ps、幅度为 (15±2)kV、持续时间 (FWHM) 为 3ns 的单极正矩形高压脉冲在 1.2mm 针对针间隙中点燃的火花放电。钨电极）在大气压下。放电发展由同步 iCCD 和条纹相机测量记录在单次操作中，揭示了两阶段传播模式。放电开始于 HV 斜率期间整个间隙 (~10mm/ns) 的快速初始击穿，然后是从两个电极到间隙中心的更慢 (~0.1mm/ns) 传播。高分辨率诊断与数值模型的结合表明，初始击穿阶段是由陡峭的 HV 斜坡期间电场强度的快速增加引起的，