The evolution of N($^4$S) species produced by filamentary streamer discharge was investigated by two-photon absorption laser-induced fluorescence technique. A triggered single streamer filament was periodically produced in pure nitrogen at pressures of 20, 50, 100 and 200\,torr, and N($^4$S) species were monitored in the centre of the discharge gap during the streamer formation, decay and afterglow. Under all of the investigated pressures, the population maxima of nitrogen atoms were observed in a microsecond timescale; i.e. well after the extinction of the streamer event. The concentration of nitrogen atoms increased with pressure. The maximum N($^4$S) concentration measured at 20\,torr was about $10^{13}$\,cm$^{-3}$, while it exceeded $10^{15}$\,cm$^{-3}$ at 200\,torr. After reaching maxima, atomic densities exhibit hyperbolic decay, which was followed up to the post-discharge time of 0.5\,ms. a#13; Our results show that only a small part of N($^4$S) is produced during the streamer transit or within 200\,ns after the transit (20\,--\,25\,\% increase with respect to the background density), while the most of nitrogen atoms are produced during the streamer channel decay in timescales from units to several tens of microseconds.

中文翻译：

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在氮气流光条件下产生的 N(4S) 原子的演化：减压下的时间分辨 TALIF 研究

采用双光子吸收激光诱导荧光技术研究了由丝状流光放电产生的N($^4$S)物种的演化。在 20、50、100 和 200 乇的压力下，在纯氮气中周期性地产生触发的单流光丝，在流光形成、衰变过程中，在放电间隙的中心监测到 N($^4$S) 物种和余辉。在所有研究的压力下，在微秒时间尺度内观察到氮原子的最大数量；即在流光事件灭绝之后。氮原子的浓度随压力增加。在 20\,torr 处测得的最大 N($^4$S) 浓度约为 $10^{13}$\,cm$^{-3}$，而超过 $10^{15}$\,cm$^ {-3}$ 200\,torr。达到最大值后，原子密度表现出双曲线衰减，其后放电时间为 0.5\,ms。#13; 我们的结果表明，在流光过境期间或过境后 200\,ns 内仅产生了一小部分 N($^4$S) (20\,--\,25\,\% 相对于背景密度），而大多数氮原子是在流光通道衰减期间产生的，时间尺度从单位到几十微秒。