Dynamics and Kinetics of Laser-Filament Plasma in Strong External Electric Fields and Applications

Takashi Fujii ； Alexei Zhidkov ； Megumu Miki ； Kiyohiro Sugiyama ； Naohiko Goto ； Shuzo Eto ； Yuji Oishi ； Eiki Hotta ； Koshichi Nemoto

《Chinese Journal of Physics》 52卷1期PartII (2014/02) Pp. 440-464

https://doi.org/10.6122/CJP.52.440

並列摘要

Physics of atmospheric laser-induced filaments in strong electric fields provides us with good instruments for the distant study and control of atmospheric and industrial high voltage discharges and accompanying processes. Dynamics and kinetics of laser filaments in strong non-uniform electric fields are studied both theoretically and experimentally with the high temporal and spatial resolution. Among others, a considerable reduction of the breakdown potential was found and was attributed to a filament-induced leader. Two breakdown modes, fast and slow, were found in 0.4 MV positive dc-voltage discharges activated by filaments. In the fast mode with duration order of a few microseconds, the filament may acquire the electrode potential and temporarily maintain it, becoming a leader. The slow mode with its duration order of 1 ms appears with a considerably smaller voltage reduction when the leader decays before the secondary streamer. Long, about a half of microsecond, non-uniform corona UV burst is observed after the laser-filament plasma appears nearby an electrode biased (positively or negatively) slightly higher than the corona discharge threshold. The effects of electron runaway in positive high-voltage-impulse discharges were studied. Strong hard (ε ＞ 100 keV) x-rays being observed from impulse atmospheric discharges just before the breakdown were completely stopped with the use of the laser-filament plasma. Runaway electrons, generating such x-rays, disappear if the laser-filament plasma is ignited perpendicularly to the runaway nearby the positive electrode. These results are important to understand the filament physics, and also useful for the applications to laser triggered lightning, electric field measurement, protection of high-voltage facility and others.

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