Observations of the Breakthrough Phase of Attachment Process in Laboratory Long Sparks

摘要

High-speed video frames and discharge current records of 34 long laboratory sparks were examined. Two consecutive frames of the breakthrough phase, depicting the evolution of the common streamer zone, were obtained in five events, all presented in this study. Two types of luminous structures were observed inside the common streamer zone just before the return stroke phase: the floating luminous segment and the luminous channel linking the opposite polarity leaders. The luminous structure served as a selected route for the return stroke channel. These results demonstrate that the transformation of high-impedance common streamer zone into a hot plasma channel may involve two main features: the common streamer zone shrinking and the dominant development of the selected route.

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