传输线模式与地闪回击电流速度

本文通过分析闪电通道中电离气体的宏观特性，提出闪电回击通道中电流的传输速度近似地等于光速的观点。认为回击锋面只是电流通过后被加速离子间的碰撞所引起的发光及电子雪崩区域的前沿，用光学方法测量的回击速度是其前沿的推进速度。由此出发，并考虑到镜像法的局限性，对闪电回击模式进行了某些改进。由新模型所计算的电场波形及峰值更接近于实际测量结果；其高频段的近似公式可以很好说明Fieux（1978），Djebari（1981）在法国及Weidman（1986）在美国所进行的人工触发闪电实验中测到的电场峰值与电流峰值的关系。

THE TRANSMISSION LINE MODEL AND CURRENT VELOCITY OF LIGHTNING RETURN STROKES

By analyzing the character of ionized gas in lightning channel, a new idea is raised . It is inferred that the velocity of current propagation along the channel is approximately equals to the velocity of light, and the return front or the streamer front is only the initial front of electron avalache caused by collision between ions accelerated by the current, and the return stroke velocity is the same as that of initial front. Based on this new opinion , an improved transmission line model of lightning return strokes is proposed. Results computed by the model show that: (i) The wave form and it's peak value of simulated field are in good agreement with that of electric field observations. (ii)Using the approximate expression for high frequency, the relation between peak amplitude of field and current obtained from artifcial triggering lightning experiments (Fieux, 1978; Djebari, 1981) and natural lightning struck to high metal structure (Weidman, 1986) can be well explained.