人工触发闪电通道的导电特性

The Electrical Conductivity of Triggered Lightning Channel

用光学多道分析仪(OMA)获得了山东地区人工触发闪电回击过程的发射光谱。与以往的自然闪电光谱相比,除了氮、氧的中性原子及一次电离的离子谱和Hα谱线外,这次人工触发闪电的光谱还记录到了微量元素ArⅠ602.5nm及ArⅡ666.5nm的谱线。在局部热力学平衡近似下,根据光谱线的相对强度等参量,计算了闪电通道等离子体的温度;利用Hα线的Stark加宽、通过半经验方法获得了闪电通道的电子密度;首次结合等离子体理论得到了闪电通道的电导率,并由此讨论了通道的导电特性,分析了通道电导率与回击电流之间的相关性,为进一步计算回击电流提供了参考数据。结果分析得出:闪电通道是良导体,电子是通道电流的主要载体;一般情况下,人工触发闪电的通道亮度比自然闪电通道大,而通道回击电流小于自然闪电。

Spectra of return strokes for artificial triggered lightning were obtained by optical multi-channel analyzer （OMA） in Shandong region. Compared with previous spectra of natural lightning, additional lines of ArⅠ 602. 5 nm and Ar Ⅱ 666. 5 nm were observed. Under the model of local thermodynamic equilibrium, electronic temperatures of the lightning channel plasma were obtained according to the relative line intensities. Meanwhile, with semi-empirical method the electron density was obtained by Ha line Stark broadening. In combination with plasma theory, electrical conductivity of the lightning channel has been calculated for the first time, and the characteristic of conductivity for lightning channel was also discussed. The relation between the electrical conductivity of channel and the return stroke current was analyzed, providing reference data for further work on computing return stroke current. Results show that the lightning channel is a good conductor, and electrons are the main carrier of channel current. The brightness of artificial triggered lightning channel is usually higher than that of natural lightning, and its current is smaller than that of the natural lightning.