闪电放电过程的近红外光谱及温度沿放电通道的演化特征

利用无狭缝红外光谱仪, 获得山东地区闪电放电过程760~970 nm范围的近红外光谱.光谱特征分析得出: 近红外光谱主要是峰值电流之后、放电后期的辐射, 谱线主要是中性原子的贡献.首次讨论了放电后期的通道温度和光谱总强度沿放电通道的演化特征.结果表明, 通道温度较回击电流上升至峰值阶段降低, 约为16000 K; 不同闪电的光谱结构、通道温度差异不大, 反映了放电等离子体复合阶段的特性; 地闪通道的温度和光谱总强度沿放电通道略呈单调变化趋势, 接地点附近最大; 云闪通道的温度和光谱总强度沿放电通道非单调变化, 在通道的拐弯、分叉以及结点附近发生突变.

Evolution characteristic of near-infrared spectra and temperature along the stroke channel of lightning discharge process

The near-infrared spectra in the range of 760~970 nm for lightning discharge processes are obtained by using a slit-less infrared spectrograph in Shandong area of China. The spectra analysis shows that the near-infrared spectrum is mainly the radiation from the later stage after the discharge peak current, and the lines of neutral nitrogen and oxygen atoms are the major components of the separation spectrum. Furthermore, the evolution characteristic of the channel temperature and the total intensity of spectra along the channel during near-infrared radiation are discussed for the first time. The results show that the channel temperature decreases to about 16000 K compared with the stage of return stroke current rising to peak; there is little difference for spectral structure and channel temperature of different lightning, which reflects the characteristics of plasma channel in the recombined phase; the channel temperature and the total intensity of spectra along the channel show a slight tendency of monotonic change for cloud-to-ground lightning, reaching the maximum near the ground; the variation is non-monotonic in cloud lightning, and the channel temperature and the total intensity of spectra are suddenly changed in the tortuous positions, branches and crunodes of the channel.