闪电放电通道等离子体成分及相关特性的研究

以无狭缝摄谱仪获得了青海和西藏地区的云对地闪电回击过程的光谱，依据谱线波长和相对强度等信息，结合等离子体相关理论，得到了放电通道温度和电子密度；在此基础上，根据Saha方程、电荷守恒方程和粒子数守恒方程计算了闪电通道主要元素各级电离的离子数密度，进而得到通道质量密度、压强及平均电离度, 并分析了不同强度闪电放电通道的电离度、粒子数密度及其分布特征。结果表明：回击通道接近于完全电离，一次电离离子占主要地位，且NⅡ离子数密度最高；不同强度的闪电放电通道中，NⅡ和OⅡ离子的相对浓度值变化不大；计算过程中考虑带电离子间库仑相互作用以后，原子电离能的计算值降低，中性原子以及一次电离离子数密度的计算值变小，高次电离离子数密度的计算值变大。

The Study on the Characteristics and Particle Densities of Lightning Discharge Plasma

According to the wavelengths, relative intensities and transition parameters of lines in cloud-to-ground lightning spectra obtained by a slit-less spectrograph in Qinghai province and Xizang municipality, and by theoretical calculations of plasma, the average temperature and electron density for individual lightning discharge channel were calculated, and then, using Saha equations, electric charge conservation equations and particle conservation equations, the particle densities of every ionized-state, the mass density, pressure and the average ionization degree were obtained. Moreover, the average ionization degree and characteristics of particle distributions in each lightning discharge channel were analyzed. Local thermodynamic equilibrium and an optically thin emitting gas were assumed in the calculations. The result shows that the characteristics of lightning discharge plasma have strong relationships with lightning intensities. For a certain return stroke channel, both temperatures and electron densities of different positions show tiny trend of falling away with increasing height along the discharge channel. Lightning channels are almost completely ionized, and the first ionized particles occupy the main station while NⅡ has the highest particle density. On the other hand, the relative concentrations of NⅡ and OⅡ are near a constant in lightning channels with different intensities. Generally speaking, the more intense the lightning discharge, the higher are the values of channel temperature, electron density and relative concentrations of highly ionized particles, but the lower the concentration of the neutral atoms. After considering the Coulomb interactions between positive and negative particles in the calculations, the results of ionization energies decrease, and the particle densities of atoms and first ionized ions become low while high-ionized ions become high. At a temperature of 28 000 K, the pressure of the discharge channel due to electrons, atoms and ions is about 10 atmospheric pressure, and it changes for different lightning stroke with different intensity. The mass density of channel is lower and changes from 0.01 to 0.1 compared to the mass density of air at standard temperature and pressure (STP).