The Correlation Between Conduction Characteristics Of Lightning Dart Leader Channel And Current Transmission Of Return Stroke Discharge

The physical characteristics of lightning discharge channels have always been the subject of concern in the field of lightning protection.The lightning process mainly includes the development of leader and the return stroke discharge.The leader,as the initial stage of the development of lightning,provides the discharge channel for the return stroke.Therefore,it is of great significance to study the correlation between the conduction characteristics of the lightning leader channel and the intensity of return discharge to reveal the current transmission characteristics.In this paper,the spectral information of natural lightning obtained by slitless grating spectrograph in Qinghai is used to calculate the physical properties of the lightning channel,such as temperature,electron density,electrical conductivity and etc.The dart leader channel and its subsequent return stoke channel are analysed by quantitative spectral.By analyzing the distribution characteristics of the physical parameters of the dart leader and the corresponding subsequent return stroke,it is found that the distribution of the conductivity along the height of the return stroke channel is similar to that of the corresponding dart leader channel,and the charge density at the tip of the leader and the bottom of the return stroke channel shows a good linear correlation.The charge density in the dart leader channel is an important factor affecting the intensity of the current of return stroke discharge.It can be inferred from the spectral characteristics that the charge density at the tip of the leader is positively correlated with the current intensity at the bottom of the return stroke channel.In the study of the calculation of electrical conductivity in the lightning plasma,it is found that different results can be obtained by using different transport equations.Combined with the theory of air plasma transport,the electrical conductivity of two groups of natural lightning is studied by using two different calculation methods.Through the analysis of the calculation results,it is found that the electrical conductivity of the lightning core channel obtained by the two methods is 10~4S/m in order of magnitude,and the electrical conductivity in the same channel decreases or remains basically unchanged with the increase of channel height.It is more reasonable to calculate the conductivity of the lightning core channel by using the transport cross section of the excited state of electrons.