Study On Spectral Diagnostic Parameters Of Artificially Triggered Lightning Channels

Artificially triggered lightning is a kind of discharge phenomenon that artificially causes atmospheric breakdown with the help of rocket leads.This discharge test can be tested at a fixed point and is closest to real natural lightning.Artificial triggered lightning can test the lightning protection performance of power and electronic devices,and provide important lightning pulse overvoltage reference data for the development of lightning protection equipment.In addition,artificial triggered lightning is more effective in ensuring the personal safety of researchers than natural lightning.Therefore,these characteristics make artificial triggered lightning play a unique and constructive role in social development.Artificial triggered lightning ionizes the atmosphere into a lightning discharge channel plasma composed of nitrogen and oxygen neutral atoms,ions,and electrons.Various spectral diagnostic parameters such as electron density(ne),electron temperature(Te),and ion abundance(η)in plasma can be used to calculate the current of lightning channels and provide important data such as pulse overvoltage for lightning protection.Therefore,it is necessary to study the spectral parameters of artificially triggered lightning plasma.The current work mainly involves the following aspects of research:(1)This thesis points out that lightning can use collision radiation model and local thermodynamic equilibrium model to describe the properties of its discharge plasma,because the electron density of lightning plasma is in the cross range of the appropriate electron density order of magnitude of the two models,and the lightning discharge meets the characterization results of plasma parameters under the two models.(2)With the help of collision radiation model and Flexible Atomic Code(FAC),this article discovered the relationship between the intensity ratio of N Ⅱ ion spectral lines and electron temperature,as well as the dependence of the intensity ratio of N Ⅰand N Ⅱ spectral lines on electron density and electron temperature.Then,specific N Ⅰand N Ⅱ spectral lines are selected,and the relationship between line intensity ratio,electron temperature,and electron density is applied to diagnose the spectral parameters of artificially triggered lightning channel plasma(electron temperature,electron density,etc.).(3)This thesis used any combination of characteristic spectral lines to diagnose the range of electron density values from 1016-1020 cm-3.However,these data are too large and scattered to be used as measurement results.In order to overcame this diagnostic difficulty,this thesis proposed the degree of accordance:the degree of coincidence between a group of spectral line combination diagnoses of Te,ne regions{Te-ne}m and another group of regions {Te-ne}n,represented by the overlapping area.The degree of accordance reflects the same diagnostic information obtained from different spectral line combinations,which indicates that the overlapping area is closer to the true state of the plasma.Finally,the electron density and electron temperature are diagnosed as(2.65±1.75)×1017 cm-3 and 25200±1000K based on this method,respectively.(4)Based on the above diagnosis of electron temperature and electron density,first of all,this thesis used the Boltzmann distribution law to study the partition functions of different atomic ions.The results show that the partition functions of neutral atoms do not need to be modified because they are not affected by electric charges.Secondly,with the aid of the calculation of the partition function,the abundance and number density of the atomic ions in the artificially triggered lightning channel were also preliminarily studied.The current results are in good agreement with the measurement results of existing natural lightning.