Precise determination of lightning plasma parameters based on the collisional-radiative model

Fine spectrum of lightning have been simulated by collisional-radiative model (CRM), and the radiation of core channel is mainly dominated by N II ion. The line-intensitiesof N II dependent on electron temperature (Te) and electron density (ne) were obtained. And it is found that the intensity proportion of 500.52 nm in the 500.5 nm multiple spectral lines and that of 567.96 nm in 568.0 nm one, i.e., I(500.52nm)/ I(500.5multiple) and I(567.96nm)/ I(568.0multiple), tend to stabilize in the Te-ne variation space, which is an inherent physical property that can be applied in determining the experimental intensity of characteristic line from the total intensity of overlapped lines. Through accurately matching the theoretical intensityratio with the experimental one, e.g., I(500.52nm)/ I(444.70nm) and I(567.96nm)/ I(444.70nm), an intersection of contours of line-intensity ratios in the two-dimensional plane of Te-ne is derived, and then, the Te and ne in lightning channel were diagnosed simultaneously. Precise spectral analysis method and plasma diagnostic technique are the basis of researching the transmission characteristics of lightning discharge, this work also has application value in articially triggered lightning, laser-guided lightning, arc discharge, etc.