The Research Of Lightning Channel Plasma Emission Spectra

Spectra of lightning return strokes in the range of 400～700 nm had been obtained by Slit-less spectrograph, and artificially triggered lightning return strokes spectra in the range of 560～670 nm had been obtained by optical multi-channel analyser (OMA).According to the relative intensities and transition parameters of lines, under the model of local thermodynamic equilibrium (LTE), temperatures of lightning channel have been calculated with multiple-line method. Simultaneously, electron density is also obtained by Saha equation. Analysing the changes of electron density and temperature with height of channel, the results show that the channel temperature and the electron density slightly decreases with increasing of height, but at some heights, the temperature and the electron density are greater. According to these ,we can infer that the changes of channel temperature and electron density with height are due to radial diffusion of lightning channel with the downward discharge channel, which resulted in the ground closer effective channel radius can not extend fully and the lower channel temperature and plasma density get greater. pinch effect of lighting channel is deduced as the main radiant point of X-ray and neutron produced in the process of lighting; Electronic recombination and bremsstrahlung radiation are main source of the background continuum. Attachment radiation is the main source of negative ions and one of the main methods of electron depletion in lightning channel. negative ions play on important role in the production of nitrogen oxides and ozone.On the basis of this, in combination with plasma theory, conductivity of the lightning channel is calculated, and the conductivity characteristic of channel is discussed. The relation between the conductivity of channel and the return stroke current is analyzed, which provide reference data for further computing return stroke current .The differences between lightning channel and plasma channel produced by laser in the atmosphere is discussed, which provide reference data for further study laser triggered lightning.