Study On The Electric Characteristics Of Lightning Discharge Plasmas

According to one spectrum of lightning return stroke at Qinghai province, it can be found that the Stark broadening are about 15～25 ? and the NI 4935 ? lines at different positions within the channel show slight asymmetry after analyzing the Stark broadening effect of NI 4935 ? line. The electron densities at different positions of the channel have been calculated combining with semi-empirical parameters of Stark broadening. The result reveals that the electron densities show a tiny trend of becoming low with increasing of height along the channel. The electron densities exhibit a nearly linear dependence on the half-widths of NI 4935 ? lines.Based on the wavelengths, relative intensities and other transition parameters of the lines in cloud lightning discharge spectra and cloud-to-ground (CG) lightning return stroke spectra captured by a Slit-less spectrograph in different regions, the temperatures and electron densities of discharge channels have been calculated, and the electrical conductivities of the channels have been further obtained using the electrical conducting theory of plasma. The results show that the conductivities for 6 cloud lightning channels are in a good agreement with those of CG lightning strokes and of long spark. The analysis of the data indicates that the electrical conductivity chiefly depends on the plasma temperature, and the higher temperatures correspond to the higher conductivities. In addition, since cloud lightning discharge channels show all possible orientations, it may be one of the main reasons why the conductivities at different positions along the channel show no visible law. Using the electrical conductivities of the CG lightning channels, the discharge current of the channels have been obtained. The analyses are made for the currents of individual lightning strokes in different areas and the currents at different positions within a given channel. The results show that the current values for CG lightning channels are in a good agreement with those measured for natural lightning. For the stroke channels with the same or approximate temperatures, the values in coast are larger than those in west plateau. In addition, the currents show a tiny decrease with the increasing of height along the channel.This work provides a new, feasible and practical way for the study of lightning discharge current and electron density, it will give some reference data to the research of lightning physical mechanism.