Theoretical study of electrical breakdown in nitrogen induced by laser radiation at 1.06μm

Abstract

The electron cascade model original proposed by Evans and Gamal (1980) to study atomic gas breakdown is extended to molecular gas breakdown calculations, including molecular electronic excitations and vibrational excitation effects. The validity of this model is studied for nitrogen at pressures ranging from 7.6*102 to 3.3*104 Torr irradiated by laser radiation of wavelength 1.06 mu m and 10 ns pulse duration. The calculated threshold intensities are in good agreement with the experiment. Calculations of the electron energy distribution function have also been performed to reflect the important electron-molecule energy exchange processes in molecular gases. It has been found that vibrational losses cause a 'precipitate decrease' in the electron energy distribution function near 2.0 eV and a very marked reduction in mean electron energy.