大気中でのレーザ誘導プラズマ形成過程の計算機シミュレーション

抄録

This paper presents a numerical analysis on the electrical breakdown process of air-like gas mixture induced by laser irradiation. We develope a computer simulation model including the Boltzmann equation to derive the electron energy distribution, and the rate equations to describe the temporal behavior of particle densities in plasmas. The calculations are performed for different laser wavelength of 308nm (XeCl), 694nm (ruby), 1.06μm (YAG) and 10.6μm (CO₂). As the results, iis found that the dominant process of the laser-induced breakdown is multi-photo absorption ionization for uv lasers but cascade ionization for longer wavelangth lasers. We also investigate the effect of the laser pulse width, gas pressure, preionization, diffusion and water vapour. The results are qualitatively consistent with the experimental results which have been reported.