Optical breakdown of aluminum vapor in the ultraviolet range

Theoretical analysis of the evolution of nonequilibrium plasma in the ultraviolet spectrum of the laser radiation field was carried out. The frequency dependence of threshold values of the intensity and the principal mechanisms of nonequilibrium ionization of aluminum vapor in the radiation range under investigation were determined by mathematical modeling. The dominant role of photo-processes, namely resonant and non-resonant photoexcitation and photoionization, was shown. Comparison of modeling results with experimental data on optical breakdown of aluminum vapor by the eximer laser radiation in nanosecond and microsecond range was shown to be in good agreement.