Breakdown of gases by CO2-laser radiation near a metal surface in the absence of developed vaporization

It is shown that optical breakdown of air and other gases near the surfaces of refractory metals can occur in the absence of developed vaporization. The concentration of metal vapors above a surface irradiated by a CO2 laser is determined. It is shown that the initial degree of the ionization of air and the absorption coefficient of laser radiation are related to the concentration of metal vapors in the air. A similarity criterion is obtained which determines the minimum surface temperature at which gas breakdown can occur. The time of breakdown development is computed.