Investigation of the dynamics of plasma formation near a target acted on by microsecond $CO_2$ laser pulses

An experimental investigation was made of the dynamics of plasma formation close to the surface of a graphite target in air and inert gases in the range of pressures 0.1-760 Torr and of laser radiation flux densities $(0,1-1,4)\cdot10^8$ W/cm${}^2$. It was found that a plasma appeared 40–130 nsec after the start of the laser pulse due to evaporation of the target and subsequent ionization of its vapor by the laser radiation.