Subsonic radiation waves in air

It is shown that fast waves of absorption of laser radiation with the propagation mechanism dominated by the role of the intrinsic radiation emitted from the resultant plasma may appear at flux densities at least an order of magnitude lower than those at which they have been observed experimentally. An expanding plasma generates a shock wave where the pressure is much higher than atmospheric. Numerical calculations relating to the spectral radiation-dynamic problem are used to study the evolution of such subsonic radiation waves traveling from the initial plasma layer and to determine the time dependences of their main parameters (up to the quasisteady propagation stage). It is shown that these effects may occur when the flux (power) density exceeds 0.1 MW/cm² for CO₂ lasers and 1 MW/cm² for neodymium lasers.