Diffusion instability in a laser radiation field

A theoretical investigation is made of the behavior of a gaseous mixture in the field of cw laser radiation. It is shown that thermal diffusion at radiation intensities above a certain critical value destabilizes inhomogeneous distributions of the concentration of the absorbing component and of the gas temperature, giving rise to a steady-state inhomogeneous periodic structure. A diffusion instability may explain splitting of a laser radiation beam into several components observed in the course of propagation of cw infrared laser radiation in gaseous mixtures.