Nucleation and random movement of filaments in the propagation of high-power laser radiation in a turbulent atmosphere

The nucleation and random movement of a nonlinear moving focus in a turbulent atmosphere during the propagation of a high-power subpicosecond laser pulse was investigated for a medium with fluctuations of the refractive index. It was shown by statistical sampling methods that under turbulent conditions the length corresponding to the establishment of a nonlinear focus in which the intensity reaches the ionisation threshold is on average reduced compared with the similar length in a regular medium. The focus, moving along a random path, outlines in air a 'curved' filament, the random displacement of which may reach several millimetres in the cross-sectional plane.