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 turbule nt atmosphere during the propagation of a high-power subpicosecond laser pu lse was investigated for a medium with fluctuations of the refractive index . It was shown by statistical sampling methods that under turbulent conditi ons the length corresponding to the establishment of a nonlinear focus in w hich the intensity reaches the ionisation threshold is on average reduced c ompared with the similar length in a regular medium. The focus, moving alon g a random path, outlines in air a 'curved' filament, the random displaceme nt of which may reach several millimetres in the cross-sectional plane.