Multifocal structure of high-power femtosecond laser radiation during filamentation in pressured gases

The results of numerical simulation of self-focusing and filamentation of high-power femtosecond laser pulses with varying pressure of the gas medium in which the radiation propagates are presented. The use of this approach is associated with the possibility of using the results obtained in laboratory conditions with abnormally high pressure at distances of several meters for scaling to real atmospheric paths hundreds of meters long at normal pressure. The practical significance of these studies is the possibility of remote diagnostics of atmospheric components and delivering energy along extended paths in the atmosphere. This approach also has its advantages in carrying out numerical calculations, since it allows reducing the time of calculations and decreasing the required computing power. The modeling is carried out for cases of propagation of high-power femtosecond laser pulses in the self-focusing and filamentation mode under conditions of increased pressure (by 64 times). The formation of the filamentation multifocal structure is considered in detail. This case is much in evidence under conditions of increased pressure of the propagation medium. The angular beam divergence is estimated for cases of different peak pulse power with varying gas pressure of the propagation medium.