INTENSE LASER-PULSE DYNAMICS IN DENSE GASES

The results of a theoretical investigation on the interaction between a strong ionizing laser pulse and an initially neutral gas are present ed, based on a 3-dimensional numerical simulation of the radiation-gas system. The electromagnetic radiation is described, in the frame of a quasi-optical model, in terms of the complex amplitude of the electri c field envelope, while the free-electron density, which determines th e laser propagation characteristics, is treated by means of a fluid mo del, considering different ionization mechanisms. Ions are assumed to be at rest and the electron motion is nonrelativistic. The macroscopic manifestations of the ionization induced scattering of the laser radi ation are discussed in detail with reference to specific experimental conditions.