Generation of a wakefield during gas ionization

One-dimensional equations are derived that describe the hydrodynamic and el ectrodynamic properties of a plasma created through gas ionization by a sho rt intense laser pulse. Different approaches (in particular, the particle-i n-cell method) are used to show that, with ionization processes included, t he excitation of a wakefield by an intense laser pulse can be described by the method of slowly varying amplitudes. It is shown that ionization proces ses enhance the wakefield excited by a moderate-intensity laser by about 10 % in the case of a linearly polarized laser and by about 50% in the case of a circularly polarized laser. Ionization processes in light gases irradiat ed with high-intensity laser pulses have essentially no effect on the wakef ield during the resonant excitation of a plasma wave by the ponderomotive f orce and play a governing role far from the resonance. (C) 2000 MAIK "Nauka /Interperiodica".