Nonlinear responses of inhomogeneous collisional plasma to pondermotive effect in the laser-plasma interaction

The pondermotive force causes interesting nonlinear processes in the interaction of the intense laser beam with plasma. The pondermotive effect modifies the profile density, and in turn, affects the propagation of the laser beam through the plasma medium. Here, it is considered the inhomogeneous collisional plasma, and assumed that a high-intensity laser beam passes through the plasma. The nonlinear electric field solutions are obtained by applying numerical methods. Due to the nonlinear ponderomotive force, the changes in the physical characteristics of the electromagnetic wave are investigated. The wave profile of laser beam and the initial electron density have an important effect on the passing of the electromagnetic field through the plasma. Here, the Gaussian and the plane wave for the wave profile and the Gaussian and linear profiles for the initial electron density are considered. The obtained numerical results show that the profile of the incident wave and also the initial electron density have significant effects on the laser-plasma interaction. It is also demonstrated that the wave profile of laser beam incident to the inhomogeneous plasma plays an important role in its absorption by the plasma.