This paper presents theoretical investigation on the self-action effects of intense laser beams propagating through collisional plasmas. Particularly, the phenomena of self-focussing, self-trapping and self-phase modulation of the laser beam have been investigated in detail. In order to see the effect of uniformity as well as non-uniformity of the irradiance over the cross-section of the laser beam on its propagation characteristics field distribution in the medium has been expressed in terms of quadruple Gaussian (QG) profile instead of Gaussian profile. Following the moment theory approach, the nonlinear partial differential equation for the slowly varying envelope of the laser beam has been reduced to a set of coupled ordinary differential equations for the evolution of beam width and longitudinal phase. The equations so obtained have been solved numerically to envision the effect of laser as well as medium parameters on the propagation characteristics of the laser beam.

本文对通过碰撞等离子体传播的强激光束的自作用效应进行了理论研究。特别地，已经详细研究了激光束的自聚焦，自陷和自相位调制的现象。为了查看光束截面上的辐照度的均匀性和非均匀性对其传播特性的影响，已用四倍高斯（QG）曲线代替高斯曲线表示了介质中的场分布轮廓。遵循矩理论方法，用于激光束缓慢变化的包络线的非线性偏微分方程已简化为用于耦合光束宽度和纵向相位的一组耦合的常微分方程。