We study the propagation dynamics of zeroth-order Bessel–Gauss laser beams in plasma in the relativistic ponderomotive regime of interaction. Based on the paraxial and Wentzel-Kramers-Brillouin approximations, we derive the nonlinear evolution equation governing the laser beam width parameter, in view of the parabolic equation approach. We predict the range of intensity for self-focusing of Bessel–Gauss laser beams with increase in plasma electron temperature. While analyzing the condition for self-trapping of Bessel–Gauss beams, we point out and discuss three regimes characterized by steady divergence, self-focusing, and oscillatory divergence of the laser-beam propagation in plasma. In particular, we consider the effect of the transverse component of the wave parameter in exploring the intensity range for self-focusing. The intensity range for self-focusing of Gaussian beam in the considered regime of interaction with plasma is also deduced as a particular case in our work.

我们研究了在相对论质动力作用下等离子体中零阶贝塞尔－高斯激光束在等离子体中的传播动力学。基于抛物线方程法，基于近轴近似和Wentzel-Kramers-Brillouin近似，我们得出控制激光束宽度参数的非线性演化方程。我们预测随着等离子体电子温度的升高，贝塞尔－高斯激光束自聚焦的强度范围。在分析贝塞尔－高斯光束自陷的条件时，我们指出并讨论了三种状态，其特征是等离子体中激光束传播的稳定发散，自聚焦和振荡发散。特别是，我们在研究自聚焦强度范围时考虑了波浪参数的横向分量的影响。