Spatiotemporal evolution of intense circularly polarized Gaussian laser pulse propagating in plasma is investigated. Self-focusing and self-compression properties of the laser pulse are studied, taking into account the ponderomotive nonlinearity, magnetic field, and state of wave polarization effects. The coupled differential equations governing the beam width (in space) and pulse length (in time) parameters are obtained via paraxial ray and Wentze−Kramers−Brillouin approximations and solved numerically. Numerical simulation showed that the pulse is compressed (in time and space) to a significant extent at a different normalized distance due to the effect of the nonlinearity of the medium. It is shown that for the right-hand circularly polarized laser, the strength of both self-focusing and self-compression of the laser pulse along the propagation direction is increased by increasing the value of the magnetic field, and consequently, the normalized intensity of the pulse is enhanced as it propagates through the plasma. In the case of a left-hand circularly polarized laser, an increase in the magnetic field causes a decrease in the strength of both self-focusing and self-compression of the laser pulse, especially in the higher values. To analyse the evolution of the laser spot size, a three-dimensional view of the normalized laser intensity at different points of the distance of propagation has also been plotted. Moreover, the results indicate a specific laser intensity range with a “saturation point” where the compression process reaches its maximum value, and outside of this range, it vanishes.

中文翻译：

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磁化等离子体中圆偏振高斯激光脉冲的时空动力学

研究了在等离子体中传播的强圆偏振高斯激光脉冲的时空演化。研究了激光脉冲的自聚焦和自压缩特性，同时考虑了有质动力非线性、磁场和波极化效应的状态。控制光束宽度（空间）和脉冲长度（时间）参数的耦合微分方程通过近轴射线和Wentze - Kramers-Brillouin获得近似和数值求解。数值模拟表明，由于介质非线性的影响，脉冲在不同的归一化距离处被显着压缩（在时间和空间上）。结果表明，对于右旋圆偏振激光器，随着磁场值的增加，激光脉冲沿传播方向的自聚焦和自压缩强度都增加，因此，归一化强度脉冲在通过等离子体传播时得到增强。在左旋圆偏振激光器的情况下，磁场的增加会导致激光脉冲的自聚焦和自压缩强度降低，尤其是在较高值时。分析激光光斑尺寸的演变，还绘制了在传播距离的不同点处归一化激光强度的三维视图。此外，结果表明具有“饱和点”的特定激光强度范围，在该“饱和点”处，压缩过程达到最大值，在此范围之外，它就消失了。