Kalmykov S Yu, Yi S Austin, Shvets G
The Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, One University Station C1500, Austin, Texas 78712, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Nov;78(5 Pt 2):057401. doi: 10.1103/PhysRevE.78.057401. Epub 2008 Nov 21.
It is demonstrated that a catastrophic relativistic self-focusing (RSF) of a high-power laser pulse can be prevented all-optically by a second, much weaker, copropagating pulse. RSF suppression occurs when the difference frequency of the pulses slightly exceeds the electron plasma frequency. The mutual defocusing is caused by the three-dimensional electron density perturbation driven by the laser beat wave slightly above the plasma resonance. A bienvelope model describing the early stage of the mutual defocusing is derived and analyzed. Later stages, characterized by the presence of a strong electromagnetic cascade, are investigated numerically. Stable propagation of the laser pulse with weakly varying spot size and peak amplitude over several Rayleigh lengths is predicted.
结果表明，高功率激光脉冲的灾难性相对论自聚焦（RSF）可以通过第二个同向传播的弱得多的脉冲全光方式来阻止。当脉冲的差频略超过电子等离子体频率时，就会发生RSF抑制。相互散焦是由略高于等离子体共振的激光拍频驱动的三维电子密度扰动引起的。推导并分析了一个描述相互散焦早期阶段的双包络模型。对以强电磁级联为特征的后期阶段进行了数值研究。预测了激光脉冲在几个瑞利长度上光斑尺寸和峰值幅度变化微弱的稳定传播。
