We perform qualitative physical analysis and particle-in-cell two-dimensional numerical simulation of the Weibel mechanism of magnetic-field generation due to the self-consistent formation of filaments of the hot-electron current with anisotropic velocity distribution, which occurs in the process of decay of a strong discontinuity in a collisionless plasma with a great difference in the number density and temperature of electrons. Anisotropy of the electron distribution is mainly stipulated by their quasiadiabatic expansion and a significant decrease in the thermal velocities in the normal direction to the front of the formed electrostatic shock wave at a weak decrease in the thermal velocities in the transverse directions. A strong magnetic field is formed in a layer with the maximum anisotropy under the front, covers the entire region of the expanding plasma, and, at the nonlinear evolution stage, acquires quasiperiodic modulation along the normal to the front, which correlates with the modulation of the electron anisotropy degree. The considered scenario of development of the Weibel instability is of interest for analysis of experiments with femtosecond laser plasma and interpretation of such phenomena in the case of a decay of strong discontinuities in a nonequilibrium space plasma.

中文翻译：

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热电子无碰撞等离子体束膨胀过程中磁场产生的威贝尔机制

由于在过程中发生具有各向异性速度分布的热电子电流细丝的自洽形成，我们对磁场产生的 Weibel 机制进行定性物理分析和细胞内粒子二维数值模拟电子数密度和温度差异很大的无碰撞等离子体中强不连续性的衰变。电子分布的各向异性主要由它们的准绝热膨胀和所形成的静电冲击波前沿的法线方向的热速度显着降低而横向热速度的微弱降低所决定。在正面下方各向异性最大的层中形成强磁场，覆盖了膨胀等离子体的整个区域，在非线性演化阶段，沿法线获得准周期调制，这与电子各向异性程度的调制有关。所考虑的 Weibel 不稳定性发展场景对于飞秒激光等离子体实验的分析以及在非平衡空间等离子体中强不连续性衰减的情况下对此类现象的解释感兴趣。