强激光在非均匀磁化电子-正电子-离子等离子体中的传播

Intense laser propagation in an inhomogeneous magnetized electron-positron-ion plasma

利用相对论双流体模型研究了左旋圆偏振强激光在非均匀磁化电子-正电子-离子(electron-positron-ion,EPI)等离子体中的传播.通过考虑相对论效应和有质动力效应,系统的控制方程简化为一个包含有磁场效应和密度非均匀效应的修正非线性薛定谔方程,并进一步研究了调制不稳定性.数值模拟结果表明:外磁场强度,正电子与负电子密度比值的增加以及等离子体密度非均匀性会增强激光束的聚焦和成丝,导致强烈的调制不稳定性和成丝不稳定性,并引起激光束与等离子体之间强烈的非线性相互作用,出现了许多非线性现象.

Based on the relativistic two-fluid model,the nonlinear interaction of left-hand circularly polarized wave in an inhomogeneous magnetized electron-positron-ion(EPI)plasma is investigated.Considering the relativistic and the ponderomotive effects,the governing equations of the system can be reduced to a modified nonlinear Schr dinger equation,in which the magnetic field and the density inhomogeneous effects are included.From the modified nonlinear Schr dinger equation,the modulation instability of the system are obtained theoretically.Numerical results also show that the laser beam focusing and filamentation of the system can be enhanced with the strength of the external magnetic field,the density ratio of the positron to the electron and the inhomogeneity of the plasma density,which leads to the strong modulational and filamentational instabilities,and rich nonlinear phenomena are emerged.