强激光在非磁化等离子体中的三维调制不稳定性

Three-dimensional modulation instability of intense laser in unmagnetized plasmas

采用Karpman方法对线偏振激光在非磁化等离子体低密度区和临界面附近的三维调制不稳定性进行了分析,得到了不稳定产生的条件及时间增长率与扰动波数之间的函数关系。在低密度区,考虑了由弱相对论效应引起电子质量变化的一级和二级非线性效应,得出二级非线性效应对调制不稳定性的影响不大。另外对低密度等离子区和临界面附近的增长率进行了比较,结果表明,临界面附近的调制不稳定增长率较低密度处的更大。

The three-dimensional modulation instability of linearly polarized laser in low density region and near the critical surface associated with the unmagnetized plasmas was investigated via Karpman method. The conditions for instability and the temporal growth rate as a function of perturbed wave number were derived. In the low density regions, the conclusion that the second-order nonlinear effect has little influence on the modulation instability was obtained by comparing the first and the second-order nonlinear effects, in- duced by the weak relativistic election mass variations. Mooreover,the growth rates in low density region and near the critical surface of plasmas are considered,and and it is suggested that the growth rate of mod- ulation instability in the latter case is greater.