稠密等离子体层的透明性

Transparency of an Overdense Plasma Layer

在圆偏振高强度激光脉冲的传播过程中 ,对稠密等离子体层从不透明向透明的转变从理论上和以模拟的方法进行了研究。在有些情况下 ,流体方程不再能给出稳态解 ,此时必须考虑相互作用的动力学部分。研究发现 ,稳态解是否存在 ,和等离子体是否透明相联系。还发现 ,透明性不仅决定于电子密度和激光强度 ,而且决定于等离子体层的厚度。当没有稳态解时 ,等离子体开始变得透明 ,称之为绝对透明。当等离子体透明时 ,几乎没有光压作用在等离子体上 ,因此电子密度几乎不变。

The transition from opacity to transparency of overdense plasma layers for the propagation of high-intensity laser pulses of circular polarization is investigated theoretically and by simulation. At some points,fluid equations cannot give a stationary solution,and then the kinetic aspects of the interaction should be considered. It is found that the regions where stationary solutions exist and therefore the plasma layer is opaque. It is also found that the opacity depends not only on the electron density and the laser intensity but also on the thickness of the plasma layer. The plasma layers become transparent where stationary solutions don′t exist,defined as absolute transparent. The electron density hardly changes because there is no light pressure acting on the plasma layer when the plasma layer is opaque.