稠密等离子体表面不稳定性的入射光偏振态效应

Effect of Laser Polarizations on Surface Instability of Dense Plasma Irradiated by Relativistic Intense Laser Pulses

用二维粒子模拟程序研究了相对论强激光和稠密等离子体相互作用引起的表面不稳定。数值模拟表明,在s偏振光作用下,等离子体表面出现了类瑞利泰勒不稳定性。形成的不稳定结构随时间发展进一步深入到等离子体内部,最终使等离子体密度形成分层泡状结构,并向前传播。这种不稳定的产生与初始等离子体密度有密切关系,在高于20倍临界密度等离子体的表面没有明显观察到这种不稳定。在p偏振激光作用下,等离子体表面不能明显地形成这种结构。因此在三维几何结构下,这种等离子体表面不稳定性将呈现各向异性。这种表面不稳定将直接影响高次谐波产生和离子加速效率。

The surface instability of a dense plasma slab irradiated by a relativistic intense laser pulse is investigated using two-dimensional particle-in-cell simulation. When the laser pulse is incident with s-polarization, Rayleigh- Taylor-like instability is observed on the plasma surface. Later the instability propagates into the plasma bulk forming bubble structures, which propagate forward subsequently. The development of this instability depends upon the initial plasma density. At high densities such as over 20 times of the critical density, this instability is not observed obviously. This surface instability is not formed for the case of p-polarization, i.e., the Rayleigh-Taylor-like instability is anisotropic in three-dimensional geometry. It is expected that this instability can have significant effect on high harmonics generation and ion acceleration.