超短超强激光导引及对电子加速的影响

Ultra-short ultra-intense laser guiding and its influence on electron acceleration

使用粒子模拟程序对30 fs超短超强激光在均匀与抛物型两种密度分布等离子体中的传输,以及在稳定传输状态下尾场的电子注入与加速形成的电子能谱进行了模拟与分析.固定入射激光束斑尺寸,在(0.4—2)×10^(19)/cm^3等离子体密度范围,对比分析了归一化峰值强度从1—6范围的激光脉冲在上述两种密度分布等离子体中传输时激光束斑尺寸的演化,结果表明抛物型分布的等离子体密度通道能够对超短超强脉冲实现良好的导引,有利于高能电子加速.对于较高密度情况,即使在均匀等离子体中依靠相对论自聚焦等机制也可以实现良好的自导引传输,有利于实验简化以及产生更大电量的加速电子.

Simulations and analyses of ultra-short ultra-intense laser propagting in plasmas with uniform and parabolic density profiles, as well as the electron injection into the wake field and the electron spectra in the stable transmission state are performed by using a particle-in-cell code. Fixing the incident laser focal spot size but changing the plasma density in a range of （0.4-2）× 10^19/cm3, comparative analyses are carded out of the evolutions of the laser beam spot during the propagation of the laser pulse in the plasmas with aforementioned two density profiles, with the normalized laser intensity ranging from 1 to 6. The results show that a plasma channel with a parabolic density profile can realize a good guiding of an ultra-short ultra-intense pulse, which is beneficial for high energy electron acceleration. However, at higher densities, self-guiding can be realized by relativistic self-focusing in uniform plasma, which is conducive to simplifying the experiment and to producing more accelerated electrons.