激光功率密度对Al膜靶后表面快电子发射的影响

报道了在20 TW皮秒激光器上完成的p偏振激光与等离子体相互作用过程中产生的快电子的角分布和能谱测量结果.实验得到：当激光功率密度小于1017 W/cm^2时,电子发射没有明显定向性,在激光入射面内多峰发射;当激光功率密度大于1017 W/cm^2,小于1018 W/cm^2时,电子主要沿靶面法线方向发射;当激光功率密度达到相对论强度时,电子主要沿激光传播方向发射;激光功率密度未达到相对论强度时,靶后表面法线方向快电子能谱拟合平均温度符合共振吸收温度定标率;激光功率密度达相对论强度以上时,靶后表面法线方向

The characteristics of the forward hot electrons produced by 20 TW p-polarized picosecond laser-plasma interactions are studied at laser intensities from subrelativistic to relativistic.The spatial distribution of forward hot electrons is multi-peak distribution,as laser intensity is under 10⁷ W/cm².When laser intensity is between 10¹⁷ and 10<sup>18>/sup> W/cm²,the peak of the hot electron beam is along the target normal direction.The peak of the hot electron beam shifts to the laser propagation direction from the target normal direction as the laser intensity reaches the relativistic.The temperature of hot electrons fit resonance absorption scaling law as the laser intensity under the relativistic.The temperature of hot electrons is much higher than that expected by the empirical scaling law as the laser intensity reaches the relativistic.