基于半解析自洽理论研究相对论激光脉冲驱动下阿秒X射线源的产生  

Attosecond X-ray generation driven by the relativistic laser pulse based on the semi-analytical self-consistent theory

作　　者：王少义[1] 谭放[1] 吴玉迟[1,2,3] 范全平[1] 矫金龙 董克攻[1] 钱凤[1] 曹磊峰[1,2,3] 谷渝秋 

机构地区：[1]中国工程物理研究院激光聚变研究中心,绵阳621900 [2]中国工程物理研究院等离子体重点实验室,绵阳621900 [3]上海交通大学协同创新中心,上海200240

出　　处：《物理学报》2017年第20期97-104,共8页Acta Physica Sinica

基　　金：国家重大科学仪器专项(批准号:2012YQ130125);国家自然科学基金(批准号:11405159;11375161;11174259);国家自然科学基金联合基金(批准号:U1630246);中国工程物理研究院院长基金(批准号:2014-1-017);中国工程物理研究院科技发展基金(批准号:2015B0401090);重点实验室基金(批准号:9140C680302130C68242);国家科技部重点研发计划(批准号:2016YFA0401100)资助的课题~~

摘　　要：发展了一种描述相对论激光脉冲与稠密等离子体相互作用产生阿秒X射线源的半解析自洽理论.该理论模型不仅可以获得等离子体界面的振荡轨迹、振荡面电场和磁场等物理参数,而且能够精确计算出激光脉冲驱动下阿秒X射线源的频谱,结果与粒子模拟程序一致.理论计算结果表明阿秒X射线源的辐射特性与等离子体界面随时演化过程相关,在周期量级激光场驱动下等离子体界面振荡振幅呈现中心不对称,通过改变激光场的载波包络相位实现对等离子体界面振荡的控制,获得准单阿秒X射线源.A semi-analytical theory of the interaction between a relativistic laser pulse and the overdense plasma to generate an attosecond X-ray source is presented. The physical parameters such as plasma oscillation trajectory, surface electric field and magnetic field can be given by this model, and the high-order harmonic spectrum is also calculated accurately from the solution of the plasma surface oscillations, the obtained result is consistent with the result from the PIC simulation program. This model can be valid for arbitrary laser duration, solid densities, and a large set of laser peak intensities（10^18–10^21 W/cm^2）. In addition, the model is not applicable for the small laser focal spots（less than ten times the laser wavelength）, although two-dimensional effects such as the pulse finite size may significantly change the movement progress of the electrons, the laser spot can be larger than ten times the laser wavelength under the general laboratory conditions.In this model, the laser energy absorption is small, and the electron kinetic pressure is also small. Due to the radiation pressure of the laser pulse, the electrons are pushed into the solid, forming a very steep density profile. As a result, the relevant forces makes the electrons ponderomotive and the longitudinal electric field is caused by the strong electric charge separation effect. This semi-analytical self-consistent theory can give us a reasonable physical description,and the momentum equation and the continuity equation of the electric and magnetic field at the boundary allow us to determine the plasma surface oscillations. The spatiotemporal characteristics of the reflected magnetic and electric field at the boundary can allow us to determine the emitting characteristics of the high order harmonic.Our results show that the radiation of the attosecond X-ray source is dependent on the plasma surface oscillation.The plasma surface oscillates with a duration about twice the laser optical cycle, and the high-order harmonics also emit twic

关 键 词：自洽振荡镜模型 高次谐波 单阿秒脉冲 

分 类 号：O434.1[机械工程—光学工程]