激光-纳米丝靶相互作用过程中超热电子的加热机理研究  

Heating mechanism of hot electrons in the interaction between laser and nanolayered target

作　　者：余金清[1,2] 金晓林[1] 周维民[2] 李斌[1] 谷渝秋[2] 

机构地区：[1]电子科技大学大功率微波电真空器件技术国防科技重点实验室,成都610054 [2]中国工程物理研究院激光聚变研究中心,绵阳621900

出　　处：《物理学报》2012年第22期280-286,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10905009;11174259;11175165;10975121);高等学校博士学科点专项科研基金(批准号:200806141034);重点实验室基金(批准号:9140c6802031003);中央高校基本研究基金(批准号:ZYGX2010J052)资助的课题~~

摘　　要：超热电子的产生及其转化效率是快点火中的重要研究内容,也是优化快点火中的激光等离子体参数、降低对点火脉冲能量需求等方面的重要依据.纳米丝靶是提高激光-超热电子转化效率的一种有效途径,为了进一步理解激光-纳米丝靶相互作用中超热电子的产生过程以及加热方式,本文应用二维PIC(Flips2D)程序进行了相关的数值模拟.通过研究电子在丝靶中的运动轨迹发现了远离互作用面的冷电子通过回流的方式向互作用面运动,然后在互作用面附近与激光场相互作用被加热;研究了单个激光周期内电子密度和电子能量密度的变化,确定了反向运动的电子的能量要远小于前向运动的电子能量,确定了反向运动的电子大部分是冷电子的回流;通过研究场与电子空间位置随时间变化的关系,确定了丝靶中超热电子的加热机理为J×B机理.The generation of hot electrons and the coupling efficiency from laser to hot electrons are very important issues in fast ignition of inertial confinement fusion, which are important for optimizing the parameters of laser pulse and plasma and reducing the requirement for laser pulse. Laser interaction with nanolayered target is considered to be one of available ways of enhancing the coupling efficiency of laser to hot electrons. In order to understand the heating mechanism of hot electrons in the interaction between laser and nanolayered target in great detail, two-dimensional particle-in-cell simulation is carried out in this paper. Reflux for cold electrons moving to the interaction-face and then being accelerated near the interaction-face is detected by observing the tracks of electrons in the nanolayered target. It is found that the energies of inverse electrons are far smaller than those of forward electrons and the most inverse electrons are from the reflux of cold electrons by investigating the variations of the electron density and the electron energy density in one laser period. The J ×B heating mechanism is found to be a dominate mechanism in the generation of hot electrons by comparing the field and the locations of hot electrons at different times.

关 键 词：纳米丝靶 PIC程序 超热电子 加热机理 

分 类 号：O532[理学—等离子体物理]