超强激光功率密度对等离子体中自生磁场和电子热传导的影响  

Influences of extra-intense laser power density on the self-generated magnetic field and electron thermal conduction in plasma

作　　者：毛建景 张凯萍 郝东山 

机构地区：[1]郑州工业应用技术学院信息工程学院,新郑451150

出　　处：《原子与分子物理学报》2015年第4期625-630,共6页Journal of Atomic and Molecular Physics

基　　金：河南省基础与前沿技术研究资助项目(092300410227);河南省教育厅科学技术研究重点项目(12B520063)

摘　　要：应用多光子非线性康普顿散射模型、3维粒子模拟模型和数值计算方法，研究了超强激光与等离子体作用中自生磁场产生和电子热传导过程，提出了将非线性康普顿散射光作为改变等离子体自生磁场和电子热传导的新机制，给出了自生磁场最大饱和值和超热电子热传导的修正方程和数值计算结果．研究发现在时间为100—160内，自生磁场能量随入射激光功率密度增大而迅速增大，之后处于较高饱和阶段．增大的初始时刻较散射前提前了20，增大阶段的时间延长了30，饱和阶段增幅为40％．入射激光功率密度为10^19～10^20w／cm^2时，自生磁场强度最大模拟值为1．47×10^4-3．75×10^4T，单电子能谱峰值出现在3．3MeV和6．6MeV附近，能谱曲线在4～15MeV和11-14．3MeV迅速衰减，在6．7MeV和13．2MeV以上时，超热电子有效温度为2．6MeV和4．5MeV，比无散射的理论值和拟合值均有一定增大．随入射激光强度增大，热流随激光脉冲一起向等离子体内流动的时间缩短，自生磁场限制热流的时间延长．对所得结果给出了初步物理解释．By using the model of multi -photon nonlinear Compton scattering, the simulation model of 3D particle and numerical method, the producing of the self - generated magnetic field and the electron thermal conduction in the effect between the extra - intense power laser and plasma are studied. A new mechanism that the self generated magnetic field and the electron thermal conduction in plasma are changed by nonlinear Compton scattering is proposed. The amended equations on the maximum saturation value of the self - generated magnetic field and the electron thermal conduction and number computing results are given. The results show that the en- ergy of the self - generated magnetic field is quickly increased with the increasing of the incident laser power density in the time 100 - 160, then the energy is kop in the higher saturation period. The time that the initial moment of increased period is moved are 20, the time of that the increased period are prolonged are 30, and increased extent of the saturation period are 40%. When the incident laser power density are 10^19 - 10^20 W/cm^2, the maximum simulation value of the self-generated magnetic field intense are 1.47 × 10^4 - 3.75 × 10^4 T, the crest values of an electron energy section are appeared near the 3.3 MeV and 6. 6 MeV, and the energy section curvature are quickly decreased in 4 - 15 MeV and 11-14. 3 MeV. The effective temperature of the extra - hot electron are 2. 6 MeV and 4.5 MeV over 6. 7 MeV and 13.2 MeV on the energy section curvature, and these values are increased than the un -scattering theory values and simulated coupling values. The time that the thermal current and laser pulse together drift to internal plasma is decreased, and the time that the self - generated magnetic field checks the thermal current is increased. The initial physics explain on these results have been given out.

关 键 词：非线性光学 等离子体 超强激光功率密度 自生磁场 电子热传导 非线性康普顿散射 

分 类 号：O53[理学—等离子体物理]