弱磁化等离子体中受激拉曼散射和受激布里渊散射抑制研究  

Suppression of Stimulated Raman Scattering and Stimulated Brillouin Scattering in Weakly Magnetized Plasmas

作　　者：周远志 郑春阳[2] 刘占军[2] 曹莉华[2] 程瑞锦 贺贤土[2] ZHOU Yuanzhi;ZHENG Chunyang;LIU Zhanjun;CAO Lihua;CHENG Ruijin;HE Xiantu(Key Laboratory of High Density Physics Simulation,Center for Applied Physics and Technology,Peking University,Beijing 100871,China;Institute of Applied Physics and Computational Mathematics,Beijing 100094,China)

机构地区：[1]北京大学物理学院,应用物理与技术研究中心高能量密度物理数值模拟教育部重点实验室,北京100871 [2]北京应用物理与计算数学研究所,北京100094

出　　处：《计算物理》2023年第2期136-146,共11页Chinese Journal of Computational Physics

基　　金：国家自然科学基金(11975059)资助项目。

摘　　要：本文针对典型激光聚变等离子体参数条件,利用动理学粒子模拟程序研究横向磁场和激光带宽在抑制受激拉曼散射(SRS)和受激布里渊散射(SBS)中的作用。模拟发现横向磁场对非均匀等离子体中SRS的非线性自共振增强有显著抑制作用,分析认为横向磁场作用于SRS激发的电子等离子体波(EPW)势阱中的俘获电子,使它们在横向上加速,对EPW造成非线性阻尼,同时减小EPW的非线性频移量,从而缩窄非均匀等离子体中SRS的自共振空间,极大降低SRS反射率。在此基础上利用横向磁场抑制SRS的特性,以及SBS增长对激光带宽的敏感性,提出了利用横向磁场和宽带激光将SRS和SBS同时抑制在低反射率水平的方案。在采用数十特斯拉横向磁场和实验中易于达到的千分之一量级的激光带宽时以及慢性约束聚变(ICF)相关参数下,SBS和SRS的反射率都得到了有效抑制。Finding ways to suppress stimulated Raman scattering(SRS)and stimulated Brillouin scattering(SBS)is an important subject in inertial confinement fusion(ICF).Under the typical laser fusion plasma conditions,the effects of transverse magnetic field and laser bandwidth on the suppression of SRS and SBS are studied by utilizing the particle-in-cell(PIC)program.It is found that the transverse magnetic field can significantly inhibit the autoresonance of SRS in the non-uniform plasma.The transverse magnetic field accelerates the electrons trapped in the electron plasma wave(EPW)excited by SRS,which causes the nonlinear damping and reduces the nonlinear frequency shift of the EPW,thus narrowing the autoresonance space and significantly reducing the SRS reflectivity.Based on the characteristics that SRS can be suppressed by a transverse magnetic field and the SBS growth is sensitive to the laser bandwidth,a scheme is proposed that utilizing the transverse magnetic field and the broadband laser to suppress SRS and SBS simultaneously.When the transverse magnetic field is on the order of 10 T and the bandwidth is on the order of 0.001,both of which are easy to achieve in experiments,the total reflectivity of SRS and SBS can be effectively suppressed in the ICF-related plasmas.

关 键 词：受激拉曼散射 受激布里渊散射 非线性动理学效应 磁化等离子体 自共振 

分 类 号：O469[理学—凝聚态物理]