激光间接驱动聚变内爆流体不稳定性研究  

Hydrodynamic instabilities of laser indirect-drive inertial-confinement-fusion implosion

作　　者：张维岩[1] 叶文华[2,3] 吴俊峰[2] 缪文勇[4] 范征锋[2] 王立锋[2,3] 谷建法[2] 戴振生[2] 曹柱荣[4] 徐小文[2] 袁永腾[4] 康洞国[2] 李永升[2] 郁晓瑾[2] 刘长礼[2] 薛创[2] 郑无敌[2] 王敏[2] 裴文兵[2] 朱少平[2] 江少恩[4] 刘慎业[4] 丁永坤[4] 贺贤土[2,3] 

机构地区：[1]中国工程物理研究院,绵阳621900 [2]北京应用物理与计算数学研究所,北京100094 [3]北京大学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 [4]中国工程物理研究院激光聚变研究中心,绵阳621900

出　　处：《中国科学：物理学、力学、天文学》2014年第1期1-23,共23页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：国家自然科学基金(批准号:10935003;11075024;11275031;11105013 11205017;11274026);国家重点基础研究发展计划(批准号:2013CB-834100)资助项目

摘　　要：激光间接驱动惯性约束聚变(ICF)内爆过程多层靶球各个界面发生的流体力学不稳定性是影响聚变点火成功的关键因素.为深入了解内爆过程这样不稳定性的发生、发展和它对聚变点火的影响,研制成了研究内爆多介质辐射流体力学过程的高精度二维(局部三维)大型LARED-S程序,并在长期研究实践中不断发展和改善.该程序模拟结果与不稳定性线性和弱非线性解析结果,以及非线性激波管实验结果都很好符合.应用这一程序,进行了大量数值模拟研究,结合理论模型分析,获得了大量流体力学不稳定性发展和演化的重要结果和物理规律认识.获得了具有不同密度、速度、磁场分布的Rayleigh-Taylor(RT)和Kelvin-Helmholtz(KH)不稳定性的线性增长率,以及它们在不可压缩条件下的弱非线性发展的解析解,表明了两者在不同Froude数、密度过渡层厚度、速度剪切层下的竞争关系;通过数值模拟,发现弱预热条件下烧蚀RT不稳定性二次谐波非线性发展导致不稳定增长尖钉(Spike)断裂的重要过程;数值模拟进一步揭露了强预热条件下,烧蚀RT不稳定性非线性发展导致不稳定增长尖钉出现射流状结构,气泡发生加速;还发现强烈的电子热传导使初始单模扰动的KH不稳定性大大削弱,然而却可能使两模扰动非线性发展增大混合尺度.在神光II激光装置上开展了一系列烧蚀RT不稳定性实验.平面靶烧蚀加速飞行轨迹实验结果与LARED-S模拟结果的比较表明腔壁辐射源能流明显小于激光注入孔的辐射能流,且辐射源的非平衡Planckian谱对靶的飞行轨迹和扰动增长有重要影响.实验分别观测到初始小扰动幅度烧蚀RT明显的增长和初始大扰动幅度尖钉变窄和气泡变宽的清晰物理图像.通过提高空间分辨率,实验获得了二次和三次谐波的增长数据.模拟结果与实验结果相符合.神光II激光装置上开展的流体不稳定性实�Hydrodynamic instabilities （HI） occurring at interfaces of a capsule in the process of laser indirect-drive inertial-confinement-fusion （ICF） implosion, plays an essential role in the success of the fusion ignition. In order to deeply understand the generation and growth of the HI and their influence on the fusion ignition, we have successfully developed the LARED-S code which is a high-order two- dimensional （local three-dimensional） radiation hydrodynamic code. The LARED-S code has been improved in our research of the HI in the past decades. It is shown that the results of LARED-S code agree well with the results of the linear and weakly nonlinear theories and the nonlinear shock tube experiments. Using the LARED-S code, we carry out a lot of numerical simulation research, obtaining a large amount of important result and physical understanding of the growth and evolution of the HI. The analytic expressions of the linear growth rate of Rayleigh-Taylor （RT） and Kelvin-Helmholtz （KH） instabilities considering the profiles of density, velocity, and magnetic field, and the their weakly nonlinear solutions in the limit of incompressible fluids, are derived. The relation of the RT instability （RTI） competing against the KH instability （KHI） is clearly shown, at different Froude numbers and widths of the density transition layer and the velocity shear layer. It is found that the jet-like spike in the ablative RTI （ARTI） in the presence of weak preheating can be ruptured by the nonlinear growth of the second harmonic. Moreover, jet-like spike pattern can be formed in the ARTI with strong preheating where a bubble acceleration process can be observed. The growth of high harmonics initiated by single-mode perturbation of the ablative KHI （AKHI） is effectively mitigated and the flow is stabilized in comparison with its classical counterpart. However, with a two-mode perturbation, the vortex pairing of the AKHI is reinforced, which would strength the mixing of materials. A serial of ARTI

关 键 词：激光惯性约束聚变 流体力学不稳定性 内爆 高能量密度物理 

分 类 号：TN24[电子电信—物理电子学] O35[理学—流体力学]