双锥对撞点火机制2020年冬季实验中的瑞利-泰勒不稳定性分析  

Analytical studies of Rayleigh-Taylor instability growth of double-cone ignition scheme in 2020 winter experimental campaign

作　　者：方可 张喆[1,3,4] 李玉同 张杰[1,4,5] Fang Ke;Zhang Zhe;Li Yu-Tong;Zhang Jie(Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Songshan Lake Materials Laboratory,Dongguan 523808,China;Collaborative Innovation Center of IFSA,Shanghai Jiao Tong University,Shanghai 200240,China;School of Physics and Astronomy,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]中国科学院物理研究所,北京凝聚态物理国家研究中心,北京100190 [2]中国科学院大学物理科学学院,北京100049 [3]松山湖材料实验室,东莞523808 [4]上海交通大学IFSA协同创新中心,上海200240 [5]上海交通大学物理与天文学院,上海200240

出　　处：《物理学报》2022年第3期222-230,共9页Acta Physica Sinica

基　　金：中国科学院战略性科技先导专项(批准号:XDA25010100,XDA25010300,XDA25030100);国家自然科学基金(批准号:U1930107,11827807)资助的课题。

摘　　要：直接驱动激光聚变通过整形后的纳秒脉冲激光辐照氘氚(DT)球壳靶,经球对称压缩加速后,在中心转滞获得高温等离子体热斑,实现聚变点火.在球壳靶受到压缩和加速过程中等离子体界面的流体力学不稳定性,特别是瑞利-泰勒不稳定性的增长有可能会对压缩壳层造成破坏,导致点火的失败.本文通过理论解析和数值模拟,对基于Zhang等提出的双锥对撞点火方案(2020 Philos.Trans.A Math.Phys.Eng.Sci.37820200015)在2020年冬季实验条件下的流体力学不稳定性增长进行了分析.结果显示理论模型与一维数值模拟中对整体压缩和加速过程的描述基本一致,在当前的近等熵波形下金锥中的壳层靶实现了低熵压缩,同时瑞利-泰勒不稳定性增长导致的最危险时刻扰动振幅和壳层厚度比可以达到约0.25,壳层依然处于安全状态,但当初始壳层表面扰动均方根振幅大于22 nm时,则可能出现壳层的破裂.因此,未来实验中的靶设计与驱动激光脉冲波形设计中可以通过增加靶壳层厚度、提高预脉冲强度、减小靶表面的粗糙度和提高激光辐照的匀滑度等方式来抑制不稳定性增长.In laser direct-driven fusion,high power lasers are used to ablate the target shell,compress and heat the fuel with the spherical focusing rocket effect,to approach to the fusion ignition conditions.The shaped nanosecond laser pulses compress and accelerate the DT target symmetrically,and forms a high density plasma hot-spot at stagnation.The hydrodynamic instabilities,especially the Rayleigh-Taylor instability,which happens at the interface of plasmas,may destroy the compressed shells,and thus reduce the temperature and density of the hot-spot.In this paper is analyzed theoretically the hydrodynamic instability growth under the conditions in the 2020 winter experiment of the double-cone ignition scheme proposed by Zhang et al.(2020 Philos.Trans.A Math.Phys.Eng.Sci.37820200015).Both analytical model and one-dimensional simulations indicate that the fuel shells are compressed with low adiabat under the current quasi-isentropic waveform.The Rayleigh-Taylor instability remains in safe region with a maximum perturbation amplitude reaching 0.25 of the shell thickness at the most peak grown moment.The growth of the hydrodynamic instabilities can be further reduced by increasing the thickness of the shell,through using high foot pre-pulses and improving the uniformity of the target surface and laser irradiation in the future design.

关 键 词：激光聚变 内爆对称性和流体力学不稳定性 

分 类 号：TL61[核科学技术—核技术及应用]