The first hydrodynamic instability growth measurements with three-dimensional (3D) surface-roughness modulations were performed on CH shell spherical implosions at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)]. The initial capsule outer-surface amplitudes were increased approximately four times, compared with the standard specifications, to increase the signal-to-noise ratio, helping to qualify a technique for measuring small 3D modulations. The instability growth measurements were performed using x-ray through-foil radiography based on time-resolved pinhole imaging. Averaging over 15 similar images significantly increased the signal-to-noise ratio, making possible a comparison with 3D simulations. At a convergence ratio of _2:4, the measured modulation levels were _3 times larger than those simulated based on the growth of the known imposed initial surface modulations. Several hypotheses are discussed, including increased instability growth due to modulations of the oxygen content in the bulk of the capsule. Future experiments will be focused on measurements with standard 3D ‘nativeroughness’ capsules as well as with deliberately imposed oxygen modulations.

在神光Ⅱ激光装置上开展了一系列辐射烧蚀Rayleigh-Taylor(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验考核了LARED-S程序的一维和二维计算。

双壳层靶中, 由于燃料被高Z壳层包裹, 其点火方式要求燃料整体点火, 不同于单壳层中心热斑点火。结合点火条件和对于其中物理过程的认识, 设计了间接驱动的冷冻双壳层点火靶。利用冷冻的氘氚(DT)燃料, 可适当提高双壳层靶的燃料装量, 获得和NIF装置条件下中心热斑点火靶相当的放能。间接驱动下, X射线烧蚀并驱动外壳层碰撞内壳层, 把能量传递给内壳层, 进而压缩和点燃冷冻的DT燃料。壳层碰撞过程是能量传递的关键, 通过调整内外壳层的质量比, 提高了碰撞效率, 相应地降低了靶丸点火的能量需求。一维数值模拟分析了该点火靶的内爆过程及定性分析了其中的流体力学不稳定性。同时, 也指出了泡沫中形成的辐射冲击波对内壳层的预热效应, 即辐射冲击波的致稳效应, 能够很好地抑制内壳层外界面处的不稳定性发展, 进而会减弱高Z内壳层和燃料的混合。