Current capsule implosions at the National Ignition Facility (NIF) using high-density-carbon ablators and laser energies close to 2 MJ have shown neutron yields in excess of 50 kJ. Improving on this performance requires understanding of the different degradation mechanisms. For many NIF implosions, nuclear diagnostic signatures have inferred residual hot-spot velocities that correlate with fuel areal density variations consistent with a low-order mode-1 asymmetry. A current working hypothesis attributes these asymmetries to a combination of beam to beam variations in the laser delivery and possibly coupling to target features, such as the diagnostic holes needed for x-ray imaging. Recently, a new source has been identified, thickness variation in the ablator shell. To gain better understanding and eventually mitigate the causes of asymmetries, 3D integrated simulations using the actual delivered laser powers are needed. To capture the effect of the diagnostic holes (DHs) using direct numerical simulation would require significantly large computational resources. Instead, our 3D simulations make use of a subgrid model developed using highly-resolved 2D simulations that include several details of the DH engineering complexity. Simulations of NIF shots using hohlraums without DHs, to isolate the effect of beam-to-beam variations, reproduce fairly well the observed nuclear diagnostic signatures. Similarly, reasonable agreement between data and simulations is also obtained in the presence of diagnostic holes. To account for the remaining discrepancies a sensitivity study of ablator thickness variation showed that 1% thickness asymmetries are comparable in effect to 1% peak drive mode-1 asymmetries. Additionally, this study identified sensitivity to variations in the imbedded doped layer (needed to shield the DT ice from the high energy x-rays generated in the hohlraum) thickness even when the inner and outer surface of the ablator are perfectly spherical.

国家点火装置（NIF）当前使用高密度碳烧蚀器和接近2 MJ的激光能量对内爆进行的内爆显示中子产量超过50 kJ。要提高此性能，需要了解不同的降级机制。对于许多NIF内爆，核诊断信号推断出了残余热点速度，该速度与与低阶模式1不对称一致的燃料面密度变化相关。当前的工作假设将这些不对称性归因于激光传输中光束之间的变化的组合，并可能耦合到目标特征，例如X射线成像所需的诊断孔。最近，已经确定了一种新的来源，即消融器外壳的厚度变化。为了更好地了解并最终减轻造成这种情况的原因对于不对称性，需要使用实际传递的激光功率进行3D集成仿真。为了使用直接数值模拟来捕获诊断孔（DH）的效果，将需要大量的计算资源。取而代之的是，我们的3D模拟使用了子网格模型，该模型是使用高度解析的2D模拟开发的，其中包括DH工程复杂性的多个细节。使用不含DH的大孔径光阑对NIF镜头进行模拟，以隔离光束对光束变化的影响，可以很好地重现观察到的核诊断特征。同样，在存在诊断漏洞的情况下，也可以获得数据与模拟之间的合理一致性。为了解决剩余的差异，对消融器厚度变化的敏感性研究表明，1％的厚度不对称实际上可与1％的峰值驱动模式1不对称产生影响。此外，这项研究还确定了即使在消融器的内表面和外表面完全球形时，对于嵌入的掺杂层（需要屏蔽DT冰以防止其在高岭土中产生的高能X射线）厚度变化的敏感性也是如此。