Inertial confinement fusion implosions must achieve high in-flight shell velocity, sufficient energy coupling between the hot spot and imploding shell, and high areal density ($\rho R=\int \rho dr$) at stagnation. Asymmetries in $\rho R$ degrade the coupling of shell kinetic energy to the hot spot and reduce the confinement of that energy. We present the first evidence that nonuniformity in the ablator shell thickness ($\sim 0.5\%$ of the total thickness) in high-density carbon experiments is a significant cause for observed 3D $\rho R$ asymmetries at the National Ignition Facility. These shell-thickness nonuniformities have significantly impacted some recent experiments leading to $\rho R$ asymmetries on the order of $\sim 25\%$ of the average $\rho R$ and hot spot velocities of $\sim 100\mathrm{km}/\mathrm{s}$. This work reveals the origin of a significant implosion performance degradation in ignition experiments and places stringent new requirements on capsule thickness metrology and symmetry.

中文翻译：

---

国家点火设施实验中高密度碳烧蚀剂不均匀性所引发的三维不对称现象的证据

惯性约束聚变内爆必须实现较高的飞行中壳速度，热点与内爆壳之间的足够能量耦合以及较高的面密度（$\rho \mathrm{[R}=\int \rho d\mathrm{[R}$）处于停滞状态。中的不对称$\rho \mathrm{[R}$降低了壳动能与热点的耦合，并降低了该能的限制。我们提出了第一个证据，表明消融器外壳厚度不均匀（$〜0.5％$ 高密度碳实验中的总厚度）是观察到3D的重要原因 $\rho \mathrm{[R}$国家点火装置的不对称性。这些壳厚度的不均匀性极大地影响了一些最近的实验，导致$\rho \mathrm{[R}$ 不对称程度为 $〜25％$ 平均值的 $\rho \mathrm{[R}$ 和热点速度 $〜100\mathrm{公里}/\mathrm{s}$。这项工作揭示了点火实验中内爆性能明显下降的根源，并对胶囊厚度的计量和对称性提出了严格的新要求。