The micrometer-scale tube that fills capsules with thermonuclear fuel in inertial confinement fusion experiments at the National Ignition Facility is also one of the implosion's main degradation sources. It seeds a perturbation that injects the ablator material into the center, radiating away some of the hot-spot energy. This paper discusses how the perturbation arises in experiments using high-density carbon ablators and how the ablator mix interacts once it enters the hot-spot. Both modeling and experiments show an in-flight areal-density perturbation and localized x-ray emission at stagnation from the fill-tube. Simulations suggest that the fill-tube is degrading an otherwise 1D implosion by ∼2×, but when other degradation sources are present, the yield reduction is closer to 20%. Characteristics of the fill-tube assembly, such as the through-hole size and the glue mass, alter the dynamics and magnitude of the degradation. These aspects point the way toward improvements in the design, some of which (smaller diameter fill-tube) have already shown improvements.

中文翻译：

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由填充管引起的国家点火装置上 ICF 内爆的混合

在国家点火设施的惯性约束聚变实验中，用热核燃料填充胶囊的微米级管也是内爆的主要降解源之一。它引发了一种扰动，将烧蚀材料注入中心，辐射掉一些热点能量。本文讨论了在使用高密度碳烧蚀剂的实验中如何产生扰动，以及烧蚀剂混合物进入热点后如何相互作用。建模和实验都显示了飞行中的面密度扰动和填充管停滞时的局部 X 射线发射。模拟表明，填充管正在将 1D 内爆降解约 2 倍，但当存在其他降解源时，产量降低接近 20%。填充管组件的特性，例如通孔尺寸和胶体质量，会改变退化的动力学和幅度。这些方面为设计改进指明了方向，其中一些（较小直径的填充管）已经显示出改进。