In inertial confinement fusion, penetrating asymmetric hohlraum preheat radiation (>1.8 keV, which includes high temperature coronal M-band emission from laser spots) can lead to asymmetric ablation front and ablator–fuel interface hydrodynamic instability growth in the imploding capsule. First experiments to infer the preheat asymmetries at the capsule were performed on the National Ignition Facility for high density carbon (HDC) capsules in low density fill (0.3 mg/cc ⁴He) Au hohlraums by time resolved imaging of 2.3 keV fluorescence emission of a smaller Mo sphere placed inside the capsule. Measured Mo emission is pole hot (P₂ > 0) since M-band is generated mainly by the outer laser beams as their irradiance at the hohlraum wall is 5× higher than for the inner beams. P₂ has a large swing vs time, giving insight into the laser heated hohlraum dynamics. P₄ asymmetry is small at the sphere due to efficient geometric smoothing of hohlraum P₄ asymmetries at large hohlraum-to-capsule radii ratios. The asymmetry at the HDC capsule is inferred from the Mo emission asymmetry accounting for the Mo/HDC radius difference and HDC capsule opacity.

中文翻译：

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通过Mo球荧光成像在ICF胶囊上进行Hohlraum X射线预热不对称测量

在惯性约束聚变中，穿透不对称的大直径预热辐射（> 1.8 keV，包括激光点产生的高温日冕M波段发射）会导致不对称的消融锋面以及消融胶囊中消融-燃料界面的流体动力学不稳定。在国家点火设施上对低密度填充（0.3 mg / cc ⁴ He）低密度金的高密度碳（HDC）胶囊进行了首次推断胶囊预热不对称的实验，方法是通过对2.3 keV荧光发射的时间分辨成像进行分析。较小的Mo球放在胶囊内。测得的Mo发射极热（P ₂ > 0），因为M波段主要是由外部激光束产生的，因为它们在水平光束壁上的辐照度比内部激光束高5倍。P₂具有随时间变化的大摆幅，可深入了解激光加热的滚轮动力学。由于球形与胶囊半径之比大时，有效的几何修整度P ₄不对称性使得球体上的P ₄不对称性小。根据Mo / HDC半径差和HDC胶囊的不透明度，可以从Mo发射不对称中推断出HDC胶囊的不对称性。