The mode-1 x-ray drive asymmetry of indirect-drive Inertial Confinement Fusion(ICF) implosions at the National Ignition Facility(NIF) has been estimated using a simple static ViewFactor model. The model takes as input measured laser performance data in the foot and peak, the hohlraum configuration, and laser to hohlraum pointing. These estimates are compared with neutron time-of-flight measurements of directionality and magnitude of the resultant hotspot bulk velocity (~20–100 μm/ns) for 39 NIF shots using High Density Carbon (HDC) ablators and show strong correlation on a statistically significant number of shots. The most important factors identified so far are random quad-to-quad peak power laser imbalances, the presence of lossy diagnostic windows and gaps on the hohlraum waist, capsule sag and capsule thickness mode 1. Typical mode-1 asymmetry in drive is currently ~0.5% for many of these sources on their own and, when summed, can lead to a neutron hotspot velocity of up to 100 μm /ns and a reduction in yield of 35% for current NIF DT layered implosions. Our goal is to identify, quantify and mitigate all potential sources of mode-1 asymmetry (which also include target and laser alignment imperfections, foot power and Cross Beam Energy Transfer imbalances) to enable higher quality implosions on NIF.

使用简单的静态 ViewFactor 模型估计了国家点火设施 (NIF) 间接驱动惯性约束聚变 (ICF) 内爆的模式 1 X 射线驱动不对称性。该模型将测量的激光性能数据在底部和峰值、空腔配置和激光到空腔指向作为输入。将这些估计值与使用高密度碳 (HDC) 烧蚀器进行 39 次 NIF 发射的所得热点体积速度（~20–100 μm/ns）的方向性和幅度的中子飞行时间测量值进行比较，并在统计上显示出强相关性大量的镜头。迄今为止确定的最重要的因素是随机四边形到四边形激光峰值功率不平衡、存在有损诊断窗口和空腔腰部间隙、胶囊下垂和胶囊厚度模式 1。驱动中的典型模式 1 不对称性目前对于这些源中的许多源而言约为 0.5%，加起来后，可能导致中子热点速度高达 100 μm /ns，并使当前 NIF 的产率降低 35% DT 分层内爆。我们的目标是识别、量化和减轻模式 1 不对称的所有潜在来源（其中还包括目标和激光对准缺陷、足功率和横梁能量转移不平衡），以实现更高质量的 NIF 内爆。