Hill M P, Williams G J, Zylstra A B, Stan C V, Lockard T E, Gumbrell E T, Rudd R E, Powell P D, Swift D C, McNaney J M, Le Galloudec K K, Remington B A, Park H-S
AWE Plc, Aldermaston RG7 4PR, United Kingdom.
Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore California 94550, USA.
Rev Sci Instrum. 2021 Mar 1;92(3):033535. doi: 10.1063/5.0043783.
Radiography of low-contrast features in high-density materials evolving on a nanosecond timescale requires a bright photon source in the tens of keV range with high temporal and spatial resolution. One application for sources in this category is the study of dynamic material strength in samples compressed to Mbar pressures at the National Ignition Facility, high-resolution measurements of plastic deformation under conditions relevant to meteor impacts, geophysics, armor development, and inertial confinement fusion. We present radiographic data and the modulation transfer function (MTF) analysis of a multi-component test object probed at ∼100 keV effective backlighter energy using a 5 μm-thin dysprosium foil driven by the NIF Advanced Radiographic Capability (ARC) short-pulse laser (∼2 kJ, 10 ps). The thin edge of the foil acts as a bright line-projection source of hard x rays, which images the test object at 13.2× magnification into a filtered and shielded image plate detector stack. The system demonstrates a superior contrast of shallow (5 μm amplitude) sinusoidal ripples on gold samples up to 90 μm thick as well as enhanced spatial and temporal resolution using only a small fraction of the laser energy compared to an existing long-pulse-driven backlighter used routinely at the NIF for dynamic strength experiments.
对在纳秒时间尺度上演变的高密度材料中的低对比度特征进行射线照相，需要一个能量在数十keV范围内、具有高时间和空间分辨率的明亮光子源。这类光源的一个应用是在国家点火装置中研究压缩到兆巴压力的样品的动态材料强度，以及在与流星撞击、地球物理学、装甲发展和惯性约束聚变相关的条件下对塑性变形进行高分辨率测量。我们展示了使用国家点火装置先进射线照相能力（ARC）短脉冲激光（约2千焦，10皮秒）驱动的5微米厚镝箔，在约100keV有效背光源能量下探测的多组分测试物体的射线照相数据和调制传递函数（MTF）分析。箔的薄边缘充当硬X射线的明亮线投影源，它将测试物体以13.2倍的放大倍率成像到一个经过滤波和屏蔽处理的成像板探测器堆栈中。与国家点火装置常规用于动态强度实验的现有长脉冲驱动背光源相比，该系统在高达90微米厚的金样品上展示了对浅（5微米幅度）正弦波纹的卓越对比度，并且仅使用了一小部分激光能量就提高了空间和时间分辨率。
