Miller S M, Slutz S A, Bland S N, Klein S R, Campbell P C, Woolstrum J M, Kuranz C C, Gomez M R, Jordan N M, McBride R D
Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA.
Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
Rev Sci Instrum. 2020 Jun 1;91(6):063507. doi: 10.1063/1.5139663.
Magnetized Liner Inertial Fusion (MagLIF) at Sandia National Laboratories involves a laser preheating stage where a few-ns laser pulse passes through a few-micron-thick plastic window to preheat gaseous fusion fuel contained within the MagLIF target. Interactions with this window reduce heating efficiency and mix window and target materials into the fuel. A recently proposed idea called "Laser Gate" involves removing the window well before the preheating laser is applied. In this article, we present experimental proof-of-principle results for a pulsed-power implementation of Laser Gate, where a thin current-carrying wire weakens the perimeter of the window, allowing the fuel pressure to push the window open and away from the preheating laser path. For this effort, transparent targets were fabricated and a test facility capable of studying this version of Laser Gate was developed. A 12-frame bright-field laser schlieren/shadowgraphy imaging system captured the window opening dynamics on microsecond timescales. The images reveal that the window remains largely intact as it opens and detaches from the target. A column of escaping pressurized gas appears to prevent the detached window from inadvertently moving into the preheating laser path.
桑迪亚国家实验室的磁化内衬惯性聚变（MagLIF）涉及一个激光预热阶段，在此阶段，一个几纳秒的激光脉冲穿过几微米厚的塑料窗口，以预热MagLIF靶内的气态聚变燃料。与该窗口的相互作用会降低加热效率，并将窗口和靶材料混入燃料中。最近提出的一种名为“激光门”的想法，是在施加预热激光之前很久就移除窗口。在本文中，我们展示了激光门脉冲功率实现方式的实验原理验证结果，即一根载流细导线会削弱窗口的周边，使燃料压力能够推开窗口并使其远离预热激光路径。为此，制作了透明靶，并开发了一个能够研究这种激光门版本的测试设施。一个12帧的明场激光纹影/阴影成像系统在微秒时间尺度上捕捉了窗口打开的动态过程。图像显示，窗口在打开并与靶分离时基本保持完整。一股逸出的加压气体柱似乎能防止分离的窗口意外移入预热激光路径。
