Abstract

This study focuses on the issue of uncontrollable debris generated by laser-matter interactions in high-power laser facilities, which significantly impairs operational efficiency. The maximum motion distance of debris, referred to as the safety distance, is a crucial parameter that this work investigates. Three prediction methods that utilize aerodynamic coefficients and trajectories are proposed, with input parameters derived from velocity curves extracted from high-resolution time-resolved images. The results obtained from these methods show good agreement with experimental data collected under laser fluence conditions ranging from 18 to 79 J/cm² that damage the rear surface of fused silica. The analytically predicted safety distance, with an input velocity fitted at 0 ns and an upper diameter limit of 10 µm, was closest to the experimental result at 155 mm. Analytically predicted values with input velocities fitted at 13,000 ns and all diameter ranges did not exceed 192.3 mm. Numerically predicted values, with input velocity fitted at 13,000 ns and a median diameter of small debris (5 µm), were 140.4 and 295.2 mm for aspect ratios of 2 and 4, respectively. The numerical method is recommended for predicting the safety distance in high-power laser facilities, but obtaining accurate estimates of transient velocity is crucial for the method’s effectiveness.

摘要

本研究重点关注高功率激光设施中激光与物质相互作用产生的无法控制的碎片问题，这会严重影响运行效率。碎片的最大运动距离，称为安全距离，是这项工作研究的一个关键参数。提出了三种利用空气动力学系数和轨迹的预测方法，输入参数来自从高分辨率时间分辨图像中提取的速度曲线。^{从这些方法获得的结果与在 18 至 79 J/cm 2}激光能量密度条件下收集的实验数据非常吻合损坏熔融石英的后表面。分析预测的安全距离，输入速度为 0 ns，直径上限为 10 µm，最接近 155 mm 处的实验结果。输入速度为 13,000 ns 且所有直径范围均不超过 192.3 mm 的分析预测值。对于纵横比为 2 和 4 的数值预测值，输入速度为 13,000 ns，小碎片的中值直径 (5 µm) 分别为 140.4 和 295.2 mm。推荐使用数值方法来预测高功率激光设施的安全距离，但获得瞬态速度的准确估计对于该方法的有效性至关重要。