The ability of laser pulse was tested for controlled ablation of the copper alloy (CuCrZr) and nanometer-thick impurity layer on the rear surface of a glass window. The target surface was moved across the focus point (FP) to vary the distance from the FP within the depth-of-focus (DOF) of the focusing lens. An Nd:YAG laser was used at its fundamental wavelength of 1064 nm in this experiment. The controlled ablation was performed to remove the impurity from the rear surface of a glass window that was taken from the H-port of the EAST tokamak. The morphology of the laser-produced craters was measured using the 3D laser scanning confocal microscope and scanning electron microscope. The depth and diameter of the craters varied according to the laser energy which focused on the unit area. The spectral intensity increases as the distance from the FP decreases. The threshold fluence values for ablation, ignition of the plasma, and spectral emission were investigated. The laser pulse energy focused before and after the FP resulted in different ablation behaviors, crater morphologies, and spectral intensity. The precise removal of impurities from the rear surface was performed at − 2 mm from the FP. The laser ablation with variable fluence can further improve the selective ablation of impurity deposition to investigate the surface of the plasma-facing components.

测试了激光脉冲对玻璃窗后表面上的铜合金 (CuCrZr) 和纳米厚杂质层进行受控烧蚀的能力。目标表面在焦点 (FP) 上移动，以在聚焦透镜的焦深 (DOF) 范围内改变距 FP 的距离。本实验中使用的 Nd:YAG 激光器的基本波长为 1064 nm。进行受控烧蚀是为了去除取自 EAST 托卡马克 H 端口的玻璃窗后表面的杂质。使用3D激光扫描共焦显微镜和扫描电子显微镜测量激光产生的弹坑的形态。凹坑的深度和直径根据聚焦在单位面积上的激光能量而变化。光谱强度随着距 FP 距离的减小而增加。研究了烧蚀、等离子体点燃和光谱发射的阈值注量值。FP 前后聚焦的激光脉冲能量导致不同的烧蚀行为、凹坑形态和光谱强度。背面杂质的精确去除是在距 FP − 2 mm 处进行的。可变注量的激光烧蚀可以进一步提高杂质沉积的选择性烧蚀，以研究面向等离子体的部件的表面。