Wong Chun-Shang, Kolasinski Robert D, Whaley Josh A
Sandia National Laboratories, Livermore, CA 94551, United States of America.
J Phys Condens Matter. 2021 Jan 6;33(1):015001. doi: 10.1088/1361-648X/abb897.
Helium ion beam interactions with materials have important implications for magnetic confinement fusion, material modification, and helium ion microscopy. These interactions depend on the precise physics of how helium ions channel into the materials, which can vary greatly based on the local crystalline orientation. In this work, we performed a dedicated experiment to investigate helium ion channeling in a well-characterized tungsten single crystal. Time-of-flight impact-collision ion scattering spectroscopy was used to obtain multi-angle maps of the backscattering intensity for 3 keV He → W(111). We found that the backscattering intensity profile arising from helium ion channeling could be well described by a shadow cone analysis. This analysis revealed that subsurface W atoms as deep as the ninth monolayer contributed to the backscattering intensity profile. Binary collision approximation simulations were performed with MARLOWE to model the experimental maps with sufficient accuracy to allow for quantitative comparisons using reliability factors. These quantitative comparisons were applied to investigate how the W lattice structure and He-W interatomic potential affect the multi-angle maps.
氦离子与材料的相互作用对磁约束聚变、材料改性和氦离子显微镜具有重要意义。这些相互作用取决于氦离子如何精确地通道化进入材料的物理过程，这会因局部晶体取向的不同而有很大差异。在这项工作中，我们进行了一项专门的实验，以研究在特征明确的钨单晶中的氦离子通道化现象。利用飞行时间碰撞离子散射光谱法获得了3 keV He → W(111)的背散射强度多角度图谱。我们发现，由氦离子通道化产生的背散射强度分布可以通过阴影锥分析很好地描述。该分析表明，深度达第九个单层的次表面钨原子对背散射强度分布有贡献。使用MARLOWE进行了二元碰撞近似模拟，以足够的精度对实验图谱进行建模，从而能够使用可靠性因子进行定量比较。这些定量比较被用于研究钨晶格结构和He-W原子间势如何影响多角度图谱。
