Center for Materials Under eXtreme Environment (CMUXE), School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907, USA.
Sci Rep. 2016 Dec 23;6:39746. doi: 10.1038/srep39746.
The goal of this work is to assess Ta as a potential plasma-facing material for future fusion reactors in terms of its response to high-flux, low-energy He ion irradiation. Ta samples were irradiated with 100 eV He ions at various fluences up to 3.5 × 10 ions m while simultaneously heated at constant temperatures in the range 823-1223 K. SEM studies show that irradiated Ta surfaces undergo significant morphology changes that have a strong dependence on both ion fluence and sample temperature. Optical reflectivity complements SEM and demonstrates a vertical growth of surface structures with increasing fluence. Ex situ XPS and XRD both show significant oxidation of the irradiated Ta surfaces, giving further qualitative information on the extent of surface modification. Overall, these irradiation-induced structures on Ta are similar to early-stage "fuzz" structures observed in W. However, Ta exhibits a higher fluence threshold for structure formation. While Ta may have less desirable bulk properties (e.g., thermal conductivity) when compared to W, its higher resilience to He ion-induced surface modification suggests that surface thermal and mechanical properties may not degrade as quickly in extreme fusion environments; this quality may be a redeeming factor for Ta as a plasma-facing material.
这项工作的目的是评估 Ta 在高通量、低能 He 离子辐照下对未来聚变反应堆作为等离子体面对材料的反应。在 823-1223 K 的恒定温度下，用 100 eV He 离子以不同的通量辐照 Ta 样品，最高达到 3.5×10 离子/m。SEM 研究表明，辐照后的 Ta 表面发生了显著的形貌变化，这强烈依赖于离子通量和样品温度。光学反射率补充了 SEM，并显示出随着通量的增加表面结构的垂直生长。原位 XPS 和 XRD 都表明辐照 Ta 表面发生了明显的氧化，进一步提供了关于表面改性程度的定性信息。总的来说，这些在 Ta 上的辐照诱导结构类似于在 W 中观察到的早期“绒毛”结构。然而，Ta 形成结构的通量阈值较高。虽然与 W 相比，Ta 的体性质（如导热系数）较差，但它对 He 离子诱导的表面改性具有更高的抵抗力，这表明在极端聚变环境中，表面热和机械性能可能不会迅速退化；这种质量可能是 Ta 作为等离子体面对材料的一个可取因素。
