Nanostructure evolution and surface modification of tungsten exposed to low energy, high flux deuterium plasma

• Published in: Fusion engineering and design Vol. 125; pp. 473 - 478
• Main Authors: Guo, Wangguo, Cheng, Long, Wang, Jun, Fu, Qingwei, Qin, Shaoyang, Yuan, Yue, Lu, Guang-Hong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.2017; Elsevier Science Ltd
• Subjects: Amorphous structure; Blistering; Blisters; Deformation; Deuterium; Deuterium plasma; Distortion; Evolution; Exposure; Fluxes; Fusion; Fusion reactors; Morphology; Nano-polycrystalline/amorphous structure; Nanostructure; Nanostructured materials; Nuclear reactors; Plasma; Plasmas; Radiation damage; Structural damage; TEM; Tungsten; Nano-polycrystalline/amorphous structure; Deuterium plasma; TEM; Tungsten
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2017.04.057

•Tungsten TEM specimens and bulk samples were directly exposed to identical deuterium plasmas of different conditions.•Deuterium plasma exposure results in stress-induced distortion, nano-polycrystalline and amorphous structure.•Blistering behaviors change dramatically under different exposure condition, and blister bursting is observed. One of the most important changes of plasma-facing material is plasma-induced damage which limits the material lifetime in fusion reactors. In this study, the influence of exposure conditions on tungsten nanostructure formation and surface modification was investigated. TEM specimens and bulk samples were prepared and exposed to deuterium plasmas with different fluxes (4.0–10.0×1021Dm−2s−1), fluences (2.5–10.0×1025Dm−2) and temperatures (343–513K), while ion energy was constant (60eV). Distortion, nano-polycrystalline and amorphous structure were observed as irradiation damage. Increasing exposure intensity results in severer damage: (1) amorphous structure arises with increasing temperature; (2) deformation region greatly extends at a higher fluence; (3) degree of lattice distortion increases in high flux. Furthermore, surface morphology featured by blisters changes dramatically as well. Nanostructures and surface morphology observation indicates that nanostructure evolution is strongly related to surface modification, and it would influence the properties of tungsten.