Long-term erosion of plasma-facing materials with different surface roughness in ASDEX Upgrade

Antti Hakola (Corresponding Author), Juuso Karhunen, Seppo Koivuranta, Jari Likonen, M. Balden, A. Herrmann, M. Mayer, H.W. Müller, R. Neu, V. Rohde, K. Sugiyama, ASDEX Upgrade Team

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    Abstract

    The effect of surface roughness on the long-term erosion patterns of tungsten coatings was investigated in the outer strike-point region of ASDEX Upgrade during its 2010–11 plasma operations. The net erosion rates of rough coatings (Ra = 5–6 μm) were three to seven times smaller than those of smooth coatings (Ra = 0.4–0.8 μm). This is because rough surfaces are largely modified and damaged in the microscopic scale but the material is re-deposited together with boron, deuterium and carbon on the shadowed sides of the most prominent surface features. In addition, we observed that W coatings were eroded on average at a rate of 0.03 nm s−1, which was three to four times smaller than the value for Cr, simulating here steel.
    Original languageEnglish
    Article number014027
    Number of pages5
    JournalPhysica Scripta
    Issue numberT159
    DOIs
    Publication statusPublished - 2014
    MoE publication typeA1 Journal article-refereed
    Event14th International conference on plasma-facing materials and components for fusion applications: PFMC-14 - Jülich, Germany
    Duration: 13 May 201317 May 2013

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    Hakola, A., Karhunen, J., Koivuranta, S., Likonen, J., Balden, M., Herrmann, A., Mayer, M., Müller, H. W., Neu, R., Rohde, V., Sugiyama, K., & ASDEX Upgrade Team (2014). Long-term erosion of plasma-facing materials with different surface roughness in ASDEX Upgrade. Physica Scripta, (T159), [014027]. https://doi.org/10.1088/0031-8949/2014/T159/014027