Interaction of candidate plasma facing materials with tokamak plasma in COMPASS

0476111 - ÚFP 2018 RIV NL eng J - Článek v odborném periodiku
Matějíček, Jiří - Weinzettl, Vladimír - Macková, Anna - Malinský, Petr - Havránek, Vladimír - Naydenkova, Diana - Klevarová, Veronika - Petersson, P. - Gasior, P. - Hakola, A. - Rubel, M. - Fortuna, E. - Kolehmainen, J. - Tervakangas, S.
Interaction of candidate plasma facing materials with tokamak plasma in COMPASS.
Journal of Nuclear Materials. Roč. 493, September (2017), s. 102-119. ISSN 0022-3115. E-ISSN 1873-4820.
[International Conference on Plasma-Facing Materials and Components for Fusion Applications/15./. Aix-en-Provence, 18.05.2015-22.05.2015]
Grant CEP: GA ČR(CZ) GA14-12837S; GA ČR(CZ) GA15-10723S; GA MŠMT(CZ) LM2015045; GA MŠMT LM2015056
Institucionální podpora: RVO:61389021 ; RVO:61389005
Klíčová slova: erosion * COMPASS tokamak * plasma-material interaction * ion beam analysis
Obor OECD: Nuclear related engineering; Nuclear related engineering (UJF-V)
Impakt faktor: 2.447, rok: 2017
http://www.sciencedirect.com/science/article/pii/S0022311517301708

The interaction of tokamak plasma with several materials considered for the plasma facing components of future fusion devices was studied in a small-size COMPASS tokamak. These included mainly tungsten as the prime candidate and chromium steel as an alternative whose suitability was to be assessed. For the experiments, thin coatings of tungsten, P92 steel and nickel on graphite substrates were prepared by arcdischarge sputtering. The samples were exposed to hydrogen and deuterium plasma discharges in the COMPASS tokamak in two modes: a) short exposure (several discharges) on a manipulator in the proximity of the separatrix, close to the central column, and b) long exposure (several months) at the
central column, aligned with the other graphite tiles. During the discharges, standard plasma diagnostics were used and a local emission of spectral lines in the visible near ultraviolet regions, corresponding to the material erosion, was monitored. Before and after the plasma exposures, the sample surfaces were observed using scanning electron microscopy, the coatings thickness was measured using Rutherford backscattering spectroscopy, and the concentration profiles of hydrogen and deuterium were measured by elastic recoil detection analysis. The uniformity of the coatings and their thickness was verified before the exposure. After the exposure, no reduction of the thickness was observed, indicating the absence of ‘global’ erosion. Erosion was observed only in isolated spots, and attributed to unipolar arcing. Slightly larger erosion was found on
the steel coatings compared to the tungsten ones. Incorporation of deuterium in a thin surface layer was observed, in dependence on the exposure mode. Additionally, boron enrichment of the long-exposure samples was observed, as a result of the tokamak chamber boronization
Trvalý link: http://hdl.handle.net/11104/0272725