Influence of surface morphology on erosion of plasma-facing components in H-mode plasmas of ASDEX Upgrade
Net erosion of plasma-facing materials was investigated at the low-field-side (outer) strike-point area of the ASDEX Upgrade (AUG) divertor during H-mode discharges with small and frequent ELMs. To this end, Au and Mo marker samples with different surface morphologies and geometries were exposed to...
| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2022-10-01
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| Series: | Nuclear Materials and Energy |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352179122001478 |
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| author | A. Lahtinen A. Hakola J. Likonen M. Balden K. Krieger S. Gouasmia I. Bogdanovic Radovic G. Provatas M. Kelemen S. Markelj M. Pedroni A. Uccello E. Vassallo D. Dellasega M. Passoni |
| author_facet | A. Lahtinen A. Hakola J. Likonen M. Balden K. Krieger S. Gouasmia I. Bogdanovic Radovic G. Provatas M. Kelemen S. Markelj M. Pedroni A. Uccello E. Vassallo D. Dellasega M. Passoni |
| author_sort | A. Lahtinen |
| collection | DOAJ |
| description | Net erosion of plasma-facing materials was investigated at the low-field-side (outer) strike-point area of the ASDEX Upgrade (AUG) divertor during H-mode discharges with small and frequent ELMs. To this end, Au and Mo marker samples with different surface morphologies and geometries were exposed to plasmas using the DIM-II divertor manipulator. The results were compared to existing erosion and deposition patterns from various L- and H-mode experiments, in the latter case the main difference was the size and frequency of the ELMs.We noticed that increasing surface roughness reduces net erosion but less than what is the case in L-mode. On the other hand, net-erosion rates in H-mode are generally 2–5 times higher than the corresponding L-mode values, in addition to which exposure in H-mode conditions results in strong local variations in the poloidal and toroidal erosion/deposition profiles. The latter observation we associate with the large migration length, on the order of several cm, of the eroded material, resulting in strong competition between erosion and re-deposition processes especially at poloidal distances > 50 mm from the strike point. Considerable net erosion was measured throughout the analysed poloidal region unlike in L-mode where the main erosion peak occurs in the vicinity of the strike point. We attribute this qualitative difference to the slow decay lengths of the plasma flux and electron temperature in the applied H-mode scenario.Both erosion and deposition require detailed analyses at the microscopic scale and the deposition patterns may be drastically different for heavy and light impurities. Generally, the rougher the surface the more material will accumulate on locally shadowed regions behind protruding surface features. However, rough surfaces also exhibit more non-uniformities in the quality or even integrity of marker coatings produced on them, thus complicating the analyses of the experimental data.We conclude that local plasma parameters have a huge impact on the PFC erosion rates and, besides incident plasma flux, surface morphology and its temporal evolution have to be taken into account for quantitative estimates of erosion rates and PFC lifetime under reactor-relevant conditions. |
| first_indexed | 2024-04-13T23:17:02Z |
| format | Article |
| id | doaj.art-09a4f26159984452a9f04c7469b10779 |
| institution | Directory Open Access Journal |
| issn | 2352-1791 |
| language | English |
| last_indexed | 2024-04-13T23:17:02Z |
| publishDate | 2022-10-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nuclear Materials and Energy |
| spelling | doaj.art-09a4f26159984452a9f04c7469b107792022-12-22T02:25:22ZengElsevierNuclear Materials and Energy2352-17912022-10-0133101266Influence of surface morphology on erosion of plasma-facing components in H-mode plasmas of ASDEX UpgradeA. Lahtinen0A. Hakola1J. Likonen2M. Balden3K. Krieger4S. Gouasmia5I. Bogdanovic Radovic6G. Provatas7M. Kelemen8S. Markelj9M. Pedroni10A. Uccello11E. Vassallo12D. Dellasega13M. Passoni14VTT, P. O. Box 1000, 02044 VTT, FinlandVTT, P. O. Box 1000, 02044 VTT, Finland; Corresponding author at: VTT, P. O. Box 1000, 02044 VTT, Finland.VTT, P. O. Box 1000, 02044 VTT, FinlandMax-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, GermanyMax-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, GermanyRuder Boskovic Institute, Bijenicka 54, 10000 Zagreb, CroatiaRuder Boskovic Institute, Bijenicka 54, 10000 Zagreb, CroatiaRuder Boskovic Institute, Bijenicka 54, 10000 Zagreb, CroatiaJozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, SloveniaJozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, SloveniaIstituto per la Scienza e Tecnologia dei Plasmi CNR, Milan, ItalyIstituto per la Scienza e Tecnologia dei Plasmi CNR, Milan, ItalyIstituto per la Scienza e Tecnologia dei Plasmi CNR, Milan, ItalyPolitecnico di Milano, Department of Energy, Milan, ItalyPolitecnico di Milano, Department of Energy, Milan, ItalyNet erosion of plasma-facing materials was investigated at the low-field-side (outer) strike-point area of the ASDEX Upgrade (AUG) divertor during H-mode discharges with small and frequent ELMs. To this end, Au and Mo marker samples with different surface morphologies and geometries were exposed to plasmas using the DIM-II divertor manipulator. The results were compared to existing erosion and deposition patterns from various L- and H-mode experiments, in the latter case the main difference was the size and frequency of the ELMs.We noticed that increasing surface roughness reduces net erosion but less than what is the case in L-mode. On the other hand, net-erosion rates in H-mode are generally 2–5 times higher than the corresponding L-mode values, in addition to which exposure in H-mode conditions results in strong local variations in the poloidal and toroidal erosion/deposition profiles. The latter observation we associate with the large migration length, on the order of several cm, of the eroded material, resulting in strong competition between erosion and re-deposition processes especially at poloidal distances > 50 mm from the strike point. Considerable net erosion was measured throughout the analysed poloidal region unlike in L-mode where the main erosion peak occurs in the vicinity of the strike point. We attribute this qualitative difference to the slow decay lengths of the plasma flux and electron temperature in the applied H-mode scenario.Both erosion and deposition require detailed analyses at the microscopic scale and the deposition patterns may be drastically different for heavy and light impurities. Generally, the rougher the surface the more material will accumulate on locally shadowed regions behind protruding surface features. However, rough surfaces also exhibit more non-uniformities in the quality or even integrity of marker coatings produced on them, thus complicating the analyses of the experimental data.We conclude that local plasma parameters have a huge impact on the PFC erosion rates and, besides incident plasma flux, surface morphology and its temporal evolution have to be taken into account for quantitative estimates of erosion rates and PFC lifetime under reactor-relevant conditions.http://www.sciencedirect.com/science/article/pii/S2352179122001478ErosionMaterial migrationASDEX UpgradeH-modeMarker samples |
| spellingShingle | A. Lahtinen A. Hakola J. Likonen M. Balden K. Krieger S. Gouasmia I. Bogdanovic Radovic G. Provatas M. Kelemen S. Markelj M. Pedroni A. Uccello E. Vassallo D. Dellasega M. Passoni Influence of surface morphology on erosion of plasma-facing components in H-mode plasmas of ASDEX Upgrade Nuclear Materials and Energy Erosion Material migration ASDEX Upgrade H-mode Marker samples |
| title | Influence of surface morphology on erosion of plasma-facing components in H-mode plasmas of ASDEX Upgrade |
| title_full | Influence of surface morphology on erosion of plasma-facing components in H-mode plasmas of ASDEX Upgrade |
| title_fullStr | Influence of surface morphology on erosion of plasma-facing components in H-mode plasmas of ASDEX Upgrade |
| title_full_unstemmed | Influence of surface morphology on erosion of plasma-facing components in H-mode plasmas of ASDEX Upgrade |
| title_short | Influence of surface morphology on erosion of plasma-facing components in H-mode plasmas of ASDEX Upgrade |
| title_sort | influence of surface morphology on erosion of plasma facing components in h mode plasmas of asdex upgrade |
| topic | Erosion Material migration ASDEX Upgrade H-mode Marker samples |
| url | http://www.sciencedirect.com/science/article/pii/S2352179122001478 |
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