Nitrogen transport in ASDEX Upgrade: Role of surface roughness and transport to the main wall
We have studied the retention of nitrogen in surfaces with varying roughness and the transport of nitrogen from the divertor to the outer midplane in experiments at the tokamak ASDEX Upgrade. To allow for a reliable identification of nitrogen retained from the plasma exposure, 5.3 · 1021 atoms of th...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2017-08-01
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| Series: | Nuclear Materials and Energy |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352179116301636 |
| _version_ | 1818984272514514944 |
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| author | G. Meisl M. Oberkofler A. Hakola K. Krieger K. Schmid S.W. Lisgo M. Mayer A. Lahtinen A. Drenik S. Potzel L. Aho-Mantila ASDEX Upgrade Team |
| author_facet | G. Meisl M. Oberkofler A. Hakola K. Krieger K. Schmid S.W. Lisgo M. Mayer A. Lahtinen A. Drenik S. Potzel L. Aho-Mantila ASDEX Upgrade Team |
| author_sort | G. Meisl |
| collection | DOAJ |
| description | We have studied the retention of nitrogen in surfaces with varying roughness and the transport of nitrogen from the divertor to the outer midplane in experiments at the tokamak ASDEX Upgrade. To allow for a reliable identification of nitrogen retained from the plasma exposure, 5.3 · 1021 atoms of the tracer isotope 15N were injected into the private flux region of the plasma. On polished W samples exposed to the plasma in the outer divertor, the N content peaks to both sides of the strike line with an areal density of 1.5 · 1020 15N/m2 and drops to a value of 1.0 · 1020 15N/m2 in the strike line region. In contrast, the N content of samples with a rougher surface peaks at the strike line and reaches areal densities of 3.0 · 1020 15N/m2. The N deposition at the outer limiters was measured via samples exposed on the midplane manipulator. At the limiter position the 15N areal density reaches a value of 0.2 · 1020 15N/m2, only a factor of ten smaller than the areal densities in the divertor. However, a comparison to WallDYN simulations shows that the observed N content is roughly a factor of 4 smaller than the value predicted by these simulations. Possible reasons for this discrepancy are the toroidal asymmetric main wall geometry, which currently cannot be fully included in the simulations, or an enhanced re-erosion of deposited N. Keywords: Tokamak, Impurity migration, Nitrogen, Roughness, WallDYN |
| first_indexed | 2024-12-20T18:16:22Z |
| format | Article |
| id | doaj.art-50324dba111f428baae3a45271cac886 |
| institution | Directory Open Access Journal |
| issn | 2352-1791 |
| language | English |
| last_indexed | 2024-12-20T18:16:22Z |
| publishDate | 2017-08-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nuclear Materials and Energy |
| spelling | doaj.art-50324dba111f428baae3a45271cac8862022-12-21T19:30:21ZengElsevierNuclear Materials and Energy2352-17912017-08-01125159Nitrogen transport in ASDEX Upgrade: Role of surface roughness and transport to the main wallG. Meisl0M. Oberkofler1A. Hakola2K. Krieger3K. Schmid4S.W. Lisgo5M. Mayer6A. Lahtinen7A. Drenik8S. Potzel9L. Aho-Mantila10ASDEX Upgrade Team11Corresponding author.; Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching, GermanyMax-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching, GermanyVTT Technical Research Centre of Finland, P.O.Box 1000, FI-02044 VTT, FinlandMax-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching, GermanyMax-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching, GermanyITER Organization, FST, Route de Vinon, CS 90 046, 13067 Saint Paul Lez Durance Cedex, FranceMax-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching, GermanyVTT Technical Research Centre of Finland, P.O.Box 1000, FI-02044 VTT, FinlandMax-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching, GermanyMax-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching, GermanyVTT Technical Research Centre of Finland, P.O.Box 1000, FI-02044 VTT, FinlandMax-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching, GermanyWe have studied the retention of nitrogen in surfaces with varying roughness and the transport of nitrogen from the divertor to the outer midplane in experiments at the tokamak ASDEX Upgrade. To allow for a reliable identification of nitrogen retained from the plasma exposure, 5.3 · 1021 atoms of the tracer isotope 15N were injected into the private flux region of the plasma. On polished W samples exposed to the plasma in the outer divertor, the N content peaks to both sides of the strike line with an areal density of 1.5 · 1020 15N/m2 and drops to a value of 1.0 · 1020 15N/m2 in the strike line region. In contrast, the N content of samples with a rougher surface peaks at the strike line and reaches areal densities of 3.0 · 1020 15N/m2. The N deposition at the outer limiters was measured via samples exposed on the midplane manipulator. At the limiter position the 15N areal density reaches a value of 0.2 · 1020 15N/m2, only a factor of ten smaller than the areal densities in the divertor. However, a comparison to WallDYN simulations shows that the observed N content is roughly a factor of 4 smaller than the value predicted by these simulations. Possible reasons for this discrepancy are the toroidal asymmetric main wall geometry, which currently cannot be fully included in the simulations, or an enhanced re-erosion of deposited N. Keywords: Tokamak, Impurity migration, Nitrogen, Roughness, WallDYNhttp://www.sciencedirect.com/science/article/pii/S2352179116301636 |
| spellingShingle | G. Meisl M. Oberkofler A. Hakola K. Krieger K. Schmid S.W. Lisgo M. Mayer A. Lahtinen A. Drenik S. Potzel L. Aho-Mantila ASDEX Upgrade Team Nitrogen transport in ASDEX Upgrade: Role of surface roughness and transport to the main wall Nuclear Materials and Energy |
| title | Nitrogen transport in ASDEX Upgrade: Role of surface roughness and transport to the main wall |
| title_full | Nitrogen transport in ASDEX Upgrade: Role of surface roughness and transport to the main wall |
| title_fullStr | Nitrogen transport in ASDEX Upgrade: Role of surface roughness and transport to the main wall |
| title_full_unstemmed | Nitrogen transport in ASDEX Upgrade: Role of surface roughness and transport to the main wall |
| title_short | Nitrogen transport in ASDEX Upgrade: Role of surface roughness and transport to the main wall |
| title_sort | nitrogen transport in asdex upgrade role of surface roughness and transport to the main wall |
| url | http://www.sciencedirect.com/science/article/pii/S2352179116301636 |
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