On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wall
The impact of the finite grid size in SOLPS-ITER edge plasma simulations is assessed for JET H-mode discharges with a metal wall. For a semi-horizontal divertor configuration it is shown that the separatrix density is at least 30% higher when a narrow scrape-off layer (SOL) grid width is chosen in S...
| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2018-12-01
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| Series: | Nuclear Materials and Energy |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352179118301248 |
| _version_ | 1819030680999297024 |
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| author | S. Wiesen S. Brezinsek X. Bonnin E. Delabie L. Frassinetti M. Groth C. Guillemaut J. Harrison D. Harting S. Henderson A. Huber U. Kruezi R.A. Pitts M. Wischmeier |
| author_facet | S. Wiesen S. Brezinsek X. Bonnin E. Delabie L. Frassinetti M. Groth C. Guillemaut J. Harrison D. Harting S. Henderson A. Huber U. Kruezi R.A. Pitts M. Wischmeier |
| author_sort | S. Wiesen |
| collection | DOAJ |
| description | The impact of the finite grid size in SOLPS-ITER edge plasma simulations is assessed for JET H-mode discharges with a metal wall. For a semi-horizontal divertor configuration it is shown that the separatrix density is at least 30% higher when a narrow scrape-off layer (SOL) grid width is chosen in SOLPS-ITER compared to the case for which the SOL grid width is maximised. The density increase is caused by kinetic neutrals being not confined inside the divertor region because of the reduced extent of the plasma grid. In this case, an enhanced level of reflections of energetic neutrals at the low-field side (LFS) metal divertor wall is observed. This leads to a shift of the ionisation source further upstream which must be accounted for as a numerical artefact. An overestimate in the cooling at the divertor entrance is observed in this case, identified by a reduced heat flux decay parameters λqdiv. Otherwise and further upstream the mid-plane heat decay length λq parameter is not affected by any change in divertor dissipation. This confirms the assumptions made for the ITER divertor design studies, i.e. that λq upstream is essentially set by the assumptions for the ratio radial to parallel heat conductivity. It is also shown that even for attached conditions the decay length relations λne > λTe > λq hold in the near-SOL upstream. Thus for interpretative edge plasma simulations one must take the (experimental) value of λne into account, rather than λq, as the former actually defines the required minimum upstream SOL grid extent. Keywords: edge plasma, modelling, SOLPS-ITER, JET, divertor |
| first_indexed | 2024-12-21T06:34:01Z |
| format | Article |
| id | doaj.art-7d4de7f8007d4b0abc30ab7d0bd46698 |
| institution | Directory Open Access Journal |
| issn | 2352-1791 |
| language | English |
| last_indexed | 2024-12-21T06:34:01Z |
| publishDate | 2018-12-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nuclear Materials and Energy |
| spelling | doaj.art-7d4de7f8007d4b0abc30ab7d0bd466982022-12-21T19:12:55ZengElsevierNuclear Materials and Energy2352-17912018-12-0117174181On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wallS. Wiesen0S. Brezinsek1X. Bonnin2E. Delabie3L. Frassinetti4M. Groth5C. Guillemaut6J. Harrison7D. Harting8S. Henderson9A. Huber10U. Kruezi11R.A. Pitts12M. Wischmeier13Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung – Plasmaphysik, 52425 Jülich, Germany; Corresponding author.Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung – Plasmaphysik, 52425 Jülich, GermanyITER Organization, Route de Vinon sur Verdon, CS90 046, 13067 St Paul Lez Durance, Cedex, FranceOak Ridge National Laboratory, Oak Ridge, TN 37831-6169, USAAssociation VR, Fusion Plasma Physics, KTH, SE-10044 Stockholm, SwedenAalto University, Espoo, FinlandInstituto de Plasmas e Fusão Nuclear, IST, Universidade de Lisboa, P-1049-001 Lisboa, PortugalCCFE, Culham Science Centre, Abingdon OX14 3DB, UKCCFE, Culham Science Centre, Abingdon OX14 3DB, UKCCFE, Culham Science Centre, Abingdon OX14 3DB, UKForschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung – Plasmaphysik, 52425 Jülich, GermanyITER Organization, Route de Vinon sur Verdon, CS90 046, 13067 St Paul Lez Durance, Cedex, FranceITER Organization, Route de Vinon sur Verdon, CS90 046, 13067 St Paul Lez Durance, Cedex, FranceMax-Planck-Institut für Plasmaphysik, 85748 Garching bei München, GermanyThe impact of the finite grid size in SOLPS-ITER edge plasma simulations is assessed for JET H-mode discharges with a metal wall. For a semi-horizontal divertor configuration it is shown that the separatrix density is at least 30% higher when a narrow scrape-off layer (SOL) grid width is chosen in SOLPS-ITER compared to the case for which the SOL grid width is maximised. The density increase is caused by kinetic neutrals being not confined inside the divertor region because of the reduced extent of the plasma grid. In this case, an enhanced level of reflections of energetic neutrals at the low-field side (LFS) metal divertor wall is observed. This leads to a shift of the ionisation source further upstream which must be accounted for as a numerical artefact. An overestimate in the cooling at the divertor entrance is observed in this case, identified by a reduced heat flux decay parameters λqdiv. Otherwise and further upstream the mid-plane heat decay length λq parameter is not affected by any change in divertor dissipation. This confirms the assumptions made for the ITER divertor design studies, i.e. that λq upstream is essentially set by the assumptions for the ratio radial to parallel heat conductivity. It is also shown that even for attached conditions the decay length relations λne > λTe > λq hold in the near-SOL upstream. Thus for interpretative edge plasma simulations one must take the (experimental) value of λne into account, rather than λq, as the former actually defines the required minimum upstream SOL grid extent. Keywords: edge plasma, modelling, SOLPS-ITER, JET, divertorhttp://www.sciencedirect.com/science/article/pii/S2352179118301248 |
| spellingShingle | S. Wiesen S. Brezinsek X. Bonnin E. Delabie L. Frassinetti M. Groth C. Guillemaut J. Harrison D. Harting S. Henderson A. Huber U. Kruezi R.A. Pitts M. Wischmeier On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wall Nuclear Materials and Energy |
| title | On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wall |
| title_full | On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wall |
| title_fullStr | On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wall |
| title_full_unstemmed | On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wall |
| title_short | On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wall |
| title_sort | on the role of finite grid extent in solps iter edge plasma simulations for jet h mode discharges with metallic wall |
| url | http://www.sciencedirect.com/science/article/pii/S2352179118301248 |
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