Divertor, scrape-off layer and pedestal particle dynamics in the ELM cycle on ASDEX Upgrade

In addition to the relaxation of the pedestal, edge localised modes (ELMs) introduce changes to the divertor and scrape-off layer (SOL) conditions. Their impact on the inter-ELM pedestal recovery is investigated, with emphasis on the electron density (ne) evolution. The typical ELM cycle occurring i...

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Autores: Laggner, F. M., Keerl, S., Gnilsen, J., Wolfrum, E., Bernert, M., Carralero, D., Guimarais, L., Nikolaeva, V., Potzel, S., Cavedon, M., Mink, F., Dunne, M. G., Birkenmeier, G., Fischer, R., Viezzer, Eleonora, Willensdorfer, M., Wischmeier, M., Aumayr, F.
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2018
País:España
Institución:Universidad de Sevilla (US)
Repositorio:idUS. Depósito de Investigación de la Universidad de Sevilla
OAI Identifier:oai:idus.us.es:11441/77885
Acceso en línea:https://hdl.handle.net/11441/77885
https://doi.org/10.1088/1361-6587/aa90bf
Access Level:acceso abierto
Palabra clave:Tokamak
H-mode
Edge localised modes
Profile evolution
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repository_id_str
spelling Divertor, scrape-off layer and pedestal particle dynamics in the ELM cycle on ASDEX UpgradeLaggner, F. M.Keerl, S.Gnilsen, J.Wolfrum, E.Bernert, M.Carralero, D.Guimarais, L.Nikolaeva, V.Potzel, S.Cavedon, M.Mink, F.Dunne, M. G.Birkenmeier, G.Fischer, R.Viezzer, EleonoraWillensdorfer, M.Wischmeier, M.Aumayr, F.TokamakH-modeEdge localised modesProfile evolutionIn addition to the relaxation of the pedestal, edge localised modes (ELMs) introduce changes to the divertor and scrape-off layer (SOL) conditions. Their impact on the inter-ELM pedestal recovery is investigated, with emphasis on the electron density (ne) evolution. The typical ELM cycle occurring in an exemplary ASDEX Upgrade discharge interval at moderate applied gas puff and heating power is characterised, utilising several divertor, SOL and pedestal diagnostics. In the studied discharge interval the inner divertor target is detached before the ELM crash, while the outer target is attached. The particles and power expelled by the ELM crash lead to a reattachment of the inner target plasma. After the ELM crash, the outer divertor target moves into a high recycling regime with large ne in front of the plate, which is accompanied by high main chamber neutral fluxes. On similar timescales, the inner target fully detaches and the high field side high density region (HFSHD) is formed reaching up to the high field side midplane. This state evolves again to the pre-ELM state, when the main chamber neutral fluxes are reduced later in the ELM cycle. Neither the timescale of the appearance of the HFSHD nor the increase of the main chamber neutral fluxes fit the timescale of the ne pedestal, which is faster. It is found that during the ne pedestal recovery, the magnetic activity at the low field side midplane is strongly reduced indicating a lower level of fluctuations. A rough estimation of the particle flux across the pedestal suggests that the particle flux is reduced in this period. In conclusion, the evolution of the ne pedestal is determined by a combination of neutral fluxes, HFSHD and reduced particle flux across the pedestal. A reduced particle flux explains the fast, experimentally observed reestablishment of the ne pedestal best, whereas neutrals and HFSHD impact on the evolution of the SOL and separatrix conditions.European Commission (EUROfusion 633053)IOP PublishingFísica Atómica, Molecular y NuclearEuropean Commission (EC)2018info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionapplication/pdfapplication/pdfhttps://hdl.handle.net/11441/77885https://doi.org/10.1088/1361-6587/aa90bfreponame:idUS. Depósito de Investigación de la Universidad de Sevillainstname:Universidad de Sevilla (US)InglésPlasma Physics and Controlled Fusion, 60, 025002.EUROfusion 633053http://iopscience.iop.org/article/10.1088/1361-6587/aa90bf/metainfo:eu-repo/semantics/openAccessoai:idus.us.es:11441/778852026-06-17T12:51:07Z
dc.title.none.fl_str_mv Divertor, scrape-off layer and pedestal particle dynamics in the ELM cycle on ASDEX Upgrade
title Divertor, scrape-off layer and pedestal particle dynamics in the ELM cycle on ASDEX Upgrade
spellingShingle Divertor, scrape-off layer and pedestal particle dynamics in the ELM cycle on ASDEX Upgrade
Laggner, F. M.
Tokamak
H-mode
Edge localised modes
Profile evolution
title_short Divertor, scrape-off layer and pedestal particle dynamics in the ELM cycle on ASDEX Upgrade
title_full Divertor, scrape-off layer and pedestal particle dynamics in the ELM cycle on ASDEX Upgrade
title_fullStr Divertor, scrape-off layer and pedestal particle dynamics in the ELM cycle on ASDEX Upgrade
title_full_unstemmed Divertor, scrape-off layer and pedestal particle dynamics in the ELM cycle on ASDEX Upgrade
title_sort Divertor, scrape-off layer and pedestal particle dynamics in the ELM cycle on ASDEX Upgrade
dc.creator.none.fl_str_mv Laggner, F. M.
Keerl, S.
Gnilsen, J.
Wolfrum, E.
Bernert, M.
Carralero, D.
Guimarais, L.
Nikolaeva, V.
Potzel, S.
Cavedon, M.
Mink, F.
Dunne, M. G.
Birkenmeier, G.
Fischer, R.
Viezzer, Eleonora
Willensdorfer, M.
Wischmeier, M.
Aumayr, F.
author Laggner, F. M.
author_facet Laggner, F. M.
Keerl, S.
Gnilsen, J.
Wolfrum, E.
Bernert, M.
Carralero, D.
Guimarais, L.
Nikolaeva, V.
Potzel, S.
Cavedon, M.
Mink, F.
Dunne, M. G.
Birkenmeier, G.
Fischer, R.
Viezzer, Eleonora
Willensdorfer, M.
Wischmeier, M.
Aumayr, F.
author_role author
author2 Keerl, S.
Gnilsen, J.
Wolfrum, E.
Bernert, M.
Carralero, D.
Guimarais, L.
Nikolaeva, V.
Potzel, S.
Cavedon, M.
Mink, F.
Dunne, M. G.
Birkenmeier, G.
Fischer, R.
Viezzer, Eleonora
Willensdorfer, M.
Wischmeier, M.
Aumayr, F.
author2_role author
author
author
author
author
author
author
author
author
author
author
author
author
author
author
author
author
dc.contributor.none.fl_str_mv Física Atómica, Molecular y Nuclear
European Commission (EC)
dc.subject.none.fl_str_mv Tokamak
H-mode
Edge localised modes
Profile evolution
topic Tokamak
H-mode
Edge localised modes
Profile evolution
description In addition to the relaxation of the pedestal, edge localised modes (ELMs) introduce changes to the divertor and scrape-off layer (SOL) conditions. Their impact on the inter-ELM pedestal recovery is investigated, with emphasis on the electron density (ne) evolution. The typical ELM cycle occurring in an exemplary ASDEX Upgrade discharge interval at moderate applied gas puff and heating power is characterised, utilising several divertor, SOL and pedestal diagnostics. In the studied discharge interval the inner divertor target is detached before the ELM crash, while the outer target is attached. The particles and power expelled by the ELM crash lead to a reattachment of the inner target plasma. After the ELM crash, the outer divertor target moves into a high recycling regime with large ne in front of the plate, which is accompanied by high main chamber neutral fluxes. On similar timescales, the inner target fully detaches and the high field side high density region (HFSHD) is formed reaching up to the high field side midplane. This state evolves again to the pre-ELM state, when the main chamber neutral fluxes are reduced later in the ELM cycle. Neither the timescale of the appearance of the HFSHD nor the increase of the main chamber neutral fluxes fit the timescale of the ne pedestal, which is faster. It is found that during the ne pedestal recovery, the magnetic activity at the low field side midplane is strongly reduced indicating a lower level of fluctuations. A rough estimation of the particle flux across the pedestal suggests that the particle flux is reduced in this period. In conclusion, the evolution of the ne pedestal is determined by a combination of neutral fluxes, HFSHD and reduced particle flux across the pedestal. A reduced particle flux explains the fast, experimentally observed reestablishment of the ne pedestal best, whereas neutrals and HFSHD impact on the evolution of the SOL and separatrix conditions.
publishDate 2018
dc.date.none.fl_str_mv 2018
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv https://hdl.handle.net/11441/77885
https://doi.org/10.1088/1361-6587/aa90bf
url https://hdl.handle.net/11441/77885
https://doi.org/10.1088/1361-6587/aa90bf
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv Plasma Physics and Controlled Fusion, 60, 025002.
EUROfusion 633053
http://iopscience.iop.org/article/10.1088/1361-6587/aa90bf/meta
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv IOP Publishing
publisher.none.fl_str_mv IOP Publishing
dc.source.none.fl_str_mv reponame:idUS. Depósito de Investigación de la Universidad de Sevilla
instname:Universidad de Sevilla (US)
instname_str Universidad de Sevilla (US)
reponame_str idUS. Depósito de Investigación de la Universidad de Sevilla
collection idUS. Depósito de Investigación de la Universidad de Sevilla
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15.300724

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