I-mode pedestal relaxation events at ASDEX Upgrade

The I-mode confinement regime can feature small edge temperature drops that can lead to an increase in the energy deposited onto the divertor targets. In this work, we show that these events are associated with a relaxation of both electron temperature and density edge profiles, with the largest dro...

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Autores: Silvagni, D., Eich, T., Happel, T., Harrer, G. F., Griener, M., Dunne, M. G., Cavedon, M., Faitsch, M., Viezzer, Eleonora
Tipo de recurso: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2020
País:España
Institución:Universidad de Sevilla (US)
Repositorio:idUS. Depósito de Investigación de la Universidad de Sevilla
OAI Identifier:oai:idus.us.es:11441/131735
Acceso en línea:https://hdl.handle.net/11441/131735
https://doi.org/10.1088/1741-4326/abb423
Access Level:acceso abierto
Palabra clave:I-mode
pedestal
power exhaust
tokamaks
elm
scrape-off layer
plasma boundary
id ES_5d4e81d834f9ba952d2077bef48ccceb
oai_identifier_str oai:idus.us.es:11441/131735
network_acronym_str ES
network_name_str España
repository_id_str
spelling I-mode pedestal relaxation events at ASDEX UpgradeSilvagni, D.Eich, T.Happel, T.Harrer, G. F.Griener, M.Dunne, M. G.Cavedon, M.Faitsch, M.Viezzer, EleonoraI-modepedestalpower exhausttokamakselmscrape-off layerplasma boundaryThe I-mode confinement regime can feature small edge temperature drops that can lead to an increase in the energy deposited onto the divertor targets. In this work, we show that these events are associated with a relaxation of both electron temperature and density edge profiles, with the largest drop found at the pedestal top position. The relative energy loss is about 1 %, and is thus lower than that of type-I ELMs for the same pedestal top collisionality. Stability analysis of edge profiles reveals that the operational points are far from the ideal peeling-ballooning boundary. Also, we show that these events appear close to the H-mode transition in the typical I-mode operational space in ASDEX Upgrade, and that no further enhancement of energy confinement is found when they occur. Moreover, scrape-off layer transport during these events is found to be very similar to type-I ELMs, with regard to timescales (≈ 800 µs), filament propagation, toroidally asymmetric energy effluxes at the midplane and asymmetry between inner and outer divertor deposited energy. In particular, the latter reveals that more energy reaches the outer divertor target. Lastly, first measurements of the divertor peak energy fluence are reported, and projections to ARC—a reactor that could potentially operate in I-mode—are drawn.EUROfusion Consortium Grant Agreement No. 633053IOP PublishingFísica Atómica, Molecular y NuclearEUROfusion Consortium2020info:eu-repo/semantics/articleinfo:eu-repo/semantics/acceptedVersionapplication/pdfapplication/pdfhttps://hdl.handle.net/11441/131735https://doi.org/10.1088/1741-4326/abb423reponame:idUS. Depósito de Investigación de la Universidad de Sevillainstname:Universidad de Sevilla (US)InglésNuclear Fusion, 60 (12), 126028.633053https://dx.doi.org/10.1088/1741-4326/abb423info:eu-repo/semantics/openAccessoai:idus.us.es:11441/1317352026-06-17T12:51:07Z
dc.title.none.fl_str_mv I-mode pedestal relaxation events at ASDEX Upgrade
title I-mode pedestal relaxation events at ASDEX Upgrade
spellingShingle I-mode pedestal relaxation events at ASDEX Upgrade
Silvagni, D.
I-mode
pedestal
power exhaust
tokamaks
elm
scrape-off layer
plasma boundary
title_short I-mode pedestal relaxation events at ASDEX Upgrade
title_full I-mode pedestal relaxation events at ASDEX Upgrade
title_fullStr I-mode pedestal relaxation events at ASDEX Upgrade
title_full_unstemmed I-mode pedestal relaxation events at ASDEX Upgrade
title_sort I-mode pedestal relaxation events at ASDEX Upgrade
dc.creator.none.fl_str_mv Silvagni, D.
Eich, T.
Happel, T.
Harrer, G. F.
Griener, M.
Dunne, M. G.
Cavedon, M.
Faitsch, M.
Viezzer, Eleonora
author Silvagni, D.
author_facet Silvagni, D.
Eich, T.
Happel, T.
Harrer, G. F.
Griener, M.
Dunne, M. G.
Cavedon, M.
Faitsch, M.
Viezzer, Eleonora
author_role author
author2 Eich, T.
Happel, T.
Harrer, G. F.
Griener, M.
Dunne, M. G.
Cavedon, M.
Faitsch, M.
Viezzer, Eleonora
author2_role author
author
author
author
author
author
author
author
dc.contributor.none.fl_str_mv Física Atómica, Molecular y Nuclear
EUROfusion Consortium
dc.subject.none.fl_str_mv I-mode
pedestal
power exhaust
tokamaks
elm
scrape-off layer
plasma boundary
topic I-mode
pedestal
power exhaust
tokamaks
elm
scrape-off layer
plasma boundary
description The I-mode confinement regime can feature small edge temperature drops that can lead to an increase in the energy deposited onto the divertor targets. In this work, we show that these events are associated with a relaxation of both electron temperature and density edge profiles, with the largest drop found at the pedestal top position. The relative energy loss is about 1 %, and is thus lower than that of type-I ELMs for the same pedestal top collisionality. Stability analysis of edge profiles reveals that the operational points are far from the ideal peeling-ballooning boundary. Also, we show that these events appear close to the H-mode transition in the typical I-mode operational space in ASDEX Upgrade, and that no further enhancement of energy confinement is found when they occur. Moreover, scrape-off layer transport during these events is found to be very similar to type-I ELMs, with regard to timescales (≈ 800 µs), filament propagation, toroidally asymmetric energy effluxes at the midplane and asymmetry between inner and outer divertor deposited energy. In particular, the latter reveals that more energy reaches the outer divertor target. Lastly, first measurements of the divertor peak energy fluence are reported, and projections to ARC—a reactor that could potentially operate in I-mode—are drawn.
publishDate 2020
dc.date.none.fl_str_mv 2020
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
format article
status_str acceptedVersion
dc.identifier.none.fl_str_mv https://hdl.handle.net/11441/131735
https://doi.org/10.1088/1741-4326/abb423
url https://hdl.handle.net/11441/131735
https://doi.org/10.1088/1741-4326/abb423
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv Nuclear Fusion, 60 (12), 126028.
633053
https://dx.doi.org/10.1088/1741-4326/abb423
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 15,301603

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