Main chamber wall plasma loads in JET-ITER-like wall at high radiated fraction
Future tokamak reactors of conventional design will require high levels of exhaust power dissipation (more than 90% of the input power) if power densities at the divertor targets are to remain compatible with active cooling. Impurity seeded H-mode discharges in JET-ITER-like Wall (ILW) have reached...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2017-08-01
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| Series: | Nuclear Materials and Energy |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352179116300977 |
| _version_ | 1818694574253539328 |
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| author | C. Guillemaut P. Drewelow G.F. Matthews A.S. Kukushkin R.A. Pitts P. Abreu S. Brezinsek M. Brix P. Carman R. Coelho S. Devaux J. Flanagan C. Giroud D. Harting C.G. Lowry C.F. Maggi F. Militello C. Perez Von Thun E.R. Solano A. Widdowson S. Wiesen M. Wischmeier D. Wood |
| author_facet | C. Guillemaut P. Drewelow G.F. Matthews A.S. Kukushkin R.A. Pitts P. Abreu S. Brezinsek M. Brix P. Carman R. Coelho S. Devaux J. Flanagan C. Giroud D. Harting C.G. Lowry C.F. Maggi F. Militello C. Perez Von Thun E.R. Solano A. Widdowson S. Wiesen M. Wischmeier D. Wood |
| author_sort | C. Guillemaut |
| collection | DOAJ |
| description | Future tokamak reactors of conventional design will require high levels of exhaust power dissipation (more than 90% of the input power) if power densities at the divertor targets are to remain compatible with active cooling. Impurity seeded H-mode discharges in JET-ITER-like Wall (ILW) have reached a maximum radiative fraction (Frad) of ∼75%. Divertor Langmuir probe (LP) measurements in these discharges indicate, however, that less than ∼3% of the thermal plasma power reaches the targets, suggesting a missing channel for power loss. This paper presents experimental evidence from limiter LP for enhanced cross-field particle fluxes on the main chamber walls at high Frad. In H-mode nitrogen-seeded discharges with Frad increasing from ∼30% to up to ∼75%, the main chamber wall particle fluence rises by a factor ∼3 while the divertor plasma fluence drops by one order of magnitude. Contribution of main chamber wall particle losses to detachment, as suggested by EDGE2D-EIRENE modeling, is not sufficient to explain the magnitude of the observed divertor fluence reduction. An intermediate detached case obtained at Frad ∼ 60% with neon seeding is also presented. Heat loads were measured using the main chamber wall thermocouples. Comparison between thermocouple and bolometry measurements shows that the fraction of the input power transported to the main chamber wall remains below ∼5%, whatever the divertor detachment state is. Main chamber sputtering of beryllium by deuterium is reduced in detached conditions only on the low field side. If the fraction of power exhaust dissipated to the main chamber wall by cross-field transport in future reactors is similar to the JET-ILW levels, wall plasma power loading should not be an issue. However, other contributions such as charge exchange may be a problem. |
| first_indexed | 2024-12-17T13:31:44Z |
| format | Article |
| id | doaj.art-7d2754285f6f46f0a33a728bfa0fe115 |
| institution | Directory Open Access Journal |
| issn | 2352-1791 |
| language | English |
| last_indexed | 2024-12-17T13:31:44Z |
| publishDate | 2017-08-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nuclear Materials and Energy |
| spelling | doaj.art-7d2754285f6f46f0a33a728bfa0fe1152022-12-21T21:46:33ZengElsevierNuclear Materials and Energy2352-17912017-08-0112234240Main chamber wall plasma loads in JET-ITER-like wall at high radiated fractionC. Guillemaut0P. Drewelow1G.F. Matthews2A.S. Kukushkin3R.A. Pitts4P. Abreu5S. Brezinsek6M. Brix7P. Carman8R. Coelho9S. Devaux10J. Flanagan11C. Giroud12D. Harting13C.G. Lowry14C.F. Maggi15F. Militello16C. Perez Von Thun17E.R. Solano18A. Widdowson19S. Wiesen20M. Wischmeier21D. Wood22EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB, UK; Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Lisboa, Lisboa, Portugal; Corresponding author at: Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Lisboa, Lisboa, Portugal.Max-Planck-Institut fur Plasmaphysik, Teilinstitut Greifswald, D-17491 Greifswald, GermanyCCFE, Culham Science Centre, Abingdon OX14 3DB, UKNRC Kurshatov Institute, Akademika Kurchatova pl., 123182 Moscow, Russia; NRNU MEPhI, Kashirskoje sh. 31, 115406 Moscow, RussiaITER Organization, Route de Vinon CS 90 046, 13067 Saint-Paul-Lez-Durance, FranceInstituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Lisboa, Lisboa, PortugalForschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung—Plasmaphysik, 52425 Jülich, GermanyCCFE, Culham Science Centre, Abingdon OX14 3DB, UKCCFE, Culham Science Centre, Abingdon OX14 3DB, UKInstituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Lisboa, Lisboa, PortugalInstitut Jean Lamour, UMR7198 CNRS—Université de Lorraine, F-54506 Vandoeuvre-les-Nancy Cedex, FranceCCFE, Culham Science Centre, Abingdon OX14 3DB, UKCCFE, Culham Science Centre, Abingdon OX14 3DB, UKCCFE, Culham Science Centre, Abingdon OX14 3DB, UKEuropean Commission, B-1049 Brussels, BelgiumCCFE, Culham Science Centre, Abingdon OX14 3DB, UKCCFE, Culham Science Centre, Abingdon OX14 3DB, UKForschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung—Plasmaphysik, 52425 Jülich, GermanyLaboratorio Nacional de Fusión, CIEMAT, 28040 Madrid, SpainCCFE, Culham Science Centre, Abingdon OX14 3DB, UKForschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung—Plasmaphysik, 52425 Jülich, GermanyMax-Planck-Institut fur Plasmaphysik, 85748 Garching bei Munchen, GermanyCCFE, Culham Science Centre, Abingdon OX14 3DB, UKFuture tokamak reactors of conventional design will require high levels of exhaust power dissipation (more than 90% of the input power) if power densities at the divertor targets are to remain compatible with active cooling. Impurity seeded H-mode discharges in JET-ITER-like Wall (ILW) have reached a maximum radiative fraction (Frad) of ∼75%. Divertor Langmuir probe (LP) measurements in these discharges indicate, however, that less than ∼3% of the thermal plasma power reaches the targets, suggesting a missing channel for power loss. This paper presents experimental evidence from limiter LP for enhanced cross-field particle fluxes on the main chamber walls at high Frad. In H-mode nitrogen-seeded discharges with Frad increasing from ∼30% to up to ∼75%, the main chamber wall particle fluence rises by a factor ∼3 while the divertor plasma fluence drops by one order of magnitude. Contribution of main chamber wall particle losses to detachment, as suggested by EDGE2D-EIRENE modeling, is not sufficient to explain the magnitude of the observed divertor fluence reduction. An intermediate detached case obtained at Frad ∼ 60% with neon seeding is also presented. Heat loads were measured using the main chamber wall thermocouples. Comparison between thermocouple and bolometry measurements shows that the fraction of the input power transported to the main chamber wall remains below ∼5%, whatever the divertor detachment state is. Main chamber sputtering of beryllium by deuterium is reduced in detached conditions only on the low field side. If the fraction of power exhaust dissipated to the main chamber wall by cross-field transport in future reactors is similar to the JET-ILW levels, wall plasma power loading should not be an issue. However, other contributions such as charge exchange may be a problem.http://www.sciencedirect.com/science/article/pii/S2352179116300977 |
| spellingShingle | C. Guillemaut P. Drewelow G.F. Matthews A.S. Kukushkin R.A. Pitts P. Abreu S. Brezinsek M. Brix P. Carman R. Coelho S. Devaux J. Flanagan C. Giroud D. Harting C.G. Lowry C.F. Maggi F. Militello C. Perez Von Thun E.R. Solano A. Widdowson S. Wiesen M. Wischmeier D. Wood Main chamber wall plasma loads in JET-ITER-like wall at high radiated fraction Nuclear Materials and Energy |
| title | Main chamber wall plasma loads in JET-ITER-like wall at high radiated fraction |
| title_full | Main chamber wall plasma loads in JET-ITER-like wall at high radiated fraction |
| title_fullStr | Main chamber wall plasma loads in JET-ITER-like wall at high radiated fraction |
| title_full_unstemmed | Main chamber wall plasma loads in JET-ITER-like wall at high radiated fraction |
| title_short | Main chamber wall plasma loads in JET-ITER-like wall at high radiated fraction |
| title_sort | main chamber wall plasma loads in jet iter like wall at high radiated fraction |
| url | http://www.sciencedirect.com/science/article/pii/S2352179116300977 |
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