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FP7

The impact of large ELMs on JET

Funded under: FP7-EURATOM

Abstract

To ensure sufficient divertor target lifetime, the loss in plasma stored energy due to ELMs in ITER should be restricted to DELTA W(ELM) </= 1 MJ. Only in JET, by virtue of its size, can such energies be approached. This contribution examines the impact of large, Type I ELMs in high current H-mode JET discharges with ITER-relevant pedestal characteristics. The ELMs provoke strong radiation losses, mostly confined to the inner divertor volume. Although the data are scattered, the average magnitude of this loss is DELTA E(RAD) ~ 0.5DELTA W(ELM), for DELTA W(ELM) < 0.55 MJ. For higher DELTA W(ELM), greater fractional radiation losses occur, reaching ~ 0.7DELTA W(ELM) at DELTA W(ELM) ~ 0.9 MJ, indicating enhanced impurity release. Even at the highest ELM energies, peak divertor target surface temperatures are too low for carbon sublimation, suggesting that thermal decomposition and/or ablation of thick co-deposited layers on the inner target may be occurring. On average, across the range of energies studied, ELMs are found to deposit between 3-4.5% of DELTA W(ELM) on main wall limiters. When applied to the data for a specific discharge in the series, the model of ELM filament parallel energy losses developed at JET requires radial ELM velocities in the interval 0.1-0.65 km s{-1} to explain these deposited energy fractions.

Additional information

Authors: PITTS R A, EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);ARNOUX G, EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);BEURSKENS M, EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);FUNDAMENSKI W, EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);STAMP M F, EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);ANDREW P, EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);MATTHEWS G F, EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);MARKI J, Centre de Recherches en Physique des Plasmas, Association EURATOM-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne (CH);GULEJOVA B, Centre de Recherches en Physique des Plasmas, Association EURATOM-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne (CH);EICH T, Max-Planck-Institut für Plasmaphysik, IPP-EURATOM Association, Garching (DE);HUBER A, Institut für Plasmaphysik, Forschungszentrum Jülich, Association EURATOM/FZJ, Trilateral Euregio Cluster, Jülich (DE);BERZINSEK S, Institut für Plasmaphysik, Forschungszentrum Jülich, Association EURATOM/FZJ, Trilateral Euregio Cluster, Jülich (DE);ESSER H G, Institut für Plasmaphysik, Forschungszentrum Jülich, Association EURATOM/FZJ, Trilateral Euregio Cluster, Jülich (DE);KRETER A, Institut für Plasmaphysik, Forschungszentrum Jülich, Association EURATOM/FZJ, Trilateral Euregio Cluster, Jülich (DE);PHILIPPS V, Institut für Plasmaphysik, Forschungszentrum Jülich, Association EURATOM/FZJ, Trilateral Euregio Cluster, Jülich (DE);LOARTE A, Département de Recherches sur la Fusion Contrôlée, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);DE LA LUNA E, Département de Recherches sur la Fusion Contrôlée, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);JACHMICH S, Association EURATOM-Belgian State, LPP-ERM/KMS (BE);SOLANO E, Associacion Euratom/CIEMAT Para Fusion, Madrid (ES)
Bibliographic Reference: An oral paper given at: 18th International Conference on Plasma-Surface Interactions in Controlled Fusion Device Organised by: Laboratorio Nacional de Fusión Held in: Toledo (ES)
Availability: This article can be accessed online by subscribers, and can be ordered online by non-subscribers, at: http://dx.doi.org/doi:10.1016/j.jnucmat.2009.01.201
Record Number: 200910373 / Last updated on: 2009-09-22
Category: PUBLICATION
Original language: en
Available languages: en