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Oct 13 – 18, 2014
Hotel Park Inn Pribaltiyskaya
Europe/Moscow timezone

Runaway Electron Generation with the ITER-like Wall and Efficiency of Massive Gas Injection at JET

Oct 16, 2014, 11:25 AM
20m
Blue 1-5 (Hotel Park Inn Pribaltiyskaya)

Blue 1-5

Hotel Park Inn Pribaltiyskaya

Saint Petersburg, Russian Federation

Speaker

Mr Cedric Reux (France)

Description

Disruptions are a major concern for next generation tokamaks, including ITER. These MHD instabilities lead to the loss of the plasma thermal energy and current on the millisecond timescale. Large electric fields created by the plasma current quench can accelerate several MA of runaway electrons (RE) up to 20 MeV. The influence of the full-metal JET ITER-Like Wall (JET-ILW) on RE is thus a key question for future all-metal PFC machines. Experiments at JET have shown that even though RE are very rare in spontaneous disruptions, they can still be generated during disruptions with fast current quenches induced by argon massive gas injections. The operational domain where runaways appear under those conditions is similar to what it was in carbon wall (JET-C). Hard X-ray spectra show energies up to 10 MeV. Although the boundary location is similar, the runaway generation might be larger in JET-ILW than JET-C inside the domain with higher currents in JET-ILW with like-to-like plasma parameters. Temperatures of up to 900°C have been observed on PFC following beam impact. Disruptions can also generate excessive heat loads on plasma facing components (PFC) and electromagnetic forces in the machine structures due to halo and eddy currents. Massive Gas Injection (MGI) is presently one of the most promising techniques to mitigate both these effects by radiating away the plasma energy. However, the fraction of energy radiated by MGI at high plasma thermal content as well as the radiation peaking are key questions to ensure good extrapolability of the method to larger tokamaks. Recent experiments at JET-ILW have confirmed that the fraction of the total energy radiated decreases with increasing thermal energy content down to 70% for 10%/90% D2/Ar mixtures. Injections on plasmas with or without a locked mode already present also show different radiation peaking pattern. This suggests that toroidal asymmetries might be strong in case of injections in an already developing disruption.
Paper Number EX/5-2
Country or International Organisation France

Primary author

Mr Cedric Reux (France)

Co-authors

Mr Alexandre Fil (CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France) Dr Ana Manzanares (Association Euratom-CIEMAT, Moncloa, Avd. Complutense, 22, 28040 Madrid 3, Spain) Dr Barry Alper (CCFE, Culham Science Centre, Abingdon OX14 3DB, UK) Dr Boris Bazylev (Institut für Hochleistungsimpuls und Mikrowellentechnik, Karlsruhe Institute of Technology, Campus Nord,76021 Karlsruhe, Germany) Dr Carlo Sozzi (Istituto di Fisica del Plasma CNR, Associazione EURATOM-ENEA) Mr Diogo Alves (Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal) Ms Emelie Nilsson (CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France.) Dr Eric Nardon (CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France.) Dr Eva Belonohy (EFDA-CSU, Culham Science Centre, Abingdon OX14 3DB, UK) Dr Francois Saint-Laurent (CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France.) Dr Ivan Lupelli (CCFE, Culham Science Centre, Abingdon OX14 3DB, UK) Dr Jan Mlynar (Institute of Plasma Physics AS CR, Za Slovankou 3, 18200 Prague 8, CZ) Dr Joan Decker (CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France.) Dr Luca Giacomelli (CCFE, Culham Science Centre, Abingdon OX14 3DB, UK) Dr Michael Lehnen (ITER Organization, Route de Vinon sur Verdon, 13115 St Paul Lez Durance, France) Dr Peter Drewelow (Max-Planck-Institut for Plasma Physics, EURATOM-Assoziation, Wendelsteinstr. 1, 17489, Greifswald, Germany) Dr Peter de Vries (ITER Organization, Route de Vinon sur Verdon, 13115 St Paul Lez Durance, France) Dr Rudi Koslowski (Forschungszentrum Jülich GmbH, Institut für Energie-und Klimaforschung-Plasmaphysik, 52425 Jülich, Germany) Dr Sebastijan Brezinsek (Forschungszentrum Jülich GmbH, Institut für Energie-und Klimaforschung-Plasmaphysik, 52425 Jülich, Germany) Dr Sergei Gerasimov (CCFE, Culham Science Centre, Abingdon OX14 3DB, UK) Dr Stefan Jachmich (Laboratory for Plasma Physics, ERM/KMS, BE-1000 Brussels, Belgium, TEC partner) Dr Stéphane Devaux (CCFE, Culham Science Centre, Abingdon OX14 3DB, UK) Dr Uron Kruezi (CCFE, Culham Science Centre, Abingdon OX14 3DB, UK) Dr Valeria Riccardo (CCFE, Culham Science Centre, Abingdon OX14 3DB, UK) Dr Vasili Kiptily (CCFE, Culham Science Centre, Abingdon OX14 3DB, UK) Dr Vladislav V Plyusnin (Instituto de Plasmas e Fusão Nuclear, Associação EURATOM-IST, Instituto Superior Tecnico)

Presentation materials