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          Institute: MPI für Plasmaphysik     Collection: Articles, Books, Inbooks     Display Documents

ID: 20428.0, MPI für Plasmaphysik / Articles, Books, Inbooks
Confinement properties of high density impurity seeded ELMy H- mode discharges at low and high triangularity on JET
Authors:Dumortier, P.; Andrew, P.; Bonheure, G.; Budny, R. V.; Buttery, R.; Charlet, M.; Coffey, I.; de Baar, M.; de Vries, P. C.; Eich, T.; Hillis, D.; Ingesson, C.; Jachmich, S.; Jackson, G.; Kallenbach, A.; Koslowski, H. R.; Lawson, K. D.; Liu, C.; Maddison, G.; Messiaen, A. M.; Monier-Garbet, P.; Murakami, M.; Nave, M. F. F.; Ongena, J.; Parail, V.; Puiatti, M. E.; Rapp, J.; Sartori, F.; Stamp, M.; Strachan, J. D.; Suttrop, W.; Telesca, G.; Tokar, M.; Unterberg, B.; Valisa, M.; von Hellermann, M.; Weyssow, B.; EFDA-JET Work Programme Collaborators
Date of Publication (YYYY-MM-DD):2002-09
Title of Journal:Plasma Physics and Controlled Fusion
Journal Abbrev.:Plasma Phys. Control. Fusion
Issue / Number:9
Start Page:1845
End Page:1861
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:The design value for ITER is based on operation at n/n(GW) = 0.85, beta(n) = 1.8 and H98(y, 2) = 1. These values have been routinely achieved in JET in argon seeded ELMy H-mode discharges in different divertor configurations and with different triangularities. Two main scenarios are emerging from the experiments. First, low triangularity (delta(u) = 0.19) in septum configuration. In this case large D-2 fuelling rates lead to confinement degradation towards L-mode. The seeding of Ar during the D-2 fuelling phase gives rise to a density close to the Greenwald value. After the switch-off of the D-2 gas fuelling ('afterpuff ' phase), the confinement recovers to H- mode quality whereas the density stays near the value reached at the end of the main fuelling phase and Z(eff) stays close to or below 2. Acting on the refuelling of Ar and D-2 in the 'afterpuff 'phase allows us to improve the stationarity of the high performance phase while maintaining up to the end of the heating phase the good confinement, density and radiation level. Second, high triangularity (delta(u) = 0.45) in vertical target configuration. In this case large fuelling rates do not lead to strong confinement degradation and the D-2 fuelling is applied continuously throughout the discharge. A radiated power fraction of up to 70%, H98(y, 2) = 0.9 at beta(n) = 2.1 and n = 1.15n(GW)-together with the formation of a radiating mantle and moderate Z(eff)-are achieved in this scenario. Furthermore, there are indications of significantly reduced heat load on the divertor target plates.
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Plasmaphysik/E1
External Affiliations:Ecole Royale Mil, Assoc Euratom Belgian State, Plasma Phys Lab,; Renaissancelaan,30 Ave Renaissance, B-1000 Brussels, Belgium; UKAEA Euratom Fus Assoc, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England; Princeton Univ, Princeton Plasma Phys Lab, Princeton, NJ 08543 USA; EURATOM, FOM, Inst Plasma Fys, NL-3430 BE Nieuwegein, Netherlands; EURATOM, Forschungszentrum Julich GMBH, Inst Plasma Phys, D-52425 Julich, Germany; Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA; DIII D Natl Fus Facil, San Diego, CA 92186 USA; Free Univ Brussels, Assoc Euratom Belgian State, Serv Phys Stat & Plasmas, B-1050 Brussels, Belgium; EURATOM, CEA CADARACHE, DRFC, F-13108 St Paul Les Durance, France; EURATOM, IST, Ctr Fus Nucl, P-1049001 Lisbon, Portugal; Conzorzio RFX Assoc Euratom ENEA Fus, Corso State Uniti 4, I-35127 Padua, Italy
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