Recent progress on JET towards the ITER reference mode of operation at high density

J. Ongena, W. Suttrop, M. Bécoulet, G. Cordey, P. Dumortier, Th. Eich, L.C. Ingesson, S. Jachmich, P. Lang, A. Loarte, P. Lomas, G.P. Maddison, A. Messiaen, M.F.F. Nave, J. Rapp, G. Saibene, R. Sartori, O. Sauter, J.D. Strachan, B. UnterbergM. Valovic, B. Alper, Ph. Andrew, Y. Baranov, J. Brzozowski, J. Bucalossi, M. Brix, R. Budny, M. Charlet, I. Coffey, M. De Baar, P. De Vries, C. Gowers, N. Hawkes, M. Von Hellermann, D.L. Hillis, J. Hogan, G.L. Jackson, E. Joffrin, C. Jupen, A. Kallenbach, H.R. Koslowski, K.D. Lawson, M. Mantsinen, G. Matthews, P. Monier-Garbet, D. McDonald, F. Milani, M. Murakami, A. Murari, R. Neu, V. Parail, S. Podda, M.E. Puiatti, E. Righi, F. Sartori, Y. Sarazin, A. Staebler, M. Stamp, G. Telesca, M. Valisa, B. Weyssow, K.-D. Zastrow

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Abstract

Recent progress towards obtaining high density and high confinement in JET as required for the ITER reference scenario at Q = 10 is summarized. Plasmas with simultaneous confinement H98(y,2)= 1 and densities up to n/nGW∼ 1 are now routinely obtained. This has been possible (i) by using plasmas at high (δ ∼ 0.5) and medium (δ ∼ 0.3-0.4) triangularity with sufficient heating power to maintain Type I ELMs, (ii) with impurity seeded plasmas at high (δ ∼ 0.5) and low (δ ≤ 0.2) triangularity, (iii) with an optimized pellet injection sequence, maintaining the energy confinement and raising the density, and (iv) by carefully tuning the gas puff rate leading to plasmas with peaked density profiles and good confinement at long time scales. These high performance discharges exhibit Type I ELMs, with a new and more favourable behaviour observed at high densities, requiring further studies. Techniques for a possible mitigation of these ELMs are discussed, and first promising results are obtained with impurity seeding in discharges at high triangularity. Scaling studies using the new data of this year show a strong dependence of confinement on upper triangularity, density and proximity to the Greenwald limit. Observed MHD instabilities and methods to avoid these in high density and high confinement plasmas are discussed. © 2001 IOP Publishing Ltd.
Original languageEnglish
Pages (from-to)-
JournalPlasma Physics and Controlled Fusion
Volume43
Issue number12A
DOIs
Publication statusPublished - 2001
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

Cite this

Ongena, J., Suttrop, W., Bécoulet, M., Cordey, G., Dumortier, P., Eich, T., ... Zastrow, K-D. (2001). Recent progress on JET towards the ITER reference mode of operation at high density. Plasma Physics and Controlled Fusion, 43(12A), -. https://doi.org/10.1088/0741-3335/43/12A/302