(EX/P3-5) Multi-machine Dimensionless Transport Experiments

D.C. McDonald1), D. Elbeze2), F. Imbeaux2), H. Leggate1), C. C. Petty3), A. Sirinelli2), J. A. Snipes4), T. Takizuka5), H. Urano5), JET-EFDA Contributors *
1) Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB, UK
2) Euratom-CEA, CEA/DSM/DRFC, CEA Cadarache, Saint-Paul lez Durance, France
3) General Atomics, PO Box 85608, San Diego, CA 92186, USA
4MIT Plasma Science and Fusion Center, Cambridge, MA 02139, USA
5) Japan Atomic Energy Agency, Naka Fusion Institute, Naka 311-0193, Japan
* See the Appendix of M.L.Watkins et al., Fusion Energy 2006 (Proc. 21st Int. Conf. Chengdu, 2006) IAEA, (2006)

Abstract.  Integrated dimensionless confinement studies have been performed on JET, C-Mod, JT-60U, DIII-D, and Tore Supra. ELMy H-mode identity experiments on JET and C-Mod have shown that, despite results indicating confinement falls as density approaches the Greenwald limit, Greenwald fraction is not a relevant parameter for confinement scaling, but that collisionality is. Studies on JT-60U show a fall in ELMy H-mode confinement with increasing β, contrasting with those on DIII-D and JET which showed a negligible effect. Analysis of a multi-machine database indicates that the differing results may be due to a change in β dependency with plasma shape. Tore Supra experiments have shown a negligible β effect on L-Mode confinement. Statistical studies of multi-machine core and edge confinement databases lead to an improved explanation of these results. The impact of these results on the understanding of plasma transport and its extrapolation to ITER will be discussed.

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