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(CT-3) Characteristics of the H-mode Pedestal and Extrapolation to ITER

T.H. Osborne1), J.G. Cordey2), R.J. Groebner1), T. Hatae3), A. Hubbard4), L.D. Horton5), Y. Kamada3), A. Kritz6), L.L. Lao1), A.W. Leonard1), A. Loarte7), M.A. Mahdavi1), D. Mossessian4), T. Onjun6), M. Ossenpenko8), T.D. Rognlien9), G. Saibene7), P.B. Snyder1), M. Sugihara10), R. Shurygin8), K. Thomsen7), M.R. Wade11), H.R. Wilson2), X.Q. Xu9), K. Yatsu12), International Tokamak Physics Activity H Mode Pedestal Working Group
1) General Atomics, San Diego, CA, USA
2) EURATOM/UKAEA Fusion Association, Culham Science Center, Abingdon, United Kingdom
3) Japan Atomic Energy Research Institute, Naka-machi, Ibaraki-ken, Japan
4) Massachusetts Institute of Technology, Cambridge, Massachusetts USA
5) Max Planck Institut für Plasmaphysik, Garching, Germany
6) Lehigh University, Bethlehem, Pennsylvania USA
7) EFDA-JET, Culham, United Kingdom
8) Institute of Nuclear Fusion, Kurchatov Institute, Russia
9) Lawrence Livermore National Laboratory, Livermore, California, USA
10) ITER Joint Work Site, Naka, Japan
11) Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
12) Plasma Research Center, University of Tsukuba, Tsukuba, Ibaraki, Japan

Abstract.  The development of a predictive capability for the characteristics of the H-mode pedestal and ELMs is important in predicting tokamak reactor performance. The H-mode pedestal effects core confinement through temperature profile stiffness. The ELM power flux can significantly impact divertor design. We discuss progress in these areas through inter-machine comparison under the venue of the International Tokamak Physics Activity, ITPA. The pressure in the H-mode transport barrier region is typically set by the ELM cycle rather than transport. Several features of the ELM onset conditions are consistent with an ideal peeling-ballooning mode instability: 1) strong shape dependence, 2) mode structure, 3) reduced p' at high collisionality, 4) p' dependence on transport barrier width. Type I ELM energy loss is found to be proportional to the energy in the H-mode pedestal. There is some consistency between the peeling-ballooning mode radial width and the ELM size. Type I ELM energy loss is reduced at high density to levels that would be tolerable in a reactor scale device through reduced conductive loss and possibly shift to a more radially localized instability.

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IAEA 2003