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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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