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(ITERP/03) Understanding of the H-mode Pedestal Characteristics Using the Multi-machine Pedestal Database

T. Hatae1), M. Sugihara2), A. Hubbard3), Yu. Igitkhanov2), Y. Kamada1), G. Janeschitz2), L. D. Horton4), N. Ohyabu5), T. H. Osborne6), M. Osipenko7), W. Suttrop4), H. Urano8), H. Weisen9)
1) Japan Atomic Energy Research Institute, Naka-machi, Ibaraki-ken, Japan
2) ITER Joint Central Team, Garching, Germany
3) MIT Plasma Science and Fusion Center, Cambridge, MA, USA
4) Max Planck Institut für Plasmaphysik, Garching, Germany
5) National Institute for Fusion Science, Gifu-ken, Japan
6) General Atomics, San Diego, CA, USA
7) Kurchatov Institute, Moscow, Russia
8) Hokkaido University, Hokkaido, Japan
9) Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Fédérale de Lausanne, Switzerland

Abstract.  With the use of a multi-machine pedestal database, essential issues for each regime of ELM types are investigated. They include (i) understanding and prediction of pedestal pressure during Type I-ELMs which is a reference operation mode of a future tokamak reactor, (ii) identification of the operation regime of Type-II ELMs which have small ELM amplitude with good confinement characteristics, (iii) identification of upper stability boundary of Type-III ELMs for access to the higher confinement regimes with Type-I or -II ELMs, (iv) relation between core confinement and pedestal temperature in conjunction with the confinement degradation in high density discharges. Scaling and model-based approaches for expressing pedestal pressure are shown to roughly scale the experimental data equally well and initial predictions for a future reactor case could be performed by them. It is identified that q and $ \delta$ are important parameters to obtain the Type-II ELM regime. A theoretical model of Type-III ELMs is shown to reproduce the upper stability boundary reasonably well. It is shown that there exists a critical pedestal temperature, below which the core confinement starts to degrade.

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