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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. Weisen^9)
 
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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