(EX/P1-7) Physics studies of the improved H-mode scenario in ASDEX Upgrade

J. Stober1), A. C. C. Sips1), C. Angioni1), C. Forest2), O. Gruber1), J. Hobirk1), L. D. Horton1), C. F. Maggi1), M. Maraschek1), P. Martin3), P. McCarthy4), V. Mertens1), Y.-S. Na5), M. Reich1), A. Stäbler1), G. Tardini1), H. Zohm1), ASDEX Upgrade Team
1) Max-Planck-Institut für Plasmaphysik, Garching, Germany
2) Dept. of Physics, University of Wisconsin, Madison, USA
3) Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova, Italy
4) Dept. of Physics, University College Cork, Assosiation EURATOM-DCU, Cork, Ireland
5) National Fusion Research Center, Daejeon, Korea

Abstract.  The 'improved H-mode' regime of ASDEX Upgrade, a candidate for the ITER hybrid scenario, has been confirmed on several other devices. However, significant debate remains on which ingredients are key for improved H-mode operation and what the differences are compared to 'standard' H-modes. This contribution reports on recent studies at ASDEX Upgrade to further characterise and understand the physics of the improved H-mode. The main focus is on the influence of the ramp-up scenario for plasma current and heating on energy confinement and MHD-activity during the subsequent steady state phase. Additionally, new results for the transfer of the improved H-mode scenario to ITER are discussed, such as dependence on Te/Ti, toroidal rotation and ρ*. Finally, the modifications of the H-mode pedestal profiles with the observed variations of stored energy and H-factor are reported and compared to the standard H-mode database.

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