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Abstract

In NBI discharges with density ramps in W7-AS, the quiescent H-mode is restricted to the same ranges of the edge rotational transform as in ECRH discharges and occurs above threshold densities = 10(20) m(-3) which increase with heating power. Higher power needs higher density for stabilization. The approach to the quiescent H-mode often occurs, with increasing density and decreasing power flow through the edge, from grassy through dithering states to bursts of ELMs and, in a few cases, quasi-periodic ELMs. This goes parallel with increasing radial gradients of the plasma pressure and E-field at the edge. Higher heating power reduces in particular the T(i) gradients and hence the E-field gradients, which effect can be compensated by higher density. The correlations found are fairly consistent when an E x B flow shear de-correlation of the turbulent transport is assumed.

Additional information

Authors: GRIGULL P, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);HIRSCH M, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);BALDZUHN J, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);EHMLER H, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);GADELMEIER F, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);GIANNONE L, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);HARTFUSS H.J, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);HILDEBRANDT D, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);JAENICKE R, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);KISSLINGER J, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);KOENIG R, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);McCORMICK K, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);WAGNER F, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);WELLER A, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);WENDLAND C, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE);W7-AS TEAM, Max-Planck-Institut f³r Plasmaphysik, EURATOM Association, Garching (DE)
Bibliographic Reference: An article published in: Elsevier; Journal of Nuclear Materials, 290-293 (2001) pp.1009-1012
Availability: An article published in: Elsevier; Journal of Nuclear Materials, 290-293 (2001) pp.1009-1012
Record Number: 200013452 / Last updated on: 2001-06-27
Category: PUBLICATION
Original language: en
Available languages: en