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Abstract

In non-inductively driven discharges, 0.9MW 2nd harmonic (X2) off-axis co-electron cyclotron current drive (ECCD) deposition is combined with 0.45MW X2 central heating to create an electron Internal Transport Barrier (eITB) in steady plasma conditions resulting in a 1.6-fold increase of the confinement time (T(Ee)) over ITER-98L-mode scaling. The eITB is associated with a reversed shear current profile enhanced by a large bootstrap current fraction (up to 80%) and is sustained for up to 10 current redistribution times. A linear dependence of the confinement improvement on the product of the global shear reversal factor (q(0)/q(min)) and the reversed shear volume (p(q-min){2}) is shown. In other discharges heated with X2 the sawteeth are destabilised (respectively stabilised) when heating just inside (respectively outside) the q=1 surface. Control of the sawteeth may allow the avoidance of Neoclassical Tearing Modes (NTMs that can be seeded by the sawtooth instability. Results on H-mode and highly elongated plasmas using the newly completed 3rd harmonic (X3) system and achieving up to 100% absorption are also discussed, along with comparison of experimental results with the TORAY-GA ray tracing code.

Additional information

Authors: HENDERSON M A ET AL, Centre de Recherches en Physique des Plasmas, Association EURATOM-Confédération Suisse, École Polytechnique Fédérale de Lausanne (CH);ANGIONI C, Max-Planck-Institut für Plasmaphysik, IPP-Euratom Association, Garching (DE);FURNO I, Los Alamos National Laboratory (US);PEYSSON Y, DRFC-CEA Cadarache (FR);RAJU D, Institute for Plasma Research, Bhat, Gujarat (IN);REIMEDES H, General Atomics, San Diego (US);SUSHKOV A, RRC Kurchatov, Moscow (RU);HENDERSON M A ET AL, Centre de Recherches en Physique des Plasmas, Association EURATOM-Confederation Suisse, Ecole Polytechnique Federale de Lausanne (CH);ANGIONI C, Max-Planck-Institut fur Plasmaphysik, IPP-Euratom Association, Garching (DE)
Bibliographic Reference: EPFL Internal report LRP 747/03, February 2003. 17pp. Free of charge Also published as an article in Fusion Engineering and Design, Volume 65, Issue 3 , April 2003, pp. 367-374.
Availability: Available from: Ecole Polytechnique Federale de Lausanne (EPFL), Ecublens, CH-1015 Lausanne Fax +41-21-6934747 The article can be accessed online (with a charge for non-subscribers) at: http://dx.doi.org/10.1016/S0920-3796%2802%2900381-
ISBN: ISSN: 0458-5895
Record Number: 200316007 / Last updated on: 2003-03-05
Category: PUBLICATION
Original language: en
Available languages: en