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Abstract

Experimental results, as well as direct magnetic turbulence measurements have shown the existence, in plasmas with strong additional heating, of a critical electron temperature gradient beyond which the turbulence is triggered and the associated electron heat diffusivity is strongly enhanced. This diffusivity presents a marked step at the space location where the critical gradient is reached. The step-like diffusivity has also been observed in the improved confinement regimes with internal transport barrier.
Comparison between theory and experiments for the transport problem is usually performed numerically with a transport code. This approach has the obvious advantage of allowing including in the comparison secondary effects, such as simultaneous density, current and ion temperature evolutions, radiative losses, etc. Nevertheless, analytical solutions of simplified versions of this problem provide deeper insight in the physical nature of the phenomena involved and could also prove to be more efficient in carrying on extensive comparisons with the experimental data. This is particularly true for the analysis of perturbative electron transport experiments in tokamaks, such as the ECRH power modulation experiments.

Additional information

Authors: ZOU X L, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);GIRUZZI G, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);BOUQUEY F, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);CLARY J, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);DARBOS C, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);LENNHOLM M, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);MAGNE R, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);SÉGUI J L, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);CLÉMENÇON A, MIT, Electrochemical Energy Laboratory, Cambridge (US);GUIVARCH C, Ecole Nationale des Ponts et Chaussées, Marne-la-Vallée (FR)
Bibliographic Reference: An oral paper given at: 31st EPS Conference on Controlled Fusion and Plasma Physics Organised by: CCLRC Rutherford Appleton Laboratory (GB); EURATOM/UKAEA Fusion Association (GB) Held at: Imperial College London (GB)
Availability: Available from Association EURATOM-CEA, Département de Recherches sur la Fusion Contrôlée, CEA Cadarache, F-13108 St Paul-Lez-Durance, France Tel: (+33) 4 42 25 70 01; Fax: (+33) 4 42 25 64 21 E-mail: dirdrfc@drfc.cad.cea.fr
Record Number: 200517982 / Last updated on: 2005-03-10
Category: PUBLICATION
Original language: en
Available languages: en