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(TH1/3) Flux Driven Turbulence in Tokamaks

X. Garbet¹, Y. Sarazin², P. Beyer², Ph. Ghendrih¹, R. E. Waltz³, M. Ottaviani¹, S. Benkadda²

¹ Association Euratom-CEA sur la Fusion Contrôlée, CEA Cadarache, France
² Equipe Turbulence Plasma, LPIIM, Centre Universitaire de Saint-Jérôme, Marseille, France
³ General Atomics, PO Box 85608, San Diego CA92186-9784, USA

Abstract.  This work deals with tokamak plasma turbulence in the case where fluxes are fixed and profiles are allowed to fluctuate. These systems are intermittent. In particular, radially propagating fronts, are usually observed over a broad range of time and spatial scales. The existence of these fronts provide a way to understand the fast transport events sometimes observed in tokamaks. It is also shown that the confinement scaling law can still be of the gyroBohm type in spite of these large scale transport events. Some departure from the gyroBohm prediction is observed at low flux, i.e. when the gradients are close to the instability threshold. Finally, it is found that the diffusivity is not the same for a turbulence calculated at fixed flux than at fixed temperature gradient, with the same time averaged profile.

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