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(TH/P1-12) Characterisation of Temperature Gradient Driven Turbulence and Transport

M.A. Ottaviani1), E. Fleurence1), X. Garbet1), Ph. Ghendrih1), V. Grandgirard1), B. Labit1), Y. Sarazin1), W. Zwingmann1), P. Bertrand2), G. Depret3), A. Ghizzo2), G. Manfredi2)
1) Association EURATOM-CEA, DSM/DRFC, CEA-Cadarache, Paul-lez-Durance , France
2) Laboratoire de Physique des Milieux Ionisés, Université Henri Poincaré, Nancy-1, Vandoeuvre-les-Nancy cedex, France
3) INRIA Lorraine/Equipe ISA, Vandoeuvre les Nancy, France

Abstract.  We report on extensive numerical studies aimed at characterising various aspects of temperature gradient driven turbulence. We specifically discuss results from 3D fluid models of ETG and of ITG turbulence, and results from a 2D+2D gyrokinetic model of trapped ion turbulence. Global transport exhibits gyro-Bohm scaling in both the ETG and the ITG model. The conductivity of the ETG model decreases weakly with beta. The heat transport is due to the EXB advection, the effect of the magnetic flutter is negligible. However the transport level is much lower than experimentally observed. In both 3D models the correlation lengths scale with the gyroradius, but they are typically a factor 10 larger. Vortices are elongated but their aspect ratio is independent of the gyroradius. Their radial size is limited by LD. The trapped ion model gives larger vortices due to the absence of LD from passing ions. Avalanches are observed in all the models, the weakest occurring in the ITG system. Their range increases with gyroradius, but more weakly than linearly. Finally, ZFs can limit the range of the avalanches, which explains why avalanches are weaker in the ITG model which is more sensitive to ZFs.

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IAEA 2003