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Abstract

The ion modes in tokamaks are studied both analytically and computationally by a variational formalism in cylindrical and toroidal geometries. They are found to exhibit a convective structure which determines the stability boundary. Toroidal effects have a destabilising influence. The coupling between the successive poloidal harmonics increases the feedback connection within the convective structure and is thereby responsible for destabilisation. The modes driven unstable by trapped ions allow a new quasi-linear phenomenon to be introduced: by transferring toroidal momentum across the magnetic surfaces, they may create a negative viscosity situation producing fluctuating differential rotations which may saturate the turbulence.

Additional information

Authors: GARBET X, CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR);LAURENT L, CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR);MOURGUES F, CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR);ROUBIN J P, CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR);SAMAIN A, CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR)
Bibliographic Reference: Paper presented: 12ème Conférence Internationale sur la Physique des Plasmas et la Recherche concernant la Fusion Nucléaire Contrôlée, Nice (FR), Oct. 12-19, 1988
Availability: Available from (1) as Paper EN 34079 ORA
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