LINEAR AND QUASI-LINEAR BEHAVIOUR OF ION MODES
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.
Bibliographic Reference: PAPER PRESENTED: 12EME CONFERENCE INTERNATIONALE SUR LA PHYSIQUE DES PLASMAS ET LA RECHERCHE CONCERNANT LA FUSION NUCLEAIRE CONTROLEE, NICE (FR), OCT. 12-19, 1988 AVAILABLE FROM COMMISSION OF THE EUROPEAN COMMUNITIES, DG XIII-C-3, L-2920 LUXEMBOURG AS PAP
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Record Number: 1989128049200 / Last updated on: 1990-11-09
Available languages: en