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Department of Electromagnetics, Chalmers University of Technology,
EURATOM-NFR Association, S-412 96 Göteborg, Sweden
R. Singh
Institute for Plasma Research, Bhat, Gandhinagar 382424, India
Abstract. A scenario for the L to H mode transition in tokamaks due to heat
flux is presented. The mechanism is stabilization of a strongly ballooning
resistive edge mode by the ion diamagnetic drift. We find that this
stabilization may occure before that of poloidal rotation as a function of
increasing ion temperature gradient at the edge. We have also found a new type
of toroidal condensation instability which is found to dominate transport in
the H-mode edge of tokamak plasmas when the temperature gradient is steeper
than the density gradient. A particle pinch develops at the edge in agreement
with experimental observations and the transport can be dominated by the ion
or electron channel.
IAEA 2001
