SHEARED ROTATION EFFECTS ON KINETIC STABILITY IN ENHANCED CONFINEMENTTOKAMAK PLASMAS, AND NONLINEAR DYNAMICS OF FLUCTUATIONS AND FLOWS IN AXISYMMETRICAL PLASMAS

Sheared rotation dynamics are widely believed to have significant infl uence on experimentally-observed confinement transitions in advanced o perating modes in major tokamak experiments, such as the Tokamak Fusio n Test Reactor (TFTR) [D. J. Grove and D. M. Meade, Nucl. Fusion 25, 1 167 (1985)], with reversed magnetic shear regions in the plasma interi or. The high-n toroidal drift modes destabilized by the combined effec ts of ion temperature gradients and trapped particles in toroidal geom etry can be strongly affected by radially-sheared toroidal and poloida l plasma rotation. In previous work with the FULL Linear microinstabil ity code, a simplified rotation model including only toroidal rotation was employed, and results were obtained. Here, a more complete rotati on model, which includes contributions from toroidal and poloidal rota tion and the ion pressure gradient to the total radial electric field, is used for a proper self-consistent treatment of this key problem. R elevant advanced operating mode cases for TFTR are presented. In addit ion, the complementary problem of the dynamics of fluctuation-driven E xB flow is investigated by an integrated program of gyrokinetic simula tion in annulus geometry and gyrofluid simulation in flux tube geometr y. (C) 1998 American Institute of Physics.