Energetic particle destabilization of shear Alfven waves in stellarators and tokamaks

An important issue for ignited devices is the resonant destabilization of shear Alfven waves by energetic populations. These instabilities have been observed in a variety of toroidal plasma experiments in recent years, including: beam destabilization toroidal Alfven instabilities (TAE) in low magnetic field tokamaks, ICRF destabilized TAEs in higher field tokamaks, and global Alfven instabilities (GAE) in low shear stellarators. In addition, excitation and study of these modes is a significant goal of the TFTR DT program and a competent of the ITER physics tasks. A gyrofluid model has been developed which includes the wave-particle resonances necessary to excite such instabilities. The TAE linear mode structure is calculated non-perturbatively, including many of the relevant damping mechanisms, such as continuum damping, non-ideal effects (ion FLR and electron collisionality), and ion/electron Landau damping. This model has been applied to both linear and non-linear regimes for a range of experimental cases using measured profiles. (author). 11 refs, 5 figs