Alpha-particle-driven nonideal toroidal Alfven eigenmodes

Abstract

The excitation of toroidal Alfven eigenmodes by high energy alpha particles is examined. Specifically, the kinetic alpha -particle response is retained directly in the linear mode coupling equations, and represents a driving source proportional to the spatial gradient of the alpha distribution. The model is an extension of the high-m, large-aspect-ratio, asymptotic boundary layer theory of the nonideal TAE and provides a self-consistent method for the determination of the instability threshold and growth rate of the excited TAE. Analytical and numerical stability thresholds are presented for the simple case of slowly varying density and shear.