  Gyrokinetic theory of nonlinear mode coupling as a mechanism for toroidal
Alfven eigenmode (TAE) saturation in the fusion plasma related parameter regime
is presented, including 1) para- metric decay of TAE into lower kinetic TAE
(LKTAE) and geodesic acoustic mode (GAM), and 2) enhanced TAE coupling to shear
Alfven wave (SAW) continuum via ion induced scattering. Our theory shows that,
for TAE saturation in the parameter range of practical interest, several
processes with comparable scattering cross sections can be equally important.
