Nonlinear saturation of toroidal Alfven eigenmodes via ion Compton scattering

摘要

The nonlinear interactions of high mode number Toroidal Alfven Eigenmodes (TAE), mediated via Compton scattering off the bulk ions, are investigated. It is shown that nonlinear J(perpendicular) x B(perpendicular) ponderomotive force produced by TAE's interaction drives sound wave like density fluctuations with low phase velocity which can resonantly interact with the bulk ion parallel motion. Consequently, fluctuation energy of TAE's is transferred to lower frequency and eventually absorbed by linearly stable TAE's near the lower shear-Alfven continuum, leading to nonlinear saturation. Explicit expression for the saturated magnetic amplitude is derived.