Nonlinear Evolution of the Multiple n Toroidicity-induced Alfven Eigenmode
Authors: Y. Chen and R. White
A numerical algorithm is estabilished for studying the simultaneous excitation of multiple n TAE modes due to energetic particles. Each mode is described by its slowly-varying mode amplitude and phase, which evolve according to equations derived from the kinetic-MHD equation. A Hamiltonian guiding center code is used to simulate the alpha particle motion. The important effect of mode overlapping on the saturation level is demonstrated for the two modes, n = 2 and n = 3. Without other damping effects, a single mode saturates at a level where no significant overlapping occurs, while the excitation of multiple modes generally leads to resonance overlapping among different modes for typical bh, which will eventually cause global particle loss.