Growth and saturation of TAE modes destabilized by ICRF produced tails

The linear growth rates of TAE (Toroidal Alfv¶en Eigenmode) modes destabilised by ICRF (Ion Cyclotron Range of Frequency) heating are calculated over a range of plasma parameters. Nonlinear saturation of a single unstable mode is investigated both analytically and numerically when wave-particle trapping is the dominant satura-tion mechanism. A numerical code has been developed based on a reduced resonance description of the wave-particle interaction (using a Hamiltonian formalism). A delta-f algorithm was incorporated to allow a low-noise description of mode evolution with particle sources and sinks present. The numerically observed saturation amplitudes cor-relate well with theoretical predictions to within 20%. Self-excited frequency sweeping resulting from the excitation of many simultaneous wave-particle resonances at dif-ferent energies is demonstrated and explained as an extension of previous published theory [Berk et al., to be published in Phys. Lett]. 1