Saturation of a single mode driven by an energetic injected beam. III. Alfvén wave problem

The saturation amplitude of Alfvén waves, excited by alpha particles produced in an ignited tokamak, is estimated. The formalism that has been developed to describe the saturation of a single mode is generalized to toroidal geometry. The saturation level is estimated for the toroidal Alfvén gap mode. The alpha particle radial flux resulting from the finite wave amplitude is found to produce relatively weak energy losses compared to the usual energy drag losses.