Non perturbative kinetic effects on Alfven eigenmodes in tokamak plasmas

An analysis has been carried out for the GAE mode observed in the TCA tokamak. Both, the fluid and the kinetic models implemented in the toroidal PENN code predict frequencies and dampings which are in good agreement with the experiment. Using the fluid model, the GAE mode is located in the plasma core and damped via resonance absorption in the plasma exterior. With the kinetic description, two conversion mechanisms lead to the Landau damping of a KAW: one is the counterpart of the fluid models' resonance absorption and occurs in the external parts of the plasma; the other has no such fluid correspondance, and is induced non perturbatively in the plasma core through toroidal coupling between the global GAE wavefield and the KAW. (author) 2 figs., 10 refs