Reduced model analysis of supercritical and subcritical chirping Alfvén eigenmodes
Résumé
We present a new method for analyzing fundamental kinetic plasma parameters such as the linear drive and the external damping rate based on experimental observations of chirping Alfvén Eigenmodes (AEs). The method consists of fitting procedures of nonlinear chirping characteristics between the so-called Berk-Breizman (BB) model [1] and the experiment. The method is validated through comparisons of kinetic plasma parameters against former analyses on the Toroidicity induced Alfvén Eigenmode (TAE) on MAST [2]. Major advantages for this technique are 1. fitting conditions estimated only from the spectrogram of the magnetic fluctuations, and 2. unified treatment of supercritical and subcritical AEs. The apparent contradiction between the linear theory and the behavior of subcritical solutions observed in simulations is clarified.
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