High frequency MHD activities observed during second harmonic ICRF heating are identified to be toroidicity-induced Alfvén eigenmodes (TAE) driven by MeV protons produced by ICRF heating. Correlation between MeV protons and TAE modes is clearly observed. TAE mode amplitude increases exponentially with increasing toroidal mode number up to more than ten. The tendency cannot be explained by present local TAE stability theories. Long suppression of TAE modes after a giant sawtooth crash can be explained by fast ion loss due to the sawtooth crash and evolving q-profile.
|Number of pages
|Physics Letters, Section A: General, Atomic and Solid State Physics
|Published - 1995 Mar 20