Alfven eigenmodes driven by Alvenic beam ions in JT-60U

摘要

Instabilities with frequency chirping in the frequency range of Alfven eigenmodes have been found in the domain 0.1%＜〈β_h〉＜1% and v_b‖＝v_A~1 with high energy neutral beam injcetion in JT-60U. One instability with a frequency inside the Alfven continuum spectrum appears and its frequency increases slowly to the toroidicity induced Alfven eigenmode (TAE) gap on the timescale of an equilibrium change (≈200 ms).