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Abstract. Instabilities with frequency chirping in the frequency range of
Alfvén eigenmodes have been found in the domain of
0.1% < < 1% and
vb|/vA
1 with high energy neutral beam
injection in JT-60U. One instability appears with frequency inside the
Alfvén continuum spectrum and its frequency increases slowly to the
Toroidicity induced Alfvén eigenmodes (TAE) gap in an equilibrium change
time scale of
200 ms. Another instability appears with frequency
inside the TAE gap and its frequency changes very fast by 10-20 kHz in 1-5
ms. During the occurrence of Fast FS modes, abrupt large-amplitude events
often appears with an enhanced drop of neutron emission rate and increase in
fast neutral particle fluxes. The loss of energetic ions increases with the
peak fluctuation amplitude of
/B
. Energy dependence
of loss ions is observed and suggests the resonant interaction between
energetic ions and a mode.
IAEA 2001