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In the large helical device(LHD)having three dimensional configuration,Alfv(?)neigenmodes(AEs)destabilized by energetic ions are widely investigated using neutral beam heatedplasmas with monotonic and non-monotonic rotational transform((?)/2π)profiles.In a plasmawith monotonic(?)/2π-profile,core-localized toroidicity-induced Alfv(?)n eigenmode(TAE)as well asglobal one are often observed.With the increase in the averaged toroidal beta value,defined as theratio of total plasma pressure to toroidal magnetic pressure,core-localized TAE with low toroidalmode number becomes global.In a relatively high beta plasma with monotonic(?)/2π-profile,two TAEs with different toroidal mode number often interact nonlinearly and generate anothermodes through three wave coupling.In a plasma with non-monotonic(?)/2π-profile generated byintense counter neutral beam current drive,reversed shear Alfv(?)n eigenmode(RSAE)and geodesicacoustic mode(GAM)excited by energetic ions were observed for the first time in a helical plasma.Nonlinear coupling was also observed between RSAE and GAM.
In the large helical device (LHD) having three dimensional configuration, Alfv (?) Neigenmodes (AEs) destabilized by energetic ions are widely used using a neutral beam heated plasma with monotonic and non-monotonic rotational transform ((?) / 2π) a plasma with monotonic (?) / 2π-profile, core-localized toroidicity-induced Alfv (?) n eigenmode (TAE) as well as global one are often observed. The increase in the averaged toroidal beta value, defined as the total of plasma pressure to toroidal magnetic pressure, core-localized TAE with low toroidalmode number becomes global. In a relatively high beta plasma with monotonic (?) / 2π-profile, two TAEs with different toroidal mode number often interact nonlinearly and generate another mode through three wave coupling .In a plasma with non-monotonic (?) / 2π-profile generated byintense counter neutral beam current drive, excited by energetic ions were observed for the first tim e in a helical plasma. Nonlinear coupling was also observed between RSAE and GAM.