Please use this identifier to cite or link to this item: http://arks.princeton.edu/ark:/88435/dsp013r074x84p
 Title: Analytic stability boundaries for compressional and global Alfven eigenmodes driven by fast ions. II. Interaction via Landau resonance. Contributors: Lestz, J.B.Gorelenkov, N.N.Belova, E.V.Tang, S.X.Crocker, N.A.U. S. Department of Energy Keywords: null Issue Date: Jan-2020 Publisher: Princeton Plasma Physics Laboratory, Princeton University Related Publication: Physics of Plasmas Abstract: Conditions for net fast ion drive are derived for beam-driven, co-propagating, sub-cyclotron compressional (CAE) and global (GAE) Alfven eigenmodes driven by the Landau resonance with super-Alfvenic fast ions. Approximations applicable to realistic neutral beam distributions and mode characteristics observed in spherical tokamaks enable the derivation of marginal stability conditions for these modes. Such conditions successfully reproduce the stability boundaries found from numerical integration of the exact expression for local fast ion drive/damping. Coupling between the CAE and GAE branches of the dispersion due to finite \omega/\omega_{ci} and k_\parallel/k_\perp is retained and found to be responsible for the existence of the GAE instability via this resonance. Encouraging agreement is demonstrated between the approximate stability criterion, simulation results, and a database of NSTX observations of co-CAEs. URI: http://arks.princeton.edu/ark:/88435/dsp013r074x84p Appears in Collections: NSTX-U

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