Excitation of kinetic geodesic acoustic modes by drift waves in nonuniform plasmas

Z. Qiu, L. Chen, F. Zonca

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Abstract

Effects of system nonuniformities and kinetic dispersiveness on the spontaneous excitation of Geodesic Acoustic Mode (GAM) by Drift Wave (DW) turbulence are investigated based on nonlinear gyrokinetic theory. The coupled nonlinear equations describing parametric decay of DW into GAM and DW lower sideband are derived and then solved both analytically and numerically to investigate the effects on the parametric decay process due to system nonuniformities, such as nonuniform diamagnetic frequency, finite radial envelope of DW pump, and kinetic dispersiveness. It is found that the parametric decay process is a convective instability for typical tokamak parameters when finite group velocities of DW and GAM associated with kinetic dispersiveness and finite radial envelope are taken into account. When, however, nonuniformity of diamagnetic frequency is taken into account, the parametric decay process becomes, time asymptotically, a quasi-exponentially growing absolute instability. © 2014 AIP Publishing LLC.
Original languageEnglish
Article number022304
Pages (from-to)-
JournalPhysics of Plasmas
Volume21
Issue number2
DOIs
Publication statusPublished - Feb 2014
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

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