Spontaneous excitation of geodesic acoustic mode by toroidal Alfvén eigenmodes

Zhiyong Qiu, Liu Chen, Fulvio Zonca

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Abstract

Spontaneous nonlinear excitation of geodesic acoustic mode (GAM) by toroidal Alfvén eigenmodes (TAE) is studied within the framework of gyrokinetic theory. The dispersion relation for the parametric decays of a pump TAE mode into a TAE lower sideband and a GAM is derived. It is shown that, in the ideal MHD first stability region, the condition for spontaneous excitation of GAM by TAEs is ω20 > V2A/(4q2R20), in which, ω0 is the pump TAE real frequency, V A is the Alfvén speed, q is the safety factor and R0 is the torus major radius. The corresponding threshold condition is also derived and suggests the decay process as an effective saturation mechanism for TAE. © Copyright EPLA, 2013.
Original languageEnglish
Article number35001
Pages (from-to)-
JournalEurophysics Letters
Volume101
Issue number3
DOIs
Publication statusPublished - Feb 2013
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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