Radial structures and nonlinear excitation of geodesic acoustic modes

F. Zonca, L. Chen

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Abstract

Geodesic acoustic modes (GAM) are shown to constitute a continuous spectrum due to radial inhomogeneities. The importance and theoretical as well as experimental implications of this fact are discussed in this work. The existence of a singular layer causes GAM to mode convert to short-wavelength kinetic GAM (KGAM) via finite ion Larmor radii; analogous to kinetic Alfvén waves (KAW). Furthermore, it is shown that KGAM can be nonlinearly excited by drift-wave (DW) turbulence via 3-wave parametric interactions, and the resultant driven-dissipative nonlinear system exhibits typical prey-predator self-regulatory dynamics, consistent with recent experimental observations on HL-2A. The degeneracy of GAM/KGAM with beta-induced Alfvén eigenmodes (BAE) is demonstrated and discussed, with emphasis on its important role in the complex self-organized behaviors of burning plasmas. © 2008 Europhysics Letters Association.
Original languageEnglish
Article number35001
Pages (from-to)-
JournalEurophysics Letters
Volume83
Issue number3
DOIs
Publication statusPublished - 1 Aug 2008
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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