Nonlinear dispersion relation of geodesic acoustic modes

Robert Hager, Klaus Hallatschek

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

The energy input and frequency shift of geodesic acoustic modes (GAMs) due to turbulence in tokamak edge plasmas are investigated in numerical two-fluid turbulence studies. Surprisingly, the turbulent GAM dispersion relation is qualitatively equivalent to the linear GAM dispersion but can have drastically enhanced group velocities. In up-down asymmetric geometry the energy input due to turbulent transport may favor the excitation of GAMs with one particular sign of the radial phase velocity relative to the magnetic drifts and may lead to pulsed GAM activity.

Original languageEnglish (US)
Article number035004
JournalPhysical review letters
Volume108
Issue number3
DOIs
StatePublished - Jan 19 2012
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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