Radial propagation of geodesic acoustic modes in up-down asymmetric magnetic geometries

Hager, Robert; Hallatschek, Klaus
March 2010
Physics of Plasmas;Mar2010, Vol. 17 Issue 3, p032112
Academic Journal
The energy approach to the analysis of the propagation of geodesic acoustic modes presented in the work of Hager and Hallatschek [Phys. Plasmas 16, 072503 (2009)] is generalized to up-down asymmetric magnetic geometries including a model for single-null configuration. By removing the neoclassical cancellation effects, up-down asymmetry can trigger a nonvanishing group velocity at zero radial wavenumber. A theoretical insight in this effect is provided by analytical calculations combined with numerical gyrokinetic and two-fluid studies. Thereby, an useful estimate of the group velocity at zero radial wavenumber is derived within a two-fluid framework.


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