NIFS-795

FULL TEXT (PDF, 341 KB)

Author(s):

K. Itoh, K. Hallatschek and S.-I. Itoh

Title:

Excitation of Geodesic Acoustic Mode in Toroidal Plasmas

Date of publication:

Mar. 2004

Key words:

zonal flow, geodesic acoustic mode, dynamic shearing of turbulence, nonlinear instability, poloidal asymmetry for turbulence

Abstract:

The instability of the geodesic acoustic mode (GAM) in tokamak turbulence is analyzed. It can be induced by dynamic shearing of the ambient turbulence by GAMs combined with the poloidal inhomogeneity of the turbulent flux. The dispersion relation is derived. The competition of the drive mechanism and the damping by turbulence viscosity is discussed. The GAMs are more unstable for high safety factors.

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