51st Annual Meeting of the APS Division of Plasma Physics
Volume 54, Number 15
Monday–Friday, November 2–6, 2009;
Atlanta, Georgia
Session TI3: RF in Tokamaks and ITER
9:30 AM–12:00 PM,
Thursday, November 5, 2009
Room: Centennial II
Chair: Paul Bonoli, Massachusetts Institute of Technology
Abstract ID: BAPS.2009.DPP.TI3.5
Abstract: TI3.00005 : Kinetic theory of geodesic acoustic modes
11:30 AM–12:00 PM
Preview Abstract
Abstract
Author:
Andrei Smolyakov
(CEA Cadarache/University of Saskatchewan, Canada)
Geodesic Acoustic Modes (GAM are linear eigen-modes of poloidal
plasma rotation
supported by plasma compressibility in toroidal geometry. GAMs
are linearly coupled to drift-waves via toroidal side-bands of
plasma pressure, can be nonlinearly driven by Reynolds stress
from small-scale fluctuations (similar to Zonal Flows) and
therefore expected to play an important role in dynamics of
drift-wave turbulence. GAMs have also been prominently featured
due to their inherent relation to Beta Alfven Eigen-modes (BAE),
particularly in plasmas with highly energetic particles
Multiple GAM and BEA modes were observed in high-temperature
tokamak plasmas and are currently subject of active experimental
and theoretical studies. This talk will describe the currents
status of GAM/BEA theory. New results will be presented
emphasizing the relation of GAM/BAE modes with neoclassical
rotation in a tokamak. It is shown that the GAM intrinsically
involve anisotropic perturbations of plasma pressure
(corresponding to parallel viscosity). Moreover, the GAMs and
standard equilibrium (neoclassical) plasma rotation represent two
limit cases of poloidal plasma rotation: high frequency
rotational mode (GAM) and the low frequency over damped (damping
is larger than the real part of the frequency) mode of the
neoclassical equilibrium rotation. Most importantly, new
regimes of global GAM/BAE modes will be reported. These regimes
occurs as a result of the parallel kinetic response of electrons
which has not been included previously. It is shown that in
certain regimes (corresponding to global modes), the electron
response becomes strongly electromagnetic and GAM/BAE modes have
significant electromagnetic component in the side-bands (thus it
is not of the Alfven type) . Resulting modifications in the mode
dispersion and mode damping will be presented and potential
consequences for GAM/BAE excitation and electron transport will
be discussed.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.DPP.TI3.5