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Title: Comprehensive comparisons of geodesic acoustic mode characteristics and dynamics between Tore Supra experiments and gyrokinetic simulations

In a dedicated collisionality scan in Tore Supra, the geodesic acoustic mode (GAM) is detected and identified with the Doppler backscattering technique. Observations are compared to the results of a simulation with the gyrokinetic code GYSELA. We found that the GAM frequency in experiments is lower than predicted by simulation and theory. Moreover, the disagreement is higher in the low collisionality scenario. Bursts of non harmonic GAM oscillations have been characterized with filtering techniques, such as the Hilbert-Huang transform. When comparing this dynamical behaviour between experiments and simulation, the probability density function of GAM amplitude and the burst autocorrelation time are found to be remarkably similar. In the simulation, where the radial profile of GAM frequency is continuous, we observed a phenomenon of radial phase mixing of the GAM oscillations, which could influence the burst autocorrelation time.
Authors:
; ; ; ; ;  [1] ; ; ; ; ;  [2] ;  [3]
  1. Laboratoire de Physique des Plasmas, École Polytechnique, CNRS, UPMC, UPSud, 91128 Palaiseau (France)
  2. CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France)
  3. Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany)
Publication Date:
OSTI Identifier:
22490932
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 6; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AMPLITUDES; BACKSCATTERING; COMPARATIVE EVALUATIONS; DOPPLER EFFECT; EXPERIMENT RESULTS; GEODESICS; OSCILLATIONS; PLASMA SIMULATION; PROBABILITY DENSITY FUNCTIONS; TORE SUPRA TOKAMAK