Plasma Shape Effects on Geodesic Acoustic Oscillations
- Centre de Recherches en Physique des Plasmas, Association Euratom -- Confederation Suisse, EPFL, 1015 Lausanne (Switzerland)
- Max-Planck Gesellschaft Institute for Plasma Physics, D-85748 Garching (Germany)
- Computer Center of the IPP, D-85748 Garching (Germany)
- Germany
Geodesic acoustic mode (GAM) oscillations in tokamak plasmas are known to be sensitive to the value of the safety factor q. Through its linear and nonlinear interactions with ITG turbulence it has recently been shown in direct numerical global simulations that the turbulence driven heat transport is larger when GAM oscilations of large amplitude are present, resulting in an anomalous transport scaling with the inverse plasma current. GAM dispersion relations have been derived for circular, large aspect ratio configurations, and, recently, for helical configurations. Linear simulation results are presented using the global, PIC, finite element codes GYGLES and ORB5 for the GAM frequency, damping rate and Rosenbluth-Hinton residual zonal flow for a scan in plasma elongation. It is found that CAM frequency slightly decreases, while GAM damping rate and residual zonal flows increase with elongation. Nonlinear ITG simulations using the ORB5 code show that elongation reduces heat transport and that this is related to the plasma current and not q alone.
- OSTI ID:
- 20895156
- Journal Information:
- AIP Conference Proceedings, Vol. 871, Issue 1; Conference: Joint Varenna-Lausanne international workshop on theory of fusion plasmas, Varenna (Italy), 28 Aug - 1 Sep 2006; Other Information: DOI: 10.1063/1.2404581; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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