On the nature of radial transport across sheared zonal flows in electrostatic ion-temperature-gradient gyrokinetic tokamak plasma turbulence
- Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States)
- Department of Physics, University of Alaska, Fairbanks, Alaska 99775-5920 (United States)
- JNL Scientific, Inc., Casa Grande, Arizona 85294-9695 (United States)
- BACV Solutions, Inc., Oak Ridge, Tennessee 37830-8222 (United States)
- UCLA, Los Angeles, California 90095-1547 (United States)
It is argued that the usual understanding of the suppression of radial turbulent transport across a sheared zonal flow based on a reduction in effective transport coefficients is, by itself, incomplete. By means of toroidal gyrokinetic simulations of electrostatic, ion-temperature-gradient turbulence, it is found instead that the character of the radial transport is altered fundamentally by the presence of a sheared zonal flow, changing from diffusive to anticorrelated and subdiffusive. Furthermore, if the flows are self-consistently driven by the turbulence via the Reynolds stresses (in contrast to being induced externally), radial transport becomes non-Gaussian as well. These results warrant a reevaluation of the traditional description of radial transport across sheared flows in tokamaks via effective transport coefficients, suggesting that such description is oversimplified and poorly captures the underlying dynamics, which may in turn compromise its predictive capabilities.
- OSTI ID:
- 21277150
- Journal Information:
- Physics of Plasmas, Vol. 16, Issue 5; Other Information: DOI: 10.1063/1.3129727; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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Nature of Transport across Sheared Zonal Flows in Electrostatic Ion-Temperature-Gradient Gyrokinetic Plasma Turbulence
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