On the nature of radial transport across sheared zonal flows in electrostatic ion-temperature-gradient gyrokinetic tokamak plasma turbulence

11 pages, 12 figures.-- PACS nrs.: 52.35.Ra, 52.55.Fa, 05.40.Fb.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.Research was carried out at Oak Ridge National Laboratory, managed by UT-Battelle LLC, for U.S. DOE under Contract No. DE-AC05-00OR22725. Research was funded by the DOE Office of Science Grant No. DE-FG02-04ER54741 at University of Alaska and Grant No. DEFG02-04ER54740 at UCLA. Simulations run, thanks to grants for use of supercomputing resources at the University of Alaska’s Arctic Region Supercomputing Center in Fairbanks, DOE’s National Energy Research Scientific Computing Center (NERSC) in Berkeley, and the Spanish National Supercomputing Network (RES) in Barcelona and Madrid.Publicad

Numerical tokamak turbulence project (OFES grand challenge)

The primary research objective of the Numerical Tokamak Turbulence Project (NTTP) is to develop a predictive ability in modeling turbulent transport due to drift-type instabilities in the core of tokamak fusion experiments, through the use of three-dimensional kinetic and fluid simulations and the derivation of reduced models

Numerical Tokamak Turbulence Project

The primary research objective of the Numerical Tokamak Turbulence Project (NTTP) is to develop a predictive ability in modeling turbulent transport due to drift-type instabilities in the core of tokamak fusion experiments, through the use of three-dimensional kinetic and fluid simulations and the derivation of reduced models