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Graduate Student Seminar - 04/17/2009

"Nondiffusive Gyrokinetic Turbulent Transport in the Z-Pinch Entropy Mode"

by Kyle Gustafson

Friday, April 17, 2009 -- 12:00 p.m.
Large Conference Room, 1207 Energy Research Facility

Advisor:  Professor William Dorland

Turbulent transport driven by gradients (temperature, density, pressure) at the gyroradius scale is hampering the use of magnetic-confinement fusion as an energy source. In this talk I will argue that the typical characterization of particle transport in terms of a local flux-gradient relationship (Fick's Law) is not always appropriate for flux-tube gyrokinetic models of plasma. Instead, one must consider the possibility of nondiffusive particle transport, where the spreading of particles is not described by a Brownian walk. This phenomenon requires correlations to appear in the perturbed electrostatic field, such that the particles execute abnormally long or short steps and/or waiting times between steps. This talk presents the results from simulations of a quasi two-dimensional plasma in a Z-pinch with a driftwave instability called the entropy mode. These results suggest that subdiffusive radial transport is present for several turbulent correlation times, at least.

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