April 15-17

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approvedsherwood2019.pdf2019-04-24 12:51:56Denis St-Onge

Abstracts

Author: Denis St-Onge
Requested Type: Poster
Submitted: 2019-02-22 11:33:24

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PPPL
100 Stellarator Rd
Princeton, NJ   08540
United States

Abstract Text:
Transfer function maps are a useful diagnostic tool for establishing the dominant three-mode interactions in the Fourier space of a nonlinear system. In this work, the transfer function maps of zonal-flow/drift-wave interactions are used to investigate the Dimits shift, which is the nonlinear upshift of the critical temperature gradient by zonal flows that signals the onset of turbulence. These maps are calculated for two two-dimensional one-field models that exhibit the Dimits shift, both in the quiescent state within the shift and in the fully turbulent state beyond it. By studying these maps, the relative importance of zonal flows in each state can be compared, with the goal of establishing a more complete understanding of why the Dimits shift eventually comes to an end.

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