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Title: Zonal flow formation in the presence of ambient mean shear

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 2; Related Information: CHORUS Timestamp: 2016-12-26 04:28:23; Journal ID: ISSN 1070-664X
American Institute of Physics
Country of Publication:
United States

Citation Formats

Hsu, Pei-Chun, and Diamond, P. H.. Zonal flow formation in the presence of ambient mean shear. United States: N. p., 2015. Web. doi:10.1063/1.4907905.
Hsu, Pei-Chun, & Diamond, P. H.. Zonal flow formation in the presence of ambient mean shear. United States. doi:10.1063/1.4907905.
Hsu, Pei-Chun, and Diamond, P. H.. 2015. "Zonal flow formation in the presence of ambient mean shear". United States. doi:10.1063/1.4907905.
title = {Zonal flow formation in the presence of ambient mean shear},
author = {Hsu, Pei-Chun and Diamond, P. H.},
abstractNote = {},
doi = {10.1063/1.4907905},
journal = {Physics of Plasmas},
number = 2,
volume = 22,
place = {United States},
year = 2015,
month = 2

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4907905

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Cited by: 1work
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  • The effect of mean shear flows on zonal flow formation is considered in the contexts of plasma drift wave turbulence and quasi-geostrophic turbulence models. The generation of zonal flows by modulational instability in the presence of large-scale mean shear flows is studied using the method of characteristics as applied to the wave kinetic equation. It is shown that mean shear flows reduce the modulational instability growth rate by shortening the coherency time of the wave spectrum with the zonal shear. The scalings of zonal flow growth rate and turbulent vorticity flux with mean shear are determined in the strong shearmore » limit.« less
  • Long-distance toroidal correlations of potential and density fluctuations have been investigated at the TEXTOR tokamak [H. Soltwisch et al., Plasma Phys. Controlled Fusion 26, 23 (1984)] in edge electrode-biasing experiments. During the biasing-induced H-mode, the dc ExB shear flow triggers a zonal flow structure and hence long-distance correlation in potential fluctuations, whereas for density fluctuations there is nearly no correlation. These results indicate an intimate interaction between the mean and zonal flows, and the significance of long range correlations in improved-confinement regimes.
  • The present work investigates the direct interaction of sheared mean flow with zonal flows (ZFs) and the effect of parallel ion motion on ZF generation in ion-temperature-gradient (ITG) background turbulence. An analytical model for the direct interaction of sheared mean flows with zonal flows is constructed. The model used for the toroidal ITG driven mode is based on the equations for ion continuity, ion temperature and parallel ion motion, whereas the ZF evolution is described by the vorticity equation. The behavior of the ZF growth rate and real frequency is examined for typical tokamak parameters. It is shown that inmore » general the zonal flow growth rate is suppressed by the presence of a sheared mean flow. In addition, with parallel ion motion effects the ZFs become more oscillatory for increasing {eta}{sub i}(=L{sub n}/L{sub Ti}) value.« less
  • Excitation of zonal flow by the modulational instability in the presence of mean shear flow is considered. The presence of the mean flow without large amplitude increases the modulational instability growth rate and favors zonal flow generation, whereas sufficiently strong mean shear significantly reduces the instability growth rate.
  • Collisionless trapped ion modes (CTIMs) turbulence exhibits a rich variety of zonal flow physics. The coupling of CTIMs with shear flow driven by the Kelvin-Helmholtz (KH) instability has been investigated. The work explores the parametric excitation of zonal flow modified by wave-particle interactions leading to a new type of resonant low-frequency zonal flow. The KH-CTIM interaction on zonal flow growth and its feedback on turbulence is investigated using semi-Lagrangian gyrokinetic Vlasov simulations based on a Hamiltonian reduction technique, where both fast scales (cyclotron plus bounce motions) are gyro-averaged.