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Title: On secondary and tertiary instability in electromagnetic plasma microturbulence

Zonal flows, widely accepted to be the secondary instability process leading to the nonlinear saturation of ion temperature gradient modes, are shown to grow at higher rates relative to the linear mode amplitude as the plasma pressure β is increased—thus, confirming that zonal flows become increasingly important in the turbulent dynamics at higher β. At the next level of nonlinear excitation, radial corrugations of the distribution function (zonal flow, zonal density, and zonal temperature) are demonstrated to modify linear growth rates moderately through perturbed-field, self-consistent gradients: on smaller scales, growth rates are reduced below the linear rate. In particular, excitation of kinetic ballooning modes well below their usual threshold is not to be expected under normal conditions. These findings strengthen the theory of the non-zonal transition [M. J. Pueschel et al., Phys. Rev. Lett. 110, 155005 (2013)].
Authors:
;  [1] ; ;  [2] ;  [3]
  1. Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
  2. Max-Planck-Institut für Plasmaphysik, EURATOM Association, D-85748 Garching (Germany)
  3. Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States)
Publication Date:
OSTI Identifier:
22218523
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 10; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BALLOONING INSTABILITY; BETA RATIO; DISTRIBUTION FUNCTIONS; ELECTRON TEMPERATURE; EXCITATION; ION TEMPERATURE; NONLINEAR PROBLEMS; PLASMA DENSITY; PLASMA PRESSURE; TEMPERATURE GRADIENTS; TURBULENCE