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Title: Comparison between kinetic-ballooning-mode-driven turbulence and ion-temperature-gradient-driven turbulence

Electromagnetic turbulence driven by kinetic ballooning modes (KBMs) in high-β plasma is investigated based on the local gyrokinetic model. Analysis of turbulent fluxes, norms, and phases of fluctuations shows that KBM turbulence gives narrower spectra and smaller phase factors than those in ion-temperature-gradient (ITG)-driven turbulence. This leads to the smaller transport fluxes in KBM turbulence than those in ITG turbulence even when they have similar linear growth rates. From the analysis of the entropy balance relation, it is found that the entropy transfer from ions to electrons through the field-particle interactions mainly drives electron perturbations, which creates radial twisted modes by rapid parallel motions of electrons in a sheared magnetic geometry. The nonlinear coupling between the dominant unstable mode and its twisted modes is important for the saturation of KBM turbulence, in contrast to the importance of zonal flow shearing in ITG turbulence. The coupling depends on the flux-tube domain with the one-poloidal-turn parallel length and on the torus periodicity constraint.
Authors:
; ; ;  [1] ; ;  [2] ;  [3]
  1. Japan Atomic Energy Agency, Rokkasho, Aomori 039-3212 (Japan)
  2. National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan)
  3. Japan Atomic Energy Agency, Kashiwa, Chiba 277-8587 (Japan)
Publication Date:
OSTI Identifier:
22252947
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 5; Other Information: (c) 2014 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; COMPARATIVE EVALUATIONS; ELECTRONS; ENTROPY; FLUCTUATIONS; LIMITING VALUES; NONLINEAR PROBLEMS; PERTURBATION THEORY; PLASMA; POWER FACTOR; TEMPERATURE GRADIENTS; TURBULENCE