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Title: Shear-flow trapped-ion-mode interaction revisited. II. Intermittent transport associated with low-frequency zonal flow dynamics

We address the mechanisms underlying low-frequency zonal flow generation in turbulent system and the associated intermittent regime of ion-temperature-gradient (ITG) turbulence. This model is in connection with the recent observation of quasi periodic zonal flow oscillation at a frequency close to 2 kHz, at the low-high transition, observed in the ASDEX Upgrade [Conway et al., Phys. Rev. Lett. 106, 065001 (2011)] and EAST tokamak [Xu et al., Phys. Rev. Lett 107, 125001 (2011)]. Turbulent bursts caused by the coupling of Kelvin-Helmholtz (KH) driven shear flows with trapped ion modes (TIMs) were investigated by means of reduced gyrokinetic simulations. It was found that ITG turbulence can be regulated by low-frequency meso-scale zonal flows driven by resonant collisionless trapped ion modes (CTIMs), through parametric-type scattering, a process in competition with the usual KH instability.
Authors:
 [1] ;  [2]
  1. Institut Jean Lamour- UMR 7168, Université de Lorraine, BP 239 F-54506 Vandoeuvre les Nancy (France)
  2. LFMA -Ecole Centrale de Lyon, Université de Lyon, 60134 Ecully (France)
Publication Date:
OSTI Identifier:
22490045
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 8; Other Information: (c) 2015 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; ASDEX TOKAMAK; COMPUTERIZED SIMULATION; FLOW MODELS; HELMHOLTZ INSTABILITY; HT-7U TOKAMAK; ION TEMPERATURE; IONS; KHZ RANGE; OSCILLATIONS; SCATTERING; SHEAR; TEMPERATURE GRADIENTS; TRAPPING