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Title: Microturbulence in DIII-D tokamak pedestal. I. Electrostatic instabilities

Gyrokinetic simulations of electrostatic driftwave instabilities in a tokamak edge have been carried out to study the turbulent transport in the pedestal of an H-mode plasma. The simulations use annulus geometry and focus on two radial regions of a DIII-D experiment: the pedestal top with a mild pressure gradient and the middle of the pedestal with a steep pressure gradient. A reactive trapped electron instability with a typical ballooning mode structure is excited by trapped electrons in the pedestal top. In the middle of the pedestal, the electrostatic instability exhibits an unusual mode structure, which peaks at the poloidal angle θ=±π/2. The simulations find that this unusual mode structure is due to the steep pressure gradients in the pedestal but not due to the particular DIII-D magnetic geometry. Realistic DIII-D geometry appears to have a stabilizing effect on the instability when compared to a simple circular tokamak geometry.
Authors:
;  [1] ;  [1] ;  [2] ;  [3]
  1. Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)
  2. (China)
  3. Institute of Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China)
Publication Date:
OSTI Identifier:
22253135
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 4; 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; DOUBLET-3 DEVICE; GEOMETRY; H-MODE PLASMA CONFINEMENT; PEAKS; PLASMA; PRESSURE GRADIENTS; SIMULATION; TRAPPED ELECTRONS