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Title: Spatial localization of resistive drift wave structure in tokamak edge plasmas with an embedded magnetic island

Resistive drift wave instability is investigated numerically in tokamak edge plasma confined by sheared slab magnetic field geometry with an embedded magnetic island. The focus is on the structural characteristics of eigenmode inside the island, where the density profile tends to be flattened. A transition of the dominant eigenmode occurs around a critical island width w{sub c}. For thin islands with a width below w{sub c}, two global long wavelength eigenmodes with approximately the same growth rate but different eigenfrequency are excited, which are stabilized by the magnetic island through two-dimensional mode coupling in both x and y (corresponding to radial and poloidal in tokamak) directions. On the other hand, a short wavelength eigenmode, which is destabilized by thick islands with a width above w{sub c}, dominates the edge fluctuation, showing a prominent structural localization in the region between the X-point and the O-point of the magnetic island. The main destabilization mechanism is identified as the mode coupling in the y direction, which is similar to the so-called toroidal coupling in tokamak plasmas. These three eigenmodes may coexist in the drift wave fluctuation for the island with a width around w{sub c}. It is demonstrated that the structural localization resultsmore » mainly from the quasilinear flattening of density profile inside the magnetic island.« less
Authors:
;  [1] ;  [2] ;  [2] ;  [3]
  1. Southwestern Institute of Physics, Sichuan, Chengdu 610041 (China)
  2. Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 6110011 (Japan)
  3. (Japan)
Publication Date:
OSTI Identifier:
22299679
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 10; 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; EIGENFREQUENCY; FLUCTUATIONS; MAGNETIC FIELDS; MAGNETIC ISLANDS; PLASMA; TOKAMAK DEVICES; WAVE PROPAGATION; WAVELENGTHS