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Title: Mitigating impact of thermal and rectified radio-frequency sheath potentials on edge localized modes

The mitigating impact of thermal and rectified radio frequency (RF) sheath potentials on the peeling-ballooning modes is studied non-linearly by employing a two-fluid three-field simulation model based on the BOUT++ framework. Additional shear flow and the Kelvin-Helmholtz effect due to the thermal and rectified RF sheath potential are induced. It is found that the shear flow increases the growth rate while the K-H effect decreases the growth rate slightly when there is a density gradient, but the energy loss of these cases is suppressed in the nonlinear phase. The stronger external electrostatic field due to the sheaths has a more significant effect on the energy loss suppression. From this study, it is found the growth rate in the linear phase mainly determines the onset of edge-localized modes, while the mode spectrum width in the nonlinear phase has an important impact on the turbulent transport. The wider mode spectrum leads to weaker turbulent transport and results in a smaller energy loss. Due to the thermal sheath and rectified RF sheath potential in the scrape-off-layer, the modified shear flow tears apart the peeling-ballooning filament and makes the mode spectrum wider, resulting in less energy loss. The perturbed electric potential and the parallelmore » current near the sheath region is also suppressed locally due to the sheath boundary condition.« less
Authors:
 [1] ;  [2] ;  [3] ; ;  [4]
  1. Institute of Plasma Physics Chinese Academy of Sciences, Hefei (China)
  2. (United States)
  3. Lawerence Livermore National Lab, Livermore, California 94550 (United States)
  4. Lodestar Research Corporation, Boulder, Colorado 80301 (United States)
Publication Date:
OSTI Identifier:
22403258
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 11; 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; EDGE LOCALIZED MODES; ENERGY LOSSES; NONLINEAR PROBLEMS; PLASMA SCRAPE-OFF LAYER; POTENTIALS; RADIOWAVE RADIATION; SHEAR