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Title: A semi-analytic power balance model for low (L) to high (H) mode transition power threshold

We present a semi-analytic model for low (L) to high (H) mode transition power threshold (P{sub th}). Two main assumptions are made in our study. First, high poloidal mode number drift resistive ballooning modes (high-m DRBM) are assumed to be the dominant turbulence driver in a narrow edge region near to last closed flux surface. Second, the pre-transition edge profile and turbulent diffusivity at the narrow edge region pertain to turbulent equipartition. An edge power balance relation is derived by calculating the dissipated power flux through both turbulent conduction and convection, and radiation in the edge region. P{sub th} is obtained by imposing the turbulence quench rule due to sheared E × B rotation. Evaluation of P{sub th} shows a good agreement with experimental results in existing machines. Increase of P{sub th} at low density (i.e., the existence of roll-over density in P{sub th} vs. density) is shown to originate from the longer scale length of the density profile than that of the temperature profile.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [4] ;  [4] ;  [5] ;  [6] ;  [7]
  1. WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of)
  2. (India)
  3. Institute for Plasma Research, Bhat Gandhinagar 2382 428 (India)
  4. (United States)
  5. Department of Earth and Space Sciences, Chalmers University of Technology, SE-412 96 Göteborg (Sweden)
  6. Euratom-CEA Association, CEA/DSM/DRFC, CEA Cadarache F-13108 Saint-Paul-Lez-Durance (France)
  7. ITER Organization, Route de Vinon Sur Verdon, A. 13115 Saint Paul Lez Durance (France)
Publication Date:
OSTI Identifier:
22304193
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 6; 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; CONVECTION; EVALUATION; H-MODE PLASMA CONFINEMENT; MAGNETIC SURFACES; SHEAR; TURBULENCE