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Title: Experimental tests of linear and nonlinear three-dimensional equilibrium models in DIII-D

DIII-D experiments using new detailed magnetic diagnostics show that linear, ideal magnetohydrodynamics (MHD) theory quantitatively describes the magnetic structure (as measured externally) of three-dimensional (3D) equilibria resulting from applied fields with toroidal mode number n = 1, while a nonlinear solution to ideal MHD force balance, using the VMEC code, requires the inclusion of n ≥ 1 to achieve similar agreement. These tests are carried out near ITER baseline parameters, providing a validated basis on which to exploit 3D fields for plasma control development. Scans of the applied poloidal spectrum and edge safety factor confirm that low-pressure, n = 1 non-axisymmetric tokamak equilibria are determined by a single, dominant, stable eigenmode. However, at higher beta, near the ideal kink mode stability limit in the absence of a conducting wall, the qualitative features of the 3D structure are observed to vary in a way that is not captured by ideal MHD.
Authors:
 [1] ;  [2] ; ; ; ; ;  [3] ; ; ; ; ;  [4] ;  [5] ;  [6] ;  [7] ;  [8]
  1. Oak Ridge Institute for Science Education, Oak Ridge, Tennessee 37830-8050 (United States)
  2. (United States)
  3. General Atomics, P.O. Box 85608, San Diego, California 92816-5608 (United States)
  4. Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States)
  5. Plasma Research Laboratory, Research School of Physical Sciences and Engineering, The Australia National University, Canberra, Australian Capital Territory 0200 (Australia)
  6. Columbia University, 2960 Broadway, New York, New York 10027 (United States)
  7. Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom)
  8. Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States)
Publication Date:
OSTI Identifier:
22490007
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 7; 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; AXIAL SYMMETRY; DOUBLET-3 DEVICE; EQUILIBRIUM; EXPERIMENT RESULTS; HIGH-BETA PLASMA; ITER TOKAMAK; KINK INSTABILITY; MAGNETOHYDRODYNAMICS; MATHEMATICAL SOLUTIONS; NONLINEAR PROBLEMS; PRESSURE RANGE KILO PA; SPECTRA; THREE-DIMENSIONAL CALCULATIONS