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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. Moreover, these tests are carried out near ITER baseline parameters, providing a validated basis on which to exploit 3D fields for plasma control development. We determine scans of the applied poloidal spectrum and edge safety factors which confirm that low-pressure, n = 1 non-axisymmetric tokamak equilibria are a single, dominant, stable eigenmode. But, 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.
 [1] ;  [2] ; ORCiD logo [3] ;  [2] ;  [3] ;  [4] ;  [3] ;  [5] ;  [2] ;  [6] ;  [3] ;  [3] ;  [2] ;  [7] ; ORCiD logo [2]
  1. Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); General Atomics, San Diego, CA (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  4. Australian National Univ., Canberra, ACT (Australia)
  5. Columbia Univ., New York, NY (United States)
  6. Culham Science Centre, Abingdon (United Kingdom). Plasma Research Lab.
  7. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; FC02-04ER54698; AC05-06OR23100; AC02-09CH11466; FG02-04ER54761
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 7; Journal ID: ISSN 1070-664X
American Institute of Physics (AIP)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1228332; OSTI ID: 1356315