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Title: MHD modeling of a DIII-D low-torque QH-mode discharge and comparison to observations

Extended-MHD modeling of DIII-D tokamak quiescent H-mode (QH-mode) discharges with nonlinear NIMROD simulations saturates into a turbulent state but does not saturate when the steady-state flow inferred from measurements is not included. This is consistent with the experimental observations of the quiescent regime on DIII-D. The simulation with flow develops into a saturated turbulent state where the n Φ = 1 and 2 toroidal modes become dominant through an inverse cascade. Each mode in the range of n Φ = 1–5 is dominant at a different time. Consistent with experimental observations during QH-mode, the simulated state leads to large particle transport relative to the thermal transport. Analysis shows that the amplitude and phase of the density and temperature perturbations differ resulting in greater fluctuation-induced convective particle transport relative to the convective thermal transport. As a result, comparison to magnetic-coil measurements shows that rotation frequencies differ between the simulation and experiment, which indicates that more sophisticated extended-MHD two-fluid modeling is required.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [2] ;  [2] ;  [2] ;  [2] ;  [3] ;  [4] ;  [2]
  1. Tech-X Corp., Boulder, CO (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Oak Ridge Associated Universities (ORAU), Oak Ridge, TN (United States)
  4. Tech-X Corp., Boulder, CO (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Grant/Contract Number:
FC02-06ER54875; AC02-05CH11231; AC02-06CH11357; FC02-04ER54698; FC02-08ER54972
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 5; Conference: manuscript associated with invited talk at APS-DPP Annual Meeting, 2016, in San Jose; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Tech-X Corp., Boulder, CO (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
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; extended-MHD modeling; quiescent H-mode; peeling-ballooning modes; nonlinear simulation; tokamak pedestal
OSTI Identifier:
1347994
Alternate Identifier(s):
OSTI ID: 1348026; OSTI ID: 1406354