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Title: Effect of rotation zero-crossing on single-fluid plasma response to three-dimensional magnetic perturbations

In order to understand the effect of rotation on the plasma's response to three-dimensional magnetic perturbations, we perform a systematic scan of the zero-crossing of the rotation profile in a DIII-D ITER-similar shape equilibrium using linear, time-independent modeling with the M3D-C1 extended magnetohydrodynamics code. We confirm that the local resonant magnetic field generally increases as the rotation decreases at a rational surface. Multiple peaks in the resonant field are observed near rational surfaces, however, and the maximum resonant field does not always correspond to zero rotation at the surface. Furthermore, we show that non-resonant current can be driven at zero- crossings not aligned with rational surfaces if there is sufficient shear in the rotation profile there, leading to an amplification of near-resonant Fourier harmonics of the perturbed magnetic field and a decrease in the far-off -resonant harmonics. The quasilinear electromagnetic torque induced by this non-resonant plasma response provides drive to flatten the rotation, possibly allowing for increased transport in the pedestal by the destabilization of turbulent modes. In addition, this torque acts to drive the rotation zero-crossing to dynamically stable points near rational surfaces, which would allow for increased resonant penetration. By one or both of these mechanisms, this torquemore » may play an important role in bifurcations into ELM suppression. Finally, we discuss how these changes to the plasma response could be detected by tokamak diagnostics. In particular, we show that the changes to the resonant field discussed here have a significant impact on the external perturbed magnetic field, which should be observable by magnetic sensors on the high-field side of tokamaks, but not on the low-field side. In addition, TRIP3D-MAFOT simulations show that none of the changes to the plasma response described here substantially affects the divertor footprint structure.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [4]
  1. Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); General Atomics, San Diego, CA (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. General Atomics, San Diego, CA (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
FG02-95ER54309; FC02-06ER54873; AC05-06OR23100; AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 59; Journal Issue: 4; Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Research Org:
General Atomics, San Diego, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; magnetic perturbations; extended magnetohydrodynamics; plasma response; rotation; torque; edge-localized modes; ELM suppression
OSTI Identifier:
1374819
Alternate Identifier(s):
OSTI ID: 1376337; OSTI ID: 1398790