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Title: Three-dimensional equilibria and island energy transport due to resonant magnetic perturbation edge localized mode suppression on DIII-D

In this research, we conducted experiments in the DIII-D tokamak that show that the plasma responds to resonant magnetic perturbations (RMPs) with toroidalmode numbers of n=2 and n=3 without field line reconnection, consistent with resistive magnetohydrodynamic predictions, while a strong nonlinear bifurcation is apparent when edge localized modes(ELMs) are suppressed. The magnetic response associated with this bifurcation is localized to the high field side of the machine and exhibits a dominant n=1 component despite the application of a constant amplitude, slowly toroidally rotating, n=2 applied field. The n=1 mode is born locked to the vacuum vessel wall, while the n=2 mode is entrained to the rotating field. Based on these magnetic response measurements and Thomson scattering measurements of flattening of the electron temperature profile, it is likely that these modes are magnetic island chains near the H-mode pedestal. The reduction in βˆ‡Te occurs near the q=4 and 5 rational surfaces, suggesting five unique islands are possible (m=8, 9, or 10 for n=2) and (m=4 or 5 for n=1). In all cases, the island width is estimated to be 2–3 cm. The Chang-Callen calculated confinement degradation due to the presence of an individual island of this size is 8%–12%, which ismore » close to the 13%–14% measured between the ELMs and suppressed states. In conclusion, this suggests that edge tearing modes may alter the pedestal causing peeling-ballooning stability during RMP induced ELM suppression.« less
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [1] ;  [5] ;  [2] ;  [1] ;  [1] ;  [2] ;  [2] ;  [6] ;  [2] ;  [2] ;  [1]
  1. General Atomics, San Diego, CA (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. Princeton Univ., NJ (United States)
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. Columbia Univ., New York, NY (United States)
  6. Culham Science Centre, Culham Centre for Fusion Energy (CCFE), Abingdon (United Kingdom)
Publication Date:
OSTI Identifier:
1302918
Grant/Contract Number:
AC05-00OR22725; FC02-04ER54698; AC02-09CH11466; AC52-07NA27344; FG02-04ER54761
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 11; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY