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

Experiments in the DIII-D tokamak show that the plasma responds to resonant magnetic perturbations (RMP) with toroidal mode numbers of n = 2 and n = 3 without field line reconnection, consistent with resistive magnetohydrodynamic predictions (MHD), while a strong nonlinear bifurcation is apparent when edge localized modes (ELM) are suppressed. The magnetic response associated with this bifurcation is localized to the high field side (HFS) 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 ∇T e 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 2more » ~ 3 cm. The Chang-Callen calculated confinement degradation due to the presence of an individual island of this size is 8 ~ 12%, which is close to the 13 ~ 14% measured between the ELMing and suppressed states. This suggests that edge tearing modes may alter the pedestal causing peeling ballooning stability during resonant magnetic perturbation (RMP) induced ELM suppression.« less
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  1. General Atomics, San Diego, CA (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Columbia Univ., New York, NY (United States)
  5. Culham Science Centre, Abingdon (United Kingdom). Culham Centre for Fusion Energy (CCFE), EURATOM/UKAEA Fusion Association
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
FC02-04ER54698; AC02-09CH11466; AC05-00OR22725; AC52-07NA27344; FG02-04ER54761
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 11; Journal ID: ISSN 1070-664X
American Institute of Physics (AIP)
Research Org:
General Atomics, San Diego, CA (United States)
Sponsoring Org:
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1226106