Three-dimensional equilibria and island energy transport due to resonant magnetic perturbation edge localized mode suppression on DIII-D
- General Atomics, San Diego, CA (United States)
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Princeton Univ., NJ (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Columbia Univ., New York, NY (United States)
- Culham Science Centre, Culham Centre for Fusion Energy (CCFE), Abingdon (United Kingdom)
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 ∇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 is 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.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); DIII-D National Fusion Facility, San Diego, CA (United States); General Atomics, San Diego, CA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC05-00OR22725; FC02-04ER54698; AC02-09CH11466; AC52-07NA27344; FG02-04ER54761
- OSTI ID:
- 1302918
- Alternate ID(s):
- OSTI ID: 1226106; OSTI ID: 1372465; OSTI ID: 1871408
- Report Number(s):
- LLNL-JRNL-834534; AT1010101; ERAT363
- Journal Information:
- Physics of Plasmas, Vol. 22, Issue 11; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Modelling of plasma response to 3D external magnetic field perturbations in EAST
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journal | October 2016 |
The density dependence of edge-localized-mode suppression and pump-out by resonant magnetic perturbations in the DIII-D tokamak
|
journal | December 2019 |
Equilibrium drives of the low and high field side n = 2 plasma response and impact on global confinement
|
journal | April 2016 |
Modal analysis of the full poloidal structure of the plasma response to n = 2 magnetic perturbations
|
journal | July 2018 |
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