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Title: The radial electric field as a measure for field penetration of resonant magnetic perturbations

In this study, we introduce a new indirect method for identifying the radial extent of the stochastic layer due to applying resonant magnetic perturbations (RMPs) in H-mode plasmas by measuring the spin-up of the plasma near the separatrix. This spin-up is a predicted consequence of enhanced loss of electrons due to magnetic stochastization. We find that in DIII-D H-mode plasmas with n = 3 RMPs applied for edge localized mode (ELM) suppression, the stochastic layer is limited to the outer 5% region in normalized magnetic flux, Ψ N. This is in contrast to vacuum modeling predictions where this layer can penetrate up to 20% in Ψ N. Theoretical predictions of a stochastic red radial electric field, E r component exceed the experimental measurements by about a factor 3 close to the separatrix, suggesting that the outer region of the plasma is weakly stochastic. Linear response calculations with M3D-C1, a resistive two-fluid model, show that in this outer 5% region, plasma response often reduces the resonant magnetic field components by 67% or more in comparison with vacuum calculations. These results for DIII-D are in reasonable agreement with results from the MAST tokamak, where the magnetic field perturbation from vacuum field calculationsmore » needed to be reduced by 75% for agreement with experimental measurements of the x-point lobe structures.« less
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [3]
  1. College of William and Mary, Williamsburg, VA (United States)
  2. Univ. of California San Diego, La Jolla, CA (United States)
  3. General Atomics, San Diego, CA (United States)
Publication Date:
Grant/Contract Number:
FC02-04ER54698
Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 54; Journal Issue: 8; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Research Org:
College of William and Mary, Williamsburg, VA (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; plasmas; stochastic layer; magnetic perturbations
OSTI Identifier:
1352934

Mordijck, Saskia, Moyer, Richard A., Ferraro, Nathaniel M., Wade, Mickey R., and Osborne, Thomas H.. The radial electric field as a measure for field penetration of resonant magnetic perturbations. United States: N. p., Web. doi:10.1088/0029-5515/54/8/082003.
Mordijck, Saskia, Moyer, Richard A., Ferraro, Nathaniel M., Wade, Mickey R., & Osborne, Thomas H.. The radial electric field as a measure for field penetration of resonant magnetic perturbations. United States. doi:10.1088/0029-5515/54/8/082003.
Mordijck, Saskia, Moyer, Richard A., Ferraro, Nathaniel M., Wade, Mickey R., and Osborne, Thomas H.. 2014. "The radial electric field as a measure for field penetration of resonant magnetic perturbations". United States. doi:10.1088/0029-5515/54/8/082003. https://www.osti.gov/servlets/purl/1352934.
@article{osti_1352934,
title = {The radial electric field as a measure for field penetration of resonant magnetic perturbations},
author = {Mordijck, Saskia and Moyer, Richard A. and Ferraro, Nathaniel M. and Wade, Mickey R. and Osborne, Thomas H.},
abstractNote = {In this study, we introduce a new indirect method for identifying the radial extent of the stochastic layer due to applying resonant magnetic perturbations (RMPs) in H-mode plasmas by measuring the spin-up of the plasma near the separatrix. This spin-up is a predicted consequence of enhanced loss of electrons due to magnetic stochastization. We find that in DIII-D H-mode plasmas with n = 3 RMPs applied for edge localized mode (ELM) suppression, the stochastic layer is limited to the outer 5% region in normalized magnetic flux, ΨN. This is in contrast to vacuum modeling predictions where this layer can penetrate up to 20% in ΨN. Theoretical predictions of a stochastic red radial electric field, Er component exceed the experimental measurements by about a factor 3 close to the separatrix, suggesting that the outer region of the plasma is weakly stochastic. Linear response calculations with M3D-C1, a resistive two-fluid model, show that in this outer 5% region, plasma response often reduces the resonant magnetic field components by 67% or more in comparison with vacuum calculations. These results for DIII-D are in reasonable agreement with results from the MAST tokamak, where the magnetic field perturbation from vacuum field calculations needed to be reduced by 75% for agreement with experimental measurements of the x-point lobe structures.},
doi = {10.1088/0029-5515/54/8/082003},
journal = {Nuclear Fusion},
number = 8,
volume = 54,
place = {United States},
year = {2014},
month = {6}
}