Title
The radial electric field as a measure for field penetration of resonant magnetic perturbations
Document Type
Article
Department/Program
Physics
Journal Title
Nuclear Fusion
Pub Date
6-2014
Volume
54
Issue
8
Abstract
In this paper 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 electron loss, due to magnetic stochastization (Kaveeva et al 2008 Nucl. Fusion 48 075003). We find that in DIII-D H-mode plasmas with n = 3 RMPs applied for edge localized mode suppression, the stochastic layer is limited to the outer 5% region in normalized magnetic flux, Psi(N). This is in contrast to vacuum modelling predictions where this layer can penetrate up to 20% in Psi(N). Theoretical predictions of a stochastic 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
Recommended Citation
Mordijck, Saskia; Moyer, R. A.; Ferraro, N. M.; Wade, M. R.; and Osborne, T. H., The radial electric field as a measure for field penetration of resonant magnetic perturbations (2014). Nuclear Fusion, 54(8).
https://www.doi.org/10.1088/0029-5515/54/8/082003
DOI
https://www.doi.org/10.1088/0029-5515/54/8/082003
