Resistive stability of cylindrical MHD equilibria with radially localized pressure gradients
Abstract
As a step toward understanding 3D magnetohydrodynamic (MHD) equilibria, for which smooth solutions may not exist, we develop a simple cylindrical model to investigate the resistive stability of MHD equilibria with alternating regions of constant and nonuniform pressure, producing states with continuous total pressure (i.e., no singular current sheets) but discontinuities in the parallel current density. We examine how the resistive stability characteristics of the model change as we increase the localization of pressure gradients at fixed radii, which approaches a discontinuous pressure profile in the zerowidth limit. Equilibria with continuous pressure are found to be unstable to moderate/highm modes and apparently tend toward ideal instability in some cases. We propose that additional geometric degrees of freedom or symmetry breaking via island formation may increase the parameter space on which equilibria of our model are physically realizable, while preserving the radial localization of pressure gradients. This is consistent with the possibility of realizing, in practice, 3D MHD equilibria which support both continuously nested flux surfaces (where ∇p ≠ 0) and chaotic field regions (where ∇p = 0)
 Authors:

 Australian National Univ., Canberra, ACT (Australia)
 Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
 Publication Date:
 Research Org.:
 Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 1543151
 Alternate Identifier(s):
 OSTI ID: 1527064
 Grant/Contract Number:
 AC0276CH03073
 Resource Type:
 Accepted Manuscript
 Journal Name:
 Physics of Plasmas
 Additional Journal Information:
 Journal Volume: 26; Journal Issue: 6; Journal ID: ISSN 1070664X
 Publisher:
 American Institute of Physics (AIP)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Citation Formats
Wright, A. M., Hudson, S. R., Dewar, R. L., and Hole, M. J. Resistive stability of cylindrical MHD equilibria with radially localized pressure gradients. United States: N. p., 2019.
Web. doi:10.1063/1.5099354.
Wright, A. M., Hudson, S. R., Dewar, R. L., & Hole, M. J. Resistive stability of cylindrical MHD equilibria with radially localized pressure gradients. United States. doi:10.1063/1.5099354.
Wright, A. M., Hudson, S. R., Dewar, R. L., and Hole, M. J. Wed .
"Resistive stability of cylindrical MHD equilibria with radially localized pressure gradients". United States. doi:10.1063/1.5099354. https://www.osti.gov/servlets/purl/1543151.
@article{osti_1543151,
title = {Resistive stability of cylindrical MHD equilibria with radially localized pressure gradients},
author = {Wright, A. M. and Hudson, S. R. and Dewar, R. L. and Hole, M. J.},
abstractNote = {As a step toward understanding 3D magnetohydrodynamic (MHD) equilibria, for which smooth solutions may not exist, we develop a simple cylindrical model to investigate the resistive stability of MHD equilibria with alternating regions of constant and nonuniform pressure, producing states with continuous total pressure (i.e., no singular current sheets) but discontinuities in the parallel current density. We examine how the resistive stability characteristics of the model change as we increase the localization of pressure gradients at fixed radii, which approaches a discontinuous pressure profile in the zerowidth limit. Equilibria with continuous pressure are found to be unstable to moderate/highm modes and apparently tend toward ideal instability in some cases. We propose that additional geometric degrees of freedom or symmetry breaking via island formation may increase the parameter space on which equilibria of our model are physically realizable, while preserving the radial localization of pressure gradients. This is consistent with the possibility of realizing, in practice, 3D MHD equilibria which support both continuously nested flux surfaces (where ∇p ≠ 0) and chaotic field regions (where ∇p = 0)},
doi = {10.1063/1.5099354},
journal = {Physics of Plasmas},
number = 6,
volume = 26,
place = {United States},
year = {2019},
month = {6}
}
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