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Title: Mode penetration induced by transient magnetic perturbations

Abstract

Three dimensional magnetic fields in tokamaks can induce forced magnetic reconnection (FMR) and produce magnetic islands on resonant surfaces. Conventional analytic solutions to FMR focus on describing the time asymptotic state given a steady-state field error. The purpose of this report is to understand the nonlinear dynamics of mode penetration, an evolution from a high-slip, flow-screened metastable equilibrium into a low-slip, field-penetrated metastable equilibrium. Here, we extend previous work by incorporating a temporally varying external magnetic field as a simple model for a magnetohydrodynamic (MHD) event that produces resonant magnetic perturbations. Proof-of-principle, extended-MHD, NIMROD computations vary parameterizations of the transient external perturbation to probe the threshold for mode penetration. We test these computational results against analytical theory that captures the temporal evolution properties of the electromagnetic and viscous forces during and after a transient. We find qualitative agreement between computational and analytical results. However, computational tools are necessary to accurately capture the threshold conditions for mode penetration induced by an MHD transient.

Authors:
ORCiD logo [1];  [1]; ORCiD logo [1];  [1]
  1. Univ. of Wisconsin, Madison, WI (United States)
Publication Date:
Research Org.:
Univ. of Wisconsin, Madison, WI (United States); Univ. of California, Oakland, CA (United States); Oak Ridge Associated Univ., Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1540249
Alternate Identifier(s):
OSTI ID: 1463222
Grant/Contract Number:  
FG02-86ER53218; FG02-92ER54139; AC02-05CH11231; SC0014664
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 8; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Beidler, M. T., Callen, J. D., Hegna, C. C., and Sovinec, C. R. Mode penetration induced by transient magnetic perturbations. United States: N. p., 2018. Web. doi:10.1063/1.5046076.
Beidler, M. T., Callen, J. D., Hegna, C. C., & Sovinec, C. R. Mode penetration induced by transient magnetic perturbations. United States. https://doi.org/10.1063/1.5046076
Beidler, M. T., Callen, J. D., Hegna, C. C., and Sovinec, C. R. Tue . "Mode penetration induced by transient magnetic perturbations". United States. https://doi.org/10.1063/1.5046076. https://www.osti.gov/servlets/purl/1540249.
@article{osti_1540249,
title = {Mode penetration induced by transient magnetic perturbations},
author = {Beidler, M. T. and Callen, J. D. and Hegna, C. C. and Sovinec, C. R.},
abstractNote = {Three dimensional magnetic fields in tokamaks can induce forced magnetic reconnection (FMR) and produce magnetic islands on resonant surfaces. Conventional analytic solutions to FMR focus on describing the time asymptotic state given a steady-state field error. The purpose of this report is to understand the nonlinear dynamics of mode penetration, an evolution from a high-slip, flow-screened metastable equilibrium into a low-slip, field-penetrated metastable equilibrium. Here, we extend previous work by incorporating a temporally varying external magnetic field as a simple model for a magnetohydrodynamic (MHD) event that produces resonant magnetic perturbations. Proof-of-principle, extended-MHD, NIMROD computations vary parameterizations of the transient external perturbation to probe the threshold for mode penetration. We test these computational results against analytical theory that captures the temporal evolution properties of the electromagnetic and viscous forces during and after a transient. We find qualitative agreement between computational and analytical results. However, computational tools are necessary to accurately capture the threshold conditions for mode penetration induced by an MHD transient.},
doi = {10.1063/1.5046076},
url = {https://www.osti.gov/biblio/1540249}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 8,
volume = 25,
place = {United States},
year = {2018},
month = {8}
}

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    Works referencing / citing this record:

    Real frequency tearing layers with parallel dynamics and the effect on error field locking and resistive wall modes
    journal, October 2019