Plummer, A, Marston, JB and Tobias, SM (2019) Joint Instability and Abrupt Nonlinear Transitions in a Differentially Rotating Plasma. Journal of Plasma Physics, 85 (1). 905850113. ISSN 0022-3778
Abstract
Global magnetohydrodynamic (MHD) instabilities are investigated in a computationally tractable two-dimensional model of the solar tachocline. The model’s differential rotation yields stability in the absence of a magnetic field, but if a magnetic field is present, a joint instability is observed. We analyse the nonlinear development of the instability via fully nonlinear direct numerical simulation, the generalized quasi-linear approximation (GQL) and direct statistical simulation (DSS) based upon low-order expansion in equal-time cumulants. As the magnetic diffusivity is decreased, the nonlinear development of the instability becomes more complicated until eventually a set of parameters is identified that produces a previously unidentified long-term cycle in which energy is transformed from kinetic energy to magnetic energy and back. We find that the periodic transitions, which mimic some aspects of solar variability – for example, the quasiperiodic seasonal exchange of energy between toroidal field and waves or eddies – are unable to be reproduced when eddy-scattering processes are excluded from the model.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © Cambridge University Press, 2019. This article has been published in a revised form in Journal of Plasma Physics https://doi.org/10.1017/S0022377819000060. This version is free to view and download for private research and study only. Not for re-distribution, re-sale or use in derivative works. |
Keywords: | astrophysical plasmas; plasma dynamics; plasma nonlinear phenomena |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mathematics (Leeds) > Applied Mathematics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 09 Jan 2019 13:51 |
Last Modified: | 18 Aug 2019 00:40 |
Status: | Published |
Publisher: | Cambridge University Press |
Identification Number: | 10.1017/S0022377819000060 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:140759 |