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dc.contributor.authorBareford, Michael
dc.contributor.authorHood, Alan
dc.contributor.authorBrowning, Philippa
dc.date.accessioned2013-03-05T09:31:03Z
dc.date.available2013-03-05T09:31:03Z
dc.date.issued2013-02
dc.identifier.citationBareford , M , Hood , A & Browning , P 2013 , ' Coronal heating by the partial relaxation of twisted loops ' Astronomy & Astrophysics , vol 550 , A40 . DOI: 10.1051/0004-6361/201219725en
dc.identifier.issn0004-6361
dc.identifier.otherPURE: 37456799
dc.identifier.otherPURE UUID: 42950eed-87ae-4087-b89d-c7282073c9bd
dc.identifier.otherArXiv: http://arxiv.org/abs/1211.3855v1
dc.identifier.otherScopus: 84872910138
dc.identifier.urihttp://hdl.handle.net/10023/3373
dc.description.abstractContext: Relaxation theory offers a straightforward method for estimating the energy that is released when a magnetic field becomes unstable, as a result of continual convective driving. Aims: We present new results obtained from nonlinear magnetohydrodynamic (MHD) simulations of idealised coronal loops. The purpose of this work is to determine whether or not the simulation results agree with Taylor relaxation, which will require a modified version of relaxation theory applicable to unbounded field configurations. Methods: A three-dimensional (3D) MHD Lagrangian-remap code is used to simulate the evolution of a line-tied cylindrical coronal loop model. This model comprises three concentric layers surrounded by a potential envelope; hence, being twisted locally, each loop configuration is distinguished by a piecewise-constant current profile. Initially, all configurations carry zero-net-current fields and are in ideally unstable equilibrium. The simulation results are compared with the predictions of helicity conserving relaxation theory. Results: For all simulations, the change in helicity is no more than 2% of the initial value; also, the numerical helicities match the analytically-determined values. Magnetic energy dissipation predominantly occurs via shock heating associated with magnetic reconnection in distributed current sheets. The energy release and final field profiles produced by the numerical simulations are in agreement with the predictions given by a new model of partial relaxation theory: the relaxed field is close to a linear force free state; however, the extent of the relaxation region is limited, while the loop undergoes some radial expansion. Conclusions: The results presented here support the use of partial relaxation theory, specifically, when calculating the heating-event distributions produced by ensembles of kink-unstable loops.en
dc.format.extent14en
dc.language.isoeng
dc.relation.ispartofAstronomy & Astrophysicsen
dc.rights(c) ESO, 2012.en
dc.subjectInstabilitiesen
dc.subjectMagnetic fieldsen
dc.subjectMagnetic reconnectionen
dc.subjectMagnetohydrodynamics (MHD)en
dc.subjectPlasmasen
dc.subjectSun: coronaen
dc.subjectQB Astronomyen
dc.subject.lccQBen
dc.titleCoronal heating by the partial relaxation of twisted loopsen
dc.typeJournal articleen
dc.description.versionPostprinten
dc.contributor.institutionUniversity of St Andrews. Applied Mathematicsen
dc.identifier.doihttps://doi.org/10.1051/0004-6361/201219725
dc.description.statusPeer revieweden


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