Rapid dissipation in a current sheet driven by footpoints motions

Fruit, G.; Craig, Ian J.D.

Rapid dissipation in a current sheet driven by footpoints motions

dc.contributor.author	Fruit, G.
dc.contributor.author	Craig, Ian J.D.
dc.date.accessioned	2011-06-28T23:16:55Z
dc.date.available	2011-06-28T23:16:55Z
dc.date.issued	2006
dc.description.abstract	Context.Wave energy dissipation by viscous and resistive damping in magnetic coronal plasmas is addressed. A two and one half dimensional, line-tied magnetic channel is considered whose footpoints are disturbed by buffeting motions of the photosphere. Aims.The aim of the analysis is to determine how effectively shear Alfvén waves, driven by footpoint motions and resonating in the channel, can be damped by visco-resistive friction. Methods.The problem is analyzed using a mixture of numerical and analytic techniques. Dynamic simulations, based on a cyclic footpoint driver, show that phase mixing resulting from variations in the magnetic field of the channel is instrumental in setting up a permanent "resonance regime" for the system. Analytic methods are used to analyze the resonance regime and to develop scaling laws for the rate of energy dissipation. Results.We show that in the general case where the Alfvén velocity profile may be linearized around the resonance, the dissipation rate is "fast" in that it is not limited by small damping coefficients. Although large energies can accumulate within the channel in the limit of very small damping, we show that by tuning the driver to low frequencies, both the energy level and the dissipation rate can be made insensitive to the level of the damping.	en_NZ
dc.format.mimetype	application/pdf
dc.identifier.citation	Fruit, G. & Craig, I.J.D. (2006). Rapid dissipation in a current sheet driven by footpoints motions. Astronomy & Astrophysics, 458(1), 307-315.	en_NZ
dc.identifier.doi	10.1051/0004-6361:20065462	en_NZ
dc.identifier.uri	https://hdl.handle.net/10289/5430
dc.language.iso	en
dc.publisher	E D P Sciences	en_NZ
dc.relation.isPartOf	Astronomy & Astrophysics	en_NZ
dc.relation.uri	http://www.aanda.org/index.php?option=com_article&access=standard&Itemid=129&url=/articles/aa/abs/2006/40/aa5462-06/aa5462-06.html	en_NZ
dc.rights	This article has been published in the journal: Astronomy & Astrophysics. Used with permission.	en_NZ
dc.subject	Magnetohydrodynamics	en_NZ
dc.subject	corona	en_NZ
dc.subject	magnetic fields	en_NZ
dc.subject	waves	en_NZ
dc.title	Rapid dissipation in a current sheet driven by footpoints motions	en_NZ
dc.type	Journal Article	en_NZ
pubs.begin-page	307	en_NZ
pubs.edition	October	en_NZ
pubs.elements-id	32111
pubs.end-page	315	en_NZ
pubs.issue	1	en_NZ
pubs.volume	458	en_NZ