On the mean field dynamo with Hall effect

Free access article

Issue		A&A Volume 452, Number 3, June IV 2006


Page(s)		773 - 779
Section		Astrophysical processes
DOI		http://dx.doi.org/10.1051/0004-6361:20054111

A&A 452, 773-779 (2006)
DOI: 10.1051/0004-6361:20054111

On the mean field dynamo with Hall effect

A. Kandus, M. J. Vasconcelos and A. H. Cerqueira

LATO-DCET-UESC, Rodovia Ilhéus-Itabuna km 16, Ilhéus, Bahia 45662-000, Brazil
e-mail: [kandus;hoth;mjvasc]@uesc.br

(Received 26 August 2005 / Accepted 7 March 2006)

Abstract
Context.MHD turbulence with Hall effect.
Aims.Study how Hall effect modifies the quenching process of the electromotive force (e.m.f.) in Mean Field Dynamo (MFD) theories.
Methods.We write down the evolution equations for the e.m.f. and for the large and small scale magnetic helicity, treat Hall effect as a perturbation and integrate the resulting equations, assuming boundary conditions such that the total divergencies vanish.
Results.For force-free large scale magnetic fields, Hall effect acts by coupling the small scale velocity and magnetic fields. For the range of parameters considered, the overall effect is a stronger quenching of the e.m.f. than in standard MHD and a damping of the inverse cascade of magnetic helicity.
Conclusions.In astrophysical environments characterized by the parameters considered here, Hall effect would produce an earlier quenching of the e.m.f. and consequently a weaker large scale magnetic field.

Key words: magnetohydrodynamics (MHD) -- plasmas -- turbulence

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