Screw dynamo and the generation of nonaxisymmetric magnetic fields

Basu, Abhik (1997) Screw dynamo and the generation of nonaxisymmetric magnetic fields. In: Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, 56 (3). pp. 2869-2874.

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Abstract

A mechanism is presented here for the amplification of large-scale nonaxisymmetric magnetic fields as a manifestation of the dynamo effect. We generalize a result on restrictions of dynamo actions due to laminar flow originally derived by Zeldovich, Ruzmaikin, and Sokolov [Magnetic Fields in Astrophysics (Gordon and Breach, New York, 1983)]. We show how a screwlike motion having phi and z components of velocity can help to grow a magnetic field. This model postulates a large-scale flow having phi and z components with radial dependences (helical flow). Shear in the radial field, because of a near-flux-freezing condition, causes amplification of the phi component of the magnetic field. The radial and axial components grow due to the presence of turbulent diffusion. The shear in the large scale flow induces an indefinite growth of magnetic field without the a effect; nevertheless, turbulent diffusion forms an important part in the overall mechanism.

Item Type:	Journal Article
Publication:	Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
Publisher:	The American Physical Society
Additional Information:	Copyright of this article belongs to The American Physical Society.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	30 Jun 2011 12:18
Last Modified:	30 Jun 2011 12:18
URI:	http://eprints.iisc.ac.in/id/eprint/38448

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