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Generation of Large-Scale Magnetic Fields by Small-Scale Dynamo in Shear Flows

Squire, J. and Bhattacharjee, A. (2015) Generation of Large-Scale Magnetic Fields by Small-Scale Dynamo in Shear Flows. Physical Review Letters, 115 (17). Art. No. 175003. ISSN 0031-9007. https://resolver.caltech.edu/CaltechAUTHORS:20151105-131228964

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Abstract

We propose a new mechanism for a turbulent mean-field dynamo in which the magnetic fluctuations resulting from a small-scale dynamo drive the generation of large-scale magnetic fields. This is in stark contrast to the common idea that small-scale magnetic fields should be harmful to large-scale dynamo action. These dynamos occur in the presence of a large-scale velocity shear and do not require net helicity, resulting from off-diagonal components of the turbulent resistivity tensor as the magnetic analogue of the “shear-current” effect. Given the inevitable existence of nonhelical small-scale magnetic fields in turbulent plasmas, as well as the generic nature of velocity shear, the suggested mechanism may help explain the generation of large-scale magnetic fields across a wide range of astrophysical objects.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1103/PhysRevLett.115.175003DOIArticle
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.115.175003PublisherArticle
http://arxiv.org/abs/1506.04109arXivDiscussion Paper
Additional Information:© 2015 American Physical Society. Received 12 June 2015; published 20 October 2015. This work was supported by a Procter Fellowship at Princeton University, and the U.S. Department of Energy Grant No. DE-AC02-09-CH11466. The authors would like to thank A. Schekochihin, J. Krommes, and I. Rogachevskii for enlightening discussion and useful suggestions, as well as G. Lesur for making the snoopy code freely available.
Group:TAPIR
Funders:
Funding AgencyGrant Number
Princeton UniversityUNSPECIFIED
Department of Energy (DOE)DE-AC02-09-CH11466
Issue or Number:17
Classification Code:PACS numbers: 47.65.Md, 47.27.eb, 52.30.Cv, 52.35.Ra
Record Number:CaltechAUTHORS:20151105-131228964
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20151105-131228964
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:61904
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:05 Nov 2015 23:42
Last Modified:03 Oct 2019 09:13

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