Generation of large-scale magnetic fields by small-scale dynamo in shear flows

J. Squire, A. Bhattacharjee

Research output: Contribution to journalArticle

13 Scopus citations

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.

Original languageEnglish (US)
Article number175003
JournalPhysical review letters
Volume115
Issue number17
DOIs
StatePublished - Oct 20 2015

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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