Large-scale magnetic field generation by randomly forced shearing waves

Journal article

A rigorous theory for the generation of a large-scale magnetic field by random nonhelically forced motions of a conducting fluid combined with a linear shear is presented in the analytically tractable limit of low magnetic Reynolds number (Rm) and weak shear. The dynamo is kinematic and due to fluctuations in the net (volume-averaged) electromotive force. This is a minimal proof-of-concept quasilinear calculation aiming to put the shear dynamo, a new effect recently found in numerical experiments, on a firm theoretical footing. Numerically observed scalings of the wave number and growth rate of the fastest-growing mode, previously not understood, are derived analytically. The simplicity of the model suggests that shear dynamo action may be a generic property of sheared magnetohydrodynamic turbulence. © 2011 American Physical Society.

Authors: Heinemann, T; McWilliams, J; Schekochihin, A

• Journal: Physical Review Letters
• Volume: 107
• Issue: 25
• Publication date: 2011-12-14
• DOI: 10.1103/PhysRevLett.107.255004
• EISSN: 1079-7114
• ISSN: 0031-9007
• Language: English