title: Large-scale magnetic field generation by randomly forced shearing waves.
abstract: 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.
authors.affiliation: Institute for Advanced Study, Princeton, New Jersey 08540, USA.
authors.forename: T
authors.initials: T
authors.lastname: Heinemann
authors.forename: J C
authors.initials: JC
authors.lastname: McWilliams
authors.forename: A A
authors.initials: AA
authors.lastname: Schekochihin