Magnetic-field generation in helical turbulence

Abstract

We investigate analytically the amplification of a weak magnetic field in a homogeneous and isotropic turbulent flow lacking reflectional symmetry (helical turbulence). We propose that the spectral distributions of magnetic energy and magnetic helicity can be found as eigenmodes of a self-adjoint, Schrödinger-type system of evolution equations. We argue that large-scale and small-scale magnetic fluctuations cannot be effectively separated, and that the conventional alpha-model is, in general, not an adequate description of the large-scale dynamo mechanism. As a consequence, the correct numerical modeling of such processes should resolve magnetic fluctuations down to the very small, resistive scales.

4 pages

References in corpus (6)

• The inverse cascade and nonlinear alpha-effect in simulations of isotropic helical hydromagnetic turbulence
• A New Dynamical Mean-Field Dynamo Theory and Closure Approach
• On magnetic field generation in Kolmogorov turbulence
• The onset of a small-scale turbulent dynamo at low magnetic Prandtl numbers
• Spectra and Growth Rates of Fluctuating Magnetic Fields in the Kinematic Dynamo Theory with Large Magnetic Prandtl Numbers
• A Solvable Model for Nonlinear Mean Field Dynamo

Cited by in corpus (33)

• MHD simulations of the magnetorotational instability in a shearing box with zero net flux. I. The issue of convergence
• Dynamo theories
• Current status of turbulent dynamo theory: From large-scale to small-scale dynamos
• A new interpretation of the far-infrared - radio correlation and the expected breakdown at high redshift
• The Turbulent Dynamo
• Large-Scale Magnetic-Field Generation by Randomly Forced Shearing Waves
• Zonal Flow Magnetic Field Interaction in the Semi-Conducting Region of Giant Planets
• Problems with kinematic mean field electrodynamics at high magnetic Reynolds numbers
• MHD simulations of the magnetorotational instability in a shearing box with zero net flux: the case Pm=4
• Generation of large-scale magnetic fields by small-scale dynamo in shear flows
• The small-scale dynamo: Breaking universality at high Mach numbers
• A unified large/small-scale dynamo in helical turbulence
• Turbulent magnetic field amplification from the smallest to the largest magnetic Prandtl numbers
• Traces of large-scale dynamo action in the kinematic stage
• On Large-Scale Dynamo Action at High Magnetic Reynolds Number
• Magnetic dynamo action at low magnetic Prandtl numbers
• Varying the forcing scale in low Prandtl number dynamos
• The magnetic shear-current effect: generation of large-scale magnetic fields by the small-scale dynamo
• The kinetic helicity needed to drive large-scale dynamos
• Magnetic dynamo action in random flows with zero and finite correlation times
• Coherent nonhelical shear dynamos driven by magnetic fluctuations at low Reynolds numbers
• Magnetic dynamo action in helical turbulence
• The mean electromotive force resulting from magnetic buoyancy instability
• Magnetorotational Dynamo Action in the Shearing Box
• Fluctuation Dynamo and Turbulent Induction at Small Prandtl Number
• The fate of alpha dynamos at large $Rm$
• Magnetic field generation in galactic molecular clouds
• Magnetic dynamo action in astrophysical turbulence
• Mean Field Electrodynamics: Triumphs and Tribulations
• Solar Magnetic Fields
• Kazantsev model in nonhelical 2.5D flows
• Saturation of turbulent helical dynamos
• Amplification of magnetic fields by dynamo action in Gaussian-correlated helical turbulence