Energy fluxes in helical magnetohydrodynamics and dynamo action

Abstract

Renormalized viscosity, renormalized resistivity, and various energy fluxes are calculated for helical magnetohydrodynamics using perturbative field theory. The calculation is to first-order in perturbation. Kinetic and magnetic helicities do not affect the renormalized parameters, but they induce an inverse cascade of magnetic energy. The sources for the the large-scale magnetic field have been shown to be (1) energy flux from large-scale velocity field to large-scale magnetic field arising due to nonhelical interactions, and (2) inverse energy flux of magnetic energy caused by helical interactions. Based on our flux results, a premitive model for galactic dynamo has been constructed. Our calculations yields dynamo time-scale for a typical galaxy to be of the order of $10^8$ years. Our field-theoretic calculations also reveal that the flux of magnetic helicity is backward, consistent with the earlier observations based on absolute equilibrium theory.

REVTEX4; A factor of 2 corrected in helicity

References in corpus (4)

• The inverse cascade and nonlinear alpha-effect in simulations of isotropic helical hydromagnetic turbulence
• Field theoretic calculation of energy cascade rates in nonhelical magnetohydrodynamic turbulence
• Calculation of renormalized viscosity and resistivity in magnetohydrodynamic turbulence
• The Dependence of Dynamo $\alpha$-Effect on Reynolds Numbers, Magnetic Prandtl Number, and the Statistics of MHD Turbulence

Cited by in corpus (8)

• Statistical Theory of Magnetohydrodynamic Turbulence: Recent Results
• Dynamo Transition in Low-dimensional Models
• Amplification of large-scale magnetic field in nonhelical magnetohydrodynamics
• On Generation of magnetic field in astrophysical bodies
• Energy transfer and locality in magnetohydrodynamic turbulence
• Fundamental MHD scales -- II: the kinematic phase of the supersonic small-scale dynamo
• Taylor's Frozen-in Hypothesis for Magnetohydrodynamic turbulence and Solar Wind
• Magnetohydrodynamic Turbulence: Chandrasekhar's Contributions \& Beyond