Magnetic helicity density and its flux in weakly inhomogeneous turbulence
arXiv:astro-ph/0509392 · doi:10.1086/507828
Abstract
A gauge invariant and hence physically meaningful definition of magnetic helicity density for random fields is proposed, using the Gauss linking formula, as the density of correlated field line linkages. This definition is applied to the random small scale field in weakly inhomogeneous turbulence, whose correlation length is small compared with the scale on which the turbulence varies. For inhomogeneous systems, with or without boundaries, our technique then allows one to study the local magnetic helicity density evolution in a gauge independent fashion, which was not possible earlier. This evolution equation is governed by local sources (owing to the mean field) and by the divergence of a magnetic helicity flux density. The role of magnetic helicity fluxes in alleviating catastrophic quenching of mean field dynamos is discussed.
4 pages, accepted by ApJ
References in corpus (6)
- Astrophysical magnetic fields and nonlinear dynamo theory
- The case for a distributed solar dynamo shaped by near-surface shear
- Galactic dynamo and helicity losses through fountain flow
- Nonlinear current helicity fluxes in turbulent dynamos and alpha quenching
- Strong mean field dynamos require supercritical helicity fluxes
- Catastrophic alpha quenching alleviated by helicity flux and shear
Cited by in corpus (66)
- Astrophysical magnetic fields and nonlinear dynamo theory
- The origin, evolution and signatures of primordial magnetic fields
- Current status of turbulent dynamo theory: From large-scale to small-scale dynamos
- Large-scale dynamos in turbulent convection with shear
- Galactic dynamos supported by magnetic helicity fluxes
- Scale-dependence of magnetic helicity in the solar wind
- Astrophysical turbulence modeling
- Advances in mean-field dynamo theory and applications to astrophysical turbulence
- Equatorial magnetic helicity flux in simulations with different gauges
- Small-scale magnetic helicity losses from a mean-field dynamo
- Galactic spiral patterns and dynamo action I: A new twist on magnetic arms
- Large-scale dynamos in rigidly rotating turbulent convection
- Dynamo-driven plasmoid ejections above a spherical surface
- From primordial seed magnetic fields to the galactic dynamo
- The mean electro-motive force, current- and cross-helicity under the influence of rotation, magnetic field and shear
- Hyperdiffusion as a Mechanism for Solar Coronal Heating
- Magnetic Helicity and Large Scale Magnetic Fields: A Primer
- Non-linear galactic dynamos: A toolbox
- Advances in theory and simulations of large-scale dynamos
- Magnetic helicity fluxes in an alpha-squared dynamo embedded in a halo
- Magnetic Spiral Arms and Galactic Outflows
- Magnetic helicity effects in astrophysical and laboratory dynamos
- The Saturation Limit of the Magnetorotational Instability
- Minimalist coupled evolution model for stellar x-ray activity, rotation, mass loss, and magnetic field
- Effects of helical magnetic fields on the cosmic microwave background
- Magnetic helicity transport in the advective gauge family
- Magnetic helicity flux in the presence of shear
- Mean-field dynamo in a turbulence with shear and kinetic helicity fluctuations
- Nonperturbative quasilinear approach to the shear dynamo problem
- Magnetic twist: a source and property of space weather
- The dual role of shear in large-scale dynamos
- An analytical dynamo solution for large-scale magnetic fields of galaxies
- Statistical Properties of Scale-Invariant Helical Magnetic Fields and Applications to Cosmology
- Explaining the Observed Relation Between Stellar Activity and Rotation
- Shear-driven and diffusive helicity fluxes in alpha-Omega dynamos
- Galactic dynamo action in presence of stochastic alpha and shear
- The critical role of magnetic helicity in astrophysical large-scale dynamos
- Accretion Disks and Dynamos: Toward a Unified Mean Field Theory
- Magnetic helicity fluxes in interface and flux transport dynamos
- Magnetic helicity fluxes from triple correlators
- Magnetic arms generated by multiple interfering galactic spiral patterns
- Statistical tests of galactic dynamo theory
- Comparisons and Connections between Mean Field Dynamo Theory and Accretion Disc Theory
- Simulations of galactic dynamos
- Non-linear Galactic Dynamos and the Magnetic Rädler Effect
- Nonlinear Galactic Dynamos and the Magnetic Pitch Angle
- Derivation and precision of mean field electrodynamics with mesoscale fluctuations
- Strong nonlocality variations in a spherical mean-field dynamo
- Astrophysics in 2006
- A model of driven and decaying magnetic turbulence in a cylinder
- A global galactic dynamo with a corona constrained by relative helicity
- A new constraint on mean-field galactic dynamo theory
- Toward Coupling Flow Driven and Magnetically Driven Dynamos
- Spatial Scales and Locality of Magnetic Helicity: Part 1
- Shedding light on the MRI driven dynamo in a stratified shearing box
- Large Scale Dynamo in a Primordial Accretion Flow -- An Interpretation from Hydrodynamic Simulation
- Coronal influence on dynamos
- Conformal anomaly and helicity effects in kinetic theory via scale-dependent coupling
- Probing magnetic fields with Square Kilometre array and its precursors
- Magnetic helicity fluxes in dynamos from rotating inhomogeneous turbulence
- Can catastrophic quenching be alleviated by separating shear and alpha effect?
- Why coronal mass ejections are necessary for the dynamo
- From convective to stellar dynamos
- Paradigm shifts in solar dynamo modeling
- Inferring magnetic helicity spectrum in spherical domains: the method and example applications
- Resistive Scaling in the Magnetic Helicity-Driven Inverse Cascade