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14
An Incoherent
 Astrophys. J
, 1997
"... We use the meanfield dynamo equations to show that spatially and temporally incoherent fluctuations in the helicity in mirrorsymmetric turbulence in a shearing flow can generate a large scale, coherent magnetic field. We illustrate this effect with simulations of a few simple systems. For statisti ..."
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We use the meanfield dynamo equations to show that spatially and temporally incoherent fluctuations in the helicity in mirrorsymmetric turbulence in a shearing flow can generate a large scale, coherent magnetic field. We illustrate this effect with simulations of a few simple systems
An Incoherent
 Astrophys. J
, 1997
"... We use the meanfield dynamo equations to show that an incoherent alpha effect in mirrorsymmetric turbulence in a shearing flow can generate a large scale, coherent magnetic field. We illustrate this effect with simulations of a few simple systems. In accretion disks, this process can lead to axisy ..."
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We use the meanfield dynamo equations to show that an incoherent alpha effect in mirrorsymmetric turbulence in a shearing flow can generate a large scale, coherent magnetic field. We illustrate this effect with simulations of a few simple systems. In accretion disks, this process can lead
AN INCOHERENT alphaOmega DYNAMO IN ACCRETION DISKS
, 1997
"... We use the meanfield dynamo equations to show that spatially and temporally incoherent fluctuations in the helicity in mirrorsymmetric turbulence in a shearing flow can generate a largescale, coherent magnetic field. We illustrate this effect with simulations of a few simple systems. For statisti ..."
Abstract

Cited by 1 (0 self)
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We use the meanfield dynamo equations to show that spatially and temporally incoherent fluctuations in the helicity in mirrorsymmetric turbulence in a shearing flow can generate a largescale, coherent magnetic field. We illustrate this effect with simulations of a few simple systems
Scaling and intermittency in incoherent α–shear dynamo
"... We consider meanfield dynamo models with fluctuating α effect, both with and without largescale shear. The α effect is chosen to be Gaussian white noise with zero mean and a given covariance. In the presence of shear, we show analytically that (in infinitely large domains) the meansquared magnetic ..."
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. In the absence of shear, an incoherent α 2 dynamo may also be possible. We further show by explicit calculation of the growth rate of third and fourthorder moments of the magnetic field that the probability density function of the mean magnetic field generated by this dynamo is nonGaussian. Key words: dynamo
1 Galactic and Accretion Disk Dynamos
, 1998
"... Dynamos in astrophysical disks are usually explained in terms of the standard alphaomega mean field dynamo model where the local helicity generates a radial field component from an azimuthal field. The subsequent shearing of the radial field gives rise to exponentially growing dynamo modes. There a ..."
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, these difficulties can be overcome by including a fluctuating helicity driven by hydrodynamic or magnetic instabilities. Unlike traditional disk dynamo models, this ‘incoherent ’ dynamo does not depend on the presence of systematic fluid helicity or any kind of vertical symmetry breaking. It will depend on geometry
MAGNETIC DIFFUSIVITY TENSOR AND DYNAMO EFFECTS IN ROTATING AND SHEARING TURBULENCE
, 2007
"... The turbulent magnetic diffusivity tensor is determined in the presence of rotation or shear. The question is addressed whether dynamo action from the shearcurrent effect can explain largescale magnetic field generation found in simulations with shear. For this purpose a set of evolution equations ..."
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Cited by 5 (2 self)
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enough to drive an incoherent alphashear dynamo. The incoherent shearcurrent effect, on the other hand, is found to be subdominant.
Global dynamo simulation of ionospheric currents and their connection with the equatorial electrojet and counter electrojet: A Ann
 Geophys
, 1983
"... Abstract. The interrelationship of equatorial and planetary scale ionospheric horizontal currents on quiet days is studied by means of a global ionospheric wind dynamo simulation. This simulation aims at reproducing magnetic and radar data first for a normal quiet day, and then for the strong counte ..."
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Cited by 3 (0 self)
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Abstract. The interrelationship of equatorial and planetary scale ionospheric horizontal currents on quiet days is studied by means of a global ionospheric wind dynamo simulation. This simulation aims at reproducing magnetic and radar data first for a normal quiet day, and then for the strong
L.: Possible ionospheric preconditioning by shear flow leading to equatorial spread
 F, Ann. Geophys
"... Abstract. Vertical shear in the zonal plasma drift speed is apparent in incoherent and coherent scatter radar observations of the bottomside F region ionosphere made at Jicamarca from about 16002200 LT. The relative importance of the factors controlling the shear, which include competition between ..."
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Cited by 5 (5 self)
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Abstract. Vertical shear in the zonal plasma drift speed is apparent in incoherent and coherent scatter radar observations of the bottomside F region ionosphere made at Jicamarca from about 16002200 LT. The relative importance of the factors controlling the shear, which include competition
Alpha effect and turbulent diffusion from convection
 ASTRONOMY & ASTROPHYSICS
, 2009
"... Aims. We study turbulent transport coefficients that describe the evolution of largescale magnetic fields in turbulent convection. Methods. We use the test field method, together with threedimensional numerical simulations of turbulent convection with shear and rotation, to compute turbulent trans ..."
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Cited by 5 (2 self)
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of depth but is also able to contribute to dynamo action in the meanfield model. The growth rates in these cases are, however, well below those in direct simulations, suggesting that an incoherent αshear dynamo may also act in the simulations. If both rotation and
Results 1  10
of
14