scholarly journals Comparisons and connections between mean field dynamo theory and accretion disc theory

2010 ◽  
Vol 331 (1) ◽  
pp. 101-109 ◽  
Author(s):  
E.G. Blackman
Keyword(s):  
Mean Field ◽  
Accretion Disc ◽  
Dynamo Theory ◽  
Mean Field Dynamo

scholarly journals Magnetic Cycles and Rotation in Active Late–Type Stars

2004 ◽  
Vol 215 ◽  
pp. 289-291
Author(s):  
Ilkka Tuominen ◽  
Svetlana V. Berdyugina ◽  
Maarit J. Korpi
Keyword(s):  
Mean Field ◽  
Point Of View ◽  
Doppler Imaging ◽  
Late Type ◽  
Dynamo Theory ◽  
Flip Flop ◽  
Cyclic Behaviour ◽  
Magnetic Cycles ◽  
Mean Field Dynamo

Observational evidence, based both on spectroscopic Doppler imaging and long-term photometry, of strongly nonaxisymmetric spot distributions in magnetically very active late-type stars, with a special cyclic behaviour (the “flip-flop” effect), is presented. Theoretical implications of these results are discussed from the point of view of nonlinear mean-field dynamo theory.

Existence and Energy Balance of the Solar Dynamo

1993 ◽  
Vol 157 ◽  
pp. 19-23
Author(s):  
J.H.G.M. van Geffen
Keyword(s):  
Magnetic Field ◽  
Energy Balance ◽  
Energy Method ◽  
Magnetic Energy ◽  
Mean Field ◽  
Solar Dynamo ◽  
Ensemble Averaging ◽  
Dynamo Theory ◽  
The Magnetic Field ◽  
Mean Field Dynamo

The idea behind the use of ensemble averaging and the finite magnetic energy method of van Geffen and Hoyng (1992) is briefly discussed. Applying this method to the solar dynamo shows that the turbulence — an essential ingredient of traditional mean field dynamo theory — poses grave problems: the turbulence makes the magnetic field so unstable that it becomes impossible to recognize any period.

scholarly journals On the mean-field theory of the Karlsruhe Dynamo Experiment

2002 ◽  
Vol 9 (3/4) ◽  
pp. 171-187 ◽  
Author(s):  
K.-H. Rädler ◽  
M. Rheinhardt ◽  
E. Apstein ◽  
H. Fuchs
Keyword(s):  
Field Theory ◽  
Key Words ◽  
Mean Field Theory ◽  
Mean Field ◽  
Experimental Results ◽  
Dynamo Theory ◽  
The Mean ◽  
Earth’S Interior ◽  
Earth's Interior ◽  
Mean Field Dynamo

Abstract. In the Forschungszentrum Karlsruhe an experiment has been constructed which demonstrates a homogeneous dynamo as is expected to exist in the Earth's interior. This experiment is discussed within the framework of mean-field dynamo theory. The main predictions of this theory are explained and compared with the experimental results. Key words. Dynamo, geodynamo, dynamo experiment, mean-field dynamo theory, a-effect

Non-Local Mean Field Dynamo Theory and Magnetic Fronts in Galaxies

2003 ◽  
Vol 97 (2) ◽  
pp. 135-148 ◽  
Author(s):  
Sergei Fedotov ◽  
Alexey Ivanov ◽  
Andrey Zubarev
Keyword(s):  
Mean Field ◽  
Dynamo Theory ◽  
Local Mean ◽  
Non Local ◽  
Mean Field Dynamo

scholarly journals HALL CURRENT EFFECTS IN MEAN-FIELD DYNAMO THEORY

2016 ◽  
Vol 829 (1) ◽  
pp. 51 ◽  
Author(s):  
Manasvi Lingam ◽  
Amitava Bhattacharjee
Keyword(s):  
Hall Current ◽  
Mean Field ◽  
Dynamo Theory ◽  
Mean Field Dynamo

scholarly journals The Alpha-Effect in Galaxies is Highly Anisotropic

1990 ◽  
Vol 140 ◽  
pp. 113-114
Author(s):  
G. Rüdiger
Keyword(s):  
Large Scale ◽  
Rotation Axis ◽  
Mean Field ◽  
Dynamo Model ◽  
Mean Flow ◽  
Dynamo Theory ◽  
Input Quantity ◽  
Alpha Effect ◽  
The Mean ◽  
Mean Field Dynamo

Besides the mean flow the alpha is the other input quantity for any mean-field dynamo model. It describes the generation of turbulent electromotive force <u × B> from a large-scale field <B> for a given turbulence. The necessary helicity of the turbulence results from the joint action of Coriolis force and density stratification. The standard estimate of 1 km/s for alpha in galaxies is a surely well-established approximation. One of the essentials, however, remains open. Due to the extremely anisotropic structure of disks the tensorial character of alpha can no longer be ignored. In stellar applications anisotropy in the α-tensor leads to a preferred excitation of non-axisymmetric magnetic fields. That is true for α2 -dynamos if the alpha parallel to the rotation axis, α||, is much smaller than that in the equatorial plane, α⊥. The idea is that also for disk-like configurations a similar behaviour makes the existence of the observed large-scale non-axisymmetric magnetic BSS modes understandable within the frame of the mean-field dynamo theory.

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