Godbillon-Vey helicity and magnetic helicity in magnetohydrodynamics
نویسندگان
چکیده
منابع مشابه
Magnetic helicity in galactic dynamos
Magnetic fields correlated on kiloparsec scales are seen in spiral galaxies. Their origin could be due to amplification of a small seed field by a turbulent galactic dynamo. We review the current status of the galactic dynamo, especially the constraints imposed by magnetic helicity conservation. We estimate the minimal strength of the large-scale magnetic field which could arise inspite of the ...
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It is shown that the turbulent dynamo -e ect converts magnetic helicity from the turbulent eld to the mean eld when the turbulence is electromagnetic while the magnetic helicity of the meaneld is transported across space when the turbulence is electrostatic or due to the electron diamagnetic e ect. In all cases, however, the dynamo e ect strictly conserves the total helicity except for a batter...
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The magnetic helicity has paramount significance in nonlinear saturation of galactic dynamo. We argue that the magnetic helicity conservation is violated at the lepton stage in the evolution of early Universe. As a result, a cosmological magnetic field which can be a seed for the galactic dynamo obtains from the beginning a substantial magnetic helicity which has to be taken into account in the...
متن کاملSpeculations on primordial magnetic helicity
We speculate that above or just below the electroweak phase transition magnetic fields are generated which have a net helicity (otherwise said, a ChernSimons term) of order of magnitude NB + NL, where NB,L is the baryon or lepton number today. (To be more precise requires much more knowledge of B,L-generating mechanisms than we currently have.) Electromagnetic helicity generation is associated ...
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ژورنال
عنوان ژورنال: Journal of Plasma Physics
سال: 2019
ISSN: 0022-3778,1469-7807
DOI: 10.1017/s0022377819000679