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Author(s):
A. Kageyama and T. Sato
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Title:
Generation Mechanism of a Dipole Field by a Magnetohydrodynamic Dynamo
Date of publication:
Oct. 1996
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Key words:
MHD dynamo, solar dynamo, geodynamo
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Abstract:
Computer simulation of a magnetohydrodynamic dynamo in a rotating spherical shell is performed. Strong magnetic field is generated by a thermal convection motion of an electrically conducting fluid. The generated magnetic field has a well-organized structure. The field is expanded by the spherical harmonics Y_l^m. The leading moment is the dipole (l=1, m = 0) which is 1.3 times larger than the second moment, octapole (l = 3, m = 0). These two moments occupy more than half of the total power of the magnetic field. Structure and the generation mechanism of the magnetic field are examined in detail. It is found that the well-known alpha-omega dynamo scenario gives a good explanation of the whole dynamo cycle. This simulation gives the first demonstration that a self-consistently solved magnetohydrodynamic convection naturally produces the alpha-omega dynamo and the dipole field is spontaneously generated.
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