Abstract Recent developments in dynamo theory are discussed both from a kinematic and hydromagnetic point of view. The relative importance of the α- and ω-effects of mean field dynamo theory is examined. In the case of the Earth, recent results point to a model of αω-type in which the primary force balance is between Coriolis, pressure, Lorentz forces with motion driven by buoyancy forces. Accordingly, the magnetic field is strong of order ( ρΩ σ ) 1 2 , where ρ is fluid density, σ is the electrical conductivity and Ω is the rotation rate, and predominantly azimuthal. It is large compared with the meridional magnetic field emerging at the Earth's surface. Within the wider framework of planetary magnetic fields detailed issues include the nature of the convection leading to the α-effect, the generation of azimuthal zonal motion (thermal winds, geostrophic flow and Taylor's condition) responsible for the ω-effect, and the steady or oscillatory nature of the ensuing dynamo.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Dynamo theory


    Contributors:

    Published in:

    Advances in Space Research ; 12 , 8 ; 257-263


    Publication date :

    1992-01-01


    Size :

    7 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English



    DYNAMO

    HASHIMOTO TSUTOMU / HASHIMOTO YUJI | European Patent Office | 2016

    Free access

    Solar magnetic fields and the dynamo theory

    Dikpati, M. / International Council of Scientific Unions | British Library Conference Proceedings | 2005


    Solar magnetic fields and the dynamo theory

    Dikpati, M. | Online Contents | 2005


    WHEEL WITH HUB DYNAMO, HUB DYNAMO, METHOD FOR ASSEMBLY OF WHEEL WITH HUB DYNAMO

    RIKIISHI MAKOTO | European Patent Office | 2019

    Free access

    HUB DYNAMO

    CHIKARAISHI MAKOTO / UEHARA SHUJI / TAKASE JUNICHI et al. | European Patent Office | 2019

    Free access