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Core Dynamo

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Encyclopedia of Solid Earth Geophysics

Part of the book series: Encyclopedia of Earth Sciences Series ((EESS))

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Synonyms

Geodynamo

Definition

Dynamo : Process for generating electrical current and magnetic field by electromagnetic induction in a moving conducting medium

Geodynamo : Dynamo process in the fluid outer core that generates Earth’s main magnetic field

Introduction

It has been firmly established that the geomagnetic field must be generated by a magnetohydrodynamic dynamo operating in the Earth’s outer core. Thermal and compositional buoyancy forces drive a convective circulation of the liquid iron alloy. Assuming that a magnetic field is present, electrical currents are induced in the moving fluid. When the magnetic field associated with these currents has the strength and geometry that is suitable for the induction process and no external source for the field is required, this is called a self-sustained dynamo. To first approximation the Earth’s core is a sphere with uniform electrical conductivity, in contrast to technical dynamos, where the currents are guided by a highly...

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Author information

Authors and Affiliations

  1. Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany

    Ulrich R. Christensen

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  1. Ulrich R. Christensen
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Correspondence to Ulrich R. Christensen .

Editor information

Editors and Affiliations

  1. Seismology, National Geophysical Research Insti, Hyderabad, India

    Harsh K. Gupta

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Christensen, U.R. (2019). Core Dynamo. In: Gupta, H.K. (eds) Encyclopedia of Solid Earth Geophysics. Encyclopedia of Earth Sciences Series. Springer, Cham. https://doi.org/10.1007/978-3-030-10475-7_38-1

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  • DOI: https://doi.org/10.1007/978-3-030-10475-7_38-1

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  • Publisher Name: Springer, Cham

  • Print ISBN: 978-3-030-10475-7

  • Online ISBN: 978-3-030-10475-7

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