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Dynamos, Mean‐Field

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Encyclopedia of Geomagnetism and Paleomagnetism

Introduction

The mean‐field concept was introduced into the dynamo theory of the magnetic fields of the Earth, the Sun, and other cosmic objects in the sixties of the last century. As was known or at least considered as very probable at that time, magnetic fields as well as the motions inside the electrically conducting interiors of these objects show rather complex geometrical structures and time behaviors. In addition antidynamo theorems suggested that dynamo action requires a certain complexity of magnetic field and motion (see Antidynamo theorems or Cowling's theorem ). No solution of the dynamo equations has been found until this time, which could be interpreted as an approximate picture of the situation in the Earth or any cosmic body.

The central idea of the mean‐field concept is to define mean magnetic fields, mean velocity fields etc., which reflect essential features of the original fields but show simpler, that is more smooth, geometrical structures and time behaviors, and...

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Authors
  1. Karl-Heinz Raedler
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Editor information

Editors and Affiliations

  1. University of Leeds,  ,  

    David Gubbins

  2. University of Hawaii,  ,  

    Emilio Herrero-Bervera

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Raedler, KH. (2007). Dynamos, Mean‐Field. In: Gubbins, D., Herrero-Bervera, E. (eds) Encyclopedia of Geomagnetism and Paleomagnetism. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-4423-6_82

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