Dynamos are devices that convert mechanical energy into electromagnetic energy. While technical dynamos depend on a suitable arrangement of multiply connected regions (usually wires) of high electrical conductivity within an insulating space, the generation of magnetic fields in planets and stars must occur in simply connected domains of essentially uniform finite conductivity. For a long time after Larmor (1919) (see Larmor, J. ) first proposed this homogeneous dynamo process as the origin of magnetic fields in sunspots it has been doubtful whether it is possible. Mathematicians and geophysicists have proved antidynamo theorems in order to determine the conditions under which homogeneous dynamos are possible. The first and most famous theorem has been formulated and proved by Cowling (1934) (see Cowling, T.G. ). He demonstrated that axisymmetric or two‐dimensional magnetic fields cannot be generated by the homogeneous dynamo process (see Cowling's Theorem ). Since the Earth's magnetic...
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Busse, F., Proctor, M. (2007). Antidynamo and Bounding Theorems. In: Gubbins, D., Herrero-Bervera, E. (eds) Encyclopedia of Geomagnetism and Paleomagnetism. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-4423-6_8
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