Stevenson, D. J. (1983) Planetary magnetic fields. Reports on Progress in Physics, 46 (5). pp. 555-620. ISSN 0034-4885 http://resolver.caltech.edu/CaltechAUTHORS:STErpp83
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As a consequence of the smallness of the electronic fine structure constant, the characteristic time scale for the free diffusive decay of a magnetic field in a planetary core is much less than the age of the Solar System, but the characteristic time scale for thermal diffusion is greater than the age of the Solar System. Consequently, primordial fields and permanent magnetism are small and the only means of providing a substantial planetary magnetic field is the dynamo process. This requires a large region which is fluid, electrically conducting and maintained in a non-uniform motion that includes a substantial RMS vertical component. The attributes of fluidity and conductivity are readily provided in the deep interiors of all planets and most satellites, either in the form of an Fe alloy with a low eutectic temperature (e.g. Fe-S-O in terrestrial bodies and satellites) or by the occupation of conduction states in fluid hydrogen or 'ice' (H2O-NH3-CH4) in giant planets. It is argued that planetary dynamos are almost certainly maintained by convection (compositional and/or thermal).
|Additional Information:||© 1983, Institute of Physics. This review was received in September 1982. Print publication: Issue 5 (May 1983). Helpful criticisms and comments from R Hide, F Busse, J Connerney and R T Merrill have improved this paper. The support of the National Aeronautics and Space Administration (Planetary Geophysics and Geochemistry Program) and the US National Science Foundation (Geophysics Program) is gratefully acknowledged.|
|Official Citation:||Planetary magnetic fields D J Stevenson 1983 Rep. Prog. Phys. 46 555-620 doi: 10.1088/0034-4885/46/5/001|
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|Deposited On:||14 Nov 2008 06:31|
|Last Modified:||26 Dec 2012 10:31|
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