dynamo theory


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dynamo theory

[′dī·nə‚mō ‚thē·ə·rē]
(geophysics)
The hypothesis which explains the regular daily variations in the earth's magnetic field in terms of electrical currents in the lower ionosphere, generated by tidal motions of the ionized air across the earth's magnetic field.
References in periodicals archive ?
In this rather inquisitive article, we have delved into the subject of the dynamo theory. Our interest was piqued by the need to reexamine the basis for dynamo theory in a flow where Euler potentials are present.
Subramanian, "Astrophysical magnetic fields and nonlinear dynamo theory," Physics Reports, vol.
Russian physicists Zel'dovich (1914-87) and Ruzmaikin discuss some topics in hydromagnetic dynamo theory in the astrophysical context of large magnetic Reynolds number, define criteria for field generation in a state of near-complete freezing-in, and offer an account of certain qualitative aspects of a turbulent dynamo operating through non-uniform rotation of a conducting medium subject to random motions with helicity.
That is, the emphasis is given more to the instabilities (magnetorotational, Tayler, etc) rather than dynamo theory. Many laboratory experiments on liquid metal and plasma behavior also inform the text.
Subramanian.: Astrophysical magnetic fields and nonlinear dynamo theory, PhRep417, 1 (2005).
Anjam, Y.N.: The Dynamo theory of Magnetic Field Generation in Astrophysical Systems, M/ Phil Thesis, Quaid-i-Azam University, Islamabad-Pakistan (2010).
Topics include foundations of dynamo theory, including self-excited dynamo action, nonlinearity and saturation, and dynamics of rotating fluids; natural dynamos and models, including the geodynamo, planetary dynamos, stellar dynamos, and galactic dynamos; and results of recent experiments.
By using dynamo theory the cycle's activity is predicted with one parameter of physical analysis [1].
Wilcox, "Using dynamo theory to predict the sunspot number in solar cycle 21," Geophysical Research Letters, vol.
Called the dynamo theory, it evokes a comparison between a planet's magnetic axis and the shaft of an electric motor.
Because sunspots have been successfullymodeled by a dynamo theory for the sun, Olson suspects that this theory may bear fruit for the earth as well.