The principle of solar wind induced planetary dynamos.
Solar wind induced planetary magnetic field systems supportable by bodies free of electrically insulating atmospheres and dynamo driven intrinsic magnetic fields
Colburn, D. S.↗
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The motional voltmeter - A method of distinction between a hot and cold moon based upon the solar wind-induced planetary dynamo current system.
Lunar interior thermal regime measurement method based on dynamo induction of electric field on planetary scale by solar wind
Colburn, D. S.↗
A precession in a disk dynamo model of the earth's dipole field
Earth dipole field disk dynamo model, studying connection between polarity intervals and precession effects
Suffolk, G. C. J.↗
The generation of magnetic fields in astrophysical bodies. III - Turbulent diffusion of fields and efficient dynamos
Galaxy gaseous disk as low mode dynamo, calculating turbulent diffusion coefficient for passive magnetic fields
Parker, E. N.↗
The generation of magnetic fields in astrophysical bodies. IV - The solar and terrestrial dynamos
Earth and sun magnetic field production models as function of dynamo states, discussing solar field effects on terrestrial space environment
Parker, E. N.↗
Effects of a dynamo electric field on the thermospheric winds
Diurnal variations of meridional winds by dynamo electric field in troposphere, comparing with Thomson scattering
Cho, H. R.↗
The generation of magnetic fields in astrophysical bodies. V - Behavior at large dynamo numbers
Astrophysical objects magnetic field generation, examining behavior at large dynamo numbers
Parker, E. N.↗
Kinematic-dynamo action under incompressible, isotropic velocity turbulence
Regenerative kinematic-dynamo action under incompressible isotropic velocity turbulence, noting turbulent Lorentz force role
Lerche, I.↗
Magnetic dynamo action in two-dimensional turbulent magneto-hydrodynamics
Two-dimensional magnetohydrodynamic turbulence is explored by means of numerical simulation. Previous analytical theory, based on non-dissipative constants of the motion in a truncated Fourier representation, is verified by following the evolution of highly non-equilibrium initial conditions numerically. Dynamo action (conversion of a significant fraction of turbulent kinetic energy into long-wavelength magnetic field energy) is observed. It is conjectured that in the presence of dissipation and external forcing, a dual cascade will be observed for zero-helicity situations. Energy will cascade to higher wave numbers simultaneously with a cascade of mean square vector potential to lower wave numbers, leading to an omni-directional magnetic energy spectrum which varies as 1/k 3 at lower wave numbers, simultaneously with a buildup of magnetic excitation at the lowest wave number of the system. Equipartition of kinetic and magnetic energies is expected at the highest wave numbers in the system.
Fyfe, D.↗
Implications of an internal dynamo for the thermal history of Mercury
Constraints placed on the thermal evolution of Mercury by the dynamo model of the planet's magnetic field are investigated. It is assumed that Mercury is a differentiated planet possessing an iron-nickel core with a radius approximately three-fourths of the planetary radius, that the mantle is made of silicates with thermal and rheological properties similar to those of earth's upper mantle, and that differentiation was a global process which resulted in the removal of radioactive heat sources from the core and the upward segregation of heat sources in the mantle. These assumptions are found to lead to the conclusion that the existence of a molten core requires the retention of a minimum concentration of heat sources throughout the mantle, the value being comparable to the mantle-wide average concentration for earth. Thus, it is suggested that the differentiation of Mercury could not have resulted in the complete removal of heat sources from the mantle into a crust near the planet's surface.
Cassen, P.↗
Lunar perturbations in columnar electron content and their interpretation in terms of dynamo electrostatic fields
Both the sun and the moon exert influences on the ionosphere, causing fluctuations in its electron content. The small lunar effects, though not negligible, are difficult to analyze because their periodicities differ little from the periodicity of the dominant solar effects. A finite duration impulse response filter was perfected, permitting the efficient splitting of our columnar electron content data into a solar, a lunar, and a residual component. The solar component plus the lunar component and the solar component alone were processed by a dynamic ionospheric simulation program that yields values of vertical plasma drifts when electron content data are used as input. The difference between the two plasma drifts so obtained was taken as being the plasma drift caused by the electric field generated by the lunar tides in the dynamo region. This technique appears to be the first to allow a direct estimation of the lunar-induced electric fields in the ionosphere.
Bernhardt, P. A.↗
Magnetic dynamo action in two-dimensional turbulent magneto-hydrodynamics
Two-dimensional magnetohydrodynamic turbulence is explored by means of numerical simulation. Previous analytical theory, based on non-dissipative constants of the motion in a truncated Fourier representation, is verified by following the evolution of highly non-equilibrium initial conditions numerically. Dynamo action (conversion of a significant fraction of turbulent kinetic energy into long-wavelength magnetic field energy) is observed. It is conjectured that in the presence of dissipation and external forcing, a dual cascade will be observed for zero-helicity situations. Energy will cascade to higher wavenumbers simultaneously with a cascade of mean square vector potential to lower wavenumbers, leading to an omni-directional magnetic energy spectrum.
Fyfe, D.↗
On the mechanism of the magnetic dynamo of the planets
Results of testing the effectiveness of the theory of precessional dynamos in the generation of the magnetic fields of the planets are presented. It is shown that the magnetic state of Earth and of the planets Mars, Jupiter, and Venus can be satisfactorily described by the formula H(i) = H(3) V(i)/V(3) T(3)/T(i) omega(i)/omega(3) sin(alpha 1)/sin(alpha 2) where H, V, T, omega and alpha are the dipole fields, volumes of liquid cores, periods of rotation, rates of precession, and angles between precession vector and angular rotation, respectively, for the planets and earth. The v(i) corresponds to known models of the internal structure. It is shown that the magnetic state of Mercury satisfies this formula if the dynamic flattening of the planet f = .000057-.000083.
Dolginov, S. S.↗
Using dynamo theory to predict the sunspot number during solar cycle 21
On physical grounds it is suggested that the polar field strength of the sun near a solar minimum is closely related to the solar activity of the following cycle. Four methods of estimating the polar magnetic field strength of the sun near solar minimum are employed to provide an estimate of the yearly mean sunspot number of cycle 21 at solar maximum of 140 + or - 20. This estimate may be considered a first-order attempt to predict the cycle activity using one parameter of physical importance based upon dynamo theory.
Schatten, K. H.↗
Dynamo action in a thin slab
We consider the dynamo action produced by convection of a partially ionized, electrically conducting gas in a magnetic field. The model consists of two thin, Cartesian unipolar inductors connected in series by the magnetic field. For the case of a uniform magnetic field we compute the total current system generated by an arbitrary gas flow; for the case of a nonuniform field, we compute only the field-aligned coupling current. Application is made to the solar atmosphere.
Barbosa, D. D.↗
Problems of interior structure, the solar dynamo and the role of SCADM in providing interior diagnostics
What is already known about the structure of the Sun, the motion of its convective zone, and the solar cycle is reviewed. Topics discussed include solar variability, solar 'seismology', velocity patterns, magnetic fields, and the dynamo theory. Observations are needed to determine global properties (solar luminosity and radius), oscillations (p and g models), velocities (variation of rotation with time and depth), and magnetic fields.
Weiss, N. O.↗
Observable solar features which provide clues to the state of the solar dynamo
Space experiments are suggested to better monitor the solar dynamo and solar luminosity variations. Polar and other magnetic fields, sunspots, coronal holes, filaments and other observable solar and solar wind phenomena can provide us with important links to test and discover physical mechanisms which relate solar activity to terrestrial weather, climate, and possibly population variations.
Schatten, K. H.↗
Hydromagnetic dynamo in the cores of Uranus and Neptune
It is noted that the explanation of the origin of a magnetic field of Uranus is difficult because the structure of the planet's interior is not well known and the strong thermal flux, which is associated with the operation of hydromagnetic dynamos in Jupiter and Saturn, seems to be absent or very low. It is shown that the composition, physical state and electrical conductivity of the planet's core permits the generation of a magnetic field within the very low observational limits of its heat emission. Further, it is suggested that the higher density and higher pressures in the core of Neptune could explain the suspected absence of a measurable field on that planet even though it is a relatively strong source of heat.
Torbett, M.↗