Showing papers on "Dipole model of the Earth's magnetic field published in 1968"
TL;DR: In this paper, the authors compared the worldwide geomagnetic data with IMP 1 magnetic records obtained in the interplanetary space, and found that the magnetic fluctuations of the magnetospheric convective system are coherent with variations in the north-south component of the inter-planetary magnetic field.
Abstract: From the comparison of the worldwide geomagnetic data with IMP 1 magnetic records obtained in the interplanetary space, it is found that the DP 2 fluctuations, which are thought to be the geomagnetic counterpart of intensity fluctuations of the magnetospheric convective system, are coherent with variations in the north-south component of the interplanetary magnetic field. This coherence is observed irrespective of whether this component is directed northward or southward. Average time delay between the crossing of an interplantary magnetic structure across the nose of the bow shock and the associated magnetic variation on the ground is 7 minutes at the pole and 9 minutes at the midday equator. Applicability of the proposed models of the magnetospheric electric field to this phenomenon is critically examined, and the penetration of the interplanetary electric field into the magnetosphere is suggested as the origin of the DP 2 phenomenon.
440 citations
TL;DR: In this article, the propagation of cosmic rays in the regular and random interplanetary magnetic fields transferred by the clouds of the inter-planetary plasma is considered and the equation for the distribution function is obtained.
154 citations
TL;DR: In this paper, the authors studied the interplanetary magnetic field radial gradients between 0.81 and 1.0 AU noting microstructure, mesostructure, macrostructure and directional distribution of discontinuities.
Abstract: Interplanetary magnetic field radial gradients between 0.81 and 1.0 AU noting microstructure, mesostructure, macrostructure and directional distribution of discontinuities
85 citations
82 citations
TL;DR: A solar wind induced planetary magnetic field system supportable by bodies free of electrically insulating atmospheres and dynamo driven intrinsic magnetic fields was proposed in this paper, with the goal of supporting solar wind-induced planetary magnetic fields.
73 citations
TL;DR: In this paper, the magnetic field in the plasma void region downstream of the moon (relative to the solar wind flow) is more intense than the ambient interplanetary magnetic field.
Abstract: Details concerning the magnetic field structure expected on the basis of the author's model of solar wind interaction with the moon are discussed. A derivation is presented that supports the finding of Colburn et al. that the magnetic field in the plasma void region downstream of the moon (relative to the solar wind flow) is more intense than the ambient interplanetary magnetic field. In the expansion region surrounding the void, the field is less than ambient. These effects should be smallest when the magnetic field is perpendicular to the flow vector. A standing shock wave trailing several lunar radii behind the moon is expected regardless of the magnetic field orientation.
66 citations
TL;DR: Cosmic ray anisotropy direction during solar proton events compared with concurrent interplanetary magnetic field vector direction, using Pioneer 6 data as mentioned in this paper, using Pioneer data sets.
Abstract: Cosmic ray anisotropy direction during solar proton events compared with concurrent interplanetary magnetic field vector direction, using Pioneer 6 data
54 citations
TL;DR: In this paper, the authors discuss solar active region development leading to magnetic loops in interplanetary medium and discuss the evolution of the magnetic field sectors evolution in the solar magnetic field.
Abstract: Interplanetary magnetic field sectors evolution /1964-1965/, discussing solar active region development leading to magnetic loops in interplanetary medium
47 citations
TL;DR: In this paper, an abridgment of a more extensive analysis of the earth's magnetic field based on observed data from the time of Gauss to the most recent epochs is presented.
Abstract: This work is an abridgment of a more extensive analysis of the earth's magnetic field based on observed data from the time of Gauss to the most recent epochs. An attempt was made to collect all Gauss-Schmidt coefficients of previous investigators, and extensive computations were made using selections of these data. Root-mean-square representations of the geomagnetic field elements are employed to depict time trends and structural dissymmetries at the earth's surface and core-mantle boundary. It is established that the magnetic dipole field is being driven destructively to smaller values by fluid motions which transform its magnetic energy into that of the near neighboring modes rather than expend it more directly as Joule heat. Concurrent with the continual decrease in field energy in the atmosphere, at least since 1900, sixth-degree analyses indicate that the mean magnetic energy density in the outermost layers of the core fluid has been increasing at a small rate. An associated phenomenon is the continued increase in hemispheric dissymmetry, the southern hemisphere preponderating. Defining an asymmetry ratio, we find by extrapolation that the geomagnetic field was sensibly symmetric in A. D. 1670. The average rate of westward drift of the geomagnetic poles during the past 130 years is 0.042°/year in azimuth angle, corresponding to a polar rotation period of 8.6 thousand years. The polar angle shows no progressive motions.
34 citations
TL;DR: In this paper, moving magnetic field lines relationship with particle drift, showing unique and significant field line identification, is analyzed and compared with the particle drift and the magnetic field line detection.
Abstract: Moving magnetic field lines relationship with particle drift, showing unique and significant field line identification
34 citations
TL;DR: Low rigidity cosmic ray modulation and interplanetary medium at solar minimum and at other phases of solar cycle was studied in this article, showing that cosmic ray modulations can be achieved at low rigidity.
Abstract: Low rigidity cosmic ray modulation and interplanetary medium at solar minimum and at other phases of solar cycle
TL;DR: In this paper, the problem of electromagnetic wave propagation from an oscillating magnetic dipole placed over a uniaxially anisotropic earth has been considered, and formal expressions for the vector potentials inside the earth have been derived.
Abstract: The problem of electromagnetic wave propagation from an oscillating magnetic dipole placed over a uniaxially anisotropic earth has been considered. Formal expressions for the vector potentials inside the earth have been derived. It has been shown that for a vertical magnetic dipole, the field components are identical to those in the case of an isotropic medium in which the conductivity is the “horizontal or longitudinal conductivity.” For a horizontal dipole, directed along the x axis, it has been shown that the vector potential inside the earth will have a y component as well as x and z components. Formal expressions for the vector potentials in air have been obtained for the case of a horizontal magnetic dipole. However when the conductivity of air is considered to be negligibly small, the field components are not affected by the anisotropy.
Journal Article•
TL;DR: Van Allen and Krimigis found that solar electrons diffuse through the interplanetary medium at a rate similar to that of protons of the same velocity, despite the disparity by a factor of 2 × 10³ in their respective magnetic rigidities.
Abstract: Van Allen and Krimigis find that solar electrons diffuse through the interplanetary medium at a rate that is similar to that of protons of the same velocity, despite the disparity by a factor of 2 × 10³ in their respective magnetic rigidities, and they suggest that this fact serves to extend knowledge of the structure of the interplanetary magnetic field to much smaller scale than has been measured by Coleman This suggestion is developed quantitatively in the framework of Roelof's theory It is found that the power spectrum of the interplanetary magnetic field varies inversely as the square of the frequency ƒ in the range 27 × 10−4 < ƒ < 05 cps
TL;DR: In this article, a solution of the angular momentum equation coupled with the Maxwell's equations is presented to give the interplanetary magnetic field structure as well as the azimuthal component of the solar wind velocity.
TL;DR: In this paper, it was shown that in the confinement volume defined by field lines encircling one or several ring-shaped coils a static plasma equilibrium should be possible even in the presence of the magnetic field from the leads.
Abstract: The field from one or several ring-shaped coils can be used as a magnetic bottle for plasma confinement. In stationary operation as a fusion device the coils have to be suspended. A possible method is provided by magnetically screened leads. Earlier investigations by the author on this problem are extended by the following results: In the confinement volume defined by field lines encircling one or several ring-shaped coils a static plasma equilibrium should be possible even in the presence of the magnetic field from the leads. The particle losses introduced by the leads are mainly non-adiabatic. They are partly due to deviations from the constancy of the equivalent magnetic moment in some very small regions where the field is weak, partly to deviations from the constancy of the longitudinal invariant which arise when a particle passes the lead region repeatedly and in finite steps. These effects produce a scattering which displaces a particle randomly across the magnetic field by about one Larmor radius for each complete lead passage. It is equivalent to a kind of ambipolar diffusion across the magnetic field.
TL;DR: In this paper, the effect of non-uniform magnetic fields on elastic wave motion was investigated for long-wavelength standing modes of free vibration in the core of the earth.
Abstract: An applied magnetic field will perturb an elastic wave that is passing through an electrical conductor. Nonuniformity in the applied field introduces an extra dissipative effect that is not present for a uniform applied field. In this paper one case of the interaction of elastic wave motion with a nonuniform field is solved by means of series expansions in the two dimensionless perturbation parameters involved. The effect of the nonuniform field dominates the effect of the uniform field in regions where the local field strength is less than half of the change in field strength per wavelength. For seismic waves in the core of the earth, the effect would be most important for long-wavelength standing modes of free vibration. However, taking accepted values for the conductivity and field strength in the core, the effect of the nonuniform field is found to be insignificant, as is the uniform field effect.
TL;DR: In this article, the influence of the earth's magnetic field on ionospheric propagation was investigated by means of a ray-tracing program, and corrections to the no-field MUF, as functions of the above parameters, were obtained.
Abstract: To investigate the influence of the earth's magnetic field on ionospheric propagation, P'(f) curves were calculated by means of a ray-tracing program. The calculations were made for a path length of 2000 km. The geomagnetic latitude of the midpoint of the path and the angle between the magnetic meridian and the path are varied in steps of 15°. Corrections to the no-field MUF, as functions of the above parameters, are obtained.
TL;DR: Interplanetary magnetic field effects on energy of geomagnetic disturbances used in determining merging at magnetopause were studied in this article, where they were used to determine the merging time.
Abstract: Interplanetary magnetic field effects on energy of geomagnetic disturbances used in determining merging at magnetopause
TL;DR: In this article, a departure from the usual assumption of a uniform magnetic field in the calculation of the Harris dispersion relation is shown to lead to new velocity-space instability, where the magnetic field variations are small and if a particle transit time through a complete cycle of the field is less than the instability growth time, an average (velocity-dependent) gyrofrequency may be assumed which leads to negative mass-type instabilities.
Abstract: A departure from the usual assumption of a uniform magnetic field in the calculation of the Harris dispersion relation is shown to lead to new velocity-space instability. If the magnetic field variations are small and if a particle transit time through a complete cycle of the field is less than the instability growth time, an average (velocity-dependent) gyrofrequency may be assumed which leads to negative-mass-type instabilities.
15 Aug 1968
TL;DR: In this article, it was shown that even in the absence of thermal and dissipative effects, a discontinuity in field and particle velocity will arise and that the electrons will share the solar wind energy in a scale length of a few kilometers.
Journal Article•
01 Jan 1968
01 Jan 1968
TL;DR: In this paper, the electromagnetic field of an oscillating magnetic dipole is calculated, assuming that the dipole was immersed in a cold, streaming plasma, and the amplitude of the magnetic dipoles moment is sufficiently weak that the linearized cold-plasma equations may be used to describe the response of the plasma.
Abstract: The electromagnetic field of an oscillating magnetic dipole is calculated, assuming that the dipole is immersed in a cold, streaming plasma The amplitude of the magnetic dipole moment is assumed to be sufficiently weak that the linearized cold-plasma equations may be used to describe the response of the plasma
The resulting field of the dipole is rather different from the field that would result if the plasma were not streaming In particular, a longitudinal electrostatic field appears as a consequence of the plasma's motion The far field of the dipole is such that the Poynting vector is not purely radial, but is tilted against the direction of the zeroth-order plasma flow
An outward flow of mechanical energy is associated with the electrostatic field However the mechanical energy flow is negligible for streaming velocities small compared with the velocity of light The force necessary to hold the dipole in place is also calculated This force vanishes when the dipole axis is parallel to the streaming direction, as does the longitudinal electric field
30 Nov 1968
TL;DR: In this article, solar wind and current sheet were considered in determining shape of magnetosphere boundary and calculation of magnetic field lines, and the current sheet was used to calculate the magnetic field line.
Abstract: Solar wind and current sheet considered in determining shape of magnetosphere boundary and calculation of magnetic field lines
Journal Article•
TL;DR: In this paper, the lower and upper limits of the magnetic field in the galactic disk are derived from two alternative models of field configuration; i.e. (0.5-1.0) X gauss near the solar system and 1.0-2.0 Gauss at the galactic center, respectively.
Abstract: An estimate of the galactic magnetic field is obtained by combining new results in the cosmic-ray electron spectruin and the recent radio data. The lower and upper limits of the magnetic field in the galactic disk are derived from two alternative models of field configuration; i.e. (0.5-1.0) X gauss near the solar system and (1.0-2.0) X gauss near the galactic center, respectively. The magnetic field in the halo is estimated to be larger than 2.5 X gauss.