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Particle fluxes in the outer geomagnetic field
Author(s) -
Vernov S. N.,
Gorchakov E. V.,
Kuznetsov S. N.,
Logachev Yu. I.,
Sosnovets E. N.,
Stolpovsky V. G.
Publication year - 1969
Publication title -
reviews of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.087
H-Index - 156
eISSN - 1944-9208
pISSN - 8755-1209
DOI - 10.1029/rg007i001p00257
Subject(s) - van allen radiation belt , physics , electron , magnetosphere , earth's magnetic field , van allen probes , radiation , geophysics , radiation zone , atomic physics , electron precipitation , magnetic field , nuclear physics , convection zone , quantum mechanics
The outer geomagnetic field comprises the outer radiation belt, consisting of electrons with energies of 10 4 –10 7 ev, and the unstable radiation zone. The outer radiation belt is bounded on its inner side by a gap, which is at various times located at a distance of 2.2–3.5 R E and in which a considerable precipitation of electrons from radiation belts occurs, possibly owing to a high intensity of electromagnetic waves. The boundary separating the outer radiation belt from the unstable radiation zone is at λ ∼ 71° and ∼9 R E in the equatorial plane on the sunlit side, and at 7–8 R E in the equatorial plane on the nightside. Beyond this, the unstable radiation zone extends out to the magnetosphere boundary and up to λ ∼ 77° on the sunlit side, and out to 14–15 R E on the nightside. The relatively rapid electron intensity variations with periods of 1–7 days are essentially absent at distances less than that of the outer belt but are distinctly seen in the outer belt. In the unstable radiation zone the intensity of electrons with energies of the order of 10 5 ev changes by several times, and good correlation is observed with the increase in K p . Analysis of the outer belt data shows that this belt is formed partly by electron diffusion into the magnetosphere (like the belt of protons with energies of 10 5 –10 7 ev) and partly by the simultaneous acceleration of electrons at various distances from the earth. A comparison of electron intensity changes with the solar activity cycle shows little or no correlation for electrons with E e > 40 kev. The intensity of electrons with E e > 500 kev has changed significantly; in 1964 it was 30 times lower than in 1959. The absence of significant dependence of the diffusion coefficients for electrons with E ∼ 10 4 –10 5 ev on the phase of the solar activity cycle shows that the relatively weak magnetic disturbances that do not change with the phase of the cycle are of major importance in diffusion. This suggests that these magnetic disturbances appear at great distances from the sun because of the instabilities of plasma itself and, therefore, that they depend little on solar activity.