The dynamics of energetic electrons in the Earth's outer radiation belt during 1968 as observed by the Lawrence Livermore National Laboratory's Spectrometer on Ogo 5

Abstract

An account is given of measurements of electrons made by the LLNL magnetic electron spectrometer (60–3000 keV in seven differential energy channels) on the Ogo 5 satellite in the earth's outer‐belt regions during 1968 and early 1969. The data were analyzed to identify those features dominated by pitch angle and radial diffusion; in doing so all aspects of phase space covered by the data were studied, including pitch angle distributions and spectral features, as well as decay rates. The pitch angle distributions are reported elsewhere. The spectra observed in the weeks after a storm at L ∼3–4.5 show the evolution of a peak at ∼1.5 MeV and pronounced minima at ∼0.5 MeV. The observed pitch angle diffusion lifetimes are identified as being the shortest decays observed and are found to be highly energy and L dependent with minimum lifetimes of ∼1–2 days occurring at L ∼3–4.5. Two contiguous periods of decay, following the intense storm injection on October 31 and November 1, were analyzed in terms of radial diffusion. Significant differences were found between the derived values of DLL for the two periods; also significant energy dependence shows in the results. Although the values of DLL vary by about a factor of 10, representative values are 0.3 day−1 at L=6, 0.06 at L=4, 0.015 at L=3, and 0.001 at L=2.5. Despite the wide variation of many prior results in the literature, there is a family of results in approximate agreement with the present results. By noting the variations in DLL, as a function of the invariant quantities, we are able to order a fair body of previous results with our new results.

Low altitude energetic electron lifetimes after enhanced magnetic activity as deduced from SAC-C and DEMETER data

“…The lifetimes show a certain dispersion depending on the after storm conditions. For instance, from a diffusion analysis, West et al (1981) found evidence to support the assumption that the most rapid decays are those observed when radial diffusion is weak and pitch angle diffusion is identified as the predominant process responsible for the decay.…”

“…the electron lifetime) will be given here. In fact, measurements of the lifetimes of energetic electrons are often considered to be the key to the understanding of the transport of these particles; for instance, they constitute key parameters in the determination of pitch angle diffusion rates (West et al, 1981).…”

Deduction of the rates of radial diffusion of protons from the structure of the Earth's radiation belts

“…This work was done in the same way as for electrons (e.g., Newkirk and Walt, 1968;Lanzerotti et al, 1970;Tomassian et al, 1972;West et al, 1981;Chiu et al, 1990;Brautigam and Albert, 2000;Brautigam et al, 2005;Ma et al, 2016), protons and other ions/nuclei (e.g., Spjeldvik, 1977;Fritz and Spjeldvik, 1981;Jentsch, 1981;Westphalen and Spjeldvik, 1982;Panasyuk, 2004;Alinejad and Armstrong, 2006;Selesnick et al, 2016). The values of D LL obtained by this method differ from each other by 2 and more orders of magnitude.…”

On the source location of radiation belt relativistic electrons

“…Previous studies using HIST electron data, of the quiet-time outer zone and of specific events Blake, 1997, 1998], used similar data analysis methods. Earlier studies of this type [West et al, 1981] used static magnetic field models.…”