Solar Electron Access to the Magnetosphere

Abstract

Solar flare particles, as suggested by Michel and Dessler (1970), can be used as probes of the geomagnetic topography. Low energy solar flare electrons, in particular, should be ideal natural test particles since their low magnetic rigidity permits them to be used to examine very small scale magnetic structure. The current status of magnetospheric topology (i.e., the lack of a clear consensus) and the fact that many groups are still making measurements of solar particles or analyzing data from previous events in an effort to establish a ‘correct’ magnetospheric model, indicate that our ‘probes’ have not been the ideal tools they were expected to be. As with any tool, quick success depends both upon the quality of the tool and the ability of the user. Here we shall examine the utility of the solar electron as a tool, its successes and failures, the use to which it has been put, and finally its areas of unexploited utility. We shall not dwell upon the solar proton access problem for several reasons: (a) The scale of geometry involved in solar proton access is such that apparently a complexity of access mechanisms is required for a complete solution; (b) The body of observational data indicate a marked dissimilarity in the electron and proton access phenomena (which may be due to the large difference in the rigidities of the particles involved); and, primarily, (c) The large volume of proton data tends to be contradictory. It is not clear that any theory, even an extreme or grotesque one, will ever explain all the proton observations due to the large number of conflicts that exist within the body of data. On the other hand, the electron data is much better behaved (due, probably, to the much smaller volume of observations and the small number of distinct research groups making the measurements). Hence, we shall limit ourselves to the small and pleasant task of organizing the electron observations.