ESRO IA/B Observations at High Latitudes of Trapped and Precipitating Protons with Energies above 100 keV

Abstract

In more than a decade now, the energetic protons in the earth’s magnetosphere have been studied directly by instruments carried aloft by rockets and satellites. The protons trapped by the geomagnetic field have been measured by a great number of satellites, starting with the measurements of Davis and Williamson (1963), who measured the protons at low latitudes in the energy range 100 keV to several MeV. Frank (1967) extended the measurements down to the 1 keV range, and positively identified the low energy protons responsible for the observed depression of the earth’s magnetic field during magnetic storms. Dynamics, loss, and replenishment of the trapped particle populations have been reviewed by Williams (1970).