Energetic protons, alpha particles, and electrons in magnetic flux transfer events

Abstract

We have analyzed energetic proton, alpha particle, and electron measurements during two magnetopause crossings of ISEE 1 which show magnetic field signatures characteristic of flux transfer events. While the ions are streaming highly collimated along the magnetic field, the electrons show either isotropic distributions or distributions which are consistent with convected small‐scale structures. Fluxes and relative abundances of ions in flux transfer events are similar to the trapped particle values. We have also observed similar particle signatures when no change in the magnetic field normal component has been measured. During the occurrence of isotropic electron distributions, the absolute electron flux (above 75 keV) is greatly reduced when compared with the flux of the trapped electron population. Thus the electrons cannot be explained by simple leakage out of the magnetosphere.