Further aspects of the proton ring current interaction with the plasmapause: Main and recovery phases

Recent storm recovery phase results from Explorer 45 (Williams and Lyons, 1974) show the existence of nearly isotropic proton pitch angle distributions with apparently empty loss cones at high equatorial L values and a transition to a rounded pitch angle distribution at lower L values, the transition altitude decreasing with decreasing energy. These recovery phase results were used to describe the hot-cold plasma interaction in the vicinity of the plasmapause region. It was concluded on the basis of low-altitude loss cone observations that a region of strong plasma turbulence exists during storm recovery phase at altitudes above Explorer 45 apogee (5.24 RE). We present in this report direct Explorer 45 observations during main phase that are consistent with the observation of the turbulent (full loss cone) region. We also present recovery phase data consistent with outward expansion of the plasmapause region due to refilling from the ionosphere.