Observation of Multiple Ion Beams in the Magnetotail Low Latitude Boundary Layer. Evidence for a Double H+ Population

摘要

The ISSE 2 plasma experiment detected the double peak population frequently found in the low latitude boundary layer of the magnetotail at times of enhanced geomagnetic activity. This population consists of ionospheric O+ and H+ mixed with solar wind plasma (typically H+ and He++). Analysis of the low energy peak indicates that it contains two clearly distinguishable proton populations. The energy ratios between the O+ and H+ beams indicate that one of the H+ populations is of ionospheric origin and flows tailward together with the ionospheric O+. The characteristics of the other H+ population suggest a higher altitude origin, and the presence of an H++ population with the same characteristics suggests that it is the solar wind H+ component.