The Extra-Magnetospheric Ion Environment as Observed by the Magnetospheric Multiscale Mission Hot Plasma Composition Analyzer (MMS-HPCA)

摘要

abstract_textpObservations within the solar wind (SW) environment outside of the Earth's magnetosphere were conducted on 6 December 2016, by the Hot Plasma Composition Analyzer of the Magnetospheric Multiscale mission. At the time of measurement, the SW was in a compressed state with a southbound interplanetary magnetic field of 9 nT and corresponding increases in proton density and dynamic pressure. High time resolution measurements of pickup ions in this region were made during the time when the Earth is situated in a solar gravitational focusing cone for interstellar neutrals. Proton measurements revealed a suprathermal ion population traveling with a maximum velocity that is two and a half times that of the SW velocity (V-sw). Helium ions exhibited pitch angle scattering that was uncorrelated with changes in the interplanetary magnetic field orientation. The time-of-flight measurements exhibited expected contributions from both protons and singly charged helium. Because the Magnetospheric Multiscale spacecraft are in the SW, counts from heavy SW ions (possibly Fe7+ or Fe8+) with M/Q = 8 AMU/e are observed with a mean energy/charge (E/Q) of 5.75 keV/e./p/abstract_text