The effect of plasma sheet ion composition on the production and
evolution of cold H+ population from the hydrogen geocorona in the inner
magnetosphere
Abstract
Both in situ measurements and numerical simulations show that the charge
exchange collisions between energetic ring current ions
(>10keV) and cold ambient neutral atoms of the upper
atmosphere and exosphere (<1eV) can be a major loss process of
the ring current ions. Owing to the high volume of energetic ion source
injected from the ion plasma sheet during storm time under strong
convection strength, there can be a significant rate of occurrence of
charge exchange collision in the inner magnetosphere, therefore
contributing a significant amount of inner magnetospheric cold proton
populations. Due to the different charge exchange cross sections among
different reactions, cold protons are generated at different rates from
different energetic ion species. In this study, both qualitative and
quantitative assessments on the production and evolution of
charge-exchange byproduct cold protons are performed via numerical
simulations, showing that the production and evolution of the cold H+
populations can be primarily driven by the plasma sheet conditions
combined with the magnetospheric convection, while having the potential
to affect the dynamics of the plasmasphere and facilitate the
early-stage local plasmaspheric refilling. Furthermore, the energetic
heavy ions composition plays an important role determining the cold H+
contribution structure from the energetic ring current ions.