Low Energy Neutral Atom Fluxes Produced by Outflowing Ionospheric Ions
at High Latitudes

D. Gallagher, and Gordon R. Wilson  (Space Science Laboratory, ES83
NASA/MSFC, Huntsville, AL 35812, 205-544-7638, e-mail:
wilsong@cspar.uah.edu)

Among the various magnetospheric imaging instruments that will be
carried on the IMAGE spacecraft is one that is designed to image
energetic neutral atoms produced by ions flowing out of the high
latitude ionosphere.  To date only a limited amount of work has been
done to model the environment and produce synthetic images from which
instrument response can be assessed.  In this project we have developed
a 3-dimensional model of cleft ion fountain, polar cap and auroral zone
upflows.  The model gives ion fluxes, as a function of position, pitch
angle and energy, for H+, He+ and O+ ions in response to changing
interplanetary conditions and levels of geomagnetic activity.  We employ
POLAR/TIDE data to constrain the energy of the upflowing ions at the
source altitude. The ion fluxes are then converted to ENA (energetic
neutral atom) fluxes using the various charge exchange reactions between
these ions and the neutral atmosphere (H, He, O) and ionosphere (O+).
The neutral atmosphere used is that given by the MSIS86 model and the
ionosphere is that given by the IRI90 model.  The effects of changing
solar and magnetic activity on the ENA fluxes will be presented.