The possibility of the IBEX ENA observations providing the in-situ measurements of the outward H fluxes in the outer exosphere

The non-thermal processes in the exosphere are important in producing H atoms with a suprathermal velocity and could significantly increase the H escape flux on top of the thermal escape. One of the important non-thermal processes is charge exchange between a cold H atom and a hot proton (Hcold + H+hot H+ + HENA). The warm plasma cloak (~10s to 100s of eV) and the plasmaspheric plume (1 to ~10s eV) could be the sources of the hot protons. Since these newly created energetic neutral atoms (ENAs) have energies greater than the escape energy, the outward H fluxes at far distance (> 8RE) is a potential indicator of the presence of non-thermal processes in the exosphere. Therefore, the possible in-situ measurements of the outward H fluxes lead to a better understanding on the distribution and dynamic variations of H atoms in the exosphere. Since NASAs Interstellar Boundary Explorer (IBEX) has highly eccentric equatorial earth orbit and highly sensitive ENA instruments with field-of-view (FOV) perpendicular to the sun-pointing spin axis, it can be a reasonable platform to observe ENA emissions from the Earths magnetosphere. This fact indicates that the IBEX-Lo ENA observations could provide the in-situ measurements of the outward H fluxes produced by charge exchange with ~1 to 100s eV population of energetic protons in the vicinity of the plasmasphere. We use the IBEX-Lo ENA observations from 4/11/2009 to 5/26/2009 with the energy ranges of 10-150 eV. We analyze the emissions measured in the restricted time intervals and spin angles that satisfy three criteria: (1) the IBEX FOV should cover the sphere of geocentric radius 4RE, (2) the IBEX should be outside the magnetopause, and (3) the IBEX Background Monitor should measure the low count rate. With the selected data, we compute the differential fluxes as a function of geocentric distances. We discuss the data analysis methodology and the possibility of our assumption.