LOW-ENERGY NEUTRAL ATOM EMISSION FROM THE EARTHS MAGNETOSPHERE

Imaging of the terrestrial magnetosphere is possible through the detec tion of low-energy neutral atoms (LENAs) produced by charge exchange b etween magnetospheric plasma ions and neutral atoms of the Earth's geo corona. We present calculations of both hydrogen and oxygen line-of-si ght LENA fluxes expected on orbit for various plasma regimes as predic ted by the Rice University Magnetospheric Specification Model. To decr ease the required computation time, we are in the process of adapting our code for massively parallel computers. The speed gains achieved fr om parallel algorithms are substantial, and we present results from co mputational runs on the Connection Machine CM-2 data parallel supercom puter. We also estimate expected image count rates and image quality b ased on realistic instrument geometric factors, energy passbands, neut ral atom scattering in the instrument, and image accumulation interval s. The results indicate that LENA imaging instruments will need a geom etric factor (G) on the order of 0.1 cm(2) sr eV/eV to be capable of i maging storm time ring currents, and a G of 1.0 cm(2) sr eV/eV in orde r to image the quiet time ring current fluxes, ion injections from the tail, and subsequent ion drifts toward the dayside magnetopause.