Comparisons of He+ in the plasmasphere with the CTIP model and EUV data from the IMAGE satellite S. D. Thom, C. R. Wilford, G. J. Bailey Space and Atmospheric Group, University of Sheffield B. R. Sandel Lunar and Planetary Laboratory, University of Arizona Helium ions in the Earth's plasmasphere resonantly scatter solar radiation at 30.4nm. The Extreme Ultraviolet Imager (EUV) of the IMAGE (Imager for Magnetopause-to-Aurora Global Exploration) mission studies the global distribution of He+ by detecting these emissions. We use a coupled thermosphere-ionosphere-plasmasphere model (CTIP) to solve the equations of continuity, momentum and energy balance for O+, H+ and more importantly for this investigation, He+. Model results are compared to IMAGE EUV data on a global scale. _______________ Presented at the 2003 CEDAR Workshop, Longmont, Colorado 15-20 June 2003