A new simple model for equatorialy mirroring protons, based on classical radial diffusion, is used here to understand the global long term dynamics of the ring current ion population. The convection access for low energy particles coming from the plasmasheet is used as a source population. Then magnetospheric acceleration processes are reproduced by using a Kp dependent radial diffusion coefficient. Comparing the results with CRRES satellite energetic ion measurements from the fifteen months of the total mission yields very good quantitative agreement for ~80 keV ring-current protons and good qualitative agreement with ~300 keV ions. ¿ 1998 American Geophysical Union