Solar cycle modulation of the radiation belt proton flux

The purpose of this paper is to predict in an exhaustive way the solar cycle time variations to be expected in the trapped radiation belt proton flux on the assumption of a neutron decay source. By ‘exhaustive’ we mean that, once the interested reader decides on suitable models for the earth's atmosphere and magnetic field (we will recommend some), he should, by reading this paper, be able to predict the time variations expected for protons of any energy and pitch angle at any point in space. We have also devoted considerable attention to a derivation from the Boltzmann equation of the simplified proton transport equation commonly used in discussing energetic protons at low L values. Emphasis is given to the various approximations involved.