A model of the secondary radiation belt

Products of nuclear reactions between primary radiation belt protons and constituents of the tenuous upper atmosphere form a collocated secondary radiation belt. A calculation of the time‐dependent secondary intensity provides a model specification of this environmental component for low‐ and medium‐altitude satellite orbits. It is based on an earlier model of the radiation belt protons, the novel feature being a determination of the secondary source function from nuclear reaction cross sections. All long‐lived secondary products are included, isotopes of H and He being dominant while the heavier Li to O isotopes are present at relatively low levels. Secondary protons are shown to be a minor correction to the primary radiation belt.