Solar cycle changes in inner-zone protons

Calculations on time dependence of the inner Van Allen belt proton population show that large changes of the population up to a factor of 50 will take place during the solar cycle. The effect is most pronounced for the region of B-L space corresponding to minimum altitudes of 300–700 km. Because protons of different energies respond to the changing solar cycle at different rates, the proton energy spectrums will change with time also.