EVOLUTION OF ENERGETIC PARTICLE FLUXES IN THE EARLY HELIOSPHERE

The variations in the fluxes of protons in the heliosphere owing to the reduction over time of the rate of mass loss by the sun and its flow speed are calculated over its entire lifetime. Two groups of protons are considered: those belonging to the solar wind with energies of about 1 keV corresponding to the directed flow velocity on the order of 400 km/s and those belonging to an anomalous component accelerated to energies on the order of 1-100 MeV at the boundary of the heliosphere. Approximation formulas are obtained for the variation in the differential intensities with time for both groups; these are consistent with available observational and theoretical data. They are used to obtain analytical dependences for the irradiation rate of water ice during different stages of the evolution of the heliosphere which are important for analyzing the radiation chemical transformation of ices in the solar system.