Abstract
The propagation of solar cosmic rays in the interplanetary medium is considered on the basis of the kinetic equation describing the small-angle multiple scattering of charged particles. Energetic particles are assumed to be injected into the interplanetary medium by an instantaneous point-like source. The spatial-temporal distribution of the density and anisotropy of high-velocity particles during the anisotropic phase of a burst of solar cosmic rays is studied. An analytical expression for the distribution function of cosmic rays in the small-angle approximation is derived; the evolution of the angular distribution of energetic particles is investigated. It has been shown that, under weak scattering of charged energetic particles on fluctuations of the interplanetary magnetic field, the intensity of solar cosmic rays impulsively increases at the initial stage of their enhancement. The anisotropy in the angular distribution of solar cosmic rays monotonously decreases with time and exhibits the highest value at the moment of the first particles' arrival to a given point of space.
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Translated by E. Petrova
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Fedorov, Y.I. The Distribution Function of Cosmic Rays at the Initial Stage of a Solar Proton Event. Kinemat. Phys. Celest. Bodies 36, 103–113 (2020). https://doi.org/10.3103/S0884591320030034
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DOI: https://doi.org/10.3103/S0884591320030034