The cosmic ray distribution function on the initial stage of the solar proton event

1Fedorov, YI
1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2020, 36(3):3-20
Start Page: Space Physics
Language: Ukrainian

The propagation of solar cosmic rays in the interplanetary medium is considered based on the kinetic equation, describing multiple small-angle scattering of charged particles. The energetic particles are assumed to be injected in the interplanetary medium by the instantaneous, point-like source. The spatio-temporal distribution of high-velocity particle density and anisotropy is studied during the anisotropic phase of solar cosmic ray enhancement. The analytical expression of cosmic ray distribution function in the small-angle approximation is derived; the evolution of energetic particle angular distribution is investigated. It is shown that under weak scattering of charged energetic particles on the interplanetary magnetic field fluctuations the impulsive enhancement of their intensity occurs. The anisotropy of angular solar cosmic ray distribution decreases with time steadily and has a maximal value in the instant of first particle arrival in the given point of space.

Keywords: cosmic rays, interplanetary medium, kinetic equation

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