Siberian Federal University

The non-stationary three-dimensional mathematical model describing evolution of proton distribution function is offered. The distribution of the ring current protons in the inner magnetosphere during the magnetic storm is studied. The temporal and spatial evolution of the proton phase space densities in a dipole field is calculated using a three-dimensional model, considering radial, pitch angle and energy diffusions. The loss terms are described due to charge exchange and wave–particle interactions. The simulation starts with a quiet time distribution. The model is tested by comparing calculated proton fluxes with Polar/MICS measurement during the magnetic storm on 21–22 October 1999. The good consent of the model pitch angle distributions of protons with the experimental data is received.