Determining the Geomagnetic Cutoff Rigidity and Modeling the Motion of Particles in the Earth’s Magnetosphere

The method for determining the geomagnetic cutoff rigidity is presented, based on tracing charged particles in the Earth’s magnetic field using the particle-in-cell model implemented in the Buneman–Boris method. The method verification results are given, along with comparisons to theoretical calculations in the ideal dipole field and existing calculations in the real field. The developed procedure shows high reliability through the replication of known effects. In a dipolar approximation, it is much more accurate than theoretical calculations. A typical pattern of the geomagnetic cutoff penumbra is reproduced.