The anomalous cosmic ray ion dynamics in the geomagnetic field Original Research Article

The dynamics of trapped anomalous cosmic ray ions in the geomagnetic field during their trapping is studied on the basis of the quasi-adiabatic model of particle motion. In this model a trajectory of the particle guiding centre is approximated by a particle trajectory crossing the dipole centre. This approach permits to reduce complicated motion of particles with rigidities right up to the boundary of finite motion in a dipole trap to motion with a constant value of magnetic moment between two successive crossings of the equatorial plane and a jump-like change of the magnetic moment during this crossing. A mapping, approximating the Poincaré one, was constructed using this model. The trapping boundaries for different ions such as C,N,O and Ne were obtained using this mapping. Besides, the instability connected with the non-dipolar character of the real geomagnetic field and its role in the dynamics of trapped ions is considered. The predicted boundaries are compared with the experimental results.