Quasi-adiabatic description of the motion of charged particles in configurations with a reversed magnetic field

Within the framework of a perturbation thoery, the behavior of charged particles in the Earth's magnetotail under the action of both a nonuniform magnetic field and an electric field is discussed. In the case of a noticeable curvature of the magnetic field lines, the introduction of adiabatic invariants is justified. The effect of multiple separatrix crossings on the motion of particles is described.