“…Resonant phenomena occur in a variety of different systems: energy exchange between coupled oscillators, Vakakis and Gendelman, 2001;Popov at al, 2001), mixing in fluids (Neishtadt et al, 1998;Ward and Homsy, 2001), celestial mechanics and astrophysics (Fux, 2001), billiards (Itin et al, 2001), Josephson junctions (Vasiliev et al, 1997) to name a few recent papers. In the present paper we apply the theory of resonant processes in Hamiltonian systems with slow and fast motions in the form, developed in (Neishtadt, 1999) (see also (Neishtadt, 1997) for references on preceding works) to the analysis of the dynamics of charged particles in nonhomogeneous electromagnetic fields in the magnetotail of the earth.…”