General approach to diffusion of periodically kicked charges in a magnetic field

The chaotic diffusion of periodically kicked charges in a uniform magnetic field is systematically approached by considering general values of a conserved quantity for the problem, namely the coordinate xc of the orbit center. The dependence of the diffusion coefficient D on the correlation function C is explicitly given. Assuming ''crystalline'' resonance conditions, exact closed expressions are derived for C, both at fixed xc and averaged over xc. This averaging removes much of the rich structure of D(K) (K is the kicking parameter), found at fixed xc.