MODULATED DIFFUSION FOR A SIMPLE LATTICE MODEL

A possible mechanism, which explains the diffusion in the phase space due to the ripples in the quadrupole currents, is studied on a simplif ied version of the SPS lattice used fur experiments. We describe the d iffusion driven by a single resonance in the space of the adiabatic in variant (action variable), by using the results of the Neishtadt's the ory. Under suitable hypothesis, it is possible to introduce a random w alk for the adiabatic invariant, which gives a quantitative descriptio n of the diffusion. The comparison with the numerical results turns ou t to be very effective.