Approximation of a diffusion induced on a kinetic equation by a dynamical system

This work is devoted to the macroscopic behavior of the particles enclosed between two parallel plates within a small distance h of up to a few mean free paths. We show that, under physically realistic assumptions of the nature of the collisions, the macroscopic behavior of the gas is described by a diffusion equation. The present paper is an extension of a previous one [1] where only T-reflection law were considered.