A kinetic model for the neutral gas between plasma and wall

Starting from the Boltzmann equation for the neutral gas in a plasma, an integral equation for the density of the neutral gas is derived. Inelastic collisions are taken into account only as charge exchange and ionisation. The integral equation is solved numerically. It is shown that the reflection mechanism of neutral particles from the wall modifies the density profile. The distribution function of the charge exchange neutrals deviates from a Maxwellian, and for fast particles (v>vth) we obtain f0 approximately v-1exp(-(v2/vi)). The total particle and energy fluxes on the wall are also calculated.