Calculation of the behaviour of neutral hydrogen in the wall region of high temperature plasmas including wall interaction

In the wall regime of high temperature discharges (e.g. tokamak experiments) neutral hydrogen plays a dominating role. The neutrals influence the local particle density and energy losses, and contribute to wall interactions by desorption of adsorbed molecular and atomic species, sputtering and backscattering. This investigation of the behaviour of the neutral component in the wall layer starts from the one-dimensional time dependent Boltzmann-equation for neutral hydrogen and assumes the data of the background plasma to be known. Charge exchange and ionisation processes are taken into account as well as interaction with the wall and an influx of atoms. Depending on density and temperature profiles of the background plasmas, the distribution function of the neutrals and their fluxes on to the wall are calculated for steady conditions. By solving the time dependent Boltzmann equation the relaxation time for the influx of cold neutral atoms into a tokamak plasma is also derived. (Auth.)