THE EFFECTS OF ELASTIC-SCATTERING IN NEUTRAL ATOM TRANSPORT

Neutral atom elastic collisions are one of the dominant interactions i n the edge of a high recycling diverted plasma. Starting from the quan tum interatomic potentials, the scattering functions are derived for H on H+, H on H-2, and He on H-2 in the energy range of 0.1-1000 eV fol lowing classical scattering theory and an impact parameter formulation . Potentials for both the gerade and ungerade electronic wavefunctions were included. An algorithm for the addition of these reactions to th e DEGAS [J. Comput. Phys. 46,'309 (1982)] code is presented and used t o simulate three test problems: (1) the transport of neutral atoms thr ough a dilute edge plasma, (2) the penetration of neutral atoms into a dense plasma from a divertor plate, and (3) the transmittance of neut ral atoms through a pump duct. In all three cases the inclusion of ela stic scattering has a significant influence on the neutral atom densit y, temperature, and flux to the walls.