MODELING OF NEUTRAL HYDROGEN VELOCITIES IN THE TOKAMAK FUSION TEST REACTOR

Monte Carlo neutral transport simulations of hydrogen velocities in th e Tokamak Fusion Test Reactor (TFTR) [K. M. McGuire et al., Phys. Plas mas 2, 2176 (1995)] are compared with experiment using the Doppler-bro adened Balmer-alpha spectral line profile. Good agreement is obtained under a range of conditions, validating the treatment of charge exchan ge, molecular dissociation, surface reflection, and sputtering in the neutral gas code DEGAS [D. Heifetz et al., J. Comput. Phys. 46, 309 (1 982)]. A residual deficiency of 10-100 eV neutrals in most of the simu lations indicates that further study of the energetics of H-2(+) disso ciation for electron energies in excess of 100 eV is needed. (C) 1996 American Institute of Physics.