Neutral particle diffusion in field-reversed configurations

Calculations are performed to study contributions to the global particle and energy loss arising from the possible influx of neutral deuterium molecules at the edge of a field-reversed configuration (FRC). Earlier work is extended to include results from a self-consistent 1-D neutral transport code. The following two situations are considered: (1) a stationary FRC plasma surrounded by cold neutral gas; and (2) an FRC translating into neutrals at an axial speed that is much greater than the thermal speed of the4 neutrals. The relevant atomic and molecular processes (dissociation, ionization, charge and atom exchange, recombination) for FRC's are reviewed. When applying the transport model to an FRC with plasma parameters similar to those measured in the FRX-C experiment, one finds that essentially all of the neutrals are converted to ions before penetrating the separatrix