The astronomical detection of molecular anions has prompted our study of their chemical reactions with atomic species that are abundant in the interstellar medium. We have recently explored the chemistry of a variety of Cx Ny− anions with hydrogen atoms and determined their reaction rate constants and products using the flowing afterglow-selected ion flow tube technique. Computational studies allow characterization of the structures of reactants and products, as well as the energetics along the reaction pathway. For anions containing one or two nitrogen atoms, reactions with hydrogen atoms are facile, and proceed primarily by associative detachment. In contrast, anions containing three nitrogen atoms are unreactive with hydrogen atoms due to reaction barriers and unfavorable thermodynamics.

We have performed an initial assessment of the feasibility of producing heavy negative ion beams as drivers for an inertial confinement fusion reactor. Negative ion beams offer the potentially important advantages relative to positive ions that they will not draw electrons from surfaces and the target chamber plasma during acceleration, compression, and focusing, and they will not have a low energy tail. Intense negative ion beams could also be efficiently converted to atomically neutral beams by photodetachment prior to entering the target chamber. Depending on the target chamber pressure, this atomic beam will undergo ionization as it crosses the chamber, but at chamber pressures at least as high as 1.3 × 10−4 torr, there may still be significant improvements in the beam spot size on the target, due to the reduction in path-averaged self-field perveance. The halogens, with their large electron affinities, are the best negative ion candidates. Fluorine and chlorine are the easiest halogens to use for near-term source experiments, whereas bromine and iodine best meet present expectations of driver mass. With regard to ion sources and photodetachment neutralizers, this approach should be feasible with existing technology. Except for the target chamber, the vacuum requirements for accelerating and transporting high energy negative ions are essentially the same as for positive ions.