Another look at photodetachment of negative deuterium ions in neutral beam injectors

Photodetachment is more desirable than other types of neutralizers of negative deuterium ions because it is cleaner, produces no gas or vapor, selectively detaches D(-) and not heavy impurities, and may be more efficient. However, good overall efficiency in comparison with the alternatives is attainable only under the appropriate conditions of ion beam current density and thickness and with sufficient efficiencies of the laser and of the mirrors of the optical cavity. Analysis of these conditions indicate that the overall efficiency of an 11 A beam of 200 keV neutral D using photodetachment is competitive with that for a beam neutralized in a gas cell, using the expected values of laser and mirror efficiencies.