Photodetachment of Negative Ion Beams in the Presence of a Background Gas

To suppress space charge blowup in an ion beam passing through a photoneutralizer, it is necessary to introduce some background gas. An analysis is presented of the neutralization of a high-energy, >200-keV negative deuterium ion beam, exposed to photodetachment while in the presence of deuterium. With a gas thickness of <0.01 Torr-cm, the neutral fraction in the output beam is found to be about the same as that gotten from the photoneutralizer operating in vacuum.