Negative hydrogen ion sources

A description is presented of the development of H- and D- sources for neutral beam heating on the next generation reactors. The volume production type of the ion source is discussed, where negative ions are formed in the plasma by dissociative attachment. From the view point of controlling source plasmas, principal mechanism of H- production, some techniques for enhancement of H- production, and extraction of H- ions are mainly discussed. Finally, a short discussion is presented of the future development of these sources. (author)