Formation of hydrogen negative ions by surface and volume processes with application to negative ion sources

Abstract

Three methods for the formation of negative ions are reviewed : double charge-exchange, whereby low-energy positive ions are converted to negative ions by two sequential electron captures in a vapor target ; electron-volume-processes wherein low-energy electrons lead to negative-ion formation by dissociative attachment or dissociative recombination by collisions with hydrogen molecules or hydrogen molecular ions and, surface processes leading to negative ions by backscattering or desorption induced by energetic particle bombardment. The application of these method to the development of hydrogen-negative-ion sources is discussed