LOW-VOLTAGE DISCHARGE IN CESIUM-HYDROGEN MIXTURE AS A SOURCE OF NEGATIVE HYDROGEN-IONS

It is shown theoretically that low-voltage Cs-H-2 discharge may be uti lized as a volume-plasma negative hydrogen ion source with very high H - concentration (N(H-) greater than or similar to 10(13) cm-3 in plasm a. The volume H- generation occurs because of dissociation attachment of heated thermal electrons to vibrationally excited H-2 molecules. Th e high rate of H- generation is explained by high electron concentrati on (n(e) approximately 10(14) cm-3), high hydrogen pressure (p(H-2) gr eater than or similar to 1 torr) and optimum value of thermal electron temperature (T(e) greater than or similar to 1 eV) in plasma. It caus es rapid pumping of vibrationally excited H-2 levels and high rate of dissociative attachment. Electron vibration kinetics in the discharge is considered and H- concentration is calculated. The optimum discharg e parameters for H- generation are determined. Experimental investigat ion of the discharge is performed. It is shown that theoretical and ex perimental plasma parameters are very close to one another.