Plasma-generator-induced effects on the dynamics of a negative-ion surface conversion source

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Abstract
The production of H− ions at a barium, magnesium, strontium, molybdenum, and lanthanum-hexaboride converter immersed in a hydrogen plasma have been investigated for pulsed and dc discharges. The scaling of the negative-ion output with incident positive-ion current on the converter depends greatly on the actual geometry and type of plasma generator. A less than linear scaling is observed in a multicusp system using filaments or rf to generate the discharge. A more than linear scaling is obtained in a configuration where the filament and the converter are separated by a permanent-magnet filter. For a rf plasma generator, there is a pronounced optimum in the relative position of antenna and converter.