ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The production process for the formation of H− ions in a surface conversion source is sputtering of hydrogen atoms from the converter surface layers by incident positive ions, followed by electron attachment via resonant charge exchange with the converter surface. The sputtering process is in direct relation to the converter surface composition. New experimental data led us to identify two different classes of converters: metallic converters, like solid barium(binary) and adlayer converters, like cesium on tungsten (ternary). For a binary converter the hydrogen in the surface layers is directly sputtered by the incoming ions. Consequently, the negative ion yield scales with the hydrogen concentration in the surface layers. In the cesium/tungsten system (ternary) the hydrogen at the surface is believed to be sandwiched between the cesium adlayer and the tungsten surface. Hence, the negative ion yield scales with the sputter coefficient of hydrogen on adsorbed cesium. This is experimentally confirmed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.349365
