Gas release from a compact powdery sample ion source

摘要

The species and the quantities of gases released during the operation of a compact powdery sample ion source were investigated. During the initial heating of the filament, H/sub 2/O was emitted from the powder and its partial pressure occupied more than 90% of the total pressure. Neither LiH nor LiN/sub 3/, emitted detectable amount of Li. Atomic and molecular nitrogens were found emitted during the operation with LiN/sub 3/, and the rate of N/sub 2/ emission due to electron stimulated decomposition was compared with the extracted ion beam. Gas efficiencies for positive and negative ions were estimated to be the order of 10/sup -4/ and 10/sup -3/, respectively. The gas release rate from the ion source can be reduced below 2/spl times/10/sup -6/ Pa-m/sup 3//s for 1 mA of electron current by heating the powder prior to the source operation.