Gas release from a compact powdery sample ion source

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, H₂O was emitted from the powder and its partial pressure occupied more than 90% of the total pressure. Neither LiH nor LiN₃, emitted detectable amount of Li. Atomic and molecular nitrogens were found emitted during the operation with LiN₃, and the rate of N₂ 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^-4 and 10^-3, respectively. The gas release rate from the ion source can be reduced below 2×10^-6 Pa-m³/s for 1 mA of electron current by heating the powder prior to the source operation