ENERGY DEFICIT MEASUREMENTS WITH A LIQUID GALLIUM ION-SOURCE

We report on an extensive study of energy deficit measurements of the energy distribution of the ion beam emitted by a gallium liquid metal ion source, in an attempt to resolve the controversy arising from the unusually wide divergence of findings by different workers. A detailed investigation is also made for the region of emission current below 1 mu A - a region rarely investigated by the vast majority of researchers, but a most important one from the point of view of the emission mechanism, as well as from an applications' standpoint. Finally, the reasons for the scatter observed in energy spread measurements are considered, and only a tentative explanation can be given, related to ion source misalignment; this misalignment arises from the fact that the liquid cone does not always form at the center of the apex region of the supporting needle.