TIP-SHAPE INVESTIGATION OF A AU-SI ALLOY LIQUID-METAL ION-SOURCE USING A HIGH-VOLTAGE TRANSMISSION ELECTRON-MICROSCOPE

The tip shape of a Au-Si liquid-metal ion source in terms of its dependence on the total ion emission current has been investigated in situ in the Halle 1 MeV electron microscope. Within the emission current range 7-90 mu A there is a linear dependence of the cone half-angle alpha and the length I of the jet-like protrusion on the increased emission current. The jet-like protrusion at the Taylor cone vertex was not so pronounced as has been observed in the cases of elementary liquid-metal ion sources. No spatial shifts of the Taylor cone are seen during the experiments. In contrast to elementary liquid-metal ion sources, there is no indication of 'Faraday droplets' being emitted from the surroundings of the Taylor cone.