CONICAL EQUIPOTENTIAL SUBSTRATE FOR LIQUID METAL SOURCES

Abstract- Morphological changes that occur at an ion bombarded surface as a result of erosion by sputtering can be utilized for the machining of cylindrical ly symmetric submicron structures. Such structuring has produced tungsten field emitters of conical configuration with variable cone half angle. A conical equipotential surface with an included half angle of 49.3" would be a useful emitter substrate for experiments designed to produce an equilibrium conical interface to a conducting fluid in an applied electric field. Taylor used a similar structure to support a Taylor cone so that the electric field near the cone could have the proper distribution when, and if, the fluid surface assumed a conical form. Two different techniques have been used in Liquid Metal Ion Sources (LMIS) for localizing the ion emission using the deformation of a liquid metal interface that occurs when the outward stress due to an electric field, uE=(1/8n)(E [~/cm1/300)*, on the liquid exceeds the inward stress due to th