The research involved in generating submicron-size positively charged liquid droplets is described. The droplets formed may be either liquid metal, or organic fluids. An analysis is developed to indicate the relationship between particle size and the parameters of field emission and surface tension. Charge/mass ratios were obtained using either a single particle detector or one of two quadruple focusing mass spectrometers. Charge/ mass distributions are shown for both metals and organic fluids. Although ions were often found, particularly with the metal fluids, narrow peak distributions of charge/mass could be obtained with no appreciable number of ions when using the organic liquids. Photomicrographs of the operating point source and discrete jet spray patterns are illustrated. The effect upon the charge/mass peak to the mass flow rate and the potential of the point emitter is demonstrated. The efficiency of an ion engine as a function of charge/mass distribution about a peak has been evaluated for several typical curves. An analy¬sis involving space charge limitations and the mechanism of droplet formation is discussed.
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