The purpose of the work described is to investigate the formation and characteristics of 'tungstate' mixed crystal cathodes. The objective is the realization of a lower work function in a relatively rugged cathode. Richardson plots and retarding field electron beam techniques were used to evaluate the work function of sample cathodes. The final set of experiments, done in individual tubes, utilized the zero field value of current for the Richardson data where possible. The zero field values were taken from Schottky plots of the I-V data. All cathodes have been made by spraying the mixed materials onto the metallic substrate. Tantalum was abandoned as a substrate due to adherence problems. Tungsten substrates have been used for high temperature processing. P-50 nickel alloy substrates were used to eliminate adherence problems and reduce activation variables to a minimum. (Author)
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