INVESTIGATIONS USING SEGMENTED COLLECTOR THERMIONIC CONVERTERS.
Yearly technical summary rept. 1 Jan-15 Dec 65,
MARTIN CO MIDDLE RIVER MD NUCLEAR DIV
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A total of five different collectors were investigated as collector materials in thermionic test converters each incorporating segmented collectors for simultaneous testing within the same environment. The metals tested were niobium, oxygenated niobium, plasma-sprayed ruthenium, molybdenum and rhenium. One ruthenium collector surface was used in each diode to permit intercomparison of the two converters. Both converters used a single plasmasprayed Ru emitter which was common to the three collectors. Ruthenium, niobium and oxygenated niobium were tested in the first converter. The collector work functions varied within about 0.1 ev from one substrate material to another, with minimum values at low as 1.1 ev. It is probable that the oxygen present in the oxygenated niobium either migrated to the other collector surfaces or evaporated and was subsequently absorbed by the other surfaces. The adsorbed oxygen and cesium vapors probably formed CsO2 and Cs-vapor layers on the substrate, thus bring about the low work functions. Molybdenum, rhenium and rruthenium were tested in the second converter. This converter did not incorporate any purposely oxygenated surfaces. The work functions obtained from these metals with adsorbed cesium were higher than those under the pressure of oxygen as expected. Author
- Electric Power Production and Distribution
- Metallurgy and Metallography