THE EFFECT OF EMITTER WORK-FUNCTION PATCHES ON THE PERFORMANCE OF CESIUM THERMIONIC CONVERTERS

Technical Report · Wed May 01 04:00:00 EDT 1963

OSTI ID:4690007

Gadzuk, J W

An experimental program to obtain the current-voltage characteristics of a metal cesium thermionic converter with a monocrystal molybdenum emitter showing the (110) crystallographic face to cesium vapor is described and the results are presented. It is shown that the continuous linear increase in output current with decreasing output voltage or, in other words, the fact that the emission current does not show a sharp saturation value, may be due to patches of different work function on the emitter surface. It is shown that an exponential Boltzmann distribution might be expected to describe the variation in work function over the emitter surface. Also, this Boltzmann distribution may account for the shape of the current-voltage characteristics obtained from a cesium thermionic converter with a monocrystal molybdenum emitter in the region of low output voltage. From the analysis of these characteristics, the percentage area with the exponential distribution is determined. The area of the exponential patch should increase as the coverage increases. Furthermore, the experimentally determined values of the pitch area decrease linearly with increasing values of the ratio of emitter temperature to cesium reservoir temperature, from which it is concluded that these patches may be caused by thermal excitation of the adsorben layer on a nonuniform substrate. (auth)

• Research Organization: Massachusetts Inst. of Tech., Cambridge. Research Lab. of Electronics
• NSA Number: NSA-17-041539
• OSTI ID: 4690007
• Report Number(s): ASD-TDR-63-748
• Country of Publication: United States
• Language: English

Related Subjects

ADSORPTION
CESIUM
CONVERSION
CRYSTALS
CURRENTS
ELECTRIC POTENTIAL
EMISSION
EXCITATION
LAYERS
MAXWELL DISTRIBUTION
MEASURED VALUES
METALS
MOLYBDENUM
MONOCRYSTALS
NESDPS Office of Nuclear Energy Space and Defense Power Systems
PHYSICS
SURFACES
TEMPERATURE
THERMIONICS
THERMODYNAMICS
VAPORS
VARIATIONS