Annual summary report on thermionic-cathode project. Progress report No. 3, 1 September 1984-31 August 1985
A planar-cathode, Pierce-type electron gun with a design perveance of .0000032 (Amps/volts to the 3/2 power) was operated with a lanthanum hexaboride (LaB/sub 6/) cathode. The cathode (useful diameter 1.9 cm) is heated by bombardment by electrons from a small tungsten filament. The bombardment heating system is stabilized by a feedback control circuit. The power required to heat the cathode is 315 W bombardment power and 200 W filament power. Heating power was reduced by careful heat shielding and reduction of heat-conduction losses. Significant additional reductions should be possible. The sintered LaB/sub 6/ cathode disk is 2.5 cm in diameter, 3.2 mm thick, and has a density of 94%. No problems have been encountered with cracking of the disk. Cathode emission is insensitive to repeated exposure to air after allowing the cathode to fully cool. The measured perveance and anode transmission of the gun are 3.2x10/sup -6/ and 94%, respectively. Current densities up to 6.5 A/sq cm have been reached with 5-micrometer pulses. Measurements were made at cathode temperatures of 1300 to 1600 C.
- Research Organization:
- Michigan Univ., Ann Arbor (USA). Dept. of Electrical Engineering and Computer Science
- OSTI ID:
- 5288424
- Report Number(s):
- AD-A-168569/2/XAB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
300403* -- Thermionic Converters-- Materials
Components
& Auxiliaries
AIR
ANODES
BORIDES
BORON COMPOUNDS
CATHODES
CONTROL
CRACKS
DIRECT ENERGY CONVERTERS
ELECTRODES
ELECTRON GUNS
ELEMENTS
EMISSION
FEEDBACK
FILAMENTS
FLUIDS
GASES
HEATING
LANTHANUM BORIDES
LANTHANUM COMPOUNDS
METALS
NESDPS Office of Nuclear Energy Space and Defense Power Systems
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
THERMAL CONDUCTIVITY
THERMIONIC CONVERTERS
THERMIONIC EMISSION
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
TUNGSTEN