Preliminary investigations of thermionic converters utilizing HOTEMA and DFVLR electrodes
Experiment results obtained from three thermionic converters using improved electrodes are reported. Two converters with ZrO/sub 2/-Mo cermet electrodes produced by a low pressure plasma spray technique at the DFVLR in Stuttgart were fabricated and tested. The first of this pair of diodes was outgassed and operated at high temperatures and did not show improved thermionic performance. The second of the two was outgassed and operated at more moderate temperatures. An encouraging barrier index of 2.00 eV at T/sub E/ = 1400/sup 0/K was recorded. Additionally, pre- and postoperational diagnostics confirmed that elemental concentrations on the emitter were nearly equal before and after operation. However, these electrodes did not give stable performance at emitter temperatures corresponding to practical ouput power densities. The Mo-Al/sub 2/O/sub 3/, Cr/sub 2/O/sub 3/ eutectic emitter developed by HOTEMA in the Netherlands exhibited stable performance at emitter temperatures up to 1650/sup 0/K. The barrier index at T/sub E/ = 1400/sup 0/K was 2.04 eV. The minimum collector work function as measured by the retarding plot method was 1.53 eV. This low work function may be related to the presence of oxygen (which was verified by postoperational diagnostics) on both the emitter and collector. These results suggest that an emitter of this type has the potential of providing significantly improved thermionic converter performance, and should be investigated further.
- Research Organization:
- Thermo Electron Corp., Waltham, MA (USA)
- DOE Contract Number:
- AC02-76ET11292
- OSTI ID:
- 6665608
- Report Number(s):
- TE-4258-442-82; ON: DE83004107
- Country of Publication:
- United States
- Language:
- English
Similar Records
DOE/JPL Advanced Thermionic Technology Program. Progress report No. 45, October-November-December 1980
DOE/JPL Advanced Thermionic Technology Program. Progress report No. 44, July-August-September 1980
Related Subjects
THERMIONIC CONVERTERS
THERMIONIC EMITTERS
FABRICATION
PERFORMANCE TESTING
ALUMINIUM OXIDES
CERMETS
CHROMIUM OXIDES
CURRENT DENSITY
ELECTRIC POTENTIAL
EXPERIMENTAL DATA
MOLYBDENUM
ZIRCONIUM OXIDES
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHROMIUM COMPOUNDS
COMPOSITE MATERIALS
DATA
DIRECT ENERGY CONVERTERS
ELEMENTS
INFORMATION
MATERIALS
METALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
TESTING
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
ZIRCONIUM COMPOUNDS
NESDPS Office of Nuclear Energy Space and Defense Power Systems
300400* - Thermionic Converters