Thermionic converters for terrestrial applications
Abstract
Performance data and post-test results of thermionic diodes subjected to long term high temperature tests are reported. A one inch diameter hemispheric converter with a CVD tungsten layer protected by a CVD SiC layer was subjected to 12,500 hr at 1730 K. The collector is Ni cooled with air, and a barrier index of 2.25 eV has been recorded at 1700 K, corresponding to an output of 2 W/sq cm at 0.25 V. No long-range degradation of the W-C interface was detected with scanning electron microscopy. Tests of six torispherically shaped, two inch diameter converters with air cooled collectors have been tested at temperatures from 1400-1750 K. A cesium vapor was supplied from a reservoir and MoO coatings were used on the collectors. The power densities of the two inch diodes were less than in the one inch diodes, i.e., barrier indices below 2.2 eV were recorded. Fully activating the MoO layer is expected to lower the barrier and allow greater outputs.
- Publication:
-
IECEC 1982; Proceedings of the Seventeenth Intersociety Energy Conversion Engineering Conference
- Pub Date:
- 1982
- Bibcode:
- 1982iece.conf.1913G
- Keywords:
-
- Energy Conversion Efficiency;
- High Temperature Tests;
- Performance Tests;
- Thermal Protection;
- Thermionic Converters;
- Thermionic Diodes;
- Accumulators;
- Air Cooling;
- Cesium Vapor;
- Cooling Systems;
- Long Term Effects;
- Energy Production and Conversion