Six-converter solar thermionic generator. Final report 10 Jan 1967-31 Mar 1968

This report covers the work accomplished during a 15-month period originated on January 10, 1967 under JPL Contract No. 9 5177 0/NAS7 -10 0.During the reporting period a six -converter solar thermionic generator (JG-4) was designed, fabricated and subjected to preliminary evaluation, including performance tests of each converter prior to its mounting on the generator.Six additional thermionic converters similar to those used in the generator were fabricated and individually tested.With the ex, option of one, each of the twelve converters tested produced more than 36 watts of output power at 0. 7 volt output voltage, and at 2000°K emitter temperature.The average power output per converter was 37. 5 watts.All converters have identical overall configuration, employing planar electrode geometry with a rhenium emitter (of about 2 cm area), and a molybdenum collector separated by about 0. 005 cm (2 mils) during operation.Critical parts of each converter and of the generator in general were subjected to detailed design analysis and performance evaluation.A thorough investigation was performed to determine the heat flux distribution and temperature profiles, the heat transfer mechanisms, and the heat dissipation requirements in the generator, iv