A research program is underway to consolidate advances made in the physics and operation of thermionic converters. A stable cesium/oxygen reservoir has been developed, and electron reflection from the collector has been investigated. It is known that addition of a small amount of oxygen to the cesium vapor in a thermionic converter makes the operation of the converter more efficient by lowering the electrode work functions. By containing the cesium/oxygen solution in a porous wick instead of a liquid reservoir, cesium/oxygen vapor with stable oxygen content can be achieved. Electron reflection from the collector has been shown to result in performance degradation in thermionic converters. The electron reflection coefficient is higher for surfaces with adsorbed cesium and oxygen layers than for bare surfaces. Increased electron reflection has prevented realization of the full benefit of the addition of oxygen to the converter. A submicron surface structure should suppress reflection from converter electrodes. Different types of surface treatments and coatings have been developed and tested. Some of these structured collectors have shown increased performance compared to a conventional polished collector. A cylindrical thermionic converter with a cesium/oxygen vapor source and electron reflection suppressing collector materials has been shown to have greater output power than a conventional thermionic converter operating at the same temperature.
Advanced Thermionic Converter Technology Development
SPACE TECHNOLOGY AND APPLICATIONS INT.FORUM-STAIF 2005: Conf.Thermophys in Micrograv;Conf Comm/Civil Next Gen.Space Transp; 22nd Symp Space Nucl.Powr Propuls.;Conf.Human/Robotic Techn.Nat'l Vision Space Expl.; 3rd Symp Space Colon.; 2nd Symp.New Frontiers ; 2005 ; Albuquerque, New Mexico (USA)
AIP Conference Proceedings ; 746 , 1 ; 918-925
06.02.2005
8 pages
Aufsatz (Konferenz)
Elektronische Ressource
Englisch
Advanced Thermionic Converter Technology Development
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