Papers by Keyword: Thermionic Energy Converter

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Authors: Hong Tao Huang, Yong Feng Wei, Jian Ping Zheng, Cheng Wen Tan
Abstract: Thermionic energy conversion is a process by which thermal energy is transformed into electrical energy directly without the intermediate steps. Microstructure of Chemical Vapor Transport Deposited (CVTD) single crystal tungsten coating working at 1600°C for 1000 h was investigated using optical microscopy and electron backscatter diffraction (EBSD) technique. The experimental results showed that the etching morphology of single crystal tungsten coating was not clear compared to the etching morphology before working. The electro-etched surface of single crystal tungsten coating mainly consist of {110} crystal planes and {112} crystal planes before working at 1600°C. The surface of the single crystal tungsten coating mainly consists of near {110} crystal planes and near {112} crystal planes instead after working at 1600°C.
Authors: Wei Jun Wang, Bo Chen, Jian Ping Zheng, Hua Zhen Lei, Li Jun Qi, Jun Zhao
Abstract: It has long been recognized that a need for practical methods for maintaining optimum cesium pressure within a thermionic energy converter has been pursued for space applications. An attractive solution to the problem is the use of a sorption type reservoir where cesium absorbed into a lattice. Four graphite materials were initially investigated for the potential usage as cesium storage media. Primary research focusing on the characteristics of loading ability, structural integrity, and dimensional change of these materials was performed by synthesizing proper cesium-graphite lamellar compounds with a two zone vapor transport method. Graphite foams show promising prospect for thermionic application as integral cesium reservoir material.
Authors: Nashun, Shinya Kawata, Kentaro Iwami, Norihiro Umeda
Abstract: The material properties of electroplated NiW alloys with potential for use as emitters in thermionic energy converters were investigated. NiW alloy films with W content ranging from 11 to 25 at% were electroplated and the material properties of the alloy films including their surface morphologies, and crystallinities, were determined. The work functions of the NiW films were also evaluated using photoemission yield spectroscopy and were found to be independent of the W content. In addition, heat treatment up to 700°C in a vacuum chamber of a NiW film with 21.4 at% W content decreased the electron yield with increasing its work function.
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