Collectors made by evaporating Mo onto Nb substrates in a low partial pressure of oxygen were studied in a demountable, fixed-spacing, planar thermionic converter featuring a common polycrystalline W emitter and an oxygen detector, which can be used to measure the effective oxygen pressure. Two collectors with oxygen contents of 2100 and 550 ppm were investigated. At spacings of 0.5 to 0.55 mm, their performances were similar with emitter bare work functions of 5.55 and 5.45 eV respectively. These values suggest that the effective oxygen pressure in the gap was around 4×10 −5 Pa , while the oxygen detector indicated much lower values. Maximum electrode output power densities and calculated maximum electrode efficiencies at an emitter temperature of 1800 K were 9 W/cm2 and 17%.


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    Title :

    Evaluation of oxygen-dispensing collectors for thermionics


    Contributors:

    Conference:

    Space technology and applications international forum -1999 ; 1999 ; Albuquerque, New Mexico (USA)


    Published in:

    AIP Conference Proceedings ; 458 , 1 ; 1452-1457


    Publication date :

    1999-01-22


    Size :

    6 pages





    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English



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