GB1158915A - Thermionic converter. - Google Patents

Abstract

1,158,915. Thermionic generators. EUROPEAN ATOMIC ENERGY COMMUNITY (EURATOM). 5 Aug., 1966 [20 Sept., 1965], No. 35190/66. Heading H1D. In a thermionic converter comprising an emitter 3 and a collector 5, a thermally and electrically insulating shield is disposed within a chamber of the converter between a portion of the emitter electrode remote from the emissive surface and a portion of the collector electrode, the shield serves to prevent a shortcircuit between the electrodes in this region and may also provide a heat shield for the insulator which spaces the emitter and collector electrodes. As shown, cylindrical tantalum emitter 3 with emissive layer 4 of tungsten is closed at its top end by a plug 11 and is connected at its lower end to a tantalum heat pipe 1 which has a series of rectangular longitudinal capillaries on its inside walls, the heat carrier being lead. Cylindrical collector 5, of Nb-1 Zr alloy, coaxially surrounds the emitter and is secured to heat pipe 2 of similar material. Heat pipe inner surface and collector outer surface have many capillaries and the heat carrier is caesium. Cover 16 seals the top of the collector and pipe 17 connects the interelectrode chamber to a caesium supply. The collector and heat pipe 2 are welded to base 14 which via sleeve 21 and flange 22 supports positive terminal 23. The negative terminal 20 is supported on flange 19 which also supports sleeve 25 to which ceramic alumina ring 24 is secured to close the interelectrode chamber. The thermally and electrically insulating shield in the form of a sleeve 27 of Al 2 O 3 is disposed between sleeves 25, 21. A further insulating heat shield 28 is disposed between, the emitter plug 11 and collector cover 16 and also serves as a centring member for the top of the emitter. In a further embodiment, Fig. 2, (not shown), the electrodes are parallel and planar and the desired interelectrode spacing is obtained by an annular niobium foil (46) of thickness equal to the electrode separation inserted in the main structural joint between halves of the converter, and the ceramic heat shield (45) in this embodiment is similarly placed to shield 27 in the Fig. 3, embodiment.