%A"Devin, B" %A"Phuc Nguyen, Xuan [Commissariat a l'Energie Atomique, Saclay (France). Centre d'Etudes Nucleaires]" %D1964 %I; CEA Saclay, 91 - Gif-sur-Yvette (France) %2 %J[] %K36 MATERIALS SCIENCE, CESIUM, CURRENT DENSITY, DISTRIBUTION, ELECTRIC CURRENTS, GRAIN SIZE, POLYCRYSTALS, REFRACTORY METALS, SCHOTTKY EFFECT, THERMIONIC CONVERSION, THERMIONIC DIODES %PMedium: ED; Size: 49 pages %TThe effects of spots (or grains) and the mean work function of a polycrystalline emitter; Les effets des taches (ou grains) et le travail de sortie moyen d'un emetteur polycristallin %XThe direct conversion of thermal energy at high temperature to electrical energy using plasma diodes is studied in the Electronic Physics Service of the French Atomic Energy Commission. Research concerns the adaptation of these diodes to nuclear reactors with a view especially to providing power for operating the instruments of space vehicles. In parallel with the semi-industrial realizations and tests, an important part of the activity of the service is directed towards fundamental research into physical phenomena convected with thermionic emission with a view to improving present performances. (authors) [French] La conversion directe de l'energie thermique a haute temperature en energie electrique par diodes a plasma est etudiee au Service d'Electronique Physique du Commissariat a l'Energie Atomique. On etudie l'adaptation de ces diodes aux reacteurs nucleaires, notamment en vue de fournir l'energie de servitude dans les vehicules spatiaux. Parallelement aux realisations et essais semi-industriels, une part importante de l'activite du Service est orientee vers l'etude fondamentale des phenomenes physiques lies a la conversion thermoionique dans le but d'ameliorer les performances actuelles. (auteurs) %0Technical Report %NCEA-R-2519;TRN: FR06R2519095228 %1 %CFrance %Rhttps://doi.org/ TRN: FR06R2519095228 FRN %GFrench