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Impregnated thermionic cathodes production was the main objective of this work. The W-30wt.%Cu composite was sintered by induction heating (1200°C). The porous matrix was obtained after decopperization (1600°C). High purity Ba-Ca aluminate was impregnated (1630°C). The amount of aluminate impregnated was 18.32wt.%. Microstructure, porosity, and particle sizes distribution were determined.
In recent years an exciting progress has been made in developing scandate cathodes that have excellent emission properties at a lower operating temperature comparing to the traditional sintered tungsten dispenser cathodes, and consequently a significantly longer life. The initial results look very promising for the development of millimeter wave and THz sources. In order to compare performance of...
Method of obtaining sintered and pressed composed materials based on BaxSr1−xHfO3, where x = 0.25, 0.50, 0.75, with 16, 20, 24, 60 % W (by mass), and experimental results of thermionic properties investigations of these materials are represented. The composition of 80% Ba0.75Sr0.25HfO3 — 20% W (by mass) is characterized by the thermionic current density of 1014 A/cm2 at T = 1620 K.
Over the years, issues with the supply of Beryllium, Beryllium Oxide, Thoriated-Tungsten wire, Rare-earth metals for magnets (Samarium-Cobalt), Tungsten, and recently Tungsten-Rhenium wire have put the supply of Microwave Tubes at risk. These Diminishing Manufacturing Source and Material Source (DMSMS) issues continue to be addressed by the Microwave Tube industry and with the help of US government...
We report on a new cathode which is based on die-pressed matrices made from scandia-doped tungsten powder. Transition temperatures from space charge to temperature limited emission are as low as 840° Cb(W) for emission of 5 Amps/cm2. Transitions are sharper than previously published scandate cathodes and compare favorably with M and ternary alloy cathodes. We present emission curves on several cathodes,...
Sc2O3 doped W nano-powder is believed to play a dominant role for improving emission capabilities of the high current density thermionic cathodes. In this study a novel nano-particle synthesis approach was adopted in order to precisely control the particle parameters. The particle characteristics and sintering behavior has been analyzed using SEM, TEM, EDS, XRD and XPS. Uniform grain size with average...
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