Title :
Scandate cathode with sharp transition
Author :
Vancil, Bernard ; Schmidt, Volker ; Lorr, John ; Brodie, Ivor
Author_Institution :
E beam, Inc., Beaverton, OR, USA
Abstract :
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, show comparisons to other types of cathodes, and offer tentative explanations for the improvement. We discuss their suitability in microwave tubes at loadings of 5-10 Amps/cm2.
Keywords :
electron emission; microwave tubes; scandium; thermionic cathodes; tungsten; die-pressed matrices; emission curve; microwave tubes; scandate cathode; scandia-doped tungsten powder; sharp transition; space charge; temperature limited emission; transition temperature; Cathodes; Electron tubes; Powders; Resistance; Space charge; Tungsten; cathodes; dispenser; impregnated; scandate; thermionic;
Conference_Titel :
Vacuum Electronics Conference (IVEC), 2013 IEEE 14th International
Conference_Location :
Paris
Print_ISBN :
978-1-4673-5976-4
DOI :
10.1109/IVEC.2013.6571037
