Title :
Scandate dispenser cathode for 220 GHz 50 W sheet beam travelling wave tube amplifier
Author :
Zhao, Jinfeng ; Li, Na ; Li, Ji ; Barnett, Larry ; Banducci, Mike ; Gamzina, Diana ; Luhmann, N.C., Jr.
Author_Institution :
Dept. of Appl. Sci., Univ. of California-Davis (UCD), Davis, CA, USA
Abstract :
Sc2O3-doped W powder for use in high current density thermionic cathodes has been made by the sol-gel method with different particle sizes. Sc2O3-W matrix cathodes have been prepared from these powders, and have shown excellent emission properties. A space charge limited current density of 40 A/cm2 at 850°C, and 170 A/cm2 at 1050°C have been obtained by using 300-500 nm Sc2O3-doped (5.0 wt.%) W powders. Life testing is ongoing with a continuously pulsed loading of 50 A/cm2 at 1050°C after >; 104 hours. The machined cathode made from 1-2 micron size Sc2O3-doped W powder can reach 160 A/cm2 at 1050°C during pulsed operation. The CW cathode testing is being developed for practical application.
Keywords :
current density; life testing; materials testing; millimetre wave amplifiers; powders; scandium compounds; sol-gel processing; thermionic cathodes; travelling wave amplifiers; tungsten; CW cathode testing; W:Sc2O3; frequency 220 GHz; high current density thermionic cathodes; life testing; matrix cathodes; powder; power 50 W; scandate dispenser cathode; sheet beam travelling wave tube amplifier; size 300 mm to 500 mm; sol-gel method; space charge limited current density; temperature 1050 degC; Cathodes; Current density; Powders; Scanning electron microscopy; Surface treatment; Testing; Tungsten; Sc2O3-doped W; high current density;
Conference_Titel :
Vacuum Electronics Conference (IVEC), 2011 IEEE International
Conference_Location :
Bangalore
Print_ISBN :
978-1-4244-8662-5
DOI :
10.1109/IVEC.2011.5746865
