High Current Density and Long-Life Nanocomposite Scandate Dispenser Cathode Fabrication

Author

Zhao, Jinfeng ; Li, Na ; Li, Ji ; Barnett, Larry R. ; Banducci, Mike ; Gamzina, Diana ; Munir, Zuhair A. ; Luhmann, Neville C.

Author_Institution

Dept. of Appl. Sci., Univ. of California, Davis, CA, USA

Volume

58

Issue

4

fYear

2011

fDate

4/1/2011 12:00:00 AM

Firstpage

1221

Lastpage

1228

Abstract

A nano-Sc₂O₃-added W powder for use in high current density thermionic cathodes has been made using a solution-gel method with the following controllable uniform average particle sizes: ~72, 146, 272, and 587 nm. Using these powders, nanostructured Sc₂O₃ -added tungsten matrices with uniform nanosized tungsten grains and homogenous pore distribution were obtained. Nanocomposite Sc₂O₃-added W impregnated cathodes have been prepared from these powders and have shown excellent emission properties. For example, space-charge-limited current densities of 40 ± 1 A · cm^-2 at 850°C and 170 ± 5 A · cm^-2 at 1050°C have been obtained using a 300-nm Sc₂O₃-added (4.77 wt.%) W powder. Life testing is ongoing with 50 ± 2.5 A · cm^-2 current density emission demonstrated at 1050°C after 10 680 h.

Keywords

cathodes; current density; nanocomposites; nanofabrication; nanoparticles; particle reinforced composites; porosity; porous materials; powders; scandium compounds; sol-gel processing; tungsten; Sc₂O₃-W; current density; emission properties; homogenous pore distribution; impregnated cathodes; life testing; long-life nanocomposite; nanosized tungsten grains; powder; scandate dispenser cathode fabrication; size 300 nm; solution-gel method; space-charge-limited current densities; temperature 1050 degC; temperature 850 degC; thermionic cathodes; time 10680 h; tungsten matrices; Cathodes; Current density; Grain size; Heating; Powders; Testing; Tungsten; $hbox{Sc}_{2}hbox{O}_{3}$-added W; Current density; nanosize;

fLanguage

English

Journal_Title

Electron Devices, IEEE Transactions on

Publisher

ieee

ISSN

0018-9383

Type

jour

DOI

10.1109/TED.2011.2109723

Filename

5729802