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A New Thermionic Cathode Based on Carbon Nanotubes with a Thin Layer of Low Work Function Barium Strontium Oxide Surface Coating

Published online by Cambridge University Press:  01 February 2011

Feng Jin ,
Yan Liu ,
Scott A Little  and
Chris M Day
Feng Jin
Affiliation:
fjin@bsu.edu, Ball State University, Phsyics and Astronomy, Muncie, Indiana, United States
Yan Liu
Affiliation:
yliu@bsu.edu, Ball State University, Phsyics and Astronomy, Munice, Indiana, United States
Scott A Little
Affiliation:
salittle@bsu.edu, Ball State University, Phsyics and Astronomy, Muncie, Indiana, United States
Chris M Day
Affiliation:
cmday@bsu.edu, Ball State University, Phsyics and Astronomy, Muncie, Indiana, United States
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Abstract

We have created a thermionic cathode structure that consists of a thin tungsten ribbon; carbon nanotubes (CNTs) on the ribbon surface; and a thin layer of low work function barium strontium oxide coating on the CNTs. This oxide coated CNT cathode was designed to combine the benefits from the high field enhancement factor from CNTs and the low work function from the emissive oxide coating. The field emission and thermionic emission properties of the cathode have been characterized. A field enhancement factor of 266 and a work function of 1.9 eV were obtained. At 1221 K, a thermionic emission current density of 1.22A/cm2 in an electric field of 1.1 V/μm was obtained, which is four orders of magnitude greater than the emission current density from the uncoated CNT cathode at the same temperature. The high emission current density at such a modest temperature is among the best ever reported for an oxide cathode.

Keywords

chemical vapor deposition (CVD) (deposition)coatingthin film
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1142: Symposium JJ – Nanotubes, Nanowires, Nanobelts and Nanocoils–Promise, Expectations and Status , 2008 , 1142-JJ15-41
Copyright
Copyright © Materials Research Society 2009

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References

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