Desorption from hot scandate cathodes: Effects on vacuum device interior surfaces after long-term operation

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2 Scopus citations

Abstract

Scandate cathodes have exhibited superior emission properties compared to current state-of-the-art “M-type” thermionic cathodes. However, their integration into vacuum devices is limited in part by a lack of knowledge regarding their functional lifespan and behavior during operation. Here, we consider thermal desorption from scandate cathodes by examining the distribution of material deposited on interior surfaces of a sealed vacuum device after ~26,000 h of cathode operation. XPS, EDS, and TEM analyses indicate that on the order of 1 wt.% of the initial impregnate is desorbed during a cathode’s lifetime, Ca does not desorb uniformly with time, and little to no Sc desorbs from the cathode surfaces (or does so at an undetectable rate). Findings from this first-ever study of a scandate cathode after extremely long-time operation yield insight into the utility of scandate cathodes as components in vacuum devices and suggest possible effects on device performance due to deposition of desorption products on interior device surfaces.

Original languageEnglish
Article number5149
Pages (from-to)1-21
Number of pages21
JournalMaterials
Volume13
Issue number22
DOIs
StatePublished - Nov 2 2020

Bibliographical note

Funding Information:
This work was financially supported by the Defense Advanced Research Projects Agency (DARPA) Innovative Vacuum Electronics Science and Technology (INVEST) program, under grant number N66001-16-1-4041. The views, opinions, and/or findings expressed are those of the author(s) and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government. The authors would like to express gratitude to Bernard Vancil of eBeam, Inc. for providing the cathode test vehicle and insight regarding the fabrication/testing process. The authors also appreciate the expertise/assistance provided by the Electron Microscopy Center at the University of Kentucky.

Funding Information:
Funding: This work was financially supported by the Defense Advanced Research Projects Agency (DARPA) Innovative Vacuum Electronics Science and Technology (INVEST) program, under grant number N66001-16-1-4041. The views, opinions, and/or findings expressed are those of the author(s) and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government.

Publisher Copyright:
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

  • Desorption
  • Electron devices
  • Scandate cathodes
  • Vacuum electronics

ASJC Scopus subject areas

  • Materials Science (all)
  • Condensed Matter Physics

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