Cesium-iodide (CsI)-coated graphite cathodes are promising electron sources for high power microwave generators, but the mechanism driving the improved emission is not well understood. Therefore, an ab initio modeling investigation on the effects of thin CsI coatings on graphite has been carried out. It is demonstrated that the CsI coatings reduce the work function of the system significantly through a mechanism of induced dipoles. The results suggest that work function modification is a major contribution to the improved emission seen when CsI coatings are applied to C.

Topics
Crystal structure, Surface collisions, Thermionic emission, Work functions, Electromagnetism, Electrostatics, Composite materials, Carbon based materials, Electron sources, Chemical elements
1.
D. R.
 
Whaley
,
B. M.
 
Gannon
,
C. R.
 
Smith
,
C. M.
 
Armstrong
, and
C. A.
 
Spindt
,
IEEE Trans. Plasma Sci.
https://doi.org/10.1109/27.887712
 
28
,
727
(
2000
).
Google Scholar
Crossref
Search ADS
 
2.
Modern Microwave and Millimeter-Wave Power Electronics
edited by
R. J.
 
Barker
,
J. H.
 
Booske
,
N. C.
 
Luhmann
, and
G. S.
 
Nusinovich
 (
IEEE
,
New York
/
Wiley-Interscience
,
New York
,
2005
).
Google Scholar
Crossref
Search ADS
 
3.
D. A.
 
Shiffler
,
M. J.
 
LaCour
,
M. D.
 
Sena
,
M. D.
 
Mitchell
,
M. D.
 
Haworth
,
K. J.
 
Hendricks
, and
T. A.
 
Spencer
,
IEEE Trans. Plasma Sci.
https://doi.org/10.1109/27.887662
 
28
,
517
(
2000
).
Google Scholar
Crossref
Search ADS
 
4.
D.
 
Shiffler
,
M.
 
LaCour
,
K.
 
Golby
,
M.
 
Sena
,
M.
 
Mitchell
,
M.
 
Haworth
,
K.
 
Hendricks
, and
T.
 
Spencer
,
IEEE Trans. Plasma Sci.
https://doi.org/10.1109/27.928942
 
29
,
445
(
2001
).
Google Scholar
Crossref
Search ADS
 
5.
D.
 
Shiffler
,
M.
 
Ruebush
,
M.
 
Haworth
,
R.
 
Umstattd
,
M.
 
LaCour
,
K.
 
Golby
,
D.
 
Zagar
, and
T.
 
Knowles
,
Rev. Sci. Instrum.
https://doi.org/10.1063/1.1516853
 
73
,
4358
(
2002
).
Google Scholar
Crossref
Search ADS
 
6.
D.
 
Shiffler
,
J.
 
Heggemeier
,
M.
 
LaCour
,
K.
 
Golby
, and
M.
 
Ruebush
,
Phys. Plasmas
https://doi.org/10.1063/1.1666571
 
11
,
1680
(
2004
).
Google Scholar
Crossref
Search ADS
 
7.
P.
 
Hohenberg
 and
W.
 
Kohn
,
Phys. Rev.
https://doi.org/10.1103/PhysRev.136.B864
 
136
,
B864
(
1964
).
Google Scholar
Crossref
Search ADS
 
8.
D. M.
 
Ceperley
 and
B. J.
 
Alder
,
Phys. Rev. Lett.
https://doi.org/10.1103/PhysRevLett.45.566
 
45
,
566
(
1980
).
Google Scholar
Crossref
Search ADS
 
9.
G.
 
Kresse
 and
D.
 
Joubert
,
Phys. Rev. B
https://doi.org/10.1103/PhysRevB.59.1758
 
59
,
1758
(
1993
).
Google Scholar
Crossref
Search ADS
 
10.
G.
 
Kresse
 and
J.
 
Furthmuller
,
Comput. Mater. Sci.
https://doi.org/10.1016/0927-0256(96)00008-0
 
6
,
15
(
1996
).
Google Scholar
Crossref
Search ADS
 
11.
I.
 
Langmuir
,
J. Am. Chem. Soc.
https://doi.org/10.1021/ja01346a022
 
54
,
2798
(
1932
).
Google Scholar
Crossref
Search ADS
 
12.
G. L.
 
Gaines
,
Insoluble Monolayers at Liquid-Gas Interfaces
(
Interscience
,
New York
,
1966
).
Google Scholar
 
13.
W.
 
Muller
,
Tech. Dig. - Int. Electron Devices Meet.
 
1991
,
399
.
14.
E. L.
 
Murphy
 and
R. H.
 
Good
,
Phys. Rev.
https://doi.org/10.1103/PhysRev.102.1464
 
102
,
1464
(
1956
).
Google Scholar
Crossref
Search ADS
 
© 2007 American Institute of Physics.
2007
American Institute of Physics
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