PAC09 - List of Authors (Shaw, J.L.)

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Shaw, J.L.

Paper	Title	Page
MO6RFP082	Theory and Modeling of Electron Emission from Cesiated Semiconductor Surfaces	566
	K. L. Jensen, J.L. Shaw, J.E. Yater NRL, Washington, DC D.W. Feldman, E.J. Montgomery, P.G. O'Shea, P.Z. Pan UMD, College Park, Maryland N.A. Moody LANL, Los Alamos, New Mexico J.J. Petillo SAIC, Burlington, Massachusetts
	Funding: We gratefully acknowledge funding provided by the Joint Technology Office and the Office of Naval Research Laser switched photocathodes are now the electron source of choice for short wavelength Free Electron Lasers. The photocathode requirements are profound: ideally, capabilities such as high peak and average current, high quantum efficiency (QE) in the visible, long lifetime in an rf injector and the ability to be repaired in situ are desired. We are pursuing cathodes with self-rejuvenating surfaces based on cesium dispenser cathode technology,, in which the physics of recesiation, evaporation, diffusion, and evolution of the surface coating and the QE are the metrics of performance. Here, we present predictive theoretical models of surface evolution and QE in a manner appropriate for inclusion in beam simulation codes, wherein emission non-uniformity and dark current affect emittance, beam halo, and dynamic evolution of bunched electron beams*. The emission models focus on bulk transport issues (including scattering processes) and surface conditions (including diffusion in the presence of random, non-uniform sub-monolayer coverage), and relate these factors to recent experimental characterizations of the surface evolution. Jensen, et al., JAP{10}2, 074902 ; Moody, et al., APL90, 114108. E. Montgomery, et al., (this conference) *Petillo, et al., Proc IEEE PAC (2007); Jensen, et al., PRST-AB 11, 081001.

Paper

Title

Page

MO6RFP082

Theory and Modeling of Electron Emission from Cesiated Semiconductor Surfaces

566

K. L. Jensen, J.L. Shaw, J.E. Yater
NRL, Washington, DC
D.W. Feldman, E.J. Montgomery, P.G. O'Shea, P.Z. Pan
UMD, College Park, Maryland
N.A. Moody
LANL, Los Alamos, New Mexico
J.J. Petillo
SAIC, Burlington, Massachusetts

Funding: We gratefully acknowledge funding provided by the Joint Technology Office and the Office of Naval Research

Laser switched photocathodes are now the electron source of choice for short wavelength Free Electron Lasers. The photocathode requirements are profound: ideally, capabilities such as high peak and average current, high quantum efficiency (QE) in the visible, long lifetime in an rf injector and the ability to be repaired in situ are desired. We are pursuing cathodes with self-rejuvenating surfaces based on cesium dispenser cathode technology*,**, in which the physics of recesiation, evaporation, diffusion, and evolution of the surface coating and the QE are the metrics of performance. Here, we present predictive theoretical models of surface evolution and QE in a manner appropriate for inclusion in beam simulation codes, wherein emission non-uniformity and dark current affect emittance, beam halo, and dynamic evolution of bunched electron beams***. The emission models focus on bulk transport issues (including scattering processes) and surface conditions (including diffusion in the presence of random, non-uniform sub-monolayer coverage), and relate these factors to recent experimental characterizations of the surface evolution.

*Jensen, et al., JAP{10}2, 074902 ; Moody, et al., APL90, 114108.
**E. Montgomery, et al., (this conference)
***Petillo, et al., Proc IEEE PAC (2007); Jensen, et al., PRST-AB 11, 081001.