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Title: Surface Science Analysis of GaAs Photocathodes Following Sustained Electron Beam Delivery

Abstract

Degradation of the photocathode materials employed in photoinjectors represents a challenge for sustained operation of nuclear physics accelerators and high power Free Electron Lasers (FEL). Several photocathode degradation processes are suspected, including defect formation by ion back bombardment, photochemistry of surface adsorbed species and irradiation-induced surface defect formation. To better understand the mechanisms of photocathode degradation, we have conducted surface and bulk analysis studies of two GaAs photocathodes removed from the FEL photoinjector after delivering electron beam for a few years. The analysis techniques include Helium Ion Microscopy (HIM), Rutherford Backscattering Spectrometry (RBS), Atomic Force Microscopy (AFM) and Secondary Ion Mass Spectrometry (SIMS). In addition, strained super-lattice GaAs photocathode samples, removed from the CEBAF photoinjector were analyzed using Transmission Electron Microscopy (TEM) and SIMS. This analysis of photocathode degradation during nominal photoinjector operating conditions represents first steps towards developing robust new photocathode designs necessary for generating sub-micron emittance electron beams required for both fourth generation light sources and intense polarized CW electron beams for nuclear and high energy physics facilities.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1044486
Report Number(s):
PNNL-SA-82424
Journal ID: ISSN 1098-4402; 45795; 40992; 40990; TRN: US1203370
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Physical Review Special Topics - Accelerators and Beams, 15(6):063501
Additional Journal Information:
Journal Volume: 15; Journal Issue: 6; Journal ID: ISSN 1098-4402
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCELERATORS; ATOMIC FORCE MICROSCOPY; DEFECTS; ELECTRON BEAMS; FREE ELECTRON LASERS; HELIUM IONS; HIGH ENERGY PHYSICS; LIGHT SOURCES; MASS SPECTROSCOPY; MICROSCOPY; NUCLEAR PHYSICS; PHOTOCATHODES; PHOTOCHEMISTRY; RUTHERFORD BACKSCATTERING SPECTROSCOPY; TRANSMISSION ELECTRON MICROSCOPY; Environmental Molecular Sciences Laboratory

Citation Formats

Shutthanandan, V, Zhu, Zihua, Stutzman, Marcy L, Hannon, Fay, Hernandez-Garcia, Carlos, Nandasiri, Manjula I, Kuchibhatla, Satyanarayana V N T, Thevuthasan, Suntharampillai, and Hess, Wayne P. Surface Science Analysis of GaAs Photocathodes Following Sustained Electron Beam Delivery. United States: N. p., 2012. Web. doi:10.1103/PhysRevSTAB.15.063501.
Shutthanandan, V, Zhu, Zihua, Stutzman, Marcy L, Hannon, Fay, Hernandez-Garcia, Carlos, Nandasiri, Manjula I, Kuchibhatla, Satyanarayana V N T, Thevuthasan, Suntharampillai, & Hess, Wayne P. Surface Science Analysis of GaAs Photocathodes Following Sustained Electron Beam Delivery. United States. https://doi.org/10.1103/PhysRevSTAB.15.063501
Shutthanandan, V, Zhu, Zihua, Stutzman, Marcy L, Hannon, Fay, Hernandez-Garcia, Carlos, Nandasiri, Manjula I, Kuchibhatla, Satyanarayana V N T, Thevuthasan, Suntharampillai, and Hess, Wayne P. Tue . "Surface Science Analysis of GaAs Photocathodes Following Sustained Electron Beam Delivery". United States. https://doi.org/10.1103/PhysRevSTAB.15.063501.
@article{osti_1044486,
title = {Surface Science Analysis of GaAs Photocathodes Following Sustained Electron Beam Delivery},
author = {Shutthanandan, V and Zhu, Zihua and Stutzman, Marcy L and Hannon, Fay and Hernandez-Garcia, Carlos and Nandasiri, Manjula I and Kuchibhatla, Satyanarayana V N T and Thevuthasan, Suntharampillai and Hess, Wayne P},
abstractNote = {Degradation of the photocathode materials employed in photoinjectors represents a challenge for sustained operation of nuclear physics accelerators and high power Free Electron Lasers (FEL). Several photocathode degradation processes are suspected, including defect formation by ion back bombardment, photochemistry of surface adsorbed species and irradiation-induced surface defect formation. To better understand the mechanisms of photocathode degradation, we have conducted surface and bulk analysis studies of two GaAs photocathodes removed from the FEL photoinjector after delivering electron beam for a few years. The analysis techniques include Helium Ion Microscopy (HIM), Rutherford Backscattering Spectrometry (RBS), Atomic Force Microscopy (AFM) and Secondary Ion Mass Spectrometry (SIMS). In addition, strained super-lattice GaAs photocathode samples, removed from the CEBAF photoinjector were analyzed using Transmission Electron Microscopy (TEM) and SIMS. This analysis of photocathode degradation during nominal photoinjector operating conditions represents first steps towards developing robust new photocathode designs necessary for generating sub-micron emittance electron beams required for both fourth generation light sources and intense polarized CW electron beams for nuclear and high energy physics facilities.},
doi = {10.1103/PhysRevSTAB.15.063501},
url = {https://www.osti.gov/biblio/1044486}, journal = {Physical Review Special Topics - Accelerators and Beams, 15(6):063501},
issn = {1098-4402},
number = 6,
volume = 15,
place = {United States},
year = {2012},
month = {6}
}