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Title: DC photogun vacuum characterization through photocathode lifetime studies

Abstract

Excellent vacuum is essential for long photocathode lifetimes in DC high voltage photoelectron guns. Vacuum Research at Thomas Jefferson National Accelerator Facility has focused on characterizing the existing vacuum systems at the CEBAF polarized photoinjector and on quantifying improvements for new systems. Vacuum chamber preprocessing, full activation of NEG pumps and NEG coating the chamber walls should improve the vacuum within the electron gun, however, pressure measurement is difficult at pressures approaching the extreme-high-vacuum (XHV) region and extractor gauge readings are not significantly different between the improved and original systems. The ultimate test of vacuum in a DC high voltage photogun is the photocathode lifetime, which is limited by the ionization and back-bombardment of residual gasses. Discussion will include our new load-locked gun design as well as lifetime measurements in both our operational and new photo-guns, and the correlations between measured vacuum and lifetimes will be investigated.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA
Sponsoring Org.:
USDOE - Office of Energy Research (ER)
OSTI Identifier:
917021
Report Number(s):
JLAB-ACO-07-711; DOE/OR/23177-0117
TRN: US0804412
DOE Contract Number:  
AC05-06OR23177
Resource Type:
Conference
Resource Relation:
Conference: 17th International Vacuum Conference, July 2-6, 2007, Stockholm , Sweden
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; CEBAF ACCELERATOR; COATINGS; DESIGN; ELECTRON GUNS; IONIZATION; LIFETIME; PHOTOCATHODES; PRESSURE MEASUREMENT; VACUUM SYSTEMS

Citation Formats

Marcy Stutzman, Joseph Grames, Matt Poelker, Kenneth Surles-Law, and Philip Adderley. DC photogun vacuum characterization through photocathode lifetime studies. United States: N. p., 2007. Web.
Marcy Stutzman, Joseph Grames, Matt Poelker, Kenneth Surles-Law, & Philip Adderley. DC photogun vacuum characterization through photocathode lifetime studies. United States.
Marcy Stutzman, Joseph Grames, Matt Poelker, Kenneth Surles-Law, and Philip Adderley. Mon . "DC photogun vacuum characterization through photocathode lifetime studies". United States. https://www.osti.gov/servlets/purl/917021.
@article{osti_917021,
title = {DC photogun vacuum characterization through photocathode lifetime studies},
author = {Marcy Stutzman and Joseph Grames and Matt Poelker and Kenneth Surles-Law and Philip Adderley},
abstractNote = {Excellent vacuum is essential for long photocathode lifetimes in DC high voltage photoelectron guns. Vacuum Research at Thomas Jefferson National Accelerator Facility has focused on characterizing the existing vacuum systems at the CEBAF polarized photoinjector and on quantifying improvements for new systems. Vacuum chamber preprocessing, full activation of NEG pumps and NEG coating the chamber walls should improve the vacuum within the electron gun, however, pressure measurement is difficult at pressures approaching the extreme-high-vacuum (XHV) region and extractor gauge readings are not significantly different between the improved and original systems. The ultimate test of vacuum in a DC high voltage photogun is the photocathode lifetime, which is limited by the ionization and back-bombardment of residual gasses. Discussion will include our new load-locked gun design as well as lifetime measurements in both our operational and new photo-guns, and the correlations between measured vacuum and lifetimes will be investigated.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2007},
month = {7}
}

Conference:
Other availability
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