skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Evaluation of electropolished stainless steel electrodes for use in DC high voltage photoelectron guns

Abstract

DC high voltage photoelectron guns are used to produce polarized electron beams for accelerator-based nuclear and high-energy physics research. Low-level field emission (~nA) from the cathode electrode degrades the vacuum within the photogun and reduces the photoelectron yield of the delicate GaAs-based photocathode used to produce the electron beams. High-level field emission (>μA) can cause significant damage the photogun. To minimize field emission, stainless steel electrodes are typically diamond-paste polished, a labor-intensive process often yielding field emission performance with a high degree of variability, sample to sample. As an alternative approach and as comparative study, the performance of electrodes electropolished by conventional commercially available methods is presented. Our observations indicate the electropolished electrodes exhibited less field emission upon the initial application of high voltage, but showed less improvement with gas conditioning compared to the diamond-paste polished electrodes. In contrast, the diamond-paste polished electrodes responded favorably to gas conditioning, and ultimately reached higher voltages and field strengths without field emission, compared to electrodes that were only electropolished. The best performing electrode was one that was both diamond-paste polished and electropolished, reaching a field strength of 18.7 MV/m while generating less than 100 pA of field emission. The speculate that the combinedmore » processes were the most effective at reducing both large and small scale topography. However, surface science evaluation indicates topography cannot be the only relevant parameter when it comes to predicting field emission performance.« less

Authors:
 [1];  [1];  [2];  [2];  [2];  [2];  [2];  [3];  [3];  [4]
  1. Old Dominion Univ., Norfolk, VA (United States)
  2. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
  3. The College of William & Mary, Williamsburg, VA (United States)
  4. NASA Langley, Hampton, VA (United States)
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1190822
Alternate Identifier(s):
OSTI ID: 1420459
Report Number(s):
JLAB-ACC-15-2089; DOE/OR/23177-3450
Journal ID: ISSN 0734-2101; JVTAD6
Grant/Contract Number:  
AC05-06OR23177; AC05-84ER40150
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films
Additional Journal Information:
Journal Volume: 33; Journal Issue: 4; Journal ID: ISSN 0734-2101
Publisher:
American Vacuum Society
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; Field emission, polishing, work functions, topography, surface measurements

Citation Formats

BastaniNejad, Mahzad, Elmustafa, Abdelmageed A., Forman, Eric, Covert, Steven, Hansknecht, John, Hernandez-Garcia, Carlos, Poelker, Matthew, Das, Lopa, Kelley, Michael, and Williams, Phillip. Evaluation of electropolished stainless steel electrodes for use in DC high voltage photoelectron guns. United States: N. p., 2015. Web. doi:10.1116/1.4920984.
BastaniNejad, Mahzad, Elmustafa, Abdelmageed A., Forman, Eric, Covert, Steven, Hansknecht, John, Hernandez-Garcia, Carlos, Poelker, Matthew, Das, Lopa, Kelley, Michael, & Williams, Phillip. Evaluation of electropolished stainless steel electrodes for use in DC high voltage photoelectron guns. United States. doi:10.1116/1.4920984.
BastaniNejad, Mahzad, Elmustafa, Abdelmageed A., Forman, Eric, Covert, Steven, Hansknecht, John, Hernandez-Garcia, Carlos, Poelker, Matthew, Das, Lopa, Kelley, Michael, and Williams, Phillip. Wed . "Evaluation of electropolished stainless steel electrodes for use in DC high voltage photoelectron guns". United States. doi:10.1116/1.4920984. https://www.osti.gov/servlets/purl/1190822.
@article{osti_1190822,
title = {Evaluation of electropolished stainless steel electrodes for use in DC high voltage photoelectron guns},
author = {BastaniNejad, Mahzad and Elmustafa, Abdelmageed A. and Forman, Eric and Covert, Steven and Hansknecht, John and Hernandez-Garcia, Carlos and Poelker, Matthew and Das, Lopa and Kelley, Michael and Williams, Phillip},
abstractNote = {DC high voltage photoelectron guns are used to produce polarized electron beams for accelerator-based nuclear and high-energy physics research. Low-level field emission (~nA) from the cathode electrode degrades the vacuum within the photogun and reduces the photoelectron yield of the delicate GaAs-based photocathode used to produce the electron beams. High-level field emission (>μA) can cause significant damage the photogun. To minimize field emission, stainless steel electrodes are typically diamond-paste polished, a labor-intensive process often yielding field emission performance with a high degree of variability, sample to sample. As an alternative approach and as comparative study, the performance of electrodes electropolished by conventional commercially available methods is presented. Our observations indicate the electropolished electrodes exhibited less field emission upon the initial application of high voltage, but showed less improvement with gas conditioning compared to the diamond-paste polished electrodes. In contrast, the diamond-paste polished electrodes responded favorably to gas conditioning, and ultimately reached higher voltages and field strengths without field emission, compared to electrodes that were only electropolished. The best performing electrode was one that was both diamond-paste polished and electropolished, reaching a field strength of 18.7 MV/m while generating less than 100 pA of field emission. The speculate that the combined processes were the most effective at reducing both large and small scale topography. However, surface science evaluation indicates topography cannot be the only relevant parameter when it comes to predicting field emission performance.},
doi = {10.1116/1.4920984},
journal = {Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films},
number = 4,
volume = 33,
place = {United States},
year = {2015},
month = {7}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 3 works
Citation information provided by
Web of Science

Save / Share: