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Title: Gas cluster ion beam surface treatments for reducing field emission and breakdown of electrodes and SRF cavities.

Abstract

Sub-micron-scale surface roughness and contamination cause field emission that can lead to high-voltage breakdown of electrodes, and these are limiting factors in the development of high gradient RF technology. We are studying various Gas Cluster Ion Beam (GCIB) treatments to smooth, clean, etch and/or chemically alter electrode surfaces to allow higher fields and accelerating gradients, and to reduce the time and cost of conditioning high-voltage electrodes. For this paper, we have processed Nb, stainless steel and Ti electrode materials using beams of Ar, O{sub 2}, or NF{sub 3} + O{sub 2} clusters with accelerating potentials up to 35 kV. Using a scanning field emission microscope (SFEM), we have repeatedly seen a dramatic reduction in the number of field emission sites on Nb coupons treated with GCIB. Smoothing effects on stainless steel and Ti substrates, evaluated using SEM and AFM imaging, show that 200-nm-wide polishing scratch marks are greatly attenuated. A 150-mm diameter GCIB-treated stainless steel electrode has shown virtually no DC field emission current at gradients over 20 MV/m.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
941497
Report Number(s):
ANL/MCS/JA-62990
Journal ID: ISSN 0168-583X; NIMBEU; TRN: US200825%%554
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nucl. Instrum. Methods Phys. Res. B; Journal Volume: 261; Journal Issue: 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; BREAKDOWN; CAVITIES; CONTAMINATION; ELECTRODES; FIELD EMISSION; ION BEAMS; MICROSCOPES; POLISHING; ROUGHNESS; STAINLESS STEELS; SUBSTRATES; SURFACE TREATMENTS

Citation Formats

Swenson, D. R., Wu, A. T., Degenkolb, E., Insepov, Z., Mathematics and Computer Science, Epion Corp., and Jefferson National Lab.. Gas cluster ion beam surface treatments for reducing field emission and breakdown of electrodes and SRF cavities.. United States: N. p., 2007. Web. doi:10.1016/j.nimb.2007.04.277.
Swenson, D. R., Wu, A. T., Degenkolb, E., Insepov, Z., Mathematics and Computer Science, Epion Corp., & Jefferson National Lab.. Gas cluster ion beam surface treatments for reducing field emission and breakdown of electrodes and SRF cavities.. United States. doi:10.1016/j.nimb.2007.04.277.
Swenson, D. R., Wu, A. T., Degenkolb, E., Insepov, Z., Mathematics and Computer Science, Epion Corp., and Jefferson National Lab.. Mon . "Gas cluster ion beam surface treatments for reducing field emission and breakdown of electrodes and SRF cavities.". United States. doi:10.1016/j.nimb.2007.04.277.
@article{osti_941497,
title = {Gas cluster ion beam surface treatments for reducing field emission and breakdown of electrodes and SRF cavities.},
author = {Swenson, D. R. and Wu, A. T. and Degenkolb, E. and Insepov, Z. and Mathematics and Computer Science and Epion Corp. and Jefferson National Lab.},
abstractNote = {Sub-micron-scale surface roughness and contamination cause field emission that can lead to high-voltage breakdown of electrodes, and these are limiting factors in the development of high gradient RF technology. We are studying various Gas Cluster Ion Beam (GCIB) treatments to smooth, clean, etch and/or chemically alter electrode surfaces to allow higher fields and accelerating gradients, and to reduce the time and cost of conditioning high-voltage electrodes. For this paper, we have processed Nb, stainless steel and Ti electrode materials using beams of Ar, O{sub 2}, or NF{sub 3} + O{sub 2} clusters with accelerating potentials up to 35 kV. Using a scanning field emission microscope (SFEM), we have repeatedly seen a dramatic reduction in the number of field emission sites on Nb coupons treated with GCIB. Smoothing effects on stainless steel and Ti substrates, evaluated using SEM and AFM imaging, show that 200-nm-wide polishing scratch marks are greatly attenuated. A 150-mm diameter GCIB-treated stainless steel electrode has shown virtually no DC field emission current at gradients over 20 MV/m.},
doi = {10.1016/j.nimb.2007.04.277},
journal = {Nucl. Instrum. Methods Phys. Res. B},
number = 2007,
volume = 261,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}