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Title: In-situ plasma processing to increase the accelerating gradients of SRF cavities

Abstract

A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipacting issues. This article discusses the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus.

Authors:
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  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1234337
Alternate Identifier(s):
OSTI ID: 1251772
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
Additional Journal Information:
Journal Volume: 812; Journal ID: ISSN 0168-9002
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 42 ENGINEERING; linear accelerator; SRF technology; plasma processing

Citation Formats

Doleans, Marc, Afanador, Ralph, Barnhart, Debra L., Degraff, Brian D., Gold, Steven W., Hannah, Brian S., Howell, Matthew P., Kim, Sang-Ho, Mammosser, John, McMahan, Christopher J., Neustadt, Thomas S., Saunders, Jeffrey W., Tyagi, Puneet V., Vandygriff, Daniel J., Vandygriff, David M., Ball, Jeffrey Allen, Blokland, Willem, Crofford, Mark T., Lee, Sung-Woo, Stewart, Stephen, and Strong, William Herb. In-situ plasma processing to increase the accelerating gradients of SRF cavities. United States: N. p., 2015. Web. https://doi.org/10.1016/j.nima.2015.12.043.
Doleans, Marc, Afanador, Ralph, Barnhart, Debra L., Degraff, Brian D., Gold, Steven W., Hannah, Brian S., Howell, Matthew P., Kim, Sang-Ho, Mammosser, John, McMahan, Christopher J., Neustadt, Thomas S., Saunders, Jeffrey W., Tyagi, Puneet V., Vandygriff, Daniel J., Vandygriff, David M., Ball, Jeffrey Allen, Blokland, Willem, Crofford, Mark T., Lee, Sung-Woo, Stewart, Stephen, & Strong, William Herb. In-situ plasma processing to increase the accelerating gradients of SRF cavities. United States. https://doi.org/10.1016/j.nima.2015.12.043
Doleans, Marc, Afanador, Ralph, Barnhart, Debra L., Degraff, Brian D., Gold, Steven W., Hannah, Brian S., Howell, Matthew P., Kim, Sang-Ho, Mammosser, John, McMahan, Christopher J., Neustadt, Thomas S., Saunders, Jeffrey W., Tyagi, Puneet V., Vandygriff, Daniel J., Vandygriff, David M., Ball, Jeffrey Allen, Blokland, Willem, Crofford, Mark T., Lee, Sung-Woo, Stewart, Stephen, and Strong, William Herb. Thu . "In-situ plasma processing to increase the accelerating gradients of SRF cavities". United States. https://doi.org/10.1016/j.nima.2015.12.043. https://www.osti.gov/servlets/purl/1234337.
@article{osti_1234337,
title = {In-situ plasma processing to increase the accelerating gradients of SRF cavities},
author = {Doleans, Marc and Afanador, Ralph and Barnhart, Debra L. and Degraff, Brian D. and Gold, Steven W. and Hannah, Brian S. and Howell, Matthew P. and Kim, Sang-Ho and Mammosser, John and McMahan, Christopher J. and Neustadt, Thomas S. and Saunders, Jeffrey W. and Tyagi, Puneet V. and Vandygriff, Daniel J. and Vandygriff, David M. and Ball, Jeffrey Allen and Blokland, Willem and Crofford, Mark T. and Lee, Sung-Woo and Stewart, Stephen and Strong, William Herb},
abstractNote = {A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipacting issues. This article discusses the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus.},
doi = {10.1016/j.nima.2015.12.043},
journal = {Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment},
number = ,
volume = 812,
place = {United States},
year = {2015},
month = {12}
}

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    Works referencing / citing this record:

    Plasma ignition and detection for in-situ cleaning of 1.3 GHz 9-cell cavities
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