Improving the work function of the niobium surface of SRF cavities by plasma processing

Tyagi, P. V.; Doleans, M.; Hannah, B.; Afanador, R.; McMahan, C.; Stewart, S.; Mammosser, J.; Howell, M.; Saunders, J.; Degraff, B.; Kim, S. -H.

doi:10.1016/j.apsusc.2016.02.030

Title: Improving the work function of the niobium surface of SRF cavities by plasma processing

Full Record
Other Related Research

Abstract

An in situ plasma processing technique using chemically reactive oxygen plasma to remove hydrocarbons from superconducting radio frequency cavity surfaces at room temperature was developed at the spallation neutron source, at Oak Ridge National Laboratory. To understand better the interaction between the plasma and niobium surface, surface studies on small samples were performed. In this article, we report the results from those surface studies. The results show that plasma processing removes hydrocarbons from top surface and improves the surface work function by 0.5₋1.0 eV. Improving the work function of RF surface of cavities can help to improve their operational performance.

Authors:

^[1]; Doleans, M. ^[1]; Hannah, B. ^[1]; Afanador, R. ^[1]; McMahan, C. ^[1]; Stewart, S. ^[1]; Mammosser, J. ^[1]; Howell, M. ^[1]; Saunders, J. ^[1]; Degraff, B. ^[1]; Kim, S. -H. ^[1]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:: Fri Jan 01 00:00:00 EST 2016

Research Org.:: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:: USDOE Office of Science (SC)

OSTI Identifier:: 1240564

Alternate Identifier(s):: OSTI ID: 1358800

Grant/Contract Number:: AC05-00OR22725

Resource Type:: Accepted Manuscript

Journal Name:: Applied Surface Science

Additional Journal Information:: Journal Volume: 369; Journal Issue: C; Journal ID: ISSN 0169-4332

Country of Publication:: United States

Language:: English

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; SRF cavity; Plasma processing; niobium; Surface science; SIMS; SKP

Citation Formats


                    Tyagi, P. V., Doleans, M., Hannah, B., Afanador, R., McMahan, C., Stewart, S., Mammosser, J., Howell, M., Saunders, J., Degraff, B., and Kim, S. -H. Improving the work function of the niobium surface of SRF cavities by plasma processing.  United States: N. p., 2016. 
Web.  doi:10.1016/j.apsusc.2016.02.030.

Copy to clipboard


                    Tyagi, P. V., Doleans, M., Hannah, B., Afanador, R., McMahan, C., Stewart, S., Mammosser, J., Howell, M., Saunders, J., Degraff, B., & Kim, S. -H. Improving the work function of the niobium surface of SRF cavities by plasma processing.  United States.  https://doi.org/10.1016/j.apsusc.2016.02.030

Copy to clipboard


                    Tyagi, P. V., Doleans, M., Hannah, B., Afanador, R., McMahan, C., Stewart, S., Mammosser, J., Howell, M., Saunders, J., Degraff, B., and Kim, S. -H. Fri .  
"Improving the work function of the niobium surface of SRF cavities by plasma processing".  United States.  https://doi.org/10.1016/j.apsusc.2016.02.030.  https://www.osti.gov/servlets/purl/1240564.

Copy to clipboard


                    
@article{osti_1240564,

  title        = {Improving the work function of the niobium surface of SRF cavities by plasma processing},

  author       = {Tyagi, P. V. and Doleans, M. and Hannah, B. and Afanador, R. and McMahan, C. and Stewart, S. and Mammosser, J. and Howell, M. and Saunders, J. and Degraff, B. and Kim, S. -H.},

  abstractNote = {An in situ plasma processing technique using chemically reactive oxygen plasma to remove hydrocarbons from superconducting radio frequency cavity surfaces at room temperature was developed at the spallation neutron source, at Oak Ridge National Laboratory. To understand better the interaction between the plasma and niobium surface, surface studies on small samples were performed. In this article, we report the results from those surface studies. The results show that plasma processing removes hydrocarbons from top surface and improves the surface work function by 0.5₋1.0 eV. Improving the work function of RF surface of cavities can help to improve their operational performance.},

  doi          = {10.1016/j.apsusc.2016.02.030},

  journal      = {Applied Surface Science},

  number       = C,

  volume       = 369,

  place        = {United States},

  year         = {Fri Jan 01 00:00:00 EST 2016},

  month        = {Fri Jan 01 00:00:00 EST 2016}

}

Copy to clipboard

Journal Article:

Free Publicly Available Full Text

Accepted Manuscript (Publisher)

Accepted Manuscript (DOE)

Publisher's Version of Record

https://doi.org/10.1016/j.apsusc.2016.02.030

Other availability

Search WorldCat to find libraries that may hold this journal

Citation Metrics:

Cited by: 14 works

Citation information provided by
Web of Science

Save / Share:

Export Metadata

Save to My Library

Similar Records in DOE PAGES and OSTI.GOV collections:

Eco-Friendly Bipolar Electrochemical Bulk Processing of SRF Cavities

Technical Report Taylor, E. Jennings ; Inman, Maria E.

The International Linear Collider (ILC) requires ~16,000 RF superconducting radio frequency niobium cavities that must be a) polished to a microscale roughness, and b) cleaned to be free of impurities that would degrade performance of the ILC. The DOE is seeking new commercially viable, fabrication technologies for SRF cavities. Current methods, such as buffered chemical polishing (BCP), use high viscosity electrolytes containing hydrofluoric acid, which is not conducive to low-cost, high volume manufacturing and is potentially harmful to workers. Therefore, we have developed an electropolishing (EP) process for Nb SRF cavities, based on a new paradigm of non-viscous environmentally benignmore »« less
Improving the Work Function of Nitrogen-Doped Niobium Surfaces for SRF Cavities by Plasma Processing

Conference Tippey, Kristin ; Afanador, Ralph ; Doleans, Marc ; ... - J.Phys.Conf.Ser.

Work function and surface chemistries of SiC-polished, electropolished, and nitrogen-doped niobium coupons were analyzed before and after plasma processing using a neon-oxygen gas mixture. These studies represent an initial enquiry into the feasibility of applying the plasma processing technique designed at ORNL for the Spallation Neutron Source (SNS) to the nitrogen-doped Nb cavities for the Coherent Light Source II (LCLS-II). Work function of all measured samples was increased after plasma processing, which indicates the strong potential of the plasma processing technique as a tool for increasing the accelerating gradient of nitrogen-doped cavities.
https://doi.org/10.18429/JACoW-IPAC2018-THPAL065

Full Text Available
Plasma Treatment of Single-Cell Niobium SRF Cavities

Conference J. Upadhyay, M. Nikolić, S. Popović, L. Vušković, H.L. Phillips, A-M. Valente-Feliciano

Superconducting radio frequency cavities of bulk Niobium are integral components of particle accelerators based on superconducting technology. Wet chemical processing is the commonly used procedure for impurities and surface defects removal and surface roughness improvement , both required to improve the RF performance of the cavity. We are studying plasma etching as an alternate technique to process these cavities. The uniformity of the plasma sheath at the inner wall of the cavity is one prerequisite for its uniform etching. We are developing electro-optic diagnostic techniques to assess the plasma uniformity. Multiple electro-optical probes are placed at different locations of themore »« less
Full Text Available
Investigation of Nitrogen Absorption Rate and Nitride Growth on SRF Cavity Grade RRR Niobium as a Function of Furnace Temperature

Conference Reece, Charles ; Kelley, Michael ; Palczewski, Ari ; ...

The current state of the art processing of niobium superconducting radio frequency cavities with nitrogen diffusion is performed at 800 C in a furnace with a partial pressure of approximately ~20 mTorr of nitrogen. Multiple studies have shown the bulk of the nitrogen absorbed by the niobium forms a thick (1-3 microns) non-superconducting nitride layer which must be removed to produce optimal RF results. The depth profiling of interstitial nitrogen and surface nitrides has already been probed using SIMS measurements for this recipe. These measurements have been successfully modelled by extrapolating data from nitride growth studies performed at atmospheric pressuremore »« less
https://doi.org/10.18429/JACoW-LINAC2016-THOP02

Full Text Available
Fabrication and Testing of Thick Film CVD Niobium-Lined Copper SRF Cavities for High-Gradient Applications, Phase II

Technical Report McNeal, Shawn R. ; Arrieta, Victor M.

Innovative process development is needed to reliably deposit superconducting niobium coatings possessing performance capabilities near those of bulk niobium on less costly copper accelerator component structures such as cavities, complex couplers, and nose cones as an alternative to solid bulk niobium. Unlike bulk or thick-film niobium (30–150 μm thick), most thin-film coatings (~5 μm thick) do not afford practical post-coating surface conditioning options. Thin-film niobium coatings on copper are prone to copper diffusion through the entire ~5-μm coating thickness and to poor thermal contact, limiting their use to low- to medium-gradient applications. Niobium-lined copper fabrication technologies for cost-effective high-Q, high-fieldmore »« less

Similar Records