Plasma processing of large curved surfaces for superconducting rf cavity modification
Abstract
In this study, plasma based surface modification of niobium is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. The development of the technology based on Cl2/Ar plasma etching has to address several crucial parameters which influence the etching rate and surface roughness, and eventually, determine cavity performance. This includes dependence of the process on the frequency of the RF generator, gas pressure, power level, the driven (inner) electrode configuration, and the chlorine concentration in the gas mixture during plasma processing. To demonstrate surface layer removal in the asymmetric non-planar geometry, we are using a simple cylindrical cavity with 8 ports symmetrically distributed over the cylinder. The ports are used for diagnosing the plasma parameters and as holders for the samples to be etched. The etching rate is highly correlated with the shape of the inner electrode, radio-frequency (RF) circuit elements, chlorine concentration in the Cl2/Ar gas mixtures, residence time of reactive species and temperature of the cavity. Using cylindrical electrodes with variable radius, large-surface ring-shaped samples and d.c. bias implementation in the external circuit we have demonstrated substantial average etching rates and outlined the possibility to optimize plasma properties with respect to maximum surface processing effect.
- Authors:
- Publication Date:
- Research Org.:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC)
- OSTI Identifier:
- 1181258
- Alternate Identifier(s):
- OSTI ID: 1165422
- Report Number(s):
- JLAB-ACC-14-1903; DOE/OR/23177-3118
Journal ID: ISSN 1098-4402; PRABFM; 122001
- Grant/Contract Number:
- SC0007879; AC05-06OR23177
- Resource Type:
- Published Article
- Journal Name:
- Physical Review Special Topics. Accelerators and Beams
- Additional Journal Information:
- Journal Name: Physical Review Special Topics. Accelerators and Beams Journal Volume: 17 Journal Issue: 12; Journal ID: ISSN 1098-4402
- Publisher:
- American Physical Society
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Citation Formats
Upadhyay, J., Im, Do, Popović, S., Valente-Feliciano, A. -M., Phillips, L., and Vušković, L. Plasma processing of large curved surfaces for superconducting rf cavity modification. United States: N. p., 2014.
Web. doi:10.1103/PhysRevSTAB.17.122001.
Upadhyay, J., Im, Do, Popović, S., Valente-Feliciano, A. -M., Phillips, L., & Vušković, L. Plasma processing of large curved surfaces for superconducting rf cavity modification. United States. https://doi.org/10.1103/PhysRevSTAB.17.122001
Upadhyay, J., Im, Do, Popović, S., Valente-Feliciano, A. -M., Phillips, L., and Vušković, L. Mon .
"Plasma processing of large curved surfaces for superconducting rf cavity modification". United States. https://doi.org/10.1103/PhysRevSTAB.17.122001.
@article{osti_1181258,
title = {Plasma processing of large curved surfaces for superconducting rf cavity modification},
author = {Upadhyay, J. and Im, Do and Popović, S. and Valente-Feliciano, A. -M. and Phillips, L. and Vušković, L.},
abstractNote = {In this study, plasma based surface modification of niobium is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. The development of the technology based on Cl2/Ar plasma etching has to address several crucial parameters which influence the etching rate and surface roughness, and eventually, determine cavity performance. This includes dependence of the process on the frequency of the RF generator, gas pressure, power level, the driven (inner) electrode configuration, and the chlorine concentration in the gas mixture during plasma processing. To demonstrate surface layer removal in the asymmetric non-planar geometry, we are using a simple cylindrical cavity with 8 ports symmetrically distributed over the cylinder. The ports are used for diagnosing the plasma parameters and as holders for the samples to be etched. The etching rate is highly correlated with the shape of the inner electrode, radio-frequency (RF) circuit elements, chlorine concentration in the Cl2/Ar gas mixtures, residence time of reactive species and temperature of the cavity. Using cylindrical electrodes with variable radius, large-surface ring-shaped samples and d.c. bias implementation in the external circuit we have demonstrated substantial average etching rates and outlined the possibility to optimize plasma properties with respect to maximum surface processing effect.},
doi = {10.1103/PhysRevSTAB.17.122001},
journal = {Physical Review Special Topics. Accelerators and Beams},
number = 12,
volume = 17,
place = {United States},
year = {Mon Dec 15 00:00:00 EST 2014},
month = {Mon Dec 15 00:00:00 EST 2014}
}
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https://doi.org/10.1103/PhysRevSTAB.17.122001
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