Determination of bulk and surface superconducting properties of N2-doped cold worked, heat treated and electro-polished SRF grade niobium
Abstract
In this study, nitrogen-doped cavities show significant performance improvement in the medium accelerating field regime due to a lowered RF surface resistivity. However, the mechanism of enhancement has not been clearly explained. Our experiments explore how N2-doping influences Nb bulk and surface superconducting properties, and compare the N2-doped properties with those obtained previously with conventionally treated samples. High purity Nb-rod was mechanically deformed and post treated based on a typical SRF cavity treatment recipe. The onset of flux penetration at Hc1, and the upper and the surface critical fields, Hc2 and Hc3, were characterized by magnetic hysteresis and AC susceptibility techniques. The surface depth profile responsible for superconductivity was examined by changing AC amplitude in AC susceptibility, and the microstructure was directly observed with EBSD-OIM. We are also investigating surface chemistry for detailed composition using XPS. We have found that N2-doping at 800 °C significantly reduces the Hc3/Hc2 ratio towards the ideal value of ~1.7, and conclude that AC susceptibility is capable of following changes to the surface properties induced by N2-doping.
- Authors:
-
[1];
- Florida State Univ., Tallahassee, FL (United States)
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- United States Steel Research and Technology Center, Pittsburgh, PA (United States)
- Publication Date:
- Research Org.:
- Florida State Univ., Tallahassee, FL (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- OSTI Identifier:
- 1244545
- Grant/Contract Number:
- SC0009960
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Proc. of International Conference on RF Superconductivity
- Additional Journal Information:
- Conference: SRF15, Whistler, BC (Canada), 13-18 Sept 2015
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; 43 PARTICLE ACCELERATORS; SRF cavities; Nb, N-doping; superconductivity; AC susceptibility
Citation Formats
Chetri, Santosh, Larbalestier, David C., Lee, Peter J., Dhakal, Pashupati, and Sung, Zu -Hawn. Determination of bulk and surface superconducting properties of N2-doped cold worked, heat treated and electro-polished SRF grade niobium. United States: N. p., 2015.
Web. doi:10.18429/JACoW-SRF2015-MOPB052.
Chetri, Santosh, Larbalestier, David C., Lee, Peter J., Dhakal, Pashupati, & Sung, Zu -Hawn. Determination of bulk and surface superconducting properties of N2-doped cold worked, heat treated and electro-polished SRF grade niobium. United States. https://doi.org/10.18429/JACoW-SRF2015-MOPB052
Chetri, Santosh, Larbalestier, David C., Lee, Peter J., Dhakal, Pashupati, and Sung, Zu -Hawn. Tue .
"Determination of bulk and surface superconducting properties of N2-doped cold worked, heat treated and electro-polished SRF grade niobium". United States. https://doi.org/10.18429/JACoW-SRF2015-MOPB052. https://www.osti.gov/servlets/purl/1244545.
@article{osti_1244545,
title = {Determination of bulk and surface superconducting properties of N2-doped cold worked, heat treated and electro-polished SRF grade niobium},
author = {Chetri, Santosh and Larbalestier, David C. and Lee, Peter J. and Dhakal, Pashupati and Sung, Zu -Hawn},
abstractNote = {In this study, nitrogen-doped cavities show significant performance improvement in the medium accelerating field regime due to a lowered RF surface resistivity. However, the mechanism of enhancement has not been clearly explained. Our experiments explore how N2-doping influences Nb bulk and surface superconducting properties, and compare the N2-doped properties with those obtained previously with conventionally treated samples. High purity Nb-rod was mechanically deformed and post treated based on a typical SRF cavity treatment recipe. The onset of flux penetration at Hc1, and the upper and the surface critical fields, Hc2 and Hc3, were characterized by magnetic hysteresis and AC susceptibility techniques. The surface depth profile responsible for superconductivity was examined by changing AC amplitude in AC susceptibility, and the microstructure was directly observed with EBSD-OIM. We are also investigating surface chemistry for detailed composition using XPS. We have found that N2-doping at 800 °C significantly reduces the Hc3/Hc2 ratio towards the ideal value of ~1.7, and conclude that AC susceptibility is capable of following changes to the surface properties induced by N2-doping.},
doi = {10.18429/JACoW-SRF2015-MOPB052},
journal = {Proc. of International Conference on RF Superconductivity},
number = ,
volume = ,
place = {United States},
year = {Tue Dec 01 00:00:00 EST 2015},
month = {Tue Dec 01 00:00:00 EST 2015}
}
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