| Title |
Introduction of Precisely Controlled Microstructural Defects into SRF Cavity Niobium Sheets and Their Impact on Local Superconducting Properties |
| Authors |
- M. Wang, T.R. Bieler, D. Kang
Michigan State University, East Lansing, Michigan, USA
- C. Compton
FRIB, East Lansing, Michigan, USA
- D.C. Larbalestier, A. Polyanskii, Z-H. Sung
ASC, Tallahassee, Florida, USA
- P.J. Lee
NHMFL, Tallahassee, Florida, USA
|
| Abstract |
When SRF cavity shapes are formed from Nb sheets, the metallurgical processing introduces microstructural defects such as dislocations and low-angle grain boundaries that can serve as pinning centers for magnetic flux that may degrade cavity performance. Therefore, the relationship between magnetic flux behavior and microstructural defects in carefully strained SRF Nb sheet was investigated. Laue X-ray and EBSD-OIM crystallographic analyses of large grain ingot slices were used to characterize microstructural defects and then predict which grains and sample orientations will produce desired model defects due to tensile deformation. Grain orientations were chosen to favor specific slip systems, which generate dislocations with special angles with respect to the sample surface. Nb bicrystals were also prepared to investigate the effects of grain boundaries on flux pinning. The generated defect structures were confirmed by OIM and TEM. Cryogenic magneto-optical imaging was used to directly observe the penetration of magnetic flux into the deformed Nb. These model samples have deformation that is similar to that expected in typical cavity forming processes.
|
| Funding |
Research supported by DOE/OHEP (contract number DE-FG02-09ER41638 at MSU and DE-SC0009960 at FSU) and the State of Florida. |
| Paper |
download MOPB018.PDF [1.946 MB / 5 pages] |
| Conference |
SRF2015, Whistler, BC, Canada |
| Series |
International Conference on RF Superconductivity (17th) |
| Proceedings |
Link to full SRF2015 Proccedings |
| Session |
Poster Session |
| Date |
14-Sep-15 14:20–17:30 |
| Main Classification |
Fundamental SRF R&D - Bulk Nb |
| Keywords |
niobium, cavity, SRF, electron, superconductivity |
| Publisher |
JACoW, Geneva, Switzerland |
| Editors |
Robert E. Laxdal (TRIUMF, Vancouver, BC, Canada); Jana Thomson (TRIUMF, Vancouver, BC, Canada); Volker RW Schaa (GSI, Darmstadt, Germany) |
| ISBN |
978-3-95450-178-6 |
| Published |
December 2015 |
| Copyright |
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