Document Type
Conference Paper
Publication Date
2025
DOI
10.18429/JACoW-SRF2025-THP12
Publication Title
Proceedings of the 22nd International Conference on RF Superconductivity (SRF '25)
Pages
638-641
Conference Name
22nd International Conference on RF Superconductivity (SRF '25), September 21-26, 2026, Tokyo, Japan
Abstract
The fabrication of SRF cavities from sheet materials includes deep-drawing, electron beam welding, chemical and mechanical polishing, high-temperature heat treatment, and material diffusion. The performance of these cavities is frequently constrained by magnetic flux trapping. In this presentation, we thoroughly examine how recrystallization influences flux expulsion in SRF cavities, using cold-worked niobium sheets from various suppliers. Our findings reveal that cold-worked sheets enhance flux expulsion, especially at lower heat treatment temperatures, by promoting improved recrystallization. In particular, a traditionally fabricated Nb cavity half-cell from an annealed poly-crystalline Nb sheet after an 800 C heat treatment leads to a bi-modal microstructure that ties in with flux trapping and inefficient flux expulsion. This non-uniform microstructure is related to varying strain profiles along the cavity shape. A novel approach to prevent this non-uniform microstructure is presented by fabricating a 1.3 GHz single cell Nb cavities with a cold-worked sheet and subsequent heat treatment leading to better flux expulsion after 800 C/3 h.
Rights
© 2026 by JACoW.
Published under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License. Any further distribution of this work must maintain attribution to the authors, the published article's title, publisher, and DOI.
Original Publication Citation
Dhakal, P., Khanal, B., Balachandran, S., Chetri, S., Lee, P., & Ciovati, G. (2025). Unveiling the interplay: Cold work, recrystallization, and flux expulsion. In L. Bian, K. Furukawa, J. Lee, J. Mira, M. Montis, V.R.W. Schaa, A. Shirakawa, & A. Uchiyama (Eds.), Proceedings of the 22nd International Conference on RF Superconductivity (SRF '25) (pp. 638-641). JACoW Publishing. https://doi.org/10.18429/JACoW-SRF2025-THP12
ORCID
0000-0001-9316-7704 (Ciovati)
Repository Citation
Dhakal, P.; Khanal, B. D.; Balachandran, S.; Chetri, S.; Lee, P. J.; and Ciovati, G., "Unveiling the Interplay: Cold Work, Recrystallization, and Flux Expulsion" (2025). Physics Faculty Publications. 1076.
https://digitalcommons.odu.edu/physics_fac_pubs/1076