Validation of Finite-Element Models of Persistent-Current Effects in Nb₃Sn Accelerator Magnets

Journal Article · Tue Jan 06 00:00:00 EST 2015 · IEEE Transactions on Applied Superconductivity

DOI:https://doi.org/10.1109/TASC.2014.2385932· OSTI ID:1213937

Wang, X. ^[1]; Ambrosio, G. ^[2]; Chlachidze, G. ^[2]; Collings, E. W. ^[3]; Dietderich, D. R. ^[1]; DiMarco, J. ^[2]; Felice, H. ^[1]; Ghosh, A. K. ^[4]; Godeke, A. ^[1]; Gourlay, S. A. ^[1]; Marchevsky, M. ^[1]; Prestemon, S. O. ^[1]; Sabbi, G. ^[1]; Sumption, M. D. ^[3]; Velev, G. V. ^[2]; Xu, X. ^[3]; Zlobin, A. V. ^[2]

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1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
3. The Ohio State Univ., Columbus, OH (United States)
4. Brookhaven National Lab. (BNL), Upton, NY (United States)

Persistent magnetization currents are induced in superconducting filaments during the current ramping in magnets. The resulting perturbation to the design magnetic field leads to field quality degradation, in particular at low field where the effect is stronger relative to the main field. The effects observed in NbTi accelerator magnets were reproduced well with the critical-state model. However, this approach becomes less accurate for the calculation of the persistent-current effects observed in Nb₃Sn accelerator magnets. Here a finite-element method based on the measured strand magnetization is validated against three state-of-art Nb3Sn accelerator magnets featuring different subelement diameters, critical currents, magnet designs and measurement temperatures. The temperature dependence of the persistent-current effects is reproduced. Based on the validated model, the impact of conductor design on the persistent current effects is discussed. The performance, limitations and possible improvements of the approach are also discussed.

• Research Organization: The Ohio State Univ., Columbus, OH (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: AC02-07CH11359; AC02-98CH10886; AC02-05CH11231; AC02-76SF00515; SC0010312
• OSTI ID: 1213937
• Journal Information: IEEE Transactions on Applied Superconductivity, Vol. 25, Issue 3; ISSN 1051-8223
• Publisher: Institute of Electrical and Electronics Engineers (IEEE)
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
36 MATERIALS SCIENCE
Nb3Sn
magnetization
accelerator