The Role of Azimuthal Prestress in the Longitudinal Degradation of Nb3Sn Superconducting Magnets

Superconducting magnet coils are subject to enormous electro-magnetic forces which push the cables away from the winding pole, and against the surrounding structure. This structure is usually optimized trying to limit the overall motion and the strains experienced by the superconducting elements. To...

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Bibliographic Details
Published in:IEEE transactions on applied superconductivity 2025-08, Vol.35 (5), p.1-5
Main Authors: Vallone, G., Ambrosio, G., Anderssen, E., Ferracin, P.
Format: Article
Language:English
Subjects:
Accelerator magnets
Cables
Coils
Coils (windings)
Computational modeling
Conductors
Cross-sections
Damage prevention
Design optimization
Lead
Loading
Luminosity
Magnet coils
Magnetic separation
mechanical aspects
Nb<named-content xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" content-type="math" xlink:type="simple"> <inline-formula> <tex-math notation="LaTeX"> _3</tex-math> </inline-formula> </named-content>Sn
Numerical models
preload
Prestressing
Quadrupoles
Strain
Superconducting magnets
Superconductivity
Training
Windings
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Description
Summary:Superconducting magnet coils are subject to enormous electro-magnetic forces which push the cables away from the winding pole, and against the surrounding structure. This structure is usually optimized trying to limit the overall motion and the strains experienced by the superconducting elements. To achieve this, preload forces are applied both in the coil cross-section and along its length. If the e.m. forces overcome these preloads, separation between the coil and the pole occurs, resulting in an overall loss of rigidity. During the magnet design process, it is often tempting to treat the optimization of the azimuthal and longitudinal preload systems separately. However, the two are inextricably related: as the cross-section preload increases, friction can prevent any motion in the longitudinal plane, and decreasing it can instead allow dangerous motions in the conductor ends. The latter can result in very high strains and, in Nb 3 Sn conductors, damage that can prevent the magnet to reach the desired performances. In an attempt to define design guidelines, in this paper we use simplified numerical models to compute, as a function of the in-plane prestress, the variation of the peak strains in the end region of the coils. Finally, we investigate the impact of the azimuthal prestress on a real magnet case, the High-Luminosity Nb 3 Sn Quadrupole MQXF.
ISSN:1051-8223
1558-2515
DOI:10.1109/TASC.2024.3519079