Ultra-low magnetization and hysteresis loss in APC Nb ₃ Sn superconductors

Journal Article · Mon Dec 01 00:00:00 EST 2025 · Supercond.Sci.Technol.

DOI:https://doi.org/10.1088/1361-6668/ae2da2· OSTI ID:3014239

Xu, X. ^[1]; Wan, F. ^[1]; Peng, X. ^[2]; Sumption, M. ^[3]

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1. Fermilab
2. Unlisted, US, OH
3. Ohio State U.

Abstract For the accelerator magnets of the next hadron collider, reducing superconductor persistent-current magnetization is not only important for achieving the desired field quality, but also crucial for its sustainability because the magnetization loss is the major heat load to the magnet cold mass. For conventional Nb 3 Sn conductors this requires reduction of effective subelement size ( D eff ). For the restacked-rod-process (RRP ® ) conductors a physical subelement size ( D sub ) as small as 35 µ m (corresponding to a D eff close to 45 µ m) can be reached, but at a significant price in J c . Another way to reduce the magnetization is by introducing artificial pinning centers (APC) using the internal oxidation approach. APC conductors outperform conventional Nb 3 Sn wires in two aspects: 1) higher J c at high fields, and 2) much lower J c and magnetization at low fields (e.g. below 5 T). In this work we explored the fabricability of APC wires with small D sub . A 180-stack APC wire was produced and drawn to 0.7- and 0.5 mm diameters with good quality, with D sub s of 34 and 24 µ m ( D eff s of 36 and 25 µ m), respectively. For the 34 µ m- D sub wire, its non-Cu J c is higher than that of an RRP ® wire used for the High-Luminosity Large Hadron Collider (HL-LHC) project above 13 T (e.g. 36% higher at 4.2 K, 18 T), while its non-Cu magnetization at 1 T, Δ M (1 T), is only 29% of the RRP ® wire. Its non-Cu hysteresis loss for a cycle between 1 and 14 T, Q h (1–14 T), is 37% of the RRP ® wire. For the 24 µ m- D sub wire, its non-Cu J c surpasses the HL-LHC RRP ® wire above 17.5 T, while its Δ M (1 T) and Q h (1–14 T) are only 17% and 23% of the RRP ® wire, respectively. Its non-Cu Q h (±3 T) even meets the specification of the International Thermonuclear Experimental Reactor project.

• Research Organization: Unlisted, US, OH; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Ohio State U.
• Sponsoring Organization: US Department of Energy
• Grant/Contract Number: 89243024CSC000002
• OSTI ID: 3014239
• Report Number(s): FERMILAB-PUB-25-0599-TD; oai:inspirehep.net:3105862; arXiv:2601.09945
• Journal Information: Supercond.Sci.Technol., Journal Name: Supercond.Sci.Technol. Journal Issue: 12 Vol. 38
• Country of Publication: United States
• Language: English