A Metallurgical Inspection Method to Assess the Damage in Performance-Limiting Nb₃Sn Accelerator Magnet Coils

Journal Article · Mon Jan 23 00:00:00 EST 2023 · IEEE Transactions on Applied Superconductivity

DOI:https://doi.org/10.1109/tasc.2023.3237662· OSTI ID:1909879

Moros, Alice ^[1]; Crouvizier, Mickael Denis  ^[1]; Santillana, Ignacio Aviles  ^[1]; Sgobba, Stefano  ^[1]; Bermudez, Susana Izquierdo  ^[1]; Lusa, Nicholas ^[1]; Troitino, Jose Ferradas  ^[1]; Milanese, Attilio  ^[1]; Todesco, Ezio  ^[1]; Devred, Arnaud  ^[1]; Ambrosio, Giorgio  ^[2]; Baldini, Maria  ^[2]; Ferracin, Paolo  ^[3]; Schmalzle, Jesse ^[4]; Vallone, Giorgio  ^[3]

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1. European Organization for Nuclear Research (CERN), Geneva (Switzerland)
2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
4. Brookhaven National Lab. (BNL), Upton, NY (United States)

The design and production of Nb₃Sn-based dipole and quadrupole magnets is critical for the realization of the High-Luminosity Large Hadron Collider (HL-LHC) at the European Organization for Nuclear Research (CERN). Nb₃Sn superconducting coils are aimed at enhancing the bending and focusing strengths of accelerator magnets for HL-LHC and beyond. Due to the brittle nature of Nb₃Sn, the coil fabrication steps are very challenging and require very careful QA/QC. Flaws in the Nb₃Sn filaments may lead to quenches, and eventually, performance limitation below nominal during magnet testing. A novel inspection method, including advanced non-destructive and destructive techniques, was developed to explore the root-causes of quenches occurring in performance-limiting coils. The most relevant results obtained for MQXF coils through this innovative inspection method are presented. This approach allows for precise assessment of the physical events associated to the quenches experienced b y magnet coils, mainly occurring under the form of damaged strands with transversely broken sub-elements. Coil-slice preparation, micro-optical observations of transverse and longitudinal cross-sections, and a deep etching technique of copper will be illustrated in the present work, with a focus on the results achieved for a CERN coil from a non-conforming quadrupole magnet prototype, and two coils fabricated in the US, in the framework of the Accelerator Upgrade Project (AUP) collaboration, from two different non-conforming quadrupole magnets, respectively. The results obtained through the proposed inspection method will be illustrated.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Contributing Organization: LARP
• Grant/Contract Number: AC02-07CH11359
• OSTI ID: 1909879
• Report Number(s): FERMILAB-PUB-22-859-TD; arXiv:2211.09684; oai:inspirehep.net:2183342; TRN: US2312182
• Journal Information: IEEE Transactions on Applied Superconductivity, Vol. 33, Issue 5; ISSN 1051-8223
• Publisher: IEEE
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
Coils
Superconducting magnets
Inspection
Etching
Microscopy
Copper
Magnetomechanical effects