학술논문
Status of the MQXFB Nb3Sn Quadrupoles for the HL-LHC
Document Type
Periodical
Author
Bermudez, S.I.; Ambrosio, G.; Apollinari, G.; Ballarino, A.; Barth, C.; Crouvizier, M.D.; Ramos, D.D.; Devred, A.; Feher, S.; Felice, H.; Ferracin, P.; Troitino, J.F.; Guinchard, M.; Lusa, N.; Mangiarotti, F.; Milanese, A.; Moros, A.; Prin, H.; Russenschuck, S.; Sgobba, S.; Todesco, E.; Willering, G.
Source
IEEE Transactions on Applied Superconductivity IEEE Trans. Appl. Supercond. Applied Superconductivity, IEEE Transactions on. 33(5):1-9 Aug, 2023
Subject
Language
ISSN
1051-8223
1558-2515
2378-7074
1558-2515
2378-7074
Abstract
The cold powering test of the first two prototypes of the MQXFB quadrupoles (MQXFBP1, now disassembled, and MQXFBP2), the Nb 3 Sn inner triplet magnets to be installed in the HL-LHC, has validated many features of the design, such as field quality and quench protection, but has found performance limitations. In fact, both magnets showed a similar phenomenology, characterized by reproducible quenches in the straight part inner layer pole turn, with absence of training and limiting the performance at 93% (MQXFBP1) and 98% (MQXFBP2) of the nominal current at 1.9 K, required for HL-LHC operation at 7 TeV. Microstructural inspections of the quenching section of the limiting coil in MQXFBP1 have identified fractured Nb 3 Sn sub-elements in strands located at one specific position of the inner layer pole turn, allowing to determine the precise origin of the performance limitation. In this paper we outline the strategy that has been defined to address the possible sources of performance limitation, namely coil manufacturing, magnet assembly and integration in the cold mass.