Erratum to “The HL-LHC Low-β Quadrupole Magnet MQXF: From Short Models to Long Prototypes” [Aug 19 Art. no. 4001309]

Abstract

Among the components to be upgraded in LHC interaction regions for the HiLumi-LHC projects are the inner triplet (or low-β) quadrupole magnets, denoted as Q1, Q2a, Q2b, and Q3. The new quadrupole magnets, called MQXF, are based on Nb3Sn superconducting magnet technology and operate at a gradient of 132.6 T/m with a conductor peak field of 11.4 T. The Q1 and Q3 are composed by magnets (called MQXFA) fabricated by the US Accelerator Upgrade Project (AUP) with a magnetic length of 4.2 m. The Q2a and Q2b consists of magnets (called MQXFB) fabricated by CERN with a magnetic length of 7.15 m. After a series of short models, constructed in close collaboration by the US and CERN, the development program is now entering in the prototyping phase, with CERN on one side and BNL, FNAL, and LBNL on the other side assembling and testing their first long magnets. We provide in this paper a description of the status of the MQXF program, with a summary of the short model test results, including quench performance, and mechanics, and an update on the fabrication, assembly and test of the long prototypes.

Conceptual Design of 20 T Hybrid Accelerator Dipole Magnets

“…By simulating the superconducting coil as a 60 sector with a uniform overall current density (jo = Icable/Ains_cable) it is possible to carry out a sensitivity analysis where the key magnet parameters are investigated, as show in [22]- [23]. The magnetic numerical model (implemented in ANSYS 2D) assumes a 0.67 ratio between jo and je (obtained by considering the Nb3Sn insulated cable for the MQXF project [24]) and a 250 mm thick iron yoke placed at 25 mm from the outer radius of the coil. In order to investigate the stress induced on the coil mid-plane by the azimuthal and radial electro-magnetic (e.m.) forces, the numerical mechanical model (implemented in ANSYS 2D) imposes an infinitely rigid structure all around the coil.…”

“…In terms of magnetic analysis, the strands diameters for both the Nb3Sn and HTS ranges from 0.85 to 1.15 mm, and the cable width from 13.3 mm to 24.4 mm. A cable compaction similar to the one of the MQXF cable [24] is assumed, again for both Nb3Sn and HTS cables. As for the sector coil analysis, a 250 mm thick iron is considered in the computations.…”

Assembly and Pre-Loading Specifications for the Series Production of the Nb3Sn MQXFA Quadrupole Magnets for the HL-LHC

“…masses (plus 2 spares), each featuring a single 7.15 m long magnet, called MQXFB with identical cross-section design as the US magnets [4], [5]. Since 2016, a total of six short models (MQXFS1, MQXFS3−7) and two long prototypes, for both the "A" magnets (MQXFAP1-2) and the "B" magnets (MQXFBP1-P2) have been fabricated and tested.…”