Magnet Design of the 150 mm Aperture Low-<formula formulatype="inline"><tex Notation="TeX">$\beta$</tex> </formula> Quadrupoles for the High Luminosity LHC

Abstract

Abstract-The High Luminosity LHC (HL-LHC) project is aimed at studying and implementing the necessary changes in the LHC to increase its luminosity by a factor five. Among the magnets that will be upgraded are the 16 superconducting low-β quadrupoles placed around the two high luminosity interaction regions (ATLAS and CMS experiments). In the current baseline scenario, these quadrupole magnets will have to generate a gradient of 140 T/m in a coil aperture of 150 mm. The resulting conductor peak field of more than 12 T will require the use of Nb 3 Sn superconducting coils. We present in this paper the HL-LHC low-β quadrupole design, based on the experience gathered by the US LARP program, and, in particular, we describe the support structure components to pre-load the coils, withstand the electro-magnetic forces, provide alignment and LHe containment, and integrate the cold mass in the LHC IRs.

Superconducting Magnet Technology for the Upgrade

“…The most advanced solutions used in TQ, LQ and HQ are now being applied to the larger aperture quadrupole. So MQXF is essentially a scaling of the design of HQ [20]. The guideline is to keep all features that have been shown to work properly in the LARP magnets.…”

CLIQ : a new quench protection technology for superconducting magnets

“…Figures 3.8a-b show as example the geometry and field-map of a two-layer quadrupole magnet, namely the 150 mm aperture quadrupole magnet for the high-luminosity LHC [131][132][133][134]. Such a magnet is composed of eight distinct coil sections, namely the two layers in each of its four poles; thus, a CLIQ-based protection system can include up to four units (1≤N C ≤4).…”

“…As an example showing the dependence of the CLIQ performance on the strand parameters, the case of the full-size, 6.8 meter long, Nb 3 Sn quadrupole magnet for the high-luminosity LHC is considered [131][132][133][134]. In section 3.3.3, it was already shown how to optimize the electrical order of the coil sections and the positioning of the leads in order to improve the CLIQ effectiveness.…”

“…The latest design of the superconductor used for this coil is composed of strands with a filament twist-pitch of 19 mm and a copper matrix with RRR=140 [132][133][134]. Since no transitory loss measurements of this superconductor are available, it is not possible to precisely determine the value of the effective transverse-resistivity factor f eff presented in equation 2.19.…”

“…The cases of two Nb 3 Sn cos-θ magnets for the high-luminosity LHC are discussed here, namely the 6.8 m long, 12 T quadrupole coil presented in section 3.3.3 [131][132][133][134] and one aperture of the 6 m long, 11 T dipole coil presented in section 3.3.2 [80,81,[127][128][129][130], with fractions of superconductor of 0.47 and 0.44, respectively [91,134].…”