Quench Protection Study of the $\hbox{Nb}_{3}\hbox{Sn}$ Low-$\beta$ Quadrupole for the LHC Luminosity Upgrade

Abstract

In the framework of the HiLumi program, the development of high field (conductor peak field 12 T) and large aperture (150 mm in diameter) superconducting quadrupoles is under way. These quadrupoles will provide the final focusing of the beam in the interaction region of the Large Hadron Collider (LHC), in the program of the luminosity upgrade. The quench protection of these magnets is a challenging aspect, mainly for the magnet dimension (8 m long), for the large value of the stored magnetic energy (12 MJ) and for the use of Nb3Sn as conductor. In this paper, the quench protection study is reported, comparing results obtained with different codes for quench analysis. The parametric analysis of the transition under different conditions for the protection scheme is also presented

Effect of coupling currents on the dynamic inductance during fast transient in superconducting magnets

“…For the next generation of high-field superconducting magnets (B peak ≈ 12-15 T), the use of Nb 3 Sn as a superconductor is foreseen. Because of the large ratio between the magnetic energy and the conductor mass, the quench protection is one of the most challenging aspects for the design of these magnets [2], and in the future it could be the limiting factor for them. The protection problem is more relevant in highfield dipole and quadrupole magnets for accelerators than in other high-field magnets, such as solenoids: in fact, the first ones require very large values of current density in the coils, whereas in the second ones, usually, stabilized conductors can be used, with much lower current density in the coil area.…”

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].…”