Design of 11 T Twin-Aperture ${\rm Nb}_{3}{\rm Sn}$ Dipole Demonstrator Magnet for LHC Upgrades

Abstract

The LHC collimation upgrade foresees two additional collimators installed in the dispersion suppressor regions of points 2, 3 and 7. To obtain the necessary longitudinal space for the collimators, a solution based on an 11 T dipole as replacement of the 8.33 T LHC main dipoles is being considered. CERN and FNAL have started a joint development program to demonstrate the feasibility of Nb 3 Sn technology for this purpose. The program started with the development and test of a 2-m-long single-aperture demonstrator magnet. The goal of the second phase is the design and construction of a series of 2-m-long twin-aperture demonstrator magnets with a nominal field of 11 T at 11.85 kA current. This paper describes the electromagnetic design and gives a forecast of the field quality including saturation of the iron yoke and persistent-current effects in the Nb 3 Sn coils. The mechanical design concepts based on separate collared coils, assembled in a vertically split iron yoke are also discussed.

Impact of the Residual Resistivity Ratio on the Stability of ${\rm Nb}_{3}{\rm Sn}$ Magnets

“…IGH critical current density, J c , Nb 3 Sn wires are the superconductors preferred option for the next generation of accelerator magnets at CERN [1]- [3]. The J c of recent Nb 3 Sn strands have reached values in excess of 3000 A/mm 2 at 12 T and 4.2 K allowing larger aperture/stronger field magnets.…”

“…The J c of recent Nb 3 Sn strands have reached values in excess of 3000 A/mm 2 at 12 T and 4.2 K allowing larger aperture/stronger field magnets. On the other hand, such large J c values may cause magneto-thermal instabilities that can drastically reduce the conductor performance by quenching the superconductor prematurely before reaching its critical current [4]- [13].…”

“…In high J c Nb 3 Sn magnets, one of the main parameters for preventing premature quenches caused by magneto-thermal instabilities is the thermal and electrical conductivity of the stabilizing copper within the Nb 3 Sn strands. A large copper conductivity allows a major amount of heat to escape from the region that is experiencing the instability, thus improving the capability of the superconductor to sustain a flux jump without quenching.…”

Superconducting Magnet Development for the LHC Upgrades

“…Two different approaches for the coil-collar interface are being explored in this R&D phase, and they will be eventually assembled in one Two-In-One magnet model that should validate the superconductor and the basic design 16) . A full size prototype should be ready in 2014.…”

Quench Performance of a 1 m Long Single-Aperture 11 T <formula formulatype="inline"><tex Notation="TeX">$ \hbox{Nb}_{3}\hbox{Sn}$</tex></formula> Dipole Model for LHC Upgrades

“…These collared coils will be tested first in a single-aperture configuration and then assembled and tested inside a common iron yoke (twinaperture configuration). In parallel, four 2 m long collared coils will be built and tested at CERN first in a single-aperture and then in a twin-aperture configuration to establish the technology transfer to CERN, and demonstrate and optimize the quench performance, field quality and quench protection of Nb 3 Sn coils and a somewhat different mechanical concept of the collar and yoke [4]. This paper describes the design features of the first 1 m long single-aperture Nb 3 Sn dipole model (MBHSP02) fabricated at Fermilab and tested in April 2013.…”