The LHC superconducting magnets

Abstract

The Large Hadron Collider (LHC) is under construction at CERN. Most of its 27 km underground tunnel will be filled with superconducting magnets, mainly 15 m long dipoles and 3 m long quadrupoles. The 1232 main dipole and 392 main quadrupole magnets, are complemented by a number of insertion quadrupole magnets: including 86 MQM (matching), 26 MQY (wide aperture) and 32 low-beta quadrupoles (the latter built by KEK and Fermilab). The about 6000 superconducting corrector magnets, many of them individually powered, are also very critical for the functioning of the accelerator. Using copper stabilized NbTi Rutherford cables or single strands, these superconducting magnets will operate in superfluid helium at 1.9 K. The paper reviews the main characteristics of these magnets and addresses the critical points of the design with respect to their use in such a complicated accelerator like LHC. Then the status of the production of the superconducting cable and of the magnets is given, with particular emphasis given to the QA/QC procedures taken to ensure the industrial production according to the tight requirements, and the results on the first 30 main dipoles is presented. Finally, the plan put in place to meet the LHC schedule is discussed. AbstractThe Large Hadron Collider (LHC) is under construction at CERN. Most of its 27 km underground tunnel will be filled with superconducting magnets, mainly 15 m long dipoles and 3 m long quadrupoles. The 1232 main dipole and 392 main quadrupole magnets, are complemented by a number of insertion quadrupole magnets: including 86 MQM (matching), 26 MQY (wide aperture) and 32 lowbeta quadrupoles (the latter built by KEK and Fermilab). The about 6000 superconducting corrector magnets, many of them individually powered, are also very critical for the functioning of the accelerator. Using copper stabilized NbTi Rutherford cables or single strands, these superconducting magnets will operate in superfluid helium at 1.9 K. The paper reviews the main characteristics of these magnets and addresses the critical points of the design with respect to their use in such a complicated accelerator like LHC. Then the status of the production of the superconducting cable and of the magnets is given, with particular emphasis given to the QA/QC procedures taken to ensure the industrial production according to the tight requirements, and the results on the first 30 main dipoles is presented. Finally, the plan put in place to meet the LHC schedule is discussed.

Superconducting Magnets for the LHC Main Lattice

“…Accelerator magnets and their characteristics have been described and discussed elsewhere [4], [10]- [15] and a description of the final features of the LHC main magnets can be found in [5], [16]. For the scope of the present paper is sufficient to recall a few of the main characteristics.…”

“…The ultimate tool for quality controls and steering the production toward the beam dynamic limit are magnetic measurements carried out on all collared coils and cold masses produced, both dipoles and quadrupoles. For more details see [5], [16], [24], [25]. From the point of view of the QA, Fig.…”

CLIQ : a new quench protection technology for superconducting magnets

“…These large-scale machines are composed of various circuits of different magnets [19][20][21][22][23][24][25]. Synchrotron accelerators, featuring a circular track with RF cavities to accelerate bunches of particles, rely on multipole magnets.…”

“…As an example, figure 5.4 shows the addition of three CLIQ leads to a 14 m long LHC twin-aperture dipole magnet [20][21][22][23]108,154]. One terminal is attached at the joint between the two apertures, and two others at the joints between poles.…”

High-field accelerator magnets beyond LHC

“…Since the time of the Tevatron, significant progress has been made in the design and production of superconductors and accelerator magnets, leading to a gain of a factor ~2 in dipole field. The ongoing superconducting magnet productions for the Large Hadron Collider (LHC) at CERN, which, among others, call for 1232 14.2-m-long, 56-mm-twin-aperture, 8.33-T arc dipole magnets, is the culmination of 20 years of superconducting accelerator magnet development around the world [4]. The idea of building the LHC first emerged in 1982 [5], and the machine is expected to be turned on in the Spring of 2007, a mere 25 years later.…”