Superconductivity is the technology that enabled the construction of the most recent generation of high-energy particle accelerators, the largest scientific instruments ever built. In this review we trace the evolution of superconducting materials for particle accelerator magnets, from the first steps in the late 1960s, through the rise and glory of Nb–Ti in the 1970s, till the 2010s, and the promises of Nb3Sn for the 2020s. We conclude with a perspective on the opportunities for high-temperature superconductors (HTSs). Many such reviews have been written in the past, as witnessed by the long list of references provided. In this review we put particular emphasis on the practical aspects of wire and tape manufacturing, cabling, engineering performance, and potential for use in accelerator magnets, while leaving in the background matters such as the physics of superconductivity and fundamental material issues.

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Superconducting Materials and Conductors:. Fabrication and Limiting Parameters

A review on independent and integrated/coupled two-phase loop thermosyphons

CMS (compact muon solenoid) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting solenoid with 6 m diameter by 12.5 m long free bore, enclosed inside a 10,000-ton return yoke. The stored magnetic energy is 2.6 GJ. The magnet is being assembled in a surface hall and will be tested at the beginning of 2005 before being transferred to an experimental hall 90 m below ground level. The design and construction of the magnet is a common project of the CMS Collaboration. The task is organized by a CERN based group with strong technical and contractual participation of CEA Saclay, ETH Zurich, Fermilab, INFN Genova, ITEP Moscow, University of Wisconsin and CERN. The return yoke, 21 m long and 14 m in diameter, is equivalent to a thickness of 1.5 m of saturated iron interleaved with four muon stations. Manufacture of the yoke and vacuum tank is completed and the first sub-detectors have been installed. The indirectly-cooled, pure-aluminum-stabilized coil is made up from five modules internally wound with four layers of a 20 kA mechanically-reinforced conductor. The manufacture of the conductor is completed and winding is in progress for a final assembly in 2004. All ancillaries are delivered or under contract. The magnet project is described, with emphasis on the present status of the fabrication.

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Status of the construction of the CMS magnet

The CMS experiment (Compact Muon Solenoid) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting solenoid with a free bore of 6 m diameter and 12.5-m length, enclosed inside a 10 000-ton return yoke. The magnet will be assembled and tested in a surface hall at Point 5 of the LHC at the beginning of 2004 before being transferred by heavy lifting means to an experimental hall 90 m below ground level. The design and construction of the magnet is a common project of the CMS Collaboration. The task is organized by a CERN based group with strong technical and contractual participation from CEA Saclay, ETH Zurich, Fermilab, INFN Genova, ITEP Moscow, University of Wisconsin and CERN. The magnet project will be described, with emphasis on the present status of the fabrication.

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Status of the CMS magnet (MT17)

Within the framework of the LHC (Large Hadron Collider) R&D program, CERN and CEA/Saclay have established a collaboration to carry out the design, building and testing of a superconducting LHC prototype quadrupole at the Saclay laboratory. The cold mass of this quadrupole is presently under construction at Saclay. The quadrupole design features a twin aperture configuration, a gradient of 250 T/m, a length of 3 m, and a free coil aperture of 56 mm. European industries participate in this project by delivering components and fabricating the tooling according to specifications prepared by Saclay. The authors present details of the magnet design and construction. Coil winding will start in summer 1991 and the first prototype should be assembled and ready for testing by mid 1992. >

Design and fabrication of the prototype superconducting quadrupole for the CERN LHC project

A large superconducting solenoid (5-m bore, 7-m length) has been designed and constructed at the CEN/Saclay for the ALEPH detector, to be installed on the LEP collider at CERN. Special features of this solenoid are described such as the Al-stabilized superconducting cable, bobbinless internal winding, vacuum impregnation, indirect cooling, thermosyphon refrigeration mode, cryostat assembly. Preliminary tests without the iron carried out successfully in April 1987, and a complete test with the iron calorimeter at CERN in September 1987 are briefly reviewed. >

Design, construction and test of the large superconducting solenoid ALEPH

The main and the 2 compensating coils of the ALEPH solenoid are supplied by four current leads designed in an unusual way to meet particular conditions arising from the indirect cooling method and from the limited space available within the vacuum vessel of this thin wall type magnet. The leads, located inside the insulating vacuum, have a bended shape and are self supported against thermal and electromagnetic forces. They are directly connected to the winding without any intermediate helium bath and they must not deposit any heat at this junction point. They consist of 2 successive parts: first a liquid helium heat exchanger which carries the current through a superconducting cable and then a more classical copper cable-in-conduit type, helium vapour heat exchanger.

Current leads for aleph solenoid

Two huge superconducting magnets are proposed for the future detectors of the Large Hadron Collider (LHC) at CERN: the ATLAS toroidal system and the CMS solenoid. Both designs are based on the use of large aluminium stabilized conductors, built from a cable coextruded with very pure aluminium and, in the CMS case, mechanically reinforced with aluminium alloy; these conductors are now developed by different manufacturers under research contracts handed by CERN. This paper presents results of the critical current density of both strands and cables at different stages of the conductor fabrication, the effect of different treatments on the aluminium residual resistivity ratio (RRR) and the characterization of the bonding between the cable and its stabilizer.

Conductor developments for the ATLAS and CMS magnets

The authors present a conceptual design of a very large air-core toroid proposed for one of the detectors under study for the future Large Hadron Collider (LHC) at CERN. The magnet will produce a toroidal field around the central calorimeter in an open structure widely accessible for the installation of muon detectors inside the field area. It consists of 12 racetrack coils, 26 m long, tied together by a set of cold ring-shape structures distributed at ten locations along the length. Each coil is made of two single pancakes clamped rigidly to a solid plate and is self-contained in its own cryogenic enclosure. The design features an Al-stabilized conductor rated at 20 kA and 3.5 T, epoxy-potted windings, and indirect cooling. Special attention has been given to the mechanical design and to the winding construction which, in spite of the unusually large size, follows classical industrial techniques. >

http://ieeexplore.ieee.org/iel4/77/6032/00233682.pdf

J.C. Lottin

Papers

Design, construction and test of the large superconducting solenoid ALEPH

Current leads for aleph solenoid

Conductor developments for the ATLAS and CMS magnets

A large superconducting air-core toroid (for LHC detectors)