R. Perin

The Large Hadron Collider (LHC) in the LEP tunnel

After the remarkable start-up of LEP, the installation of a Large Hadron Collider, LHC, in the LEP tunnel will open a new era for the High Energy Physics. This report summarizes the main LHC parameters and subsytems and describes the more recent studies and developments.

Design of a high-field twin aperture superconducting dipole model

An initial design for the Large Hadron Collider to be installed in the tunnel of the CERN LEP machine is based on the so-called two-in-one concept, originally proposed and tested at Brookhaven National Laboratory for fields up to approximately 5 T. The dipole magnets of the two rings have a common magnetic circuit and are located in one cryostat. Two major lines of development are followed for the construction of models of high-field magnets: (1) using Nb/sub 3/Sn superconducting cables at 4.5 K, and (2) using NbTi alloy superconducting cables at 2 K. The models discussed are 1 m long twin aperture dipoles. They employ NbTi alloy superconducting cables at 2 K but, apart from the coils, the mechanical design concepts are equally valid for magnets using using Nb/sub 3/Sn cables. A role of the models is to test the various components and procedures of fabrication in order to obtain the best performances at lowest cost. Possible variants in the design are mentioned. >

The superconducting magnet system for the LHC

The new facility for the Large Hadron Collider (LHC) will mainly consist of a 27-km-long double ring of high-field superconducting magnets installed in the Large Electron-Positron Collider (LEP) tunnel, above the LEP machine components. The magnet system comprises nearly 2000 twin-aperture, 8-10-T, 10-m-long, dipole bending magnets, more than 500 250-T/m, twin-aperture quadrupoles, and a very large number of other superconducting magnetic components. A general description of the system is given together with the main features of the design of the regular lattice magnets. Also described is the present state of the magnet R&D program, which, after the successful phase of short model magnets, is now aimed at the construction of a full prototype 100-m-long cell for the LHC machine.

Status of LHC programme and magnet development

The Large Hadron Collider (LHC) is a superconducting accelerator/collider for protons, heavy ions and electron-proton collisions in the multi-TeV energy range, which will be installed at CERN in the 27 km tunnel of LEP. This new facility will mainly consist of a double ring of high field superconducting magnets operating in superfluid helium at a temperature of 1.9 K. To reach the wanted beam energy (7 TeV for protons) the main dipole magnets will operate at about 8.4 T and the quadrupoles at 220 T/m field gradient. These main magnets have a two-in-one configuration with the magnetic channels for the two beams placed in a common yoke and cryostat. The LHC will have more than 10000 superconducting magnetic units. The arcs of the machine will require about 1250, 14 m long dipoles and 400, 3 m long quadrupoles. After a general outline of the project with more detailed information on the design of the magnets, the paper describes the state of magnet R&D and presents results of short models, among which one reached the record dipole field of 10.5 T, as well as of industry made full scale prototypes which have been successfully tested and measured.<<ETX>>

Progress on the superconducting magnets for the Large Hadron Collider

After a review of the proposed CERN Large Hadron Collider (LHC) project, the present design of the high-field superconducting magnets is described. One half of each standard cell for the ring of the magnet system under development consists of four ( approximately 10-m long) dipole magnets, a focusing quadrupole magnet, a tuning quadrupole, a combined sextupole/dipole corrector magnet, and a beam observation station. Only the main features of the dipole design are given. Both presently possible routes to high-field/high-current density magnets, using NbTi superconductors at superfluid helium temperatures or Nb/sub 3/Sn at 4.5 K, are summarized. Other major systems such as the vacuum chamber, proton synchrotron, and cavities are also noted. The work then presents the main aspects and the first results of the research and development program that was undertaken in close collaboration with various European industries and laboratories. Emphasis here is on the development of suitable NbTi and Nb/sub 3/Sn wires and cables, and the construction of magnet models (1-m long) and of a 9-m long twin-aperture prototype dipole. >

Test results on 10 T LHC superconducting one metre long dipole models

Superconducting twin-aperture dipole model magnets for the CERN future superconducting collider, the Large Hadron Collider (LHC), were built. The authors report on the magnet quench behavior and the field measurements at low and high magnetic induction. They describe the results obtained with 1-m-long models which have been made in industry. To test different design ideas, four magnets were built with a number of technical variants relating to the type of cable and electrical insulation, details in coils, material, shape and assembly method of the collars and the material of the outer shrinking cylinder. Tests performed on two magnets called MTA-JS and MTA-H are discussed. Measurements of the losses in the superconducting cables and the quenching field at various field ramp rates are used to investigate the temperature margin in superfluid helium under steady-state losses.<<ETX>>

Design, fabrication variants and results of LHC twin-aperture models

In the framework of the R&D program for the development of high-field superconducting magnets suitable for LHC (Large Hadron Collider), four twin-aperture, 1 m long, dipole models have been contracted to industry. The magnets are working at superfluid helium temperature below 2 K. The value of the maximum central magnetic field at the short sample limit is 10 T. The main design characteristics and principles of construction are recalled. The four models have technical variants which are described. Superconducting cables of 17 mm width have been developed in collaboration with industry. The measured critical current densities on cables and results of magnet tests are reported. >

First Nb3Sn, 1m Long Superconducting Dipole Model Magnets for LHC Break the 10 Tesla Field Threshold

In late 1986 CERN and ELIN joined in a collaboration to develop a 1 m long, 50 mm aperture Nb3Sn high field dipole model magnet for LHC. CERN provided the basic know-how and the cables and ELIN was doing design and manufacturing both of a mirror test dipole followed by a final dipole magnet. A winding technology has been developed based on the “wind and react” method. The excitation coils are wound of two different, 17 mm wide, Nb3Sn cables with an inorganic insulation. After reaction the coils are epoxy vacuum impregnated and mounted into a mechanical support structure consisting of Al-collars, a split cold iron yoke and an outer aluminium cylinder. Design and technology were proven in a magnetic mirror dipole where a single pole was tested in February 1989: a maximum magnetic field of 10’2 T was reached at 17’4 kA and 4’3 K after a few quenches. The dipole magnet itself was successfully tested at the beginning of June 1989: a central bore field of 9’5 T was reached at 4’3K, the maximum field at the Nb3Sn cable being about 10’05T.

The first, industry made, model magnet for the CERN Large Hadron Collider

The first magnet model for the LHC (Large Hadron Collider) is a single-aperture, 1-m-long, dipole magnet based on NbTi cable technology and designed for an 8-T nominal field at 2 K. It reached and passed its nominal field without any quench and attained 9.1 T, where it operated without quenching before the first campaign of tests was voluntarily stopped. In a second test campaign a 9.3 T central field was attained. After a description of the magnet, the authors discuss the cable characteristics, manufacturing tools, and magnet performance. >

Development of 10 T dipole magnets for the Large Hadron Collider

Development of high field dipole model magnets for future high energy accelerators has been carried out as a part of the cooperative accelerator program between CERN and KEK. A single aperture dipole model magnet was completed and tested. The magnet reached 8.0 T at 4.3 K and 9.87 T at 1.8 K. A twin aperture dipole model magnet with an identical coil design is being assembled. The development status and test results are described.<<ETX>>