protons/beam. The energy stored in one beam is 350 MJ, more than seven orders of magnitude above the quench limit of a superconducting magnet. After briefly recalling the challenges and design choices of the machine, status and future prospects are discussed.

https://epaper.kek.jp/e02/papers/moxgb003.pdf

Status of the lhc

NbTi superconductors with low ac loss: A review

The main lattice of the Large Hadron Collider (LHC) employs about 1600 main magnets and more than 4000 corrector magnets. All superconducting and working in pressurized superfluid helium bath, these impressive line of magnets fills more than 20 km of the underground tunnel. With almost 70 main dipoles already delivered and 10 main quadrupoles almost completed, we passed the 5% of the production and now all manufacturers have fully entered into series production. In this paper the most critical issues encountered in the ramping up in such a real large scale fabrication is addressed; uniformity of the coil size and of prestress, special welding technique, tolerances on curvature (dipoles) or straightness (quadrupoles) and of the cold mass extremities, harmonic content and, most important, the integrated field uniformity among magnets. The actual limits and the solution for improvements are discussed. Finally a realistic schedule based on actual achievements is presented.

/pdf/superconducting-magnets-for-the-lhc-main-lattice-4kzohcj0ah.pdf

Superconducting magnets for the LHC main lattice

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 3.3 m long quadrupoles. In total 1248 dipole and 400 quadrupole magnets will be built (including spares), all wound with copper stabilized NbTi Rutherford cables and designed to operate in superfluid helium at 1.9 K. The dipoles operative field is 8.3 T, the system being designed for possible operation up to 9 T (ultimate field). The pre-series dipole production has started in 2000 in three companies while the series dipole construction will start at the beginning of 2003. As far as quadrupoles are concerned, the prototypal phase (carried out at CEA-Saclay, F) is followed directly by the series construction, started in March 2002. In the paper the magnet main characteristics are reviewed and the special tooling, put in place to fulfill the mass production with suitable accuracy and safety margin, is described. The results obtained on the first fifteen pre-series magnets as well as the effect of the corrective actions taken to meet the necessary field quality are discussed. Finally a realistic plan of the project, foreseeing that last dipoles are delivered in summer 2006, is presented.

/pdf/the-lhc-main-dipoles-and-quadrupoles-toward-series-3myyu1580z.pdf

The LHC main dipoles and quadrupoles toward series production

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.

/pdf/superconducting-materials-and-conductors-fabrication-and-539ox8ddpx.pdf

Superconducting Materials and Conductors:. Fabrication and Limiting Parameters

Six contracts have been placed with industrial companies for the production of 1200 tons of the superconducting (SC) cables needed for the main dipoles and quadrupoles of the Large Hadron Collider (LHC). In addition, two contracts have been placed for the supply of 470 tons of NbTi and 26 tons of Nb sheets. The main characteristic of the specification is that it is functional. This means that the physical, mechanical and electrical properties of strands and cables are specified without defining the manufacturing processes. Facilities for the high precision measurements of the wire and cable properties have been implemented at CERN, such as strand and cable critical current, copper to superconductor ratio, interstrand resistance, magnetization, RRR at 4.2 K and 1.9 K. The production has started showing that the highly demanding specifications can be fulfilled. This paper reviews the organization of the contracts, the test facilities installed at CERN, the various types of measurements and the results of the main physical properties obtained on the first batches. The status of the deliveries is presented.

/pdf/status-of-the-lhc-superconducting-cable-mass-production-1kht18ndsf.pdf

Status of the LHC superconducting cable mass production

The Large Hadron Collider (LHC) superconducting dipole cold mass is a cylindrical structure 15 m long, made of a shrinking cylinder which contains iron laminations and collared coils. This structure, weighing about 28 tons, is horizontally bent by 5 mrad. Its shape should be preserved from the assembly phase to the operational condition at cryogenic temperature. Hence, an accurate comprehension of the mechanical behavior of the cold mass is required. In particular, the flexural rigidity in both horizontal and vertical directions represents one of the foremost properties. To determine the flexural rigidity, deformations of the cold mass induced by the self weight have been measured and compared with the predictions of an analytical structural model. Particular care has been taken in reducing the experimental error by an appropriate fitting procedure.

/pdf/a-method-to-determine-the-flexural-rigidity-of-the-main-2a8i36nlr5.pdf

G. Cavallari

Papers

Status of the LHC superconducting cable mass production

A method to determine the flexural rigidity of the main dipole for the Large Hadron Collider