The ITER Magnets: Design and Construction Status

Abstract

The ITER magnet procurement is now well underway. The magnet systems consist of 4 superconducting coil sets (toroidal field (TF), poloidal field (PF), central solenoid (CS) and correction coils (CC)) which use both NbTi and -based conductors. The magnets sit at the core of the ITER machine and are tightly integrated with each other and the main vacuum vessel. The total weight of the system is about 10000 t, of which about 500 t are strands and 250 t, NbTi. The reaction of the magnetic forces is a delicate balance that requires tight control of tolerances and the use of high-strength, fatigue-resistance steel forgings. Integration and support of the coils and their supplies, while maintaining the necessary tolerances and clearance gaps, have been completed in steps, the last being the inclusion of the feeder systems. Twenty-one procurement agreements have now been signed with 6 of the ITER Domestic Agencies for all of the magnets together with the supporting feeder subsystems. All of them except one (for the CS coils) are so-called Build to Print agreements where the IO provides the detailed design including full three-dimensional CAD models. The production of the first components is underway (about 175 t of strand was finished by July 2011) and manufacturing prototypes of TF coil components are being completed. The paper will present a design overview and the manufacturing status.

Comparisons of internal self-field magnetic flux densities between recent Nb3Sn fusion magnet CICC cable designs

“…ITER will be a fully superconducting tokamak incorporating Nb 3 Sn, NbTi and some HTS superconductor technology for its huge magnets and current leads [1].…”

Analysis of the quench propagation along Nb3Sn Rutherford cables with the THELMA code. Part I: Geometric and thermal models

“…In the case of fusion magnets, the use of cable-in-conduit conductor (CICC) should give satisfying mechanical properties and guarantee an efficient conductor cooling even in the presence of plasma perturbations [6], however the impact of the resistive joints thermal load and possible termination-induced current imbalances on the cable stability are still an open issue. On the other side, the new generation of accelerator magnets will make use of Rutherford cables made with Nb 3 Sn conductors, capable of generating a magnetic field of 16 T [7], and potentially up to 20 T [5,8].…”

Design of load-to-failure tests of high-voltage insulation breaks for ITER's cryogenic network

“…Magnet systems for plasma confinement, in fusion energy experiments such as ITER, include a wide range of coils composed of cable-in-conduit conductors (CICCs) [1]. These CICCs consist of various types of stainless steel jackets, densely filled with superconducting strands based on either Nb 3 Sn or NbTi, and subsequently compacted [2].…”