The Central Solenoid Model Coil Project (L- 1)

The Central Solenoid Model Coil (CSMC) project has two main objectives:

• to verify the conductor performance under ITER-relevant conditions
• to demonstrate the major steps in the manufacturing of the conductor and of the ITER Central Solenoid

The CS Model Coil consists of two modules nested inside each other. Both modules were wound of Nb3Sn cable-in conduit conductors having square jacket of Incoloy 908. The conductor manufacture was a a collaborative activity between all the ITER partners. The strands and cables were produced in the US, Japan and Europe. The Jacket came from US while all the jacketing was done at Ansaldo Superconduttori in Italy. The Inner Module has an inner diameter of 1.8 m, outer diameter of 2.7 m and height of 2.8 m. It was fabricated by Lockheed Martin under the supervision of the US Home Team. The Outer Module has an inner diameter of 2.7 m, outer diameter of 3.6 m and height of 2.8 m. It was fabricated by Toshiba under the supervision of the Japanese Home Team.

The CSMC testing has taken place in a dedicated test facility provided by the Japanese Home Team at JAERI in Naka. To test a conductor, the CSMC can fit an "insert coil" within the bore of the main coil, which can be equipped with many more sensors than the CSMC. At present, three insert coils relevant for ITER are foreseen (one for the CS conductor, one for the TF and one for the PF conductor).

The CS insert was produced by Mitsubishi (Japan) and the TF Insert by the Efremov Institute (Russian Federation). The European Home Team will provide a PF insert coil made of an NbTi cable-inconduit conductor.

Apart from testing the insert coils, the operation of the main coil did provide a verification of the insulation performance under load and demonstrate the integrated performance of both joints and conductor for several conductor lengths and two different joint concepts.

In summer 2000, the CSMC was operated successfully at a current of 46 kA, and a magnetic field of 13T, giving a stored magnetic energy of 640 MJ. This is the highest stored energy ever achieved in a Nb3Sn coil. The coil could also be ramped up to full current with a speed up to 1.2 T/s.

Figure 1:Layers at different stages of manufacturing at Toshiba, courtesy of JAERI, Japan