Superconductors for the ITER model coils

Abstract

The use of superconducting materials needed for the ITER magnetic systems is discussed. The requirements for Nb 3Sn multifilamentary strands designed for the ITER model coils are presented. It is shown that in each of the join ITER partners (EU, Japan, Russia, US) the technology of the Nb 3Sn strand manufacture had been developed for both bronze and internal tin methods, which meets the ITER specifications. In HP-2 strands with 0.81 mm diameter and a Cu volume fraction equal to 60%, the non-copper critical current density ( J c) exceeds 550 A/mm 2 at 12 T, and hysteresis losses ( W) are less than 200 mJ/cm 3 (±3 T). In the HP-1 strands J c exceeds 700 A/mm 2 and hysteresis losses are less than 600 mJ/cm 3. The process of manufacturing central solenoid and toroidal field model coil conductors is discussed.