Development of high current Nb3Sn multifilament superconducting material following the ECN powder method

A number of different types of multifilament superconducting wires containing Nb3Sn following the powder method have been made in lengths of about 500 meters. The formation of the superconducting Nb3Sn layer is based upon the reaction between NbSn2powder and the niobium tube which contains this powder. By a careful control of the composition of the wire, the powder core and the wire drawing procedures, it is now possible to make a composite with very good superconducting properties. High current densities can be achieved after a heat treatment at a temperature between 675 and 700°C during 50 to 100 hours. The analysis of the kinetics of the growth of the A-15 layers and the wire drawing characteristics has led to the conclusion that the overall current density can still be further increased to values as high as 3 × 10⁸Am^-2at 14 tesla. The dynamic stability is not seriously affected by this optimization since the copper to superconducting ratio is 5.2 to 1. In this paper the composition, the manufacturing procedures and the main superconducting properties will be described. We will further outline our plans for further production of this kind of material on a larger scale.