An Internal Tin Tube Nb3Sn Conductor with Sn-B Core for Improved Non-Copper Critical Current Density

The high energy physics community seeks high performance multifilament superconducting wire for use in magnets operating in the range of 12-15T or higher. Nb3Sn conductors fabricated by the internal tin (IT) method presently represent the state-of-the-art for these applications. The internal tin tube (ITT) method holds the promise to compete with such conductors if their performance can be raised to a sufficiently high level. One problem with ITT conductors is that it is difficult to avoid the formation of large-grained Nb3Sn. This is an impediment to high performance. Sn-B alloys formed by melt diffusion of powders have been shown to result in thick layers of fine grained Nb3Sn when reacted with niobium in jelly roll composites. In the proposed project, Sn-B powder mixtures will be employed as the tin source in multifilamentary ITT composites. It is anticipated that high performance can be achieved by virtue of the fine Nb3Sn grain size that can be achieved using this technique. Commercial Applications and Other Benefits: High performance multifilamentary Nb3Sn will find application in high energy physics particle accelerators and magnetic confinement fusion machines. Commercially, such conductor will find application in high frequency NMR magnets by taking advantage of the higher critical current density in order to reduce the size and overall cost of the magnet system.