Lessons Learned on the Development and Manufacture of Internal-Tin Nb3Sn Strand from Work on ITER CSMC and Other Fusion and HEP Applications

For many years the fusion community provided the main incentive for the development of internal-tin Nb3Sn. Several tonnes of moderate current density conductor with low AC losses were supplied for the U.S. Section of ITER CSMC. When the US abandoned the ITER project in 1998, the manufacturers began to concentrate on higher current density conductors for High Energy Physics. While there are significant differences between the strands for these two different applications, development in both areas has sufficient work in common to be of benefit to both communities. As the US reconsiders its position on ITER, the paper reviews some of the past work and the present state of development in both fields