Design of internal-tin Nb/sub 3/Sn current switch strand and strand for accelerator magnets

Different areas of internal-tin Nb/sub 3/Sn strands application have been analyzed. It was shown that internal-tin strands could be most promising for use in persistent current switches and for high field, enhanced current magnet systems. Appropriate Nb/sub 3/Sn internal-tin strands have been designed, fabricated and tested. The design of Nb/sub 3/Sn strand for current switch consists of high resistance Cu-Sn-Ni matrix and Nb/sub 3/Sn filaments. It was shown that Nb/sub 3/Sn switch strand 0.9 mm in dia has a current capacity of 1 kA at 4.2 K, 1 T and resistance above 8 /spl mu//spl Omega/*cm at 20 K. For the magnets of next generation accelerators Nb/sub 3/Sn internal-tin strand with enhanced current capacity has been designed. Critical current density of that strand was above 2000 A/mm/sup 2/ at 4.2 K, 12 T, 0.1 /spl mu/V/cm.