Nb3Sn superconductor is the most common choice for very high magneticfield generation. The highest field generated today by Nb3Sn solenoids is in the 20-21 T range. There are numerous superconducting magnets in this field range inphysics laboratories, and a growing number of 900MHz NMR magnets are inoperation around the world. In an R&D magnet developed for Large HadronCollider applications, a record high magnetic field of 14.7 T has been achieved usingmodified jelly roll strand having critical current density (Jc) of ~2000 A/mm2 (12 T,4.2 K)[1]. Oxford Instruments, Superconducting Technology (OI-ST) produces highperformance Nb3Sn wire via several different "internal Sn" routes. Recently,research at OI-ST has produced strand made by the restacked rod process that hasachieved 12 T, 4.2 K non-Cu Jc values of 3000 A/mm2. This high Jc level wasachieved by a combination of optimized Cu, Nb, and Sn ratios and improved heattreatment schedules. Similar conductors developed for high field use have shownengineering current density (JE) values well over 150 A/mm2 at 23.5 T, 1.8 K. Thesecurrent density improvements may enable 16 T dipole magnets for particleaccelerators, and 1 GHz magnets for NMR.
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