Optimizing $\hbox {Nb}_{3}\hbox {Sn}$ Conductors for High Field Applications

Flexibility of design means internal tin Nb₃Sn strands can be tailored for particular applications. For particle accelerator applications, the development work is focused on reducing the effective filament diameter whilst maintaining high J_c and RRR. We will present our latest results on new distributed barrier strand designs that modify Nb, Sn, and Cu ratios to enhance RRR and maintain J_c in strands having subelement diameter of less than 45 μm. For laboratory magnets, cryogen-free operation is becoming the norm. To that end, we are continuing to develop single barrier internal tin strands having minimal ac losses but high I_c values of critical current. For high field NMR magnets, where the highest J_c in the highest magnetic field is critical, highest performance strand has average J_c values over 1600 A/mm2 at 4.2 K, 15 T. We will also present summary of strand performance for the ITER TF coil and our latest results on RRP strand for cable-in-conduit applications.