Development of Fine Multifilamentary ${\rm Nb}_{3}{\rm Al}$ Conductors

A new configuration of Nb₃Al conductor with a fine multifilamentary structure is presented. The wire is fabricated by a simple re-stacking (RS) method, in which rapid-quenched ductile BCC Nb-Al phase wires are re-stacked into a stabilizing Cu tube and co-drawn into a final form. Such a simple stabilization method will be effective to cut the Nb₃Al fabrication cost. The developed RS Nb₃Al conductor has a non-Cu J _c of almost about 1000 A/mm² at 15 T, 4.2 K. The effective filament diameter is 14 mum and the hysteresis loss (+/- 3 T) is 370 mJ/cm³, which is small enough with respect to the ITER target specification.