Development of stabilized Nb3Sn wire containing a reduced number of filaments

Progress is reported on the development of production techniques for stabilized Nb
3
Sn multifilament wire based on reaction of niobium clad NbSn
2
powder filaments. The superconducting properties - T
c
above 17.9 K and J
c
(4.2 K, 14 T) of 2.2 × 10
⁹
A/m
²
- are shown to be independent of filament diameter. The requirement of adiabatic stability imposes an upper limit of approximately 900 μm
²
on the cross sectional area of Nb
3
Sn in the filaments. A production sequence based on wire drawing is illustrated by a 0.56 mm 19-filament wire with a Cu/s.c. ratio of 6.0, which has a critical current of 152 A at 4.2 K and 8 T. Development work on a more economic reduction by extrusion is being continued.