Critical current of Nb3Sn practical superconductors in high magnetic field

The critical currents of Nb
3
Sn practical superconductors were measured in high magnetic fields up to 22 T at 4.2 K. The conductors investigated were MF Nb
3
Sn wire, CVD-Nb
3
Sn tape and diffusion processed Nb
3
Sn tape. The measurements show that the conductors have excellent superconducting properties. The multifilamentary Nb
3
Sn wire possesses a higher overall current density Jc
^ov
(Nb
3
Sn + bronze), especially in high fields above 12T. Its Jc
^ov
, for example, is 2.4 × 10
⁴
A/cm
²
at 15T. The CVD-Nb
3
Sn tape displays a higher Jc in the fields up to 12T, while the diffusion processed Nb
3
Sn tape has an excellent Jc(Nb
3
Sn) in high field. Their Jc(Nb
3
Sn) ,for instance, are 4.0 × 10
⁵
A/cm
²
(at 11T) for CVD-Nb
3
Sn and 1.7 × 10
⁵
A/cm
²
(at 15T) for diffusion processed Nb
3
Sn tape, respectively. The upper critical field Bc2 are determined extrapolately by using Kramer's scaling law for flux pinning. A discussion is presented respect of the results of measurement and the upper critical field.