Unifying the strain and temperature scaling laws for the pinning force density in superconducting niobium-tin multifilamentary wires

Systematic variable temperature measurements of the transport critical current density (J(c)) tolerance to strain (epsilon), performed on a bronze processed niobium-tin multifilamentary wire in high magnetic fields up to 15 T, are reported. The results show that B-c2*(T,epsilon), the field at which the pinning force density (F-p) extrapolates to zero, can be written as B-c2*(0,epsilon)g[T/T-c*(epsilon)], where g is a function of the reduced temperature T/T-c*(epsilon) and T-c*(epsilon) is the temperature at which B-c2* extrapolates to zero. We propose a magnetic field, temperature, and strain scaling law for F-p which unifies Ekin's strain scaling law and the Fietz-Webb variable temperature scaling law. It is of the form F-p=J(c)xB=A(epsilon)[B-c2*(T,epsilon)](n)b(p)(1-b)(q), where n, p, and q are constants, A(epsilon) is a function of strain alone, and b is the reduced field B/B-c2*. (C) 1999 American Institute of Physics. [S0021-8979(99)04412-6].