A general scaling relation for the critical current density in Nb3Sn

Abstract

We review the scaling relations for the critical current density (Jc) in Nb3Sn wires and include recent findings on the variation of the upper critical field (Hc2) with temperature (T) and A15 composition. We highlight deficiencies in the Summers/Ekin relations, which are not able to account for the correct Jc(T) dependence. Available Jc(H) results indicate that the magnetic field dependence for all wires can be described with Kramer's flux shear model, if non-linearities in Kramer plots are attributed to A15 inhomogeneities. The strain (eps) dependence is introduced through a temperature and strain dependent Hc2*(T,eps) and Ginzburg- Landau parameter kappa1(T,eps) and a strain dependent critical temperature Tc(eps). This is more consistent than the usual Ekin unification, which uses two separate and different dependencies on Hc2*(T) and Hc2*(eps). Using a correct temperature dependence and accounting for the A15 inhomogeneities leads to a remarkable simple relation for Jc(H,T,eps). Finally, a new relation for s(eps) is proposed, based on the first, second and third strain invariants.

Accepted Topical Review for Superconductor, Science and Technology

References in corpus (4)

• A Review of the Properties of Nb3Sn and Their Variation with A15 Composition, Morphology and Strain State
• The upper critical field of filamentary Nb3Sn conductors
• Specific heat of Nb_3Sn: The case for a second energy gap
• Simulations of the effects of tin composition gradients on the superconducting properties of Nb3Sn conductors

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