Strain scaling law for flux pinning in practical superconductors. Part 1: Basic relationship and application to Nb3Sn conductors

摘要: Abstract Critical current and flux pinning densities have been determined for a series of Nb3Sn, V3Ga, Nb3Ge, NbTi conductors as function uniaxial tensile strain in magnetic fields ranging from 4 to 19 T. An empirical relationship has found at 4.2 K that describes these data over the entire range field under both compressive strain. The force F obey scaling law form = [B c2 ∗(ϵ)] n f(b) , where Bc2∗ is strain-dependent upper-critical high-field critical-current measurements only reduced b  B/B ∗ . detailed shape depends on super-conducting material reaction conditions, but was be nearly constant given type superconductor. For Nb3Sn 1 ± 0.3, multifilamentary V3Gan≅1.3, CVD-Nb3Ge tape n≅1.6, n≅3.3. importance this that, least, it possible measure one then immediately able predict (and thus critical current) other levels simply by results [Bc2∗(ϵ)]n. Part I paper presents basic uniaxial-strain focuses its application conductors. with 0.3 hold all Nb-Sn based examined far, including commercial-multifilamentary conductors, extremely fine-filament composites, partially-reacted specimens, ‘insitu’ Nb-Hf/Cu-Sn-Ga dependence was-found universal highly-reacted commercial greatly simplifying group practical superconductors. These are discussed within context models general relation proposed which unifies usual temperature-scaling strain-scaling relation.