Speaker
Description
We present a study on performance limitations and effects on pinning force scaling behavior of A-15 phase inhomogeneity, in particular Sn concentration gradients, in commercial PIT and RRP Nb3Sn wires. Our results were obtained from SQUID magnetometry, scanning Hall probe microscopy, and numerical simulations. Our key findings are that even small radial Sn concentration gradients inside sub-elements cause a significant spatial variation of the critical current density, and that the local superconducting properties of individual sub-elements exhibit a much larger deviation than suggested by SEM examinations of wire cross sections. We point out the potential performance gain achievable by reducing the A-15 inhomogeneity, and discuss the pitfalls in pinning force scaling analysis related to Sn concentration gradients.
