Assessing composition gradients in multifilamentary superconductors by means of magnetometry methods

TL;DR

This paper introduces two magnetometry techniques, AC magnetometry and Scanning Hall Probe Microscopy, for assessing composition gradients in multifilamentary superconductors, demonstrated on Nb3Sn wires and compared with EDX results.

Contribution

It presents novel magnetometry methods for evaluating composition gradients in superconductors, including an iterative evaluation procedure and direct visualization capabilities.

Findings

AC magnetometry effectively assesses critical temperature gradients.

Scanning Hall Probe Microscopy visualizes magnetic field penetration related to composition.

Results compare favorably with EDX measurements.

Abstract

We present two magnetometry-based methods suitable for assessing gradients in the critical temperature and hence the composition of multifilamentary superconductors: AC magnetometry and Scanning Hall Probe Microscopy. The novelty of the former technique lies in the iterative evaluation procedure we developed, whereas the strength of the latter is the direct visualization of the temperature dependent penetration of a magnetic field into the superconductor. Using the example of a PIT Nb3Sn wire, we demonstrate the application of these techniques, and compare the respective results to each other and to EDX measurements of the Sn distribution within the sub-elements of the wire.