Magnetization Measurements of High-JcNb₃Sn$ Strands

This is the authors' abstract. We don't add key points for this paper.

High critical current density Nb3Sn wires (Jc> 2500 A/mm2at 4.2 K and 12 T) are the conductors considered for next-generation accelerator magnets. At present, the large magnetization of these strands is a concern within the scientific community because of the impact it might have on the magnet field quality. In order to characterize the magnetic behavior of these wires, an extensive campaign of magnetization measurements was launched at CERN. Powder-in-tube strands by Bruker-EAS and Restacked Rod Process strands by Oxford Superconducting Technology were measured between 0 and 10.5 T at different temperatures (ranging from 1.9 to 14.5 K). The samples, based on strands with different subelements dimensions (35 to 80 μm), were measured with a vibrating sample magnetometer. The experimental data were analyzed to: (1) calculate the effective filament size and the optimal parameters for the pinning force scaling law and (2) define the field-temperature region where there are flux jumps. It was found that the flux-jump can limit the maximum magnetization of the Nb3Sn wires and that the maximum magnetization at higher temperatures can be larger than the one at lower temperatures. In this paper, the experimental results and the analysis are reported and discussed.