Magnetization Measurements of High-$J_{\rm c}$$\hbox{Nb}_{3}\hbox{Sn}$ Strands

B. Bordini, D. Richter, P. Alknes, A. Ballarino, L. Bottura, L. Oberli
2013 IEEE transactions on applied superconductivity  
High critical current density Nb 3 Sn wires (J c > 2500 A/mm 2 at 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 (PIT) strands by Bruker-EAS and
more » ... s by Bruker-EAS and Restacked Rod Process (RRP ® ) strands by Oxford Superconducting Technology (OST) were measured between 0 T and 10.5 T at different temperatures (ranging from 1.9 K to 14.5 K). The samples, based on strands with different subelements dimensions (35 to 80 μm), were measured with a Vibrating Sample Magnetometer (VSM). The experimental data were analyzed to: 1) calculate the effective filament size and the optimal parameters for the pinning force scaling law; 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 Nb 3 Sn 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. Abstract-High critical current density Nb 3 Sn wires (J c > 2500 A/mm 2 at 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 (PIT) strands by Bruker-EAS and Restacked Rod Process (RRP ® ) strands by Oxford Superconducting Technology (OST) were measured between 0 T and 10.5 T at different temperatures (ranging from 1.9 K to 14.5 K). The samples, based on strands with different sub-elements dimensions (35 to 80 μm), were measured with a Vibrating Sample Magnetometer (VSM). The experimental data were analyzed to: 1) calculate the effective filament size and the optimal parameters for the pinning force scaling law; 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 Nb 3 Sn 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.
doi:10.1109/tasc.2013.2240754 fatcat:7owcxd2pvvh5pc2qmfi67g2zze