Characterization of ${\rm Nb}_{3}{\rm Al}$ Strands Subjected to an Axial-Strain for a Fusion DEMO Reactor

A Nb₃Al strand, produced by the ldquorapid-heating, quenching and transformation annealing (RHQT)rdquo process, has been developed in collaboration between JAEA and NIMS aiming at application to the conductor in a fusion DEMO reactor. A detailed description of critical current characteristics of the Nb₃Al RHQT strand may assist in predicting accurate conductor performance. Calculations of the critical current density are adjusted to 5 scaling laws. Advantages of the newly developed strand compared to the Nb₃Sn ITER strand and the Nb₃Al Insert strand include improved strain tolerance and a higher current density at around 16 T. Performance parameters of the Nb₃Al RHQT strand include 450 A/mm² at 15.9 T, 5.7 K and -0.4%. These performance parameters fulfill the requirements of the TF conductor of the fusion DEMO reactor. Therefore, the Nb₃Al RHQT strand represents an improved performance with prospective application in the fusion DEMO reactor. In addition, the Nb₃Al RHQT strand has the potential to enhance further the critical current density.