Critical Transport Current Properties in the High-temperature Region of Cu added MgB₂ Wire using a Mg₂Cu Compound as the Additional Source Material

Abstract

The advantages of using a MgB₂ compound in fusion applications are not only higher T_c (39 K) and low cost but also lower induced radioactivity than Nb-based superconductors. However, the J_c value of MgB₂ wire is lower than that of Nbbased superconducting wire, and further improvement in J_c is required for use in advanced fusion reactor applications. Furthermore, the selection of low-activation sheath material is also required to keep the low induced radioactivity property. We prepared a Cu-added MgB₂/Ta/Cu mono-cored wire using a Mg₂Cu compound as the source material via a low-temperature diffusion process, and the transport J_c-B performances in the 4.2 K to 20 K temperature region were measured in order to investigate the possibility of the high-temperature operation.