Some Factors Involved in the Development of a Tubular Process for Nb3Sn Conductors

A process designed to produce Nb₃Sn conductors by simply restacking Nb 7.5 wt.%Ta tubes with Cu-clad Sn cores is being explored. Previous work has shown that, in this tubular process, the A-15 compound forms in a somewhat different manner from that in the conventional internal-tin process. It was necessary therefore to determine if this had a significant effect on the properties of the A-15 formed. This was done with subelements containing different percentages of Nb 7.5 wt.%Ta, Sn and Cu. The initial work on single subelements has been extended to include restacks with relatively large numbers of subelements. The critical current density (J_c) of the various designs is reported and some of the factors involved in optimizing the properties are discussed.