Development of continuous wrapping tantalum barriers for internal-tin Nb3Sn multi-filamentary wires

A process, continuous wrapping tantalum barrier, has been developed and investigated in order to reduce the manufacturing cost. By avoiding inserting expensive tantalum tube, a long sheet barrier was directly used to wrap a prior restack. In this work, a tantalum barrier with 20 % overlap was wrapped onto sub-elements. Then 18-filament Nb₃Sn plus 1 copper core restack billet was successfully drawn down and extruded into round wire as thin as a diameter of 0.84 mm. The longitudinal and cross-sectional images revealed most of barriers were continuous and intact. However, further experiments are needed to optimize the process in order to keep the all barriers continuous and intact after manufacturing.