Manufacture and evaluation of Nb3Sn conductors fabricated by the MJR method

The bronze matrix/niobium filament process has become established as a commercially viable method for producing multifilamentary Nb3Sn superconductors. This paper describes a new method, the Modified Jelly-Roll (MJR) approach, which can produce a structure similar to that in a conventionally fabricated multifilamentary Nb3Sn conductor. This approach utilizes alternate sheets of niobium expanded metal and bronze, which are rolled into a "jelly-roll" configuration and then extruded. During extrusion and subsequent drawing, the junctures in the niobium are elongated and the material develops a filamentary structure. This method may offer significant advantages in terms of reduced fabrication time and cost over the conventional approach. Results of a manufacturing development program will be presented in which two lengths of conductor were made to High-Field Test Facility conductor specifications. In addition, critical current and transition temperature measurements of the sub-elements used to construct the HFTF-type lengths will be reported.