Manufacture and evaluation of Nb<inf>3</inf>Sn conductors fabricated by the MJR method

Abstract

The bronze matrix/niobium filament process has become established as a commercially viable method for producing multifilamentary Nb <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Sn 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 Nb <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Sn 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.