A 24-filament NbTi superconducting wire for application in magnetic resonance imaging magnets

A 24-filament NbTi superconducting wire in copper matrix, has been developed by Pirelli S.A. Companhia Industrial Brasileira, to be used in magnets for Magnetic Resonance Imaging. The fabrication process starts with the production of a very long monofilament wire. The 24 filaments are then continuously assembled in the proper configuration and drawn down to the final size. This process avoids the hot extrusion stage that is necessary in the fabrication method commonly used. The wire produced has a very sharp superconducting-to-normal resistive transition, with values of n (the exponent of the resistivity as a function of the current through the transition) unusually high. The current capacity is comparable to that of similar commercially available wires. (author)