CRITICAL CURRENT DENSITIES OF JELLY-ROLL AND POWDER METALLURGY Nb3Al WIRES AS A FUNCTION OF TEMPERATURE AND MAGNETIC FIELD

Critical current densities of multi-filamentary Nb3Al wire made with the Jelly-Roll process (JR) and mono-core powder metallurgy process (PM) wire were measured as a function of temperature and magnetic field. The temperature dependence of the resistive critical field Bc2 was measured in PM wires. There is a significant difference between these resistive Bc2 values and the ones determined by Kramer plots. The field dependence of the critical current depends on the manufacturing method. In general, it follows a relationship that falls between pure Kramer and one where the pinning force is inversely proportional with B2. In contrast with Nb3Sn no maximum in the bulk pinning force is observed down to 3 T (0.15×Bc2).