Flux pinning in Nb3Sn multifilamentary conductors

Magnetization measurements on diffused reacted samples were made at several temperatures T, between 4.20K and T/sub c/ and magnetic fields H up to 75 kOe. The samples were distinguished from each other by different heat treatments and diameter size ranges from 200 to 500 μm. From these measurements, J/sub c/(H,T) and F/sub p/(H,T) curves were derived, where F/sub p/ is the flux pinning force density. For all samples, F/sub p/(H,T)/F/sub pmax/ (T) vs H/H/sub c2/ needs to be described by two functions, one for T less than 80K and the other for T greater than 80K, in contrast to other materials where flux pinning is usually described by a single function