Flux pinning in Nb3Sn multifilamentary conductors

Magnetization measurements on diffused reacted samples were made at several temperatures T, between 4.2K and T
c
and magnetic fields H up to 75 kOe. The samples were distinguished from each other by different heat treatments and diameter sizes ranges from 200-500 μm. From these measurements J
c
(H,T) and F
p
(H,T) curves were derived where F
p
is the flux pinning force density. For all samples, F
p
(H,T)/F
pmax
(T) vs H/H
c2
needs to be described by two functions, one for T < 8K and the other for T > 8k. This is in contrast to other materials where flux pinning is usually described by a single function.