We report an experimental study aiming to demonstrate the not neglegible role of un-reacted Nb on the magnetic instabilities
in superconducting Nb3Sn multifilamentary wires, observable through partial flux jumps at magnetic field values below 0.5 T.
The analyzed wires were recently developed for dipoles required in future high energy proton accelerators and are based on
the Powder-In-Tube technology. We studied both not reacted (only involving Nb filaments) and reacted wires, finding flux
jump instabilities in both cases, when performing magnetic measurements. The results can be interpreted on the basis of
the critical state modeland are coherent with the intrinsic stability criterion. |
