Patent ID: 8626254

Claim:
A metal assembly precursor for a superconductor, comprising: at least one conductor element adapted to provide a superconducting filament in the finished superconductor, each at least one conductor element configured as a rod; at least one doping element providing a doping source for doping the conductor element, each at least one doping element configured as a rod, the at least one doping element rod being distinct from the at least one conductor element rod; a sleeve element made of Cu or a Cu-alloy arranged outside the conductor element and the doping element; and a Sn-source; wherein the conductor elements comprise a conductor core containing Nb and possible impurities, the doping elements comprising a doping core comprising a NbTi-alloy with a Ti content between 20-60% by weight, and a doping element casing made of Cu or a Cu-alloy; wherein the assembly comprises at least as many doping elements arranged outside the conductor elements as the number of conductor elements; wherein the doping elements comprise a diffusion-blocking layer arranged as a coating on the doping core and adapter to block the diffusion of the doping substance at temperatures below a desired diffusion temperature; wherein the doping element casing is arranged around the core and the diffusion-blocking layer.