Characterization of superconductors with artificial pinning microstructures

Extension of the APC approach to Nb3Sn requires that a second phase be introduced into the Nb3S reaction layer with the intent of increasing the volume pinning strength. This can be achieved by either the refinement of the Nb3S grains due to the presence of a second phase or by the second phase itself pinning flux. If a bronze-type process is to be used a different addition than Zr is required since internal oxidation of Nb is not possible. The criteria for elements to be candidates for the APC approach are discussed. The results for one of the candidates (Ag) show that it is not incorporated into the Nb3S, however, its addition did increase the growth rate