Development of a forced-cooled Nb3Sn bundle conductor

Forced flow cable conductors using Nb3Sn superconductors have been developed. In manufacturing the cable-in-conduit type conductors, some problems are considered. Initial phase of investigations of these problems have been carried out. Some results of the investigations are discussed and described in this paper. Using a roll-forming method, the reliable manufacture of the long length cable-in-conduit type conductors has been achieved. By forming the Cu2O+ Cu²S film on the surface of strands, there was no adhesion between strands after the heat treatment at high temperature for a long time. Both Nb3Sn superconductors by the bronze process and the tube method have achieved a critical current density in the non copper area of more than 400A/mm²at 12T, 4.2K.