Study on High Residual Resistance Ratio (RRR) of Wire in Channel Superconductor Wire

This paper studies the process and technology to obtain high Residual Resistance Ratio (RRR) of Wire in Channel (WIC) NbTi/Cu superconducting wires through three methods. The first method is online annealing on medium frequency furnace using NbTi/Cu wire and C10100 copper channel wire in hard state before soldering. The second method uses C10100 copper channel wire to anneal in the vacuum furnace, followed by soldering using NbTi/Cu wire and C10100 copper channel wire in annealing state. And the third method uses C11000 copper channel wire of higher oxygen content and NbTi/Cu wire to solder directly. The results show that the three methods can improve the RRR value. Specifically, with the increase of power, the first method can raise the RRR of WIC. With the increase of anneal temperature, the second method can raise the RRR of C10100 copper channel wire and WIC wire. Finally, the third method can promote the RRR of C11000 copper channel wire and WIC wire to relatively higher levels, which is excellent for mass production.