Large T/sub c/, B/sub c2/ and I/sub c/ enhancement effect due to the prebending treatment for bronze route Nb/sub 3/Sn wires

In order to develop a react-and-wind (R&W) processed Nb/sub 3/Sn superconducting magnet, we investigated the influence on the superconducting properties due to the prebending treatment. Since a reacted Nb/sub 3/Sn superconducting wire reveals a very sensitive response from stress and strain, we focus on the prebending treatment which is repeatedly applied to the Nb/sub 3/Sn wire through several pulleys in the R&W coil winding process. We found that the prebending treatment doubles the I/sub c/ value at 20 T and 4.2 K for bronze route Nb/sub 3/Sn wires. This I/sub c/ enhancement effect comes from the T/sub c/ and B/sub c2/ enhancement. It turned out that T/sub c/ increases from 17.4 to 17.9 K and as a result B/sub c2/ also increases from 23.7 to 25.2 T at 4.5 K for bronze route multifilamentary Nb/sub 3/Sn wires prebent at bending strain of 1.0% and at 5 repeated times.