The effect of Sn arrangement and intermediate pre-heating on critical current in internal tin processed Nb3Sn wires

Internal tin processed Nb3Sn wires of different diameters were locally heat ed before reaction heat treatment. Local heating at an intermediate stage o f drawing process decreased the superconducting properties and workability. When the local heating temperatures were lower than the melting point of S n, non-Cu J(C) 's decreased a little compared to non-locally heated wire. B ut when the local heating temperatures were higher than melting point of Sn , non-Cu J(C) 's decreased significantly. This study also suggested it is i mportant that the Sn reservoir be arranged uniformly and is dispersed.