Critical current degradation in Nb3Sn cables under transverse pressure

The critical current degradation of a few sample Rutherford-type Nb3Sn cables is investigated as a function of transverse pressure. A comparison is made between Nb3Sn strands produced by the powder-in-tube, bronze, and modified jelly roll processes. The (keystoned) Rutherford cables are charged at 11 T under transverse pressures up to 250 MPa. Large differences in critical current reduction are observed, ranging from 6 to about 60% at 200 MPa, depending on the type of Nb3Sn. It appears that about 40% of the total reduction is irreversible. Moreover, the irreversible part shows relaxation, and a partial recovery is possible by thermal cyclin