Critical current measurements of High-Jc Nb3Sn Rutherford cables under Transverse Compression

摘要

For the LHC upgrade, CERN has launched a large program to develop next generation accelerator magnets based on high-Jc Nb3Sn Rutherford cables. These magnets are characterized by a magnetic field and/or an aperture significantly larger than that of current Nb-Ti LHC magnets. The increased field/aperture will require coil pre-stresses much larger than 100 MPa. Since Nb3Sn cables are extremely sensitive to strain, critical current measurements under traverse compression are essential to estimate the transport current properties of the conductor within the magnet. To this purpose CERN has developed a sample holder (to be used in the FRESCA test station) that allows testing Rutherford cables under a transverse force of up to 2 MN/m. The new holder can house cable samples up to 1.8 m long and 20 mm wide. The large transverse force is only applied over the sample high field region, which is 70 cm long and over which the FRESCA dipole magnet generates a homogeneous fields of up to 10 T. Recently the critical current of the first cable sample has been measured at different transversal loads ranging from 90 MPa to 155 MPa. The measurement was carried out at 4.3 K on a 10 mm wide Rutherford cable based on eighteen Powder In Tube (PIT) wires with a diameter of 1.0 mm. In this paper the results of the test are reported, discussed and compared with recently measured data of the same single wire (1.0 mm PIT) tested under transverse loads.