A control line for the qualification of large quantities of superconducting wires

The fabrication of the coils for the toroidal field of Tore Supra has now been ordered. The first lengths of conductors are expected in February 1983. A special line has been developed, in order to control at room temperature the overall production of the 320 kms of conductor in a continuous process. Special attention is drawn on the shape, the mechanical integrity and homogeneity of the conductor. The geometrical sizes are measured by two special devices. One uses Hall probes moving in the bore of permanent magnets, the other explores the outer surfaces with diamonds attached to electric sensors. The resistance of each meter of conductor can be directly related to the local amount of Niobium-Titanium, and provides a very good information on the homogeneity of the composite. A device developed by the CEA using induced eddy currents is able to detect very local changes in the amount of copper, and the presence of voids, bad bonding, inclusions and surface defects.