Evaluation of the scattering in critical current and Niobium-Titanium volume fraction along a length of conductor

The knowledge of critical current at any point of a length of a conductor has always been a wish for a coil designer. It is now possible to contemplate this matter without running the whole length at helium bath temperature. From the local resistance per metre of composite measured at room temperature it is possible to derive the cross sectional area of the Niobium-Titanium. We show from samples taken along lengths of different conductors that the cross sectional areas derived from weighing the Niobium-Titanium and from the resistance per metre measurements are in very good agreement and that the current density is constant along a given length. As a result the critical current can be estimated from three measurements: critical current, weight of the Niobium-Titanium in a sample taken at one end and the measurement on line of the resistance per metre.