139 conductors were manufactured for the magnetic system of the ITER toroidal field coils in total by 6 different teams based on 5 different suppliers of Nb3Sn wires. Despite the fact that all conductors and superconducting wires were manufactured according to the same criteria, there were some differences in the manufacturing technologies of the components themselves, and in the result of the acceptance tests. Samples of some of the conductors passed acceptance tests, where the dependence of Tcs on the number of cycles of inputting the operating current into the samples when they were in a magnetic field was determined. The results of these tests showed that there are not only quantitative, but also qualitative differences in the Tcs (N) dependence. These differences are also observed within the same supplier. It would be useful to understand which parameters most strongly contribute to Tcs (N) in order to possibly improve this characteristic. For this purpose, the article provides a statistical analysis of the test results of 49 samples of conductors. The results are being discussed.

The test results of the ITER toroidal field conductors demonstrated a decrease of the current sharing temperature (Tcs) with an increase in the number of electromagnetic cycles in general. This is associating with several factors. One of them is the superconducting Nb3Sn filaments cracking and another one is the redistribution of the relative deformation of the Nb3Sn strands under Lorentz forces. Despite these factors, some conductors have shown the absence or significantly less degradation of Tcs during electromagnetic cycling. This article considers another possible reason for a more stable conductors Tcs behavior, namely, the local compression of Nb3Sn wires in the cross section of a conductor. In this article presents the results of a quantitative analysis Nb3Sn superconducting filaments cracking of strands extracted from a conductor that has passed electromagnetic cycling and the model of a conductor compaction, as well as calculation results based on this model are presented also.