Recent Results from R&D on Superconductors at CRPP

Abstract. Prototype conductors for the ITER magnets have been tested extensively in the SULTAN facility at CRPP in the last decade. The in depth characterization of the high current carrying conductors provided a valuable feedback in the design, with performance optimization and cost reduction. From the transient stability results, the temperature margin required to withstand the plasma disruption has been found to be much smaller than originally assumed. A comparison between two specially designed conductors showed that the copper fraction in the superconducting Nb3Sn composite can be reduced without affecting the stability, leading to a substantial reduction of the overall amount of superconducting composite to be procured for the ITER magnets. AC loss measurements carried out over a broad range of frequency, brought evidence of two regimes of losses, complementing the test results of the ITER model coils and indicating that the correct eddy currents loss to be retained in the design for plasma disruption and initiation is much smaller than the value extrapolated from the slow charge of the model coils. Other results on current distribution, cyclic load and joint performance are briefly reported