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Critical-Current Measurements on ITER Nb3Sn Strands: Effect of Temperature



Loren F. Goodrich, Najib Cheggour, John (Jack) W. Ekin, Theodore C. Stauffer


Transport critical-current (IIc) measurements were made on commercial multifilamentary Nb3Sn strands at temperatures (T) from 4 to 17 K and magnetic fields (H) from 0 to 14 T. Samples investigated were taken from the stage 1 pre-production strand for the central solenoid of the International Thermonuclear Experimental Reactor (ITER) project. Specimens were mounted on a three-turn Ti-6Al-4V (percent by mass) mandrel, which was a shorter version of the standard ITER critical-current mandrel. The measurements covered the range of critical currents from less than 0.1 A to over 700 A. To verify the accuracy of the variable-temperature measurements, we compared critical-current values obtained on a specimen that was immersed in liquid helium at 5 K to those measured on the same specimen in flowing helium gas at the same temperature. This comparison indicated our ability to control specimen temperature to within 60 mK during measurements. The critical-current data presented include electric-field versus temperature (E-T) characteristics, Ic(T) at constant H, and extrapolated effective upper critical field as a function of temperature. These data are needed to determine the temperature margin of ITER magnets.
IEEE Transactions on Applied Superconductivity


Critical-current density, fusion energy, niobium-tin, superconducting wires, upper critical field, variable temperature


Goodrich, L. , Cheggour, N. , Ekin, J. and Stauffer, T. (2005), Critical-Current Measurements on ITER Nb3Sn Strands: Effect of Temperature, IEEE Transactions on Applied Superconductivity, [online], (Accessed May 23, 2024)


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Created July 28, 2005, Updated October 12, 2021