ITER $\hbox {Nb}_{3}\hbox {Sn}$ and NbTi Strands Benchmarking at ASIPP

To ensure accurate and consistent measurement of the physical and superconducting properties of the Nb₃Sn and NbTi composite strand, a strand test facility benchmarking effort for the International Thermonuclear Experimental Reactor (ITER) was initiated in August 2008. Three rounds of benchmarking have been finished. The first round was referred to as the bronze-route Nb₃Sn strand, while the second and third benchmarking were referred to as Internal Tin Nb₃Sn and NbTi strand, respectively. As the referenced lab of the Chinese Domestic Agency, the superconducting strand test lab from the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) participated in all the three rounds of benchmarking. The benchmarking includes tests for critical current (IC), n-index, hysteresis loss, Residual Resistivity Ratio (RRR), strand diameter, Cu fraction, twist pitch (TP), twist direction, and metal plating thickness. The results from ASIPP were acceptable except for the RRR measurements on Nb₃Sn strands for the first and second benchmarking. Improvements have been made mainly for RRR and TP measurements, and the test reports for the third benchmarking were approved by the ITER organization. The test facility and test results were presented in this paper.