Comparison of Critical Current Versus Axial Strain Measurements on Internal Tin Strand at ASIPP and University of Twente

In the last decades, various methods have been used to characterize superconducting behavior versus axial strain. In cooperation with the University of Twente (UT), the Institute of Plasma Physics Chinese Academy of Sciences (ASIPP) built a facility practically similar to the so-called “Pacman” spring device. The facility allows critical current measurements of an Nb₃Sn strand at different temperature, magnetic field and applied axial strain. In the process of validating the new setup, an ITER Internal-Tin (IT) strand, which has also been measured at the UT, is tested with the ASIPP Pacman. The ITER IT wire has an irreversible strain limit around +0.3%. At ASIPP, the strand was characterized in a magnetic field from 10 to 13 T and applied axial strain from -0.7% to +0.5%. Similarities of the data obtained (I_C(ε), I_C(B) and irreversible strain limit) from the two institutes were remarkable.