The Influence of Dispersedly Distributed Cracks on Critical Current of the Nb3Sn Strand
- 101 Downloads
The Nb3Sn strand is the presently most widely used high field superconductor. However, one important fact is that the transport properties of an Nb3Sn strand will degrade obviously when it is subjected to high mechanical loads. Based on the dispersed distribution of cracks in the bronze strand due to a high axial tensile strain, we propose an analytical strand model to describe the influence of cracks on the critical current of the Nb3Sn strand. The dependence of the critical current I c of the strand on crack density is investigated theoretically. It is shown that the calculation results by this model agree with the experimental data. The influence of filament-to-matrix resistance r c on transport degradation is also discussed since r c is a key parameter for the total voltage calculation and its realistic value is of great importance for accurate results. We also compared the influence of dispersed and collective cracks on transport properties with specific conditions.
KeywordsNb3Sn strand Dispersed distribution Crack density Filament-to-matrix resistance Critical current density
This work was financially supported by the Funds of the National Science Foundation of China (No. 11372096, 11402073, and 11672100), the Fundamental Research Funds for the Central Universities (No. 2017B13114), and the Program for Research Fund for the Doctoral Program of Higher Education of China. The authors gratefully acknowledge these financial supports.
- 6.Sheth, M.K., Lee, P., McRae, D.M., Walsh, R., Starch, W.L., Jewell, M.C., Devred, A., Larbalestier, D.C.: Procedures for evaluating filament cracking during fatigue testing of Nb3Sn strand, pp. 201–208. https://doi.org/10.1063/1.4712097 (2012)
- 10.Jewell, M.C.: The effect of strand architecture on the fracture propensity of Nb3Sn composite wires. University of Wisconsin, Madison (2008)Google Scholar
- 21.Shin, J.K., Ochiai, S., Okuda, H., Sugano, M., Oh, S.S.: Change of the V–I curve and critical current with applied tensile strain due to cracking of filaments in Bi2223 composite tape. Supercond. Sci. Technol. 21(11), 115007 (2008). https://doi.org/10.1088/0953-2048/21/11/115007 ADSCrossRefGoogle Scholar
- 24.Bruzzone, P., Bagnasco, M., Ciazynski, D., Corte, A.D., Zenobio, A.D., Herzog, R., Ilyin, Y., Lacroix, B., Muzzi, L., Nijhuis, A.: Test results of two ITER TF conductor short samples using high current density Nb3Sn strands. IEEE Trans. Appl. Supercond. 17(2), 1370–1373 (2007)ADSCrossRefGoogle Scholar
- 26.Godeke, A., Dhalle, M., Morelli, A., Stobbelaar, L., van Weeren, H., van Eck, H.J.N., Abbas, W., Nijhuis, A., den Ouden, A., ten Haken, B.: A device to investigate the axial strain dependence of the critical current density in superconductors. Rev. Sci. Instrum. 75(12), 5112–5118 (2004). https://doi.org/10.1063/1.1819384 ADSCrossRefGoogle Scholar