Development of Nb3Al/Cu Multifilamentary Superconductors
The Nb3A1 superconductor has been expected to the application under the high field, such as the one for International Thermo-nuclear Experimental Reactor (ITER), on the point of superior characteristics of Ic under stress. The present status of the development of Nb3A1 superconducting wires manufactured by the Jelly-Roll process is presented in this paper. The recent development has achieved the Nb3A1 superconductor stabilized by the copper matrix with a high critical current density and a low hysteresis loss. In the development, the microstructure of Nb-Al compound phases, each identified by EDS, are observed. The volume of each Nb-Al phase calculated by the Image Analysis System is discussed in terms of its dependence of Jc. With a non-copper critical current density of more than 550 A/mm2 at 12T, the wire features excellent high field characteristics, for example μ0Hc2 is 21.5T. Also, this wire has less degradation of Ic by strain compared to Nb3Sn. Hysteresis losses in the wire was measured by the magnetization method. For the field perpendicular to the wire length, it was shown that the effective filament diameter is almost equal to the actual filament diameter (21μm). On the other hand, the hysteresis loss for the parallel field was around one-fourth as large as that for the perpendicular one, corresponding to an effective filament diameter of approximately 8 µm. The 40kA-class cable-in-conduit conductor was fabricated to demonstrate its applicability to fusion magnets. The critical current test of the conductor proves that the capacity of 40kA is attained at 11.2T. The practical 10kA-–100m class long length cable-in-conduit conductor, of which conduit is Titanium, was fabricated first in the world.
KeywordsCritical Current Density Wire Diameter Hysteresis Loss Parallel Field Transmission Electron Microscopy Photo
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- 2.B. Annaratone, R. Buzzese, S. Ceresara, V. Pericoli-Ridolfini, G.Pitto and N.Sacchetti, “Effect of the Thickness of Al Layer on the Transport Properties of Nb3A1 Superconducting Wires”, IEEE Trans. on Mag., MAG-17, 1000–1001, 1981.Google Scholar
- 3.J. W. Ekin, “Strain Effects in Superconducting Compound”, Advances in Cryogenic Engineering Materials, 30, 823–836, 1984.Google Scholar
- 4.K. Ohmatsu, G. Oku, H. Takei, M. Nagata, T. Ando, M. Nishi, Y. Takahashi and S. Shimamoto, “Development of Nb3A1 Multifilamentary Wire by Jelly-roll Process”, IAEA Specialists’ Meeting on Superconducting materials and Magnets, Tokyo, September 1989.Google Scholar
- 5.D. Zeritis, T. Ando, Y. Takahashi, M. Nishi, H. Nakajima and S. Shimamoto, “The transverse stress effect on the Critical current density of Jelly-roll multifilamentary Nb3A1 wires”, IEEE Trans. on Mag. MAG-27, 1829–1830, 1991.Google Scholar
- 6.T. Ando, Y. Takahashi, M. Nishi, Y. Yamada, K. Ohmatsu, M. Nagata, “AC losses in a Multifilamentary Nb3AI/Cu Composite Superconductor by a Jelly-Roll Process”, ICMC’91, Huntsville, June, 1991.Google Scholar
- 7.Y. Yamada, K. Ohmatsu, M. Nagata, T. Ando, Y. Takahashi, M. Nishi, “Development of Nb3A1 Superconductor Using the Jelly-Roll Process”, Sumitomo Electric Technical Review, 33, 83–90, 1992.Google Scholar
- 9.S. Saito, K. Ikeda, S. Ikeda, A. Nagata, K. Noto, “Nb3A1 Superconducting wires fabricated by the clad-chip extrusion method”, 11th International Conference on Magnet Techonology, Tsukuba, August, 1989.Google Scholar
- 11.W. Specking, H. Kiesel, H. Nakajima, T. Ando, H. Tsuji, Y. Yamada, M. Nagata, “First Results of Strain Effects on Ic of Nb3Al Cable-in-Conduit Fusion Superconductors” Applied Superconductivity Conference. Chicago, 1992.Google Scholar
- 12.T. Ando, Y. Takahashi, M. Sugimoto, M. Nishi, H. Tsuji, Y. Yamada, M. Nagata, “Development of Nb3A1 Cable-in-Conduit Fusion Superconductors”, Applied Superconductivity Conference. Chicago, 1992.Google Scholar