In order to verify the feasibility of applying high-Jc Nb_(3)Sn strand in fusion magnet,a full-size cable-in-conduit conductor(CICC)with short twist pitch(STP)cable pattern was manufactured and tested in SULTAN facili...In order to verify the feasibility of applying high-Jc Nb_(3)Sn strand in fusion magnet,a full-size cable-in-conduit conductor(CICC)with short twist pitch(STP)cable pattern was manufactured and tested in SULTAN facility at SPC,Switzerland.Three levels of cyclic electromagnetic(EM)load were applied on the sample stepwise,no visible decrease of current sharing temperature(TcsT was observed until the EM load increased to 80 kA×10.8 T,after that the Tcs decreased dramatically with the EM cycles,which suggested that irreversible deformation,causing a change in the strain state,or even damage has occurred in the superconducting strands.For investigating the reason which caused the conductor performance degradation,the tested conductor was dissected for metallographic observation.Eight segments which subjected to different EM loads were extracted from one of the legs,the geometric feature changes of the cable cross-sections were analyzed and compared.A good correlation was found between the decrease of the Tcs and deformation of the cable cross section.A mass of cracks were found on the sub-elements of strands in the segment which subjected to highest EM load,but the amount of crack is much lower in other segments.Combining the analyses,it is speculated that the critical EM load which causes irreversible degradation is between 850 kN/m and 870 kN/m for this conductor.The results could be a reference in high-Jc Nb_(3)Sn CICC design.展开更多
Since the discovery of high T_c oxide superconductor, scientists and engineers aredeeply concerned with the possibility of its application to the electric machine withstrong operating current at high magnetic fields. ...Since the discovery of high T_c oxide superconductor, scientists and engineers aredeeply concerned with the possibility of its application to the electric machine withstrong operating current at high magnetic fields. Because of the serious problem ofweak link in the sintered bulk materials processed by regular ceramic powder technolo-gy, the critical current density at 77.3 K is low and it gets much lower with theincreasing magnetic field. Scientists look forward to heighening J_c of the high T_c ma-展开更多
The microstructure and defects in melt-textured growth (MTG) YBa2Cu3O7-x (YBCO) bulk material have been studied systematically using high resolution transmission electron microscopy (HREM), and the relationship betwee...The microstructure and defects in melt-textured growth (MTG) YBa2Cu3O7-x (YBCO) bulk material have been studied systematically using high resolution transmission electron microscopy (HREM), and the relationship between the anisotropic critical current density Jc and the microstructure has been explored. The results indicate that there are numerous dense and nonunifonnly-distributed intergrowth-type layered defects orienting parallel to the ab plane in MTG-YBCO. These defects may serve as effective flux pinning centres for H//ab. The layered defects parallel to the ab plane together with the {110} twin boundaries are probably responsible for the anisotiopic behaviour of Jc depending upon the orientation of the external magnetic field.展开更多
基金supported by the National Key R&D Program of China(Grant No.2017YFE0301404)the Comprehensive Research Facility for Fusion Technology Program of China under Contract No.2018-000052-73-01-001228。
文摘In order to verify the feasibility of applying high-Jc Nb_(3)Sn strand in fusion magnet,a full-size cable-in-conduit conductor(CICC)with short twist pitch(STP)cable pattern was manufactured and tested in SULTAN facility at SPC,Switzerland.Three levels of cyclic electromagnetic(EM)load were applied on the sample stepwise,no visible decrease of current sharing temperature(TcsT was observed until the EM load increased to 80 kA×10.8 T,after that the Tcs decreased dramatically with the EM cycles,which suggested that irreversible deformation,causing a change in the strain state,or even damage has occurred in the superconducting strands.For investigating the reason which caused the conductor performance degradation,the tested conductor was dissected for metallographic observation.Eight segments which subjected to different EM loads were extracted from one of the legs,the geometric feature changes of the cable cross-sections were analyzed and compared.A good correlation was found between the decrease of the Tcs and deformation of the cable cross section.A mass of cracks were found on the sub-elements of strands in the segment which subjected to highest EM load,but the amount of crack is much lower in other segments.Combining the analyses,it is speculated that the critical EM load which causes irreversible degradation is between 850 kN/m and 870 kN/m for this conductor.The results could be a reference in high-Jc Nb_(3)Sn CICC design.
基金Project supported by the National Center for R & D on Superconductivity of China.
文摘Since the discovery of high T_c oxide superconductor, scientists and engineers aredeeply concerned with the possibility of its application to the electric machine withstrong operating current at high magnetic fields. Because of the serious problem ofweak link in the sintered bulk materials processed by regular ceramic powder technolo-gy, the critical current density at 77.3 K is low and it gets much lower with theincreasing magnetic field. Scientists look forward to heighening J_c of the high T_c ma-
基金Project supported by the National Center for R & D on Superconductivity of China and the Chinese Academy of Sciences.
文摘The microstructure and defects in melt-textured growth (MTG) YBa2Cu3O7-x (YBCO) bulk material have been studied systematically using high resolution transmission electron microscopy (HREM), and the relationship between the anisotropic critical current density Jc and the microstructure has been explored. The results indicate that there are numerous dense and nonunifonnly-distributed intergrowth-type layered defects orienting parallel to the ab plane in MTG-YBCO. These defects may serve as effective flux pinning centres for H//ab. The layered defects parallel to the ab plane together with the {110} twin boundaries are probably responsible for the anisotiopic behaviour of Jc depending upon the orientation of the external magnetic field.
