Western Superconducting Technologies Co Ltd Development of Nb

Western Superconducting Technologies Co. , Ltd 西部超导 Development of Nb 3 Sn wire for high magnetic field at WST Xiaguang Sun June 16, 2015

Western Superconducting Technologies Co. , Ltd 西部超导 Outline Ø Introduction of WST Main products in WST Ø Performances of sample Ø Main challenges Ø Conclusions

Western Superconducting Technologies Co. , Ltd 西部超导 WST was founded on February 28, 2003, and the main aim was ITER project. China undertook: (WST produced all the strands) • 180 t Nb. Ti strand: 69% PF, 100% CC and Feeder • 30 t Nb 3 Sn strand: 7% TF International Thermonuclear Experimental Reactor (ITER)

Western Superconducting Technologies Co. , Ltd 西部超导 Low Temperature Superconducting Strands for ITER Nb. Ti Bronze Nb 3 Sn Internal Tin Nb 3 Sn ITER PROJECT

Western Superconducting Technologies Co. , Ltd 西部超导 Nb. Ti/Cu Superconducting Wires for MRI/NMR Round wires Nb. Ti strands for MRI

Western Superconducting Technologies Co. , Ltd 西部超导 Ic stability of strands designed for ITER project Ic (4. 22 K, 12 T) IT Nb 3 Sn strand Bronze Nb 3 Sn strand Nb. Ti strand All values are larger than the lower ITER limit with good stability.

Western Superconducting Technologies Co. , Ltd 西部超导 Based on the IT-Nb 3 Sn/Cu wire for ITER project Cross-section of IT Nb 3 Sn Jc as a function of magnetic field * S. Hong et al. MT 19 2005 Aim at Jc >2000 A/mm 2(12 T, 4. 2 K), or even reach to 3000 A/mm 2

Western Superconducting Technologies Co. , Ltd 西部超导 Performances of sample Jc, non as a function of Nb content As the Nb content increases: predicted Ø Jc, non increases； Ø The difficulty of wire manufacture will be double. And a higher Jc was in plan this year, that is Jc>3000 A/mm 2 Jc non as a function of Nb content

Western Superconducting Technologies Co. , Ltd 西部超导 Performances of sample Jc, non as a function of Nb filament size Ø When the Nb size is 6 um, Jc, non reaches the highest value； Ø When the Nb size is below 2 um, the filament breackage may be the main problems. Jc non. Cu as a function of Nb filment size As the Nb filament size decreases, Jcn firstly increases and then decreases.

Western Superconducting Technologies Co. , Ltd 西部超导 Performances of sample F(N) as functions of B(T) with different heattreatment Ø 1#~6#：Nb/Sn=2. 5 Ø 3 -1#~3 -3#：Nb/Sn=2. 0 Ø 1#~4#：heat-treatment at 660℃ Ø 5#： heat-treatment at 750 ℃ Ø 6#，3 -1#~3 -3#：heat-treatment at 650℃ F(N) as functions of B(T) at different HT temperature The better HT temperature is near to 650℃.

Western Superconducting Technologies Co. , Ltd 西部超导 Performances of sample RRR value as a function of heat-treatment time When the heat-treatment temperature is fixed at 650℃ Ø As the time prolong, RRR value decreases; Ø The time is lower than 20 h, Jc is lower than 2000 A/mm 2. New design for higher RRR as a function of heat-treatment time The better HT time is near to 40 h. value was in plan this year, that is high Jc with improved RRR.

Western Superconducting Technologies Co. , Ltd 西部超导 Performances of sample The final size of sub-elements 54 sub-elements 84 sub-elements As the numbers of sub-element increases from 54 to 84, Ø The final size of sub-element decreases, from ~90 um to ~80 um; Ø The breackage increases during wire drawing. To reduce the sub-element size is in the following work. To decrease the sub-element size is a big challenge.

Western Superconducting Technologies Co. , Ltd 西部超导 Performances of sample Information of the wire Table of the wire paramater Items parameter Size Φ 0. 621～ 0. 81 mm No. of sub-elements 54 No. of Nb filaments in sub-element 324 No. of Nb. Ti filaments in sub-element 18 No. of Nb filaments 342× 54=18468 Cu：non-Cu 1. 3 Nb filament size 2~5μm Ic（12 T，4. 2 K） 129～ 600 A Jcn（12 T，4. 2 K） 2000～ 2700 A/mm 2

Western Superconducting Technologies Co. , Ltd 西部超导 Main challenges already challenges Unit length >1000 m (Jcn<2500 A/mm 2) >1000 m (Jcn>2500 A/mm 2) Jc, non 2000~2700 A/mm 2 >3000 A/mm 2 Deff. 70~90 um 40~50 um grain size (after HT) 100~200 nm 20~50 nm

Western Superconducting Technologies Co. , Ltd 西部超导 Conclusions Ø WST succeeded in producing superconducting strands for ITER project with good stability; Ø Based on producing IT Nb 3 Sn strand, WST have made a progress on R&D of high Jc Nb 3 Sn strand； Ø The development of high field magnet gives us challenges to improve performances of Nb 3 Sn strand.

Western Superconducting Technologies Co. , Ltd 西部超导 Thanks for your attention!