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Li Z.Y.,Shanghai JiaoTong University | Li J.,Shanghai JiaoTong University | Wang Y.,Shanghai Superconductor Technology Corporation | Yao Z.,Shanghai JiaoTong University | And 5 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2016

In higherature superconducting (HTS) applications, the external magnetic field affects the performance of the critical current and the ac loss. In this study, to improve the performance, narrowing and twisting processes are first suggested for the second-generation (2G) HTS wires: the original wire with 4-12-mm width is incised into several narrow wires with the same width under 2 mm, and narrow wires are twisted around each other as tight as possible. Using the narrow wires, we prepared various types of novel wire samples with stacking and twisting structures. The main results show that the feasibility of the narrow wires with stack and twist structures is confirmed from both critical current and ac loss points of view. © 2002-2011 IEEE. Source


Ma J.,Shanghai JiaoTong University | Zhu J.M.,Shanghai Superconductor Technology Corporation | Wu W.,Shanghai JiaoTong University | Sheng J.,Shanghai JiaoTong University | And 4 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2016

Given the limited length of ReBCO coated conductors (CCs), a large number of joints is necessary in hightemperature superconducting (HTS) applications. The quality of joints largely determines the stability of the HTS applications, because joints are usually weaker than ReBCO CCs themselves concerning mechanical and electrical characteristics. To address this problem, a novel type of CC joint, which employs a fabrication process similar to CC lamination, is developed (named after "lamination joint" for convenience). In this paper, the behaviors of the lamination joints under axial tension loads and dc/ac overcurrent are investigated. Single fully laminated CCs and joints fabricated by a conventional soldering method are also studied for comparison. The lamination joints exhibit similar critical axial tensile forces (around 700 N) to the single fully laminated CCs, which are much larger than that of the conventional soldering joints. Moreover, overcurrent tests show that the lamination joints have smaller possibilities to burn out than the single fully laminated CCs. Moreover, the lamination joints are much more stable in quality and are mass producible since they are automatically fabricated by a lamination system. Furthermore, a joint resistance of several nΩ can be achieved by simply extending the splicing length to several meters. © 2016 IEEE. Source


Liu L.,Shanghai JiaoTong University | Li Y.,Shanghai JiaoTong University | Li Y.,Shanghai Superconductor Technology Corporation | Wu X.,Shanghai JiaoTong University | And 2 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2015

Through collaboration with SJTU, a pilot REBCO coated conductor fabrication line has been set up at the Shanghai Superconductor Technology Corporation Ltd., in 2013. To reduce the cost of coated conductor tapes, simplified tape architecture was developed, i.e., PLD-REBCO/Sputter-CeO2/IBAD-MgO on metal tapes with amorphous oxide barrier layer. High-quality long REBCO coated conductors have been successfully fabricated by pulsed laser deposition (PLD) plus magnetron sputter and ion-beam-assisted deposition (IBAD) processes. Under optimized conditions, the IBAD-MgO layers showed pure (001) orientation and excellent in-plane texture. AFM observation showed MgO layer had very smooth surface. The RMS is less than 1 nm. On the textured MgO layer, sputter deposited single CeO2 cap layer showed pure (001) orientation and excellent in-plane texture of 47-6°. A reel-to-reel PLD process with high deposition rate was already scaled up to 100-m/h tape speed. One-micrometer-thick REBCO films had a high critical current density of over 3.0 MA/cm2 (at 77 K, self-field). The critical current density of 2 μm thick films is still more than 2.5 MA/cm2. Hundred-meterlong coated conductor tapes with over 500 A/cm performance have been routinely fabricated. Currently, the process optimization for kilometer-long coated conductor tapes is underway. © 2002-2011 IEEE. Source


Li Y.,Shanghai JiaoTong University | Li Y.,Shanghai Superconductor Technology Corporation | Liu L.,Shanghai JiaoTong University | Wu X.,Shanghai JiaoTong University
Physica C: Superconductivity and its Applications | Year: 2015

In China, the First National Key Project on CC Program started in 2009, which was focused on developing hundred meter long class CC tapes based on PLD/RABiTS processes. In this project, SJTU mainly worked on all of functional layer deposition process development. Northwest Institute for Non-ferrous Metal Research worked on RABiTS tape fabrication. At the end of the project in 2011, SJTU successfully fabricated hundred meter long CC tapes with over 300. A/cm (at 77. K, self field) on RABiTS tapes. To develop high performance CC tapes by PLD/IBAD-MgO processes, a pilot CC fabrication line was set up at Shanghai Superconductor Technology Corporation, Ltd. in 2013. High quality long REBCO coated conductors have been successfully fabricated on flexible polycrystalline metal tapes by PLD plus magnetron sputter and IBAD processes. Under optimized conditions, the IBAD-MgO layers showed pure (0. 0. 1) orientation and excellent in-plane texture. The in-plane phi-scan rocking curve is 4-6 degrees. AFM observation showed MgO layer had very smooth surface. The RMS is less 1. nm. On the textured MgO layer, sputter deposited single cerium oxide cap-layer showed pure (0. 0. 1) orientation and excellent in-plane texture of 4-6. degree. Reel-to-reel PLD process with high deposition rate was already scaled up to 100. m/h tape speed. Hundred meters long coated conductor tapes with over 500. A/cm performance have been routinely fabricated. And now, the process optimization for kilometer long coated conductor tapes is underway. © 2015 Elsevier B.V. Source


Miao Q.,Shanghai JiaoTong University | Zhu J.M.,Shanghai Superconductor Technology Corporation | Cheng M.,Shanghai Superconductor Technology Corporation | Zhang Z.,Shanghai Municipal Electric Power Company | And 5 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2015

Joints play an important role in the application of YBaCuO-coated conductors. Given the limited length and various requirements of tapes, large numbers of joints are needed in some applications. Therefore, developing stable joints between tapes and achieving low joint resistance has become an important issue for the application of YBCO tapes. In this paper, we propose a novel superconducting joint production process and fabricate these joints with a lamination machine. A few meters or more than 10 m of joint overlapping length can be achieved, and the joint resistance can be as low as 2.25 nΩ when the overlapping length reaches 8 m. A series of experiments has been carried out to explore the joint resistance changing law, with overlap length increases, and the joint characteristics. The results show that joint resistance is inversely proportional to the overlap length. Although long bridge joints cost more, they have an incomparable advantage in that the joint resistance is distributed over the bridge joint, which allows for more stable operation and less liquid nitrogen boiloff. After joint lamination processing, the burnout current rises from 276 to 523 A. Critical current and joint resistance are not affected by the overcurrent before the joint burns out. © 2015 IEEE. Source

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