This study explores ternary Ag-added InSn solders to develop low-resistance, reliable, and mechanically robust joints between YBCO tapes, an essential requirement for superconducting magnets, including the magnets in the fusion industry. To investigate the impact of Ag addition to the widely used SnIn solder, several solders were made by adding small amounts of Ag (1-5wt.% ) to the eutectic In-Sn solder. Lap joints were fabricated between YBCO tapes using these solders and were characterized for electrical resistivity, microstructure, and mechanical properties. According to the results, Ag addition changes the solder bulk structure with minimum impact on the interface and mainly dissolves in the In-rich phase of the solder. The joints made with Ag-added solders show significantly higher mechanical strength and ductility, with fracture shifting from the joint to the tape outside the joint region, and reasonably low electrical resistance. The optimized 5wt.% Ag addition to the binary In-Sn solder showed the best compromised joining performance as a result of a homogenous joint microstructure, offering a promising approach towards more reliable joints for superconducting magnet applications.
{"title":"Development of Ag-Added InSn Solders for ReBCO Joints","authors":"Nooshin Goodarzi;Kévin Berger;Alexander Molodyk;Mark Ainslie;Tayebeh Mousavi","doi":"10.1109/TASC.2025.3646983","DOIUrl":"https://doi.org/10.1109/TASC.2025.3646983","url":null,"abstract":"This study explores ternary Ag-added InSn solders to develop low-resistance, reliable, and mechanically robust joints between YBCO tapes, an essential requirement for superconducting magnets, including the magnets in the fusion industry. To investigate the impact of Ag addition to the widely used SnIn solder, several solders were made by adding small amounts of Ag (1-5wt.% ) to the eutectic In-Sn solder. Lap joints were fabricated between YBCO tapes using these solders and were characterized for electrical resistivity, microstructure, and mechanical properties. According to the results, Ag addition changes the solder bulk structure with minimum impact on the interface and mainly dissolves in the In-rich phase of the solder. The joints made with Ag-added solders show significantly higher mechanical strength and ductility, with fracture shifting from the joint to the tape outside the joint region, and reasonably low electrical resistance. The optimized 5wt.% Ag addition to the binary In-Sn solder showed the best compromised joining performance as a result of a homogenous joint microstructure, offering a promising approach towards more reliable joints for superconducting magnet applications.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/TASC.2026.3652981
Louis Denis;Benoît Vanderheyden;Christophe Geuzaine
The simulation of large-scale high-temperature superconducting (HTS) magnets is a computational challenge due to the multiple spatial scales involved, from the magnet to the detailed turn-to-turn geometry. To reduce the computational cost associated with finite-element (FE) simulations of insulated HTS coils, the simultaneous multi-scale homogeneous (SMSH) method can be considered. It combines a macroscopic-scale homogenized magnet model with multiple single-tape models and solves both scales monolithically. In this work, the SMSH method is reformulated using the $h$-$phi$ thin-shell (TS) approximation, where analyzed tapes are collapsed into thin surfaces, simplifying mesh generation. Moreover, the magnetic field is expressed as the gradient of the magnetic scalar potential outside the analyzed tapes. The discretized field is then described with nodal functions, further reducing the size of the FE problem compared to standard $h$ formulations. The proposed $h$-$phi$ SMSH-TS method is verified against state-of-the-art homogenization methods on a 2-D benchmark problem of stacks of HTS tapes. The results show good agreement in terms of AC losses, turn voltage and local current density, with a significant reduction in simulation time compared to reference models. All models are open-source.
{"title":"Simultaneous Multi-Scale Homogeneous H-Phi Thin-Shell Model for Efficient Simulations of Stacked HTS Coils","authors":"Louis Denis;Benoît Vanderheyden;Christophe Geuzaine","doi":"10.1109/TASC.2026.3652981","DOIUrl":"https://doi.org/10.1109/TASC.2026.3652981","url":null,"abstract":"The simulation of large-scale high-temperature superconducting (HTS) magnets is a computational challenge due to the multiple spatial scales involved, from the magnet to the detailed turn-to-turn geometry. To reduce the computational cost associated with finite-element (FE) simulations of insulated HTS coils, the simultaneous multi-scale homogeneous (SMSH) method can be considered. It combines a macroscopic-scale homogenized magnet model with multiple single-tape models and solves both scales monolithically. In this work, the SMSH method is reformulated using the <inline-formula><tex-math>$h$</tex-math></inline-formula>-<inline-formula><tex-math>$phi$</tex-math></inline-formula> thin-shell (TS) approximation, where analyzed tapes are collapsed into thin surfaces, simplifying mesh generation. Moreover, the magnetic field is expressed as the gradient of the magnetic scalar potential outside the analyzed tapes. The discretized field is then described with nodal functions, further reducing the size of the FE problem compared to standard <inline-formula><tex-math>$h$</tex-math></inline-formula> formulations. The proposed <inline-formula><tex-math>$h$</tex-math></inline-formula>-<inline-formula><tex-math>$phi$</tex-math></inline-formula> SMSH-TS method is verified against state-of-the-art homogenization methods on a 2-D benchmark problem of stacks of HTS tapes. The results show good agreement in terms of AC losses, turn voltage and local current density, with a significant reduction in simulation time compared to reference models. All models are open-source.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-7"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study optimized the structural design of NbTi superconducting wires using the analysis method combining finite element simulation with experiments. By adjusting the matrix material of the NbTi mono-filament billet, the overall deformation uniformity of the filaments was significantly improved. Considering both the optimal structural parameters obtained from simulations and the practical requirements of assembly feasibility and processing yield, the final design has been confirmed, with the matrix material of the NbTi mono-filament billet being Cu2Mn, and the spacing-to-diameter ratio (S/D) parameter and filament spacing of the NbTi multi-filament billet being 0.50 and 5.20 mm, respectively. Based on this design, NbTi multi-filament wire with 24 filaments and a copper-to-non-copper ratio of 7 was fabricated using conventional drawing and aging heat treatment processes. The wire was finally drawn to a diameter of 1.0 mm and subjected to superconducting performance tests. The results showed that, under 4.2 K and 4 T, the optimized design achieved a critical current density (Jc) of 3804 A/mm2, representing an 11.8% improvement compared with 3400 A/mm2 for the existing structure.
本研究采用有限元模拟与实验相结合的分析方法对NbTi超导导线的结构设计进行了优化。通过调整NbTi单丝坯的基体材料，可以显著提高单丝坯的整体变形均匀性。综合考虑模拟得到的最优结构参数以及装配可行性和加工良率的实际要求，确定了最终设计方案，即NbTi单长丝坯的基体材料为Cu2Mn， NbTi多长丝坯的间距/直径比（S/D）参数为0.50 mm，长丝间距为5.20 mm。在此基础上，采用常规拉伸和时效热处理工艺制备了24根铜非铜比为7的NbTi多丝丝。最后将钢丝拉制成直径1.0 mm，并进行超导性能测试。结果表明，在4.2 K和4 T条件下，优化设计的临界电流密度（Jc）为3804 a /mm2，比现有结构的3400 a /mm2提高了11.8%。
{"title":"Optimization of Filament Structure in NbTi Superconducting Wires in WST","authors":"Zhang Kailin;Guo Qiang;Jiang Longtao;Han Luyang;Wang Han;Zhao Jiajun;Li Hengchao;Zhu Yanmin;Yan Lingxiao;Wang Ruilong;Zhou Zijing;Wang Shuai;Liu Xianghong;Feng Yong;Li Jianfeng;Zhang Pingxiang","doi":"10.1109/TASC.2026.3652108","DOIUrl":"https://doi.org/10.1109/TASC.2026.3652108","url":null,"abstract":"This study optimized the structural design of NbTi superconducting wires using the analysis method combining finite element simulation with experiments. By adjusting the matrix material of the NbTi mono-filament billet, the overall deformation uniformity of the filaments was significantly improved. Considering both the optimal structural parameters obtained from simulations and the practical requirements of assembly feasibility and processing yield, the final design has been confirmed, with the matrix material of the NbTi mono-filament billet being Cu2Mn, and the spacing-to-diameter ratio (S/D) parameter and filament spacing of the NbTi multi-filament billet being 0.50 and 5.20 mm, respectively. Based on this design, NbTi multi-filament wire with 24 filaments and a copper-to-non-copper ratio of 7 was fabricated using conventional drawing and aging heat treatment processes. The wire was finally drawn to a diameter of 1.0 mm and subjected to superconducting performance tests. The results showed that, under 4.2 K and 4 T, the optimized design achieved a critical current density (<italic>J<sub>c</sub></i>) of 3804 A/mm<sup>2</sup>, representing an 11.8% improvement compared with 3400 A/mm<sup>2</sup> for the existing structure.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/TASC.2026.3652458
Matthew A. Koc;Jason Austermann;James Beall;Johannes Hubmayr;Joel N. Ullom;Michael Vissers;Jordan Wheeler
Development of high-speed, spatial-mapping spectrometers in the millimeter and far-infrared frequencies would enable entirely new research avenues in astronomy and cosmology. An “on-chip” spectrometer is one such technology that could enable Line Intensity Mapping. Recent work has shown the promise of high-speed imaging; however, a limiting factor is that many of these devices suffer from low optical efficiency. Here we present the fabrication of a metalized, Si waveguide filter-bank fabricated using deep reactive ion etching for use in millimeter spectroscopy. Our design simultaneously provides high-density pixel packing, high optical efficiency, high spectral resolution, and is readily compatible with simple and multiplexable MKID arrays. Gold plated test waveguide and filter show excellent match to simulations with a measured resolving power of 263 and a loss quality factor of 1116 at room temperature. The results show promise for extending the measurements to larger, multiwavelength designs.
{"title":"Development of Silicon Micromachined Waveguide Filter-Banks for On-Chip Spectrometers","authors":"Matthew A. Koc;Jason Austermann;James Beall;Johannes Hubmayr;Joel N. Ullom;Michael Vissers;Jordan Wheeler","doi":"10.1109/TASC.2026.3652458","DOIUrl":"https://doi.org/10.1109/TASC.2026.3652458","url":null,"abstract":"Development of high-speed, spatial-mapping spectrometers in the millimeter and far-infrared frequencies would enable entirely new research avenues in astronomy and cosmology. An “on-chip” spectrometer is one such technology that could enable Line Intensity Mapping. Recent work has shown the promise of high-speed imaging; however, a limiting factor is that many of these devices suffer from low optical efficiency. Here we present the fabrication of a metalized, Si waveguide filter-bank fabricated using deep reactive ion etching for use in millimeter spectroscopy. Our design simultaneously provides high-density pixel packing, high optical efficiency, high spectral resolution, and is readily compatible with simple and multiplexable MKID arrays. Gold plated test waveguide and filter show excellent match to simulations with a measured resolving power of 263 and a loss quality factor of 1116 at room temperature. The results show promise for extending the measurements to larger, multiwavelength designs.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 6","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/TASC.2026.3653352
Wenhao Li;Zhenan Jiang;Difan Zhou;Chuanbing Cai
AC loss is a critical consideration in the design of high temperature superconducting (HTS) magnets. REBCO coils exhibit excellent current-carrying capabilities and are popular choices for applications such as fusion magnets and superconducting magnetic energy storage. However, there is currently a lack of research on the AC loss of REBCO coils under low temperature and high field conditions. A quantitative understanding of AC loss over wide temperature and magnetic field ranges is urgently needed. This paper investigates the dynamic resistance, magnetization loss, and total loss of a small double-pancake coil (DPC) based on a 2D axisymmetric H-formulation, at temperatures of 25 K, 50 K, and 77 K in perpendicular AC magnetic fields up to 5 T. The results show that at different temperatures, the dynamic resistance, total loss, and loss components of the DPC can all be scaled by its critical current, ${{I}_{{rm{c, coil}}}}$. This implies that results from the high-temperature, low-field regime can be used to predict the loss values in the low-temperature, high-field regime. In addition, these scaling behaviors are quantitatively explained by the extended equations. This study is expected to provide a valuable reference for the estimation of losses in high-field magnets.
{"title":"AC Loss Scaling of a REBCO Double-Pancake Coil Over Wide Temperature and Magnetic Field Regimes","authors":"Wenhao Li;Zhenan Jiang;Difan Zhou;Chuanbing Cai","doi":"10.1109/TASC.2026.3653352","DOIUrl":"https://doi.org/10.1109/TASC.2026.3653352","url":null,"abstract":"AC loss is a critical consideration in the design of high temperature superconducting (HTS) magnets. REBCO coils exhibit excellent current-carrying capabilities and are popular choices for applications such as fusion magnets and superconducting magnetic energy storage. However, there is currently a lack of research on the AC loss of REBCO coils under low temperature and high field conditions. A quantitative understanding of AC loss over wide temperature and magnetic field ranges is urgently needed. This paper investigates the dynamic resistance, magnetization loss, and total loss of a small double-pancake coil (DPC) based on a 2D axisymmetric <italic>H</i>-formulation, at temperatures of 25 K, 50 K, and 77 K in perpendicular AC magnetic fields up to 5 T. The results show that at different temperatures, the dynamic resistance, total loss, and loss components of the DPC can all be scaled by its critical current, <inline-formula><tex-math>${{I}_{{rm{c, coil}}}}$</tex-math></inline-formula>. This implies that results from the high-temperature, low-field regime can be used to predict the loss values in the low-temperature, high-field regime. In addition, these scaling behaviors are quantitatively explained by the extended equations. This study is expected to provide a valuable reference for the estimation of losses in high-field magnets.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/TASC.2026.3651413
Bin Feng;Jun Ma;Zhixuan Zhang;Hanlin Zhu;Huaqian Xiao;Xuezhi Luo;Yingjie Guan;Phil Mellor;Nick Simpson
When a perpendicular AC magnetic field is applied to type-II high-temperature superconductors carrying direct current (DC), a DC voltage will be induced, which is called the dynamic resistance effect. This work investigates the dynamic resistance of REBCO coated conductors under various operating conditions. An experimental platform was developed to measure the dynamic resistance of a high-temperature superconducting (HTS) tape under different DC current ratios, magnetic field amplitudes, and frequencies. A finite element model based on H-formulation was built using COMSOL Multiphysics to simulate the dynamic resistance behaviors. The simulation results agree well with experimental measurements results and empirical formulas, supporting the accuracy of the numerical model. The results indicate that dynamic resistance will increase with the rise of DC current and the amplitude of the applied AC magnetic field. Furthermore, we compared the dynamic resistance of multi-filamentary REBCO tapes with those of standard REBCO tapes. The multifilament design can effectively reduce dynamic resistance. These results will help design and develop low-loss HTS excitation windings for high temperature superconducting electrical machines.
{"title":"Experimental Study on the Dynamic Resistance of HTS REBCO Coated Conductor Tape","authors":"Bin Feng;Jun Ma;Zhixuan Zhang;Hanlin Zhu;Huaqian Xiao;Xuezhi Luo;Yingjie Guan;Phil Mellor;Nick Simpson","doi":"10.1109/TASC.2026.3651413","DOIUrl":"https://doi.org/10.1109/TASC.2026.3651413","url":null,"abstract":"When a perpendicular AC magnetic field is applied to type-II high-temperature superconductors carrying direct current (DC), a DC voltage will be induced, which is called the dynamic resistance effect. This work investigates the dynamic resistance of REBCO coated conductors under various operating conditions. An experimental platform was developed to measure the dynamic resistance of a high-temperature superconducting (HTS) tape under different DC current ratios, magnetic field amplitudes, and frequencies. A finite element model based on <italic>H</i>-formulation was built using COMSOL Multiphysics to simulate the dynamic resistance behaviors. The simulation results agree well with experimental measurements results and empirical formulas, supporting the accuracy of the numerical model. The results indicate that dynamic resistance will increase with the rise of DC current and the amplitude of the applied AC magnetic field. Furthermore, we compared the dynamic resistance of multi-filamentary REBCO tapes with those of standard REBCO tapes. The multifilament design can effectively reduce dynamic resistance. These results will help design and develop low-loss HTS excitation windings for high temperature superconducting electrical machines.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-7"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pulsed Laser Deposition (PLD) offers a powerful route for the fabrication of high-quality YBCO films with exceptional crystallographic alignment. In this study, the influence of film thickness on the corresponding electrical properties was investigated, with a particular emphasis on their correlation with microstructural features. Transport measurements indicate that the critical current density (Jc) shows a progressive decline as the film thickness increases, a phenomenon that can be directly related to the microstructural characteristics observed. These findings provide valuable insight into the inherent challenges associated with growing thick films and may guide future strategies for optimizing their properties in high-field applications. Furthermore, understanding these mechanisms is crucial for advancing the design and performance of high-temperature superconducting magnets and other electronic devices that require thick, high-performance films.
{"title":"Optimization of High-Quality YBCO Thin Films Deposited by PLD as a Function of Thickness","authors":"Violetta Poletto Dotsenko;Antonella Mancini;Achille Angrisani Armenio;Alessandro Rufoloni;Alessandra Fava;Giovanni Sotgiu;Francesco Rizzo","doi":"10.1109/TASC.2026.3652031","DOIUrl":"https://doi.org/10.1109/TASC.2026.3652031","url":null,"abstract":"Pulsed Laser Deposition (PLD) offers a powerful route for the fabrication of high-quality YBCO films with exceptional crystallographic alignment. In this study, the influence of film thickness on the corresponding electrical properties was investigated, with a particular emphasis on their correlation with microstructural features. Transport measurements indicate that the critical current density (<italic>J<sub>c</sub></i>) shows a progressive decline as the film thickness increases, a phenomenon that can be directly related to the microstructural characteristics observed. These findings provide valuable insight into the inherent challenges associated with growing thick films and may guide future strategies for optimizing their properties in high-field applications. Furthermore, understanding these mechanisms is crucial for advancing the design and performance of high-temperature superconducting magnets and other electronic devices that require thick, high-performance films.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/TASC.2026.3652116
Shunta Ito;Ataru Ichinose;Tomoya Horide;Yutaka Yoshida
To achieve both high in-field critical current density (Jc) and high deposition rates in REBa2C3Oγ (REBCO) coated conductors, we investigated liquid-phase-assisted crystal growth using a non-stoichiometric target composition. Conventional pulsed laser deposition (PLD) with a stoichiometric target suffers from degradation of BaHfO3 (BHO) nanorod alignment at high deposition rates, resulting in a significant reduction in Jc. In this study, a newly designed target with the composition Y:Ba:Cu = 1:2.3:3.7 was employed to induce liquid-phase formation during PLD growth. Structural and compositional analyses revealed the presence of Cu-rich precipitates and microstructural features characteristic of liquid-mediated growth. The use of a YBCO+BHO seed layer prevented the reaction between Ba species and the CeO2 surface of the substrate. Consequently, the formation of BaCeO3 was effectively suppressed at elevated substrate temperatures. Furthermore, YBCO+BHO films grown from the non-stoichiometric target maintained well-aligned nanorods even at high deposition frequencies (100 Hz), exhibiting Jc values comparable to those of films deposited at low rates. These findings demonstrate that liquid-phase-assisted growth enabled by non-stoichiometric target design is an effective strategy for achieving both high Jc and high-rate deposition in REBCO films. This approach provides new insights into the control of liquid-phase formation in PLD processes and offers a promising pathway for cost-effective fabrication of high-performance coated conductors.
{"title":"Liquid-Assisted Growth in Non-Stoichiometric YBa2Cu3Oy+BaHfO3 Films for High-Rate Deposition with Enhanced Jc","authors":"Shunta Ito;Ataru Ichinose;Tomoya Horide;Yutaka Yoshida","doi":"10.1109/TASC.2026.3652116","DOIUrl":"https://doi.org/10.1109/TASC.2026.3652116","url":null,"abstract":"To achieve both high in-field critical current density (<italic>J</i><sub>c</sub>) and high deposition rates in REBa<sub>2</sub>C<sub>3</sub>O<sub>γ</sub> (REBCO) coated conductors, we investigated liquid-phase-assisted crystal growth using a non-stoichiometric target composition. Conventional pulsed laser deposition (PLD) with a stoichiometric target suffers from degradation of BaHfO<sub>3</sub> (BHO) nanorod alignment at high deposition rates, resulting in a significant reduction in <italic>J</i><sub>c</sub>. In this study, a newly designed target with the composition Y:Ba:Cu = 1:2.3:3.7 was employed to induce liquid-phase formation during PLD growth. Structural and compositional analyses revealed the presence of Cu-rich precipitates and microstructural features characteristic of liquid-mediated growth. The use of a YBCO+BHO seed layer prevented the reaction between Ba species and the CeO<sub>2</sub> surface of the substrate. Consequently, the formation of BaCeO<sub>3</sub> was effectively suppressed at elevated substrate temperatures. Furthermore, YBCO+BHO films grown from the non-stoichiometric target maintained well-aligned nanorods even at high deposition frequencies (100 Hz), exhibiting <italic>J</i><sub>c</sub> values comparable to those of films deposited at low rates. These findings demonstrate that liquid-phase-assisted growth enabled by non-stoichiometric target design is an effective strategy for achieving both high <italic>J</i><sub>c</sub> and high-rate deposition in REBCO films. This approach provides new insights into the control of liquid-phase formation in PLD processes and offers a promising pathway for cost-effective fabrication of high-performance coated conductors.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/TASC.2026.3653349
Yusuke Sogabe;Sho Honda;Naoyuki Amemiya
Spiral Copper-plated Striated Coated-conductor (SCSC) cables are anticipated to be a game-changer for ac applications of high-temperature superconducting technology due to their low ac losses and high robustness. Experiments and numerical electromagnetic field analyses have confirmed that the structure of SCSC cables is effective in reducing dynamic losses and dynamic resistances, which is a problem in flux pumps and rotating machines. However, these results were confirmed for a single copper-plated multifilament coated conductor in a spiral configuration. It remains unclear whether they hold true for SCSC cables with the multilayer structure required for practical current-carrying capacity. Particularly, there is concern that the effect of reducing the dynamic resistance of SCSC cables may be lost due to tape-to-tape interactions caused by an increase in the number of layers or the number of tapes within a layer. We evaluated this using numerical electromagnetic field analyses.
{"title":"Numerical Electromagnetic Field Analyses of Dynamic Losses and Dynamic Resistances in Multilayered Spiral Copper-Plated Striated Coated-Conductor Cables","authors":"Yusuke Sogabe;Sho Honda;Naoyuki Amemiya","doi":"10.1109/TASC.2026.3653349","DOIUrl":"https://doi.org/10.1109/TASC.2026.3653349","url":null,"abstract":"Spiral Copper-plated Striated Coated-conductor (SCSC) cables are anticipated to be a game-changer for ac applications of high-temperature superconducting technology due to their low ac losses and high robustness. Experiments and numerical electromagnetic field analyses have confirmed that the structure of SCSC cables is effective in reducing dynamic losses and dynamic resistances, which is a problem in flux pumps and rotating machines. However, these results were confirmed for a single copper-plated multifilament coated conductor in a spiral configuration. It remains unclear whether they hold true for SCSC cables with the multilayer structure required for practical current-carrying capacity. Particularly, there is concern that the effect of reducing the dynamic resistance of SCSC cables may be lost due to tape-to-tape interactions caused by an increase in the number of layers or the number of tapes within a layer. We evaluated this using numerical electromagnetic field analyses.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1109/TASC.2026.3651414
Caida Fu;Chiheng Dong;Meng Han;He Huang;Dongliang Wang;Xianping Zhang;Yanwei Ma
The scalable manufacturing of high-performance iron-based superconducting (IBS) tapes is contingent upon solving two critical challenges in rolling processes: the lack of uniform core densification and the occurrence of cross-sectional distortion known as the saddle-core morphology. Both issues originate from the mechanical incompatibility between the silver sheath and the porous superconducting core, which leads to nonuniform compaction and degraded current transport. Here, we establish a multi-scale finite element model that explicitly couples the elastoplastic deformation of the silver sheath with the compaction behavior of the superconducting core governed by a modified Drucker-Prager Cap model. The simulations show that high interfacial friction between the silver sheath and the flat roller induces shear dilation and bulging, while low initial core density amplifies strain inhomogeneity. Guided by these mechanisms, we demonstrate that applying interfacial lubrication and optimizing initial packing density and rolling reduction can suppress dilation and enable homogeneous densification. This work delivers essential theoretical insights and practical guidance for the production of high-performance IBS tapes for high-field applications.
{"title":"Lubrication-Enabled Homogeneous Densification and Morphology Control in Iron-Based Superconducting Tapes","authors":"Caida Fu;Chiheng Dong;Meng Han;He Huang;Dongliang Wang;Xianping Zhang;Yanwei Ma","doi":"10.1109/TASC.2026.3651414","DOIUrl":"https://doi.org/10.1109/TASC.2026.3651414","url":null,"abstract":"The scalable manufacturing of high-performance iron-based superconducting (IBS) tapes is contingent upon solving two critical challenges in rolling processes: the lack of uniform core densification and the occurrence of cross-sectional distortion known as the saddle-core morphology. Both issues originate from the mechanical incompatibility between the silver sheath and the porous superconducting core, which leads to nonuniform compaction and degraded current transport. Here, we establish a multi-scale finite element model that explicitly couples the elastoplastic deformation of the silver sheath with the compaction behavior of the superconducting core governed by a modified Drucker-Prager Cap model. The simulations show that high interfacial friction between the silver sheath and the flat roller induces shear dilation and bulging, while low initial core density amplifies strain inhomogeneity. Guided by these mechanisms, we demonstrate that applying interfacial lubrication and optimizing initial packing density and rolling reduction can suppress dilation and enable homogeneous densification. This work delivers essential theoretical insights and practical guidance for the production of high-performance IBS tapes for high-field applications.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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