IEEE Transactions on Applied Superconductivity最新文献

{"title":"Active Reduction of Charging Time Constant in Iron Core NI-HTS Magnet for Superconducting Motor","authors":"Kuinan Wang;Yuanzhi Zhang;Mingyuan Liu;Xinhong Gao;Dawei Li;Ronghai Qu","doi":"10.1109/TASC.2026.3669889","DOIUrl":"10.1109/TASC.2026.3669889","url":null,"abstract":"The iron core in superconducting motors significantly increases the time constant of no-insulation (NI) high-temperature superconducting (HTS) coils, which limits the dynamic response capability required for applications such as quench protection. This paper proposes an active method for reducing the time constant of NI HTS coils by utilizing the motor’s inherent magnetic circuit. Specifically, stator windings are introduced to form a coupled system with the NI coil, which dynamically reduces the equivalent inductance during the discharge process. A calculation model for the stator windings and NI coil coupling is established, combining mathematical analysis with finite element model (FEM) to verify the proposed approach. Simulation results demonstrate that the proposed method can effectively reduce the time constant of iron-core NI HTS coils under the considered operating conditions, confirming the feasibility of improving the dynamic performance of such coils in HTS motor.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148487650","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}

{"title":"Removing the Metal Layer From REBCO-Coated Conductors and Constructing Oxygen Channels via a Laser-Electrochemical Hybrid Process","authors":"Ziming Wang;Hao Liang;Shuowei Gao;Jiulong Zhang;Jinhao Shi;Han Yang;Xintao Zhang;Zhenchuang Zhang;Huan Jin;Huajun Liu;Jinggang Qin;Fang Liu","doi":"10.1109/TASC.2026.3668726","DOIUrl":"10.1109/TASC.2026.3668726","url":null,"abstract":"The selective removal of metallic stabilizers is a key segment for both the fabrication of superconducting joints and the surface characterization of the superconducting layer in REBCO-coated conductors (CCs). However, the REBCO is highly susceptible to chemical corrosion, and conventional wet etching techniques often induce irreversible degradation due to delamination of the superconducting layer. To address this challenge, this study presents a non-destructive electrochemical etching process. We successfully validated the application of this etching method on REBCO CCs fabricated using three distinct superconducting layer deposition techniques, achieving a single-pass etching length of up to 30 millimeters while fully preserving superconducting properties. Moreover, a hybrid process combining electrochemical etching and laser cutting was employed to successfully construct oxygen channels on the surface of the superconducting layer. This method not only produced a 20mm-long etched sample containing three oxygen channels but also achieved a critical current with virtually no degradation.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148487879","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}

{"title":"AC Loss Reduction in HTS Stator Windings of an Air-Cored Axial-Flux Wind Turbine Generator via Optimized End-Winding Designs","authors":"Shuangrong You;Ozan Keysan;Adil Shah;Hongye Zhang;Markus Mueller","doi":"10.1109/TASC.2025.3645153","DOIUrl":"10.1109/TASC.2025.3645153","url":null,"abstract":"High AC loss in stator windings is one of the key challenges in realizing fully high-temperature superconducting (HTS) wind turbine generators, which offer significant advantages in compactness and weight compared to conventional machines. Among the sources of AC loss, the perpendicular magnetic field component (relative to the HTS tape surface) is particularly dominant, while the parallel field contributes much less. Therefore, minimizing the perpendicular field in the stator windings is essential when designing a fully HTS generator. In this work, we present a 5 MW-class, air-cored, axial-flux fully HTS wind turbine generator modeled using the finite element method (FEM). The <italic>T</i>-<italic>A</i> formulation and interpolated <italic>J</i>_c(<italic>B</i>) characteristics are used to simulate the electromagnetic behavior of the HTS windings. A moving mesh approach is employed to simulate the rotor movement. Simulation results show that the outer-stage stator windings experience significantly higher AC loss than the inner-stage windings, despite delivering the same power output. By optimizing the rotor end-winding geometry, the perpendicular magnetic field in the outer-stage windings was significantly reduced, resulting in a 77% decrease in total AC loss across the HTS stator windings.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148487978","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}

{"title":"Development of 2 km-Class Carbon-Doped MgB2 Wire With Uniform Critical Current Property","authors":"Dong Gun Lee;Jun Hyuk Choi;Minoru Maeda;Seyong Choi;Jung Ho Kim","doi":"10.1109/TASC.2026.3670799","DOIUrl":"10.1109/TASC.2026.3670799","url":null,"abstract":"Kilometer-scale carbon-doped MgB₂ superconducting wires were fabricated using a three-dimensional vibrating powder-filling powder-in-tube process and systematically evaluated for uniformity and performance. The optimized process enabled fabrication of a 2.1 km-long 18-filament conductor with a critical current density (<italic>J</i>_c) of 1.13 × 10⁵ A/cm² at 20 K and 2 T, showing only ∼2% variation along its length. Carbon substitution enhanced high-field performance primarily through impurity scattering, while the <italic>n</i>-value demonstrated a strong proportionality with <italic>J</i>_c across all measured conditions. This correlation establishes the <italic>n</i>-value as not only a research parameter but also a practical quality-control metric for industrial wire production. The combined achievements of process innovation and transport uniformity highlight the feasibility of MgB₂ conductors for MRI magnets, high-field research magnets, and superconducting power transmission.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148488156","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}

{"title":"Partial Homogenization Methods to Simulate HTS Tapes Using the H and T-A Formulations","authors":"Inês S. P. Peixoto;Dmitry Sotnikov;Luis F. D. Bucho;João F. P. Fernandes;Silvio Vaschetto;Paulo J. da Costa Branco;Douglas Araujo;Bernhard Auchmann","doi":"10.1109/TASC.2026.3660617","DOIUrl":"10.1109/TASC.2026.3660617","url":null,"abstract":"REBCO coated conductor tapes are a promising technology for developing high-field accelerator magnets since their increased current carrying capacity and operational temperature allows achieving higher-fields and current levels with higher thermal margin. Superconducting materials still present challenges associated with their non-negligible losses in transient conditions, hence, finite element analyses become essential to design feasible superconducting systems. The <italic>H</i> formulation is known in literature for its accuracy, while the <italic>T-A</i> formulation offers computational efficiency. Nonetheless, both methods remain computationally demanding, especially when the superconducting tapes are modelled considering the extreme aspect ratios of different materials in the layered tapes. Homogenized models have been proposed to reduce computational requirements, however, modelling all layers as a single domain can impose the current to flow through all conducting layers rather than only the REBCO layer, even when its resistivity is very low. This study presents a comparative analysis using the <italic>H</i> and the <italic>T-A</i> formulations for a partially homogenized model, where the superconducting layer is modelled independently from the remaining conducting layers, and a fully homogenized model. The models' accuracy for transport loss estimation in transient conditions is discussed and compared with experimental loss measurements for a REBCO tape powered with AC currents.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148488172","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}

{"title":"Long-Term Evaluation of Joint Resistivity in Lap Joints of REBCO Tapes With Indium Depending on Pre-Joint Process and Storage Temperature","authors":"Reo Tamura;Satoshi Ito;Ryoichiro Hayasaka;Nagato Yanagi;Hidetoshi Hashizume","doi":"10.1109/TASC.2026.3668736","DOIUrl":"10.1109/TASC.2026.3668736","url":null,"abstract":"Bridge-type mechanical lap joints with indium foil insertion have been developed for joint winding of high-temperature superconducting (HTS) helical coils in heliotron-type stellarator fusion reactors. While joints between copper-stabilized Rare-earth Barium Copper Oxide (REBCO) tapes have demonstrated consistently low resistance, their long-term stability remains insufficiently understood. In this study, we first quantified volumetric resistivity of CuIn₂ formed at the Cu/In interface using a mechanical lap joint of copper-stabilized REBCO tapes with indium insertion based on four-terminal resistance measurement and cross-sectional Scanning Electron Microscope and Energy Dispersive X-ray Spectroscopy (SEM-EDX) analysis. Subsequently, we evaluated the time-dependent evolution of joint resistivity under different pre-treatment conditions (with or without ethanol cleaning) and storage temperatures (300 K or 77 K). Based on these results, a model was developed to separate diffusion-driven and non-diffusional contributions to joint resistivity. The results revealed that storage at 300 K leads to a monotonic increase in joint resistivity, primarily due to CuIn₂ growth, while storage at 77 K suppresses such changes. Additionally, in samples not treated with ethanol cleaning, a significant increase in resistivity occurring with a delay at 300 K was observed, consistent with corrosion-related mechanisms.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148488282","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}

{"title":"Microstructure and Superconducting Properties of Yttrium Barium Copper Oxide Thin Film With Patterned Substrates for Ultra-Fine Multi-Filaments","authors":"Akiyoshi Matsumoto;Shuuichi Ooi;Satoshi Hata;Taiki Wada;Ryo Teranishi;Yuji Tsuchiya","doi":"10.1109/TASC.2026.3655686","DOIUrl":"10.1109/TASC.2026.3655686","url":null,"abstract":"Yttrium barium copper oxide (YBCO) superconductors are promising candidates for superconducting magnets operating at low temperatures and high magnetic fields, as well as for advanced electric power devices. Commercially available YBCO wires are manufactured in tape form, by depositing a thin YBCO layer atop multiple buffer layers on a metal substrate. This coated conductor structure closely resembles a single crystal, with well-aligned crystallographic axes, thereby exhibiting high critical current densities. However, challenges remain in reducing screening currents and AC losses for practical applications. In this study, we present a multifilamentary YBCO thin film design with patterned elevated stripes, fabricated using photolithography on substrates. Various stripe materials, including SiO₂, and Al₂O, were evaluated by depositing YBCO on the STO/stripe structures. Magnetooptical imaging demonstrated that non-superconducting stripes separate the superconducting regions, irrespective of the stripe material used. Transmission electron microscopy (TEM/STEM)-EDX analysis revealed that YBCO on STO/SiO₂ stripes formed crystals with varied orientations, whereas STO/Al₂O₃ stripes resulted in the formation of impurity phases. These findings indicate that substrate patterning with stripe structures is a viable approach for realizing multifilamentary coated conductors, potentially reducing AC losses and enhancing future superconductor applications.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-4"},"PeriodicalIF":1.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148489457","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}

{"title":"A Possible Approach to Improve Angular Dependent Critical Current Characteristics of REBCO Coated Conductors by Face-to-Face Double Stacked Architecture","authors":"Miyuki Nakamura;Takanobu Kiss;Zeyu Wu;Ivan Veshchunov;Kamil Etxagibel;Vladimir Vyatkin;Marat Gaifullin;Valery Petrykin;Sergey Lee","doi":"10.1109/TASC.2026.3653723","DOIUrl":"10.1109/TASC.2026.3653723","url":null,"abstract":"REBa₂Cu₃O_7-δ (REBCO, RE: rare earth element) coated conductors (CCs) have superior in-field performance compared to low-temperature superconductors and Bi-based superconductors, however, due to its crystal structure, REBCO CCs exhibit significant anisotropy, i.e., critical current density (<italic>J</i>_c) is generally high for <italic>B</i> // <italic>a-b</i> and low for <italic>B</i> // <italic>c</i>-axis. Isotropic angular dependence would be ideal for such applications as magnets and coils, because anisotropic angular dependence will hinder current carrying capability in the winding and also make it more difficult for quench protection. To realize an isotropic angular dependence, artificial pinning centers (APCs), such as BaMO₃ (M: Metal), have been introduced to enhance <italic>J</i>_c for <italic>B</i> // <italic>c</i>-axis. However, it is still challenging to enhance pinning over all angles. In this study, we investigated a possible way to improve the angular dependence of REBCO CCs by applying face-to-face double-stacked (FFDS) configuration. Our previous study showed that FFDS interface resistivity is around 50 nΩcm² at 77 K, enabling sufficient current sharing with small enough dissipation in cases of local <italic>J</i>_c degradation in one side of the REBCO CC. In addition, Based on this finding, we examined whether to compensate for the angular dependence of the REBCO CCs. We made a FFDS CC by combining two REBCO CCs with different angular dependences, i.e., YBa₂Cu₃O_7-δ (YBCO) CC with low <italic>J</i>_c for <italic>B</i> // <italic>c</i>-axis and EuBa₂Cu₃O_7-δ (EuBCO) with BaHfO₃ (BHO) doping CC which has high <italic>J</i>_c for <italic>B</i> // <italic>c</i>-axis. <italic>Current–voltage (I-V)</i> measurements at various angles confirmed that FFDS CCs facilitate current sharing under applied fields. As a result, we analyze the <italic>I</i>-<italic>V</i> characteristics by applying an equivalent circuit model and confirmed the more isotropic angle dependence of <italic>I</i>_c properties as designed. In conclusion, the FFDS configuration provides a practical means to current-carrying performance compared to the original CC strands and presents a practical method for tailoring REBCO CCs angular dependence with flexibility.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-4"},"PeriodicalIF":1.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148490317","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}

{"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":"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":"2026-08-01","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}

{"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":"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":"2026-08-01","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}