{"title":"Fast-Recovery Superconducting Fault Current Limiter Based on a Novel Skeleton Topology for Future Cryo-Electric Aircraft: Reclosing and Repetitive Fault Cases","authors":"Dedao Yan;Mohammad Yazdani-Asrami;Wenjuan Song","doi":"10.1109/TASC.2025.3587754","DOIUrl":"https://doi.org/10.1109/TASC.2025.3587754","url":null,"abstract":"Recovery characteristic of superconducting fault current limiters (SFCLs) is a critical factor during their design process. After a low impedance fault, an SFCL cannot return to the superconducting state abruptly, due to the large heat generation during fault and the resultant high temperature above critical temperature <italic>T<sub>c</sub></i>. Fast recovery of the SFCL will ensure fast reclosing and continuation of power supply in the power distribution network of an e-aircraft. In this work, a skeleton-based design of the helical bifilar SFCL was proposed to achieve fast recovery. The new structure ensures a larger cooling surface area between the high-temperature superconducting (HTS) tape and the coolant, thus enhancing recovery performance and reducing the recovery time of the SFCL. Multiple fault current limitation characterization profiles, including limited current, voltage drop across the SFCL, and resistance and temperature of the SFCL, were analyzed and compared with those of the classic helical bifilar SFCL. Studies were conducted on different initial operating temperatures, different HTS tape length usages, and different reclosing time ranges. The results show that the recovery time has been shortened from 2.2 to 0.49 s by the proposed new SFCL, as compared to the classic helical bifilar SFCL. This skeleton-based fast-recovery SFCL provides new ideas for fault management in future cryo-electric aircraft.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 7","pages":"1-12"},"PeriodicalIF":1.7,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144695612","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}
Hongli Suo;Yang Gao;Xiaoru Tian;Zili Zhang;Hongbo Sun;Jianhua Liu;Lei Wang;Qiuliang Wang
{"title":"Investigation of Wetting Property and Joint Fabrication Pressure on the Resistance and Microstructure of Soldering Joints for REBCO Conductors","authors":"Hongli Suo;Yang Gao;Xiaoru Tian;Zili Zhang;Hongbo Sun;Jianhua Liu;Lei Wang;Qiuliang Wang","doi":"10.1109/TASC.2025.3587640","DOIUrl":"https://doi.org/10.1109/TASC.2025.3587640","url":null,"abstract":"In this work, we systematically investigate the relationship between wetting property, joint resistance, and microstructure for soldered rare-earth Ba<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> (REBCO) joints using six different surface conditions and three different fabrication pressures. As expected, increasing fabrication pressure can decrease the joint resistance. However, it is found that the wetting property can cause significant differences among the different surface conditions. Moreover, a poor wetting property can directly cause higher joint resistance, even under high fabrication pressure. This can partially explain the difference in the joint resistance found in the literature. At the same time, microcomputed tomography was introduced in the investigation of the REBCO joint. This enables nondestructive characterization of the joint microstructure, which can help us better understand the factors influencing microstructure and joint resistance.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 7","pages":"1-16"},"PeriodicalIF":1.7,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144695614","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}
Yuhan Yang;Jinxing Zheng;Lei Wang;Yuan Cheng;Ming Li
{"title":"Investigation of Transport AC Loss Characteristics in a Double-Layer Tenon–Mortise Modularized Conductor (TMMC)","authors":"Yuhan Yang;Jinxing Zheng;Lei Wang;Yuan Cheng;Ming Li","doi":"10.1109/TASC.2025.3586316","DOIUrl":"https://doi.org/10.1109/TASC.2025.3586316","url":null,"abstract":"The accurate evaluation of the ac loss is considered to be of great importance for the design and optimization of high-temperature superconducting (HTS) conductors. Along these lines, a new type of HTS conductor named tenon–mortise modularized conductor (TMMC), composed of a multilayer concentric round subconductor, was developed. Notably, the tenon–mortise connection structure of the TMMC requires a large amount of copper formers, significantly modifying its ac loss characteristics. Initially, a 2-D model for the TMMC was established to analyze the ac loss evaluation under sinusoidal current. The simulations demonstrated that the hysteresis loss in the tapes of the copper-former TMMC was the predominant component of ac loss at lower transport current frequencies. However, as the current frequency increased, the current and losses in the copper formers significantly rose. Subsequently, the ac loss of the TMMC with copper formers under low-frequency triangular wave current was evaluated through experimental and simulation methods. The results indicated that under varying current amplitudes and frequencies, the experimental and simulation results of ac loss exhibit a consistent trend, with an average numerical error of approximately 32.2%. Collectively, our work provides valuable insights for the optimization of TMMC designs and offers guidance for future research and applications in high-field magnet and power system technologies.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 7","pages":"1-8"},"PeriodicalIF":1.7,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144680858","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}
Runar Mellerud;Christian Hartmann;Casper Leonard Klop;Rémi Dorget;Jonas Kristiansen Nøland
{"title":"The Torus Axial Flux Machine: Unlocking a Low-Loss Superconducting Armature?","authors":"Runar Mellerud;Christian Hartmann;Casper Leonard Klop;Rémi Dorget;Jonas Kristiansen Nøland","doi":"10.1109/TASC.2025.3585976","DOIUrl":"https://doi.org/10.1109/TASC.2025.3585976","url":null,"abstract":"High-temperature superconductors (HTSs) could enable a new paradigm for lightweight and efficient electric machine designs. While superconducting rotors have been successfully implemented, the adoption of superconducting armatures has been hindered by high ac losses, leading to impractically high cryogenic cooling demands. This article introduces a slotted torus axial flux machine topology to address this challenge, leveraging toroidal windings to align HTS tapes with slot leakage flux, avoiding complex end windings while achieving ac losses at least an order of magnitude below HTS armatures with tooth-coil tape orientation. A 1-MW proof-of-concept aviation motor design demonstrates the feasibility of this approach, achieving an active torque density of 51.1 Nm/kg with HTS ac losses below 0.03% of the output power and total cryogenic losses slightly exceeding 0.1% when including the steel losses. The study highlights the importance of HTS tape orientation within the slot and using flux diverters for the end windings to minimize losses. Furthermore, it illustrates how an even higher cryogenic efficiency can be reached by lowering the electrical frequency. The promising results motivate further development and optimization of superconducting machines with this topology.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 7","pages":"1-10"},"PeriodicalIF":1.7,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144680841","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":"SuperLink: Development and Impacts of a Superconducting Power Cable in a 110-kV Distribution Network","authors":"Wescley Tiago Batista de Sousa;Friederike Boehm;Steffen Grohmann;Mathias Noe;Dag Willén;Alexander Alekseev;Patrik Mansheim;Robert Bach;Werner Prusseit;Cornelia Hintze;Robert Prinz;Peter Michalek","doi":"10.1109/TASC.2025.3585422","DOIUrl":"https://doi.org/10.1109/TASC.2025.3585422","url":null,"abstract":"The SuperLink project has developed an advanced cable design technology utilizing superconducting wires with high engineering current density, designed to meet the demands of urban power distribution networks. The project aims to deliver a versatile and easily deployable 110-kV power link tailored to the infrastructure requirements of metropolitan areas, such as Munich, Germany. Achieving a 500-MVA power transmission capacity over a 15-km distance necessitates exceptional performance in several key areas: low ac losses in high-temperature superconducting conductors, robust and compact cryogenic dielectric systems, and highly efficient thermal insulation. This study outlines the fundamental design principles of the SuperLink cable and provides a comprehensive analysis of its integration into a 110-kV network. Load flow simulations were conducted to assess network performance under different supply scenarios, with a focus on line loading and fault current levels. The results demonstrate that the SuperLink cable not only alleviates overloaded existing lines but also reduces overall network losses, highlighting its potential to enhance grid efficiency and reliability in urban environments","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 7","pages":"1-11"},"PeriodicalIF":1.7,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144695613","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}
Rong Guo;Shaotao Dai;Qihuan Dong;Liguang Hu;Jian Cheng;Peng Yu;Bangzhu Wang
{"title":"Current Transmission and Resistance Characteristics of Bridge Joints in Three-Phase Coaxial Superconducting Cables","authors":"Rong Guo;Shaotao Dai;Qihuan Dong;Liguang Hu;Jian Cheng;Peng Yu;Bangzhu Wang","doi":"10.1109/TASC.2025.3583762","DOIUrl":"https://doi.org/10.1109/TASC.2025.3583762","url":null,"abstract":"In the design and manufacturing process of intermediate joints for three-phase coaxial superconducting cables, optimizing the joint structure and minimizing resistance loss are essential to improving transmission efficiency and long-term stability. However, the concentric connection of superconducting functional layers of all three phases at the intermediate joint creates a resistance-concentrated region, leading to higher thermal loads and increased quenching risk. Currently, most research on superconducting tape joints focuses on lap joints. However, for the connection of the superconducting layer in intermediate joints, bridge joints are more advantageous. Bridge joints can address the issue of reversed tape orientation that often occurs in lap joints, enabling a more symmetric current transmission path. Thanks to their symmetrical structure and flexible welding orientation, bridge joints are better suited to meet the integrated performance requirements of joints in complex systems. This design facilitates compact system layouts and is more appropriate for large-scale industrial deployment in complex installation environments. Through experimental and simulation analysis of the current transmission behavior and resistance-influencing factors of bridge joints in three-phase coaxial superconducting cables, this study reveals that the current transmission efficiency in the superconducting layer bridge joint region is directly related to the geometric configuration of the joint. Among the configurations, the face-to-face design demonstrates superior current-carrying capacity due to its more direct current transmission path. This research provides theoretical guidance for optimizing the design of superconducting joints and improving the stability and performance of superconducting cables in practical applications.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 6","pages":"1-12"},"PeriodicalIF":1.7,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144634769","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 Changes in Parameters for Nb-Based Superconducting Digital Circuits","authors":"Mutsuo Hidaka;Shuichi Nagasawa","doi":"10.1109/TASC.2025.3583012","DOIUrl":"https://doi.org/10.1109/TASC.2025.3583012","url":null,"abstract":"The same process evaluation chips for Nb-based superconducting digital circuits were measured at liquid He temperature (4 K) just after fabrication and after storage at room temperature for up to 16 years. The critical current (<italic>I</i><sub>c</sub>) of the Josephson junction, resistance, inductance, and <italic>I</i><sub>c</sub> of the Nb–Nb contacts before and after storage were compared. <italic>I</i><sub>c</sub> decreased by around 5% and resistance increased about 2% after ten years. Neither change depended on the JJ area nor on resistor width. Therefore, we concluded they were changes in critical current density (<italic>J</i><sub>c</sub>) and sheet resistance (<italic>R</i><sub>sq</sub>). Because <italic>J</i><sub>c</sub> did not change in the chip thermally annealed just after fabrication, we concluded that the long-term <italic>J</i><sub>c</sub> changes were caused by the same mechanism as thermal annealing. Although the long-term change in <italic>J</i><sub>c</sub> is not critical for superconducting digital circuit operation, it could cause circuit malfunctions in some cases. Therefore, some measures are required, such as light annealing, after fabrication or cold storage. The effect of the resistance change on superconducting digital circuit operation was small. No inductance changes were observed. <italic>I</i><sub>c</sub> of Nb–Nb contacts decreased by several tens of percent over ten years but was still sufficient for the digital circuits to function.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 6","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144657460","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":"Bending Strain Dependence of Critical Current in BSCCO and REBCO Tapes","authors":"Kozo Osamura;Shutaro Machiya","doi":"10.1109/TASC.2025.3581904","DOIUrl":"https://doi.org/10.1109/TASC.2025.3581904","url":null,"abstract":"Applying BSCCO and REBCO tapes to various engineering purposes, three modes of tensile and edgewise- and flatwise- bending are essential to deform the tape in pancake and spiral windings as well as twisting. Both kinds of tape consist of brittle superconducting (SC) oxide and several metallic components. Fine SC filaments are embedded in Ag matrix in BSCCO tape while single SC layer is put on the metallic sheet in REBCO one. These texture difference influences clearly on the bending dependence of critical current (<italic>I<sub>c</sub></i>). The <italic>I<sub>c</sub></i> of BSCCO tape decreased up to 95% of <italic>I</i><sub>c0</sub>/<italic>I</i><sub>c00</sub> when the tape is bent to ∼53 mm diameter by flatwise bending and 1325–1682 mm by edgewise one. The equivalent flatwise bending strain was 0.29% –0.39% when the critical current degradation starts, while the critical edgewise strain was 0.29% –0.31%. In the case of REBCO tape, the <italic>I<sub>c</sub></i> did not decrease up to 10 mm flatwise bending while it decreased by 405 mm edgewise bending. The degradation was observed to start from 1.04% edgewise bending strain while the flatwise bending did not give degradation up to 0.92% . The fracture behavior induced in BSCCO and REBCO tapes was discussed. The degradation starts from fracture of BSCCO filaments, while it originates to a delamination between the oxide and the metal interface in REBCO tape.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 6","pages":"1-11"},"PeriodicalIF":1.7,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144606290","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}