Pub Date : 2024-07-24DOI: 10.1088/1361-6668/ad6718
Yong Chen, Qiuliang Wang, Kangshuai Wang, Benzhe Zhou, Shixian Liu, Xiaoyu Ji, Lei Wang, Jianhua Liu
The T-A formulation based on thin film approximation has been widely used in electromagnetic modeling of high temperature superconducting (HTS) coated conductors (CCs). However, with the emergence of no-insulation (NI) HTS coils and its variant HTS coils, the electrical connection of HTS coils has become increasingly complex, and the traditional T-A formulation is challenging to handle the problems of conductors with non-negligible thickness and current sharing. This paper firstly describes the Neumann boundary condition of the T-A formulation under 2D axisymmetric symmetry in detail, as well as the conversion of different boundary conditions. And additional voltage variable is added to correct the Newman boundary condition from the perspective of circuit. Then, considering HTS CCs series or parallel stacking to carry current, the effectiveness of this method is verified by comparing with benchmark model. Finally, we extend the application range of the T-A formulation with modified Newman boundary conditions to simulate thick superconductors, and naturally process current sharing of azimuthal and radial current in circular NI HTS coils.
{"title":"2D axisymmetric electromagnetic modeling of HTS coils based on T-A formulation with modified Newman boundary conditions","authors":"Yong Chen, Qiuliang Wang, Kangshuai Wang, Benzhe Zhou, Shixian Liu, Xiaoyu Ji, Lei Wang, Jianhua Liu","doi":"10.1088/1361-6668/ad6718","DOIUrl":"https://doi.org/10.1088/1361-6668/ad6718","url":null,"abstract":"\u0000 The T-A formulation based on thin film approximation has been widely used in electromagnetic modeling of high temperature superconducting (HTS) coated conductors (CCs). However, with the emergence of no-insulation (NI) HTS coils and its variant HTS coils, the electrical connection of HTS coils has become increasingly complex, and the traditional T-A formulation is challenging to handle the problems of conductors with non-negligible thickness and current sharing. This paper firstly describes the Neumann boundary condition of the T-A formulation under 2D axisymmetric symmetry in detail, as well as the conversion of different boundary conditions. And additional voltage variable is added to correct the Newman boundary condition from the perspective of circuit. Then, considering HTS CCs series or parallel stacking to carry current, the effectiveness of this method is verified by comparing with benchmark model. Finally, we extend the application range of the T-A formulation with modified Newman boundary conditions to simulate thick superconductors, and naturally process current sharing of azimuthal and radial current in circular NI HTS coils.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"37 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141810292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-23DOI: 10.1088/1361-6668/ad637d
Erik Zimmermann, Abdur Rehman Jalil, Michael Schleenvoigt, Jan Karthein, Benedikt Frohn, Gerrit Behner, Florian Lentz, Stefan Trellenkamp, Elmar Neumann, Peter Schüffelgen, Hans Lüth, Detlev Grützmacher and Thomas Schäpers
Nanoscale superconducting quantum interference devices are fabricated in-situ from a single Bi0.26Sb1.74Te3 nanoribbon that is defined using selective-area growth and contacted with superconducting Nb electrodes via a shadow mask technique. We present magnetic flux periodic interference in both, fully and non-fully proximitized nanoribbons. The pronounced oscillations are attributed to interference effects of coherent transport through the topological surface states encompassing the cross-section of the nanoribbon.
{"title":"Topological insulator based axial superconducting quantum interferometer structures","authors":"Erik Zimmermann, Abdur Rehman Jalil, Michael Schleenvoigt, Jan Karthein, Benedikt Frohn, Gerrit Behner, Florian Lentz, Stefan Trellenkamp, Elmar Neumann, Peter Schüffelgen, Hans Lüth, Detlev Grützmacher and Thomas Schäpers","doi":"10.1088/1361-6668/ad637d","DOIUrl":"https://doi.org/10.1088/1361-6668/ad637d","url":null,"abstract":"Nanoscale superconducting quantum interference devices are fabricated in-situ from a single Bi0.26Sb1.74Te3 nanoribbon that is defined using selective-area growth and contacted with superconducting Nb electrodes via a shadow mask technique. We present magnetic flux periodic interference in both, fully and non-fully proximitized nanoribbons. The pronounced oscillations are attributed to interference effects of coherent transport through the topological surface states encompassing the cross-section of the nanoribbon.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141770786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-22DOI: 10.1088/1361-6668/ad663f
Peifeng Gao, Yameng Zhang, Xiaohui Lin, Sikan Chen, Jiamin Zhu, M. Guan, Xingzhe Wang
RE-Ba-Cu-O (REBCO, where RE = Y, Gd, Sm, and other rare earth elements) coated conductor (CC) tapes exhibit considerable potential for application within the domains of high-energy physics and high-field science. Nevertheless, weak interfacial properties pose a significant obstacle, impeding the progress and practical implementation in high-field scenarios. The anvil tension method has been extensively employed for the assessment of transverse delamination strength of REBCO CC tapes. However, the outcomes derived from anvil tension exhibit severe dispersion, thereby impeding its efficacy in evaluating material performance. The underlying cause of this phenomenon remains unidentified. In this study, error analysis of anvil measurement method in determining the transverse tensile delamination strength (TTDS) of REBCO CC tapes was conducted based on finite element (FE) numerical simulations. A two-dimensional multilayer elastic-plastic delamination FE model with main layers of REBCO CC tapes, solder connecting layers and anvil materials were developed based on the bilinear cohesive zone model. The effects of anvil test conditions and the structural configuration of the conductor itself on the test results were discussed. Simulation results show that localized premature cracking of the interface due to stress concentration and plastic yielding of the CC tape around the loading boundary is the root reason for the discrepancy between the anvil test results and the true interfacial strength. Therefore, anvil test conditions (including top anvil dimensions, soldering conditions, loading eccentricity angle, and anvil material properties) as well as the structural configuration of the conductor itself (including edge initial crack length, edge encapsulation width, and stabilizer thickness) have a significant impact on anvil test-based TTDS results.
RE-Ba-Cu-O（REBCO，其中 RE = Y、Gd、Sm 和其他稀土元素）涂层导体（CC）带在高能物理和高场科学领域具有相当大的应用潜力。然而，薄弱的界面特性构成了一个重大障碍，阻碍了高场应用的进展和实际应用。砧板拉伸法已被广泛用于评估 REBCO CC 磁带的横向分层强度。然而，砧板拉伸法得出的结果表现出严重的分散性，从而阻碍了其在评估材料性能方面的功效。造成这种现象的根本原因仍未查明。在本研究中，基于有限元（FE）数值模拟，对确定 REBCO CC 胶带横向拉伸分层强度（TTDS）的砧板测量方法进行了误差分析。基于双线性内聚区模型，建立了包含 REBCO CC 胶带主层、焊料连接层和砧板材料的二维多层弹塑性分层 FE 模型。讨论了砧座测试条件和导体本身的结构配置对测试结果的影响。模拟结果表明，CC 带在加载边界附近的应力集中和塑性屈服导致的界面局部过早开裂是砧座测试结果与真实界面强度之间存在差异的根本原因。因此，砧座测试条件（包括顶部砧座尺寸、焊接条件、加载偏心角和砧座材料特性）以及导体本身的结构配置（包括边缘初始裂纹长度、边缘封装宽度和稳定器厚度）对基于砧座测试的 TTDS 结果有重大影响。
{"title":"Error analysis for determining transverse tensile delamination strength of REBCO coated conductors by anvil test: numerical simulation demonstrations","authors":"Peifeng Gao, Yameng Zhang, Xiaohui Lin, Sikan Chen, Jiamin Zhu, M. Guan, Xingzhe Wang","doi":"10.1088/1361-6668/ad663f","DOIUrl":"https://doi.org/10.1088/1361-6668/ad663f","url":null,"abstract":"\u0000 RE-Ba-Cu-O (REBCO, where RE = Y, Gd, Sm, and other rare earth elements) coated conductor (CC) tapes exhibit considerable potential for application within the domains of high-energy physics and high-field science. Nevertheless, weak interfacial properties pose a significant obstacle, impeding the progress and practical implementation in high-field scenarios. The anvil tension method has been extensively employed for the assessment of transverse delamination strength of REBCO CC tapes. However, the outcomes derived from anvil tension exhibit severe dispersion, thereby impeding its efficacy in evaluating material performance. The underlying cause of this phenomenon remains unidentified. In this study, error analysis of anvil measurement method in determining the transverse tensile delamination strength (TTDS) of REBCO CC tapes was conducted based on finite element (FE) numerical simulations. A two-dimensional multilayer elastic-plastic delamination FE model with main layers of REBCO CC tapes, solder connecting layers and anvil materials were developed based on the bilinear cohesive zone model. The effects of anvil test conditions and the structural configuration of the conductor itself on the test results were discussed. Simulation results show that localized premature cracking of the interface due to stress concentration and plastic yielding of the CC tape around the loading boundary is the root reason for the discrepancy between the anvil test results and the true interfacial strength. Therefore, anvil test conditions (including top anvil dimensions, soldering conditions, loading eccentricity angle, and anvil material properties) as well as the structural configuration of the conductor itself (including edge initial crack length, edge encapsulation width, and stabilizer thickness) have a significant impact on anvil test-based TTDS results.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"16 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141815532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-21DOI: 10.1088/1361-6668/ad5a45
Somak Basistha, Soumyajit Mandal, John Jesudasan, Vivas Bagwe and Pratap Raychaudhuri
We investigate the low-frequency electrodynamics in the vortex state of two type-II superconducting films, namely, a moderate-to-strongly pinned Niobium Nitride (NbN) and a very weakly pinned amorphous Molybdenum Germanium (a-MoGe) film. We employ a two-coil mutual inductance technique to extract the complex penetration depth, . The sample response is studied through the temperature variation of in the mixed state, where we employ a model developed by Coffey and Clem (the CC model) to extract different vortex lattice (VL) parameters, such as the restoring pinning force constant (Labusch parameter), VL drag coefficient and pinning potential barrier. We observe that a consistent description of the inductive and dissipative part of the response is only possible when we take the viscous drag on the vortices to be several orders of magnitude larger than the viscous drag estimated from the Bardeen–Stephen model.
我们研究了两种 II 型超导薄膜涡旋态的低频电动力学，即中强引脚氮化铌（NbN）薄膜和极弱引脚非晶钼锗（a-MoGe）薄膜。我们采用双线圈互感技术来提取复合穿透深度（.）。我们采用 Coffey 和 Clem 开发的模型（CC 模型）来提取不同的涡流晶格（VL）参数，如恢复引脚力常数（拉布什参数）、VL 阻力系数和引脚势垒。我们发现，只有当我们认为旋涡上的粘性阻力比根据巴丁-斯蒂芬模型估计的粘性阻力大几个数量级时，才有可能对响应的感应和耗散部分进行一致的描述。
{"title":"Low-frequency electrodynamics in the mixed state of superconducting NbN and a-MoGe films using two-coil mutual inductance technique","authors":"Somak Basistha, Soumyajit Mandal, John Jesudasan, Vivas Bagwe and Pratap Raychaudhuri","doi":"10.1088/1361-6668/ad5a45","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5a45","url":null,"abstract":"We investigate the low-frequency electrodynamics in the vortex state of two type-II superconducting films, namely, a moderate-to-strongly pinned Niobium Nitride (NbN) and a very weakly pinned amorphous Molybdenum Germanium (a-MoGe) film. We employ a two-coil mutual inductance technique to extract the complex penetration depth, . The sample response is studied through the temperature variation of in the mixed state, where we employ a model developed by Coffey and Clem (the CC model) to extract different vortex lattice (VL) parameters, such as the restoring pinning force constant (Labusch parameter), VL drag coefficient and pinning potential barrier. We observe that a consistent description of the inductive and dissipative part of the response is only possible when we take the viscous drag on the vortices to be several orders of magnitude larger than the viscous drag estimated from the Bardeen–Stephen model.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"83 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141741180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Developing closed-loop magnets that operate in a persistent current mode (PCM) is crucial for achieving higher resolution and sensitivity in NMR and MRI devices. To the best of our knowledge, we report a novel closed-loop multi-pancake (MP) HTS magnet operated on PCM based on a novel jointless winding method with superconducting joints of REBCO coated conductors (CCs). The in-field characteristics of the CC and the joints were investigated to determine the operating parameters of the magnet. The steady central field of the magnet reached ∼408.4 mT at 77 K with an operating current of 16.5 A. The joint resistance was inferred from a higher excitation current of 17 A to be at least less than 2.5 × 10−10Ω. Although the Ic value of the joint was considerably lower than that of the CC at self-field, it could maintain similar comparable or even higher in-field Ic compared to the CC, which is immensely beneficial for magnet applications. This study provides some insights into the design and construction of closed-loop MP magnets operating in PCM.
开发以持续电流模式（PCM）运行的闭环磁体对于在核磁共振和磁共振成像设备中实现更高分辨率和灵敏度至关重要。据我们所知，我们报告了一种新型闭环多薄饼 (MP) HTS 磁体，该磁体基于一种新型无接头绕组方法和 REBCO 涂层导体 (CC) 超导接头，以持久电流模式 (PCM) 运行。研究了 CC 和接头的场内特性，以确定磁体的运行参数。在 77 K 的工作电流为 16.5 A 时，磁体的稳定中心场达到 ∼408.4 mT。虽然接头的 Ic 值大大低于 CC 在自场时的 Ic 值，但与 CC 相比，它能保持类似甚至更高的场内 Ic 值，这对磁体应用大有裨益。这项研究为在 PCM 中运行的闭环 MP 磁体的设计和构造提供了一些启示。
{"title":"Development of a multi-pancake HTS magnet operated in persistent current mode based on superconducting joint of REBCO coated conductors","authors":"Daxing Huang, Hao Dong, Tongxin Wang, Hongwei Gu and Fazhu Ding","doi":"10.1088/1361-6668/ad5b26","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5b26","url":null,"abstract":"Developing closed-loop magnets that operate in a persistent current mode (PCM) is crucial for achieving higher resolution and sensitivity in NMR and MRI devices. To the best of our knowledge, we report a novel closed-loop multi-pancake (MP) HTS magnet operated on PCM based on a novel jointless winding method with superconducting joints of REBCO coated conductors (CCs). The in-field characteristics of the CC and the joints were investigated to determine the operating parameters of the magnet. The steady central field of the magnet reached ∼408.4 mT at 77 K with an operating current of 16.5 A. The joint resistance was inferred from a higher excitation current of 17 A to be at least less than 2.5 × 10−10Ω. Although the Ic value of the joint was considerably lower than that of the CC at self-field, it could maintain similar comparable or even higher in-field Ic compared to the CC, which is immensely beneficial for magnet applications. This study provides some insights into the design and construction of closed-loop MP magnets operating in PCM.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"335 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141741182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-18DOI: 10.1088/1361-6668/ad59d0
Alireza Sadeghi, Wenjuan Song and Mohammad Yazdani-Asrami
High-temperature superconducting (HTS) cables are promising solutions for electric power transmission of renewable energy resources, where their fault performance study is vital to avoid power interruptions in the grid. In this study, a fast intelligent surrogate model was presented to estimate the fault performance of a 22.9 kV/50 MW HTS cable to make fast fault performance analysis of the HTS cables possible during the design stage. Different fault scenarios were considered under different fault durations, fault resistances, and types of faults. Then, the fault energy, fault current, fault type, fault duration, and fault resistance were fed into the surrogate model as inputs. The outputs were the temperature of the rare-earth barium copper oxide (ReBCO) tapes, the former temperature, the ReBCO layer current, and the total resistance of each phase. For surrogate modelling, cascade forward neural networks (CFNNs) were used. The results show that the CFNN-based model estimated the fault performance of the cable with an average accuracy of 99.1%. Finally, the impact of considering fault energy, fault current, and both, as the inputs of the models, on the final accuracy were explored. The results show that by considering the fault energy, the accuracy of the surrogate model can be increased.
{"title":"Intelligent surrogate model of a high-temperature superconducting cable for reliable energy delivery: short-circuit fault performance","authors":"Alireza Sadeghi, Wenjuan Song and Mohammad Yazdani-Asrami","doi":"10.1088/1361-6668/ad59d0","DOIUrl":"https://doi.org/10.1088/1361-6668/ad59d0","url":null,"abstract":"High-temperature superconducting (HTS) cables are promising solutions for electric power transmission of renewable energy resources, where their fault performance study is vital to avoid power interruptions in the grid. In this study, a fast intelligent surrogate model was presented to estimate the fault performance of a 22.9 kV/50 MW HTS cable to make fast fault performance analysis of the HTS cables possible during the design stage. Different fault scenarios were considered under different fault durations, fault resistances, and types of faults. Then, the fault energy, fault current, fault type, fault duration, and fault resistance were fed into the surrogate model as inputs. The outputs were the temperature of the rare-earth barium copper oxide (ReBCO) tapes, the former temperature, the ReBCO layer current, and the total resistance of each phase. For surrogate modelling, cascade forward neural networks (CFNNs) were used. The results show that the CFNN-based model estimated the fault performance of the cable with an average accuracy of 99.1%. Finally, the impact of considering fault energy, fault current, and both, as the inputs of the models, on the final accuracy were explored. The results show that by considering the fault energy, the accuracy of the surrogate model can be increased.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"107 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141741181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-17DOI: 10.1088/1361-6668/ad6484
F. Gomory, J. Šouc
Variation of critical current along the conductor length is the feature commonly encountered in industrially produced REBCO tapes called coated conductors (CC). Reduction of critical current exceeding several percent in the portions few millimetres long can be observed in the data obtained by reel-to-reel characterisation provided by manufacturers. Metallic layers in the CC architecture can take over some current in such „weak spot”, and help to keep the local temperature stable, preventing its thermal runaway and conversion to a “hot spot”. Understanding the phenomenon is particularly crucial when the space and weight limitations do not allow to add metallic layer with the thickness, that would be sufficient to match the lost transport capability of superconductor. For this purpose, we studied a set of samples, representing both standard as well as infrequent profiles of weak spots identified in direct transport experiments. Analytical theory was then utilised as basic tool for recovering the properties serving as input for numerical modelling. Temperature profiles and current redistribution in the weak spot locations were found, and the effect of cooling conditions and metallic layer thickness on the weak spot resistance against thermal runaway analysed. Quantitative assessment of the possibility to improve the performance of CC tape by adding Cu stabilising layer or improving cooling settings could help to optimise the architecture of coated conductor intended for use in electric transport.
临界电流沿导体长度的变化是工业生产的 REBCO 磁带（称为涂层导体 (CC)）中常见的特征。从制造商提供的卷对卷表征数据中可以观察到，在几毫米长的部分，临界电流的减小超过了百分之几。CC 结构中的金属层可以分担此类 "薄弱点 "的部分电流，并有助于保持局部温度稳定，防止其热失控并转化为 "热点"。由于空间和重量的限制，无法添加厚度足以匹配超导体传输能力损失的金属层时，理解这一现象就显得尤为重要。为此，我们研究了一组样品，它们代表了在直接传输实验中发现的薄弱点的标准剖面和非频繁剖面。然后利用分析理论作为恢复特性的基本工具，作为数值建模的输入。研究发现了薄弱点位置的温度曲线和电流再分布，并分析了冷却条件和金属层厚度对薄弱点抗热失控的影响。通过添加铜稳定层或改进冷却设置，对提高 CC 磁带性能的可能性进行定量评估，有助于优化用于电动交通的涂层导体结构。
{"title":"Analysis of current and heat transfer in location with reduced critical current in coated conductor tape","authors":"F. Gomory, J. Šouc","doi":"10.1088/1361-6668/ad6484","DOIUrl":"https://doi.org/10.1088/1361-6668/ad6484","url":null,"abstract":"\u0000 Variation of critical current along the conductor length is the feature commonly encountered in industrially produced REBCO tapes called coated conductors (CC). Reduction of critical current exceeding several percent in the portions few millimetres long can be observed in the data obtained by reel-to-reel characterisation provided by manufacturers. Metallic layers in the CC architecture can take over some current in such „weak spot”, and help to keep the local temperature stable, preventing its thermal runaway and conversion to a “hot spot”. Understanding the phenomenon is particularly crucial when the space and weight limitations do not allow to add metallic layer with the thickness, that would be sufficient to match the lost transport capability of superconductor. For this purpose, we studied a set of samples, representing both standard as well as infrequent profiles of weak spots identified in direct transport experiments. Analytical theory was then utilised as basic tool for recovering the properties serving as input for numerical modelling. Temperature profiles and current redistribution in the weak spot locations were found, and the effect of cooling conditions and metallic layer thickness on the weak spot resistance against thermal runaway analysed. Quantitative assessment of the possibility to improve the performance of CC tape by adding Cu stabilising layer or improving cooling settings could help to optimise the architecture of coated conductor intended for use in electric transport.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":" 23","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141830286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
No-electrical-insulation (NEI) magnets gradually exhibit significant appeal due to their robust thermal stability and elevated mechanical strength. However, when exposed to AC conditions, the magnets would suffer more significant AC losses in dynamic electromagnetic devices, such as motors and maglev systems. Presently, the numerical methods for predicting the electromagnetic and loss behaviors of large-scale NEI magnets entail high computation costs due to the substantial degrees of freedom or complicated modeling strategies. Thus, we propose a fully finite-element method referred to the field-circuit coupling method to efficiently assess the overall behaviors of NEI magnets while preserving adequate accuracy. This method couples the T-A formula and the single-turn equivalent circuit through global voltage, to avoid the costly and complicated inductance calculation, and to simultaneously consider the induced current. By further integrating the homogenization method, the calculation speed can be increased up to ten times. Additionally, we study the critical current, electromagnetic and loss behaviors of the NEI magnets based on the proposed model. We identify some measurement methods that offer more precise estimations of the critical current and the turn-to-turn contact resistance of NEI magnets. Meanwhile, the results indicate the severe impact of high AC fields on the losses, and emphasize the importance of a reliable shielding structure for operational safety. Finally, the influence of turn-to-turn contact resistivity on the loss behavior is also investigated, which can provide valuable insights for the design of the NEI magnets in dynamic electromagnetic devices.
{"title":"AC losses calculation of No-electrical-insulation HTS magnets with field-circuit coupling method","authors":"Ruichen Wang, Guangtong Ma, Pengbo Zhou, Songlin Li, Boqiang Liu, Weikang Tian","doi":"10.1088/1361-6668/ad637c","DOIUrl":"https://doi.org/10.1088/1361-6668/ad637c","url":null,"abstract":"\u0000 No-electrical-insulation (NEI) magnets gradually exhibit significant appeal due to their robust thermal stability and elevated mechanical strength. However, when exposed to AC conditions, the magnets would suffer more significant AC losses in dynamic electromagnetic devices, such as motors and maglev systems. Presently, the numerical methods for predicting the electromagnetic and loss behaviors of large-scale NEI magnets entail high computation costs due to the substantial degrees of freedom or complicated modeling strategies. Thus, we propose a fully finite-element method referred to the field-circuit coupling method to efficiently assess the overall behaviors of NEI magnets while preserving adequate accuracy. This method couples the T-A formula and the single-turn equivalent circuit through global voltage, to avoid the costly and complicated inductance calculation, and to simultaneously consider the induced current. By further integrating the homogenization method, the calculation speed can be increased up to ten times. Additionally, we study the critical current, electromagnetic and loss behaviors of the NEI magnets based on the proposed model. We identify some measurement methods that offer more precise estimations of the critical current and the turn-to-turn contact resistance of NEI magnets. Meanwhile, the results indicate the severe impact of high AC fields on the losses, and emphasize the importance of a reliable shielding structure for operational safety. Finally, the influence of turn-to-turn contact resistivity on the loss behavior is also investigated, which can provide valuable insights for the design of the NEI magnets in dynamic electromagnetic devices.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"29 22","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141645709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.1088/1361-6668/ad5fbf
Gan Zhai, William P Halperin, Arneil P Reyes, Sam Posen, Zuhawn Sung, Chiara Tarantini, Michael D Brown and David C Larbalestier
The superconductor Nb3Sn has important applications for construction of very high-field superconducting magnets. In this work we investigate its microscopic electronic structure with 93Nb nuclear magnetic resonance (NMR). The high-quality Nb3Sn powder sample was studied in both 3.2 T and 7 T magnetic fields in the temperature range from 4 K to 300 K. From measurement of the spectrum and its theoretical analysis, we find evidence for anisotropy despite its cubic crystal structure. Magnetic alignment of the powder grains in the superconducting state was also observed. The Knight shift and spin-lattice relaxation rate, , were measured and the latter compared with BCS theory for the energy gap at 3.2 T and at 7 T, indicating suppression of the order parameter by magnetic field.
超导体 Nb3Sn 在制造极高磁场超导磁体方面有着重要的应用。在这项工作中，我们利用 93Nb 核磁共振（NMR）研究了它的微观电子结构。我们在 3.2 T 和 7 T 的磁场中，在 4 K 至 300 K 的温度范围内对高质量 Nb3Sn 粉末样品进行了研究。我们还观察到超导状态下粉末颗粒的磁排列。我们测量了奈特位移和自旋晶格弛豫速率，并将后者与 BCS 理论在 3.2 T 和 7 T 时的能隙进行了比较，结果表明磁场抑制了阶次参数。
{"title":"Nuclear magnetic resonance investigation of superconducting and normal state Nb3Sn","authors":"Gan Zhai, William P Halperin, Arneil P Reyes, Sam Posen, Zuhawn Sung, Chiara Tarantini, Michael D Brown and David C Larbalestier","doi":"10.1088/1361-6668/ad5fbf","DOIUrl":"https://doi.org/10.1088/1361-6668/ad5fbf","url":null,"abstract":"The superconductor Nb3Sn has important applications for construction of very high-field superconducting magnets. In this work we investigate its microscopic electronic structure with 93Nb nuclear magnetic resonance (NMR). The high-quality Nb3Sn powder sample was studied in both 3.2 T and 7 T magnetic fields in the temperature range from 4 K to 300 K. From measurement of the spectrum and its theoretical analysis, we find evidence for anisotropy despite its cubic crystal structure. Magnetic alignment of the powder grains in the superconducting state was also observed. The Knight shift and spin-lattice relaxation rate, , were measured and the latter compared with BCS theory for the energy gap at 3.2 T and at 7 T, indicating suppression of the order parameter by magnetic field.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141720998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.1088/1361-6668/ad637b
Wescley Tiago Batista de Sousa, D. Kottonau, J. M. Pina, A. Morandi, M. Noe
Due the integration of superconducting technologies into electrical networks around the world, its precise simulations in power grids are increasingly becoming a desirable outcome. Over the years, sophisticated methods have been used to model superconducting power cables and, in this way, predict its behavior under different conditions. Most of the available models, however, are not advisable to be used and embedded in power system simulators. In this manuscript, we focus on the development of a method specifically for modelling superconducting cables in traditional power grid simulators. We start developing the model through a case example, within the basic concepts are introduced and later expanded to general cases. The model also incorporates the transient behavior of the cooling media, which is mandatory for such cables. It has been observed that the proposed model requires less computational effort and is able to deliver accurate results when compared to more advanced methods.
{"title":"Thermal-electrical analogy for simulations of superconducting power cables","authors":"Wescley Tiago Batista de Sousa, D. Kottonau, J. M. Pina, A. Morandi, M. Noe","doi":"10.1088/1361-6668/ad637b","DOIUrl":"https://doi.org/10.1088/1361-6668/ad637b","url":null,"abstract":"\u0000 Due the integration of superconducting technologies into electrical networks around the world, its precise simulations in power grids are increasingly becoming a desirable outcome. Over the years, sophisticated methods have been used to model superconducting power cables and, in this way, predict its behavior under different conditions. Most of the available models, however, are not advisable to be used and embedded in power system simulators. In this manuscript, we focus on the development of a method specifically for modelling superconducting cables in traditional power grid simulators. We start developing the model through a case example, within the basic concepts are introduced and later expanded to general cases. The model also incorporates the transient behavior of the cooling media, which is mandatory for such cables. It has been observed that the proposed model requires less computational effort and is able to deliver accurate results when compared to more advanced methods.","PeriodicalId":21985,"journal":{"name":"Superconductor Science and Technology","volume":"52 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141644396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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