Pub Date : 2025-12-24DOI: 10.1109/TASC.2025.3648278
Magnus Bøgh Borregaard Christensen;Peter Koch;Tomasz Podzorny;Jan Østergaard
Superconducting magnet impedance measurements are vital for assessing magnet health and electrical integrity. To further enhance monitoring capabilities beyond contemporary methods that largely rely on manual intervention, recent efforts have focused on enabling in situ and continuous measurements during magnet operation. This evolution is becoming increasingly relevant due to the growing complexity and aging of modern particle accelerator facilities. However, implementing such measurements presents challenges, particularly due to operational constraints and interference from the power converter. This article focuses on noise reduction techniques aimed at reducing the variance of impedance estimates derived from samples collected by a differential probing measurement system. A key contribution is the analysis of a unique, high-resolution dataset comprising uninterrupted impedance measurements across both steady-state magnet current plateaus and current ramping stages. This dataset enables inspection of the interaction between injected stimuli and power converter noise throughout key stages of a magnet's powering cycle, an aspect not previously explored and reported in the literature. Using a differential measurement configuration, we extract a reference of the power converter noise and apply Wiener filtering to reduce the variance of impedance estimates. We evaluate two denoising strategies, a static approach with fixed filter coefficients and an adaptive method with periodically updated coefficients. For long estimation windows (1 s), neither approach yields significant improvements. However, for short windows (10 ms), both methods achieve substantial variance reduction of up to two orders of magnitude. Under certain operating conditions, the adaptive method provides a further improvement of approximately one order of magnitude over the static approach, highlighting the potential advantage of adaptivity for real-time impedance monitoring.
{"title":"Noise Analysis and Variance Reduction of Continuous Impedance Measurements of Energized Superconducting Magnets","authors":"Magnus Bøgh Borregaard Christensen;Peter Koch;Tomasz Podzorny;Jan Østergaard","doi":"10.1109/TASC.2025.3648278","DOIUrl":"https://doi.org/10.1109/TASC.2025.3648278","url":null,"abstract":"Superconducting magnet impedance measurements are vital for assessing magnet health and electrical integrity. To further enhance monitoring capabilities beyond contemporary methods that largely rely on manual intervention, recent efforts have focused on enabling in situ and continuous measurements during magnet operation. This evolution is becoming increasingly relevant due to the growing complexity and aging of modern particle accelerator facilities. However, implementing such measurements presents challenges, particularly due to operational constraints and interference from the power converter. This article focuses on noise reduction techniques aimed at reducing the variance of impedance estimates derived from samples collected by a differential probing measurement system. A key contribution is the analysis of a unique, high-resolution dataset comprising uninterrupted impedance measurements across both steady-state magnet current plateaus and current ramping stages. This dataset enables inspection of the interaction between injected stimuli and power converter noise throughout key stages of a magnet's powering cycle, an aspect not previously explored and reported in the literature. Using a differential measurement configuration, we extract a reference of the power converter noise and apply Wiener filtering to reduce the variance of impedance estimates. We evaluate two denoising strategies, a static approach with fixed filter coefficients and an adaptive method with periodically updated coefficients. For long estimation windows (1 s), neither approach yields significant improvements. However, for short windows (10 ms), both methods achieve substantial variance reduction of up to two orders of magnitude. Under certain operating conditions, the adaptive method provides a further improvement of approximately one order of magnitude over the static approach, highlighting the potential advantage of adaptivity for real-time impedance monitoring.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 2","pages":"1-20"},"PeriodicalIF":1.8,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11314731","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We propose an optimization method for a superconductor-insulator-superconductor (SIS) mixer-based amplifier circuit that employs SIS up- and down-converters. Such a novel amplifier configuration could enable superior low-noise performance for future broadband amplifier systems, such as those for large arrays of superconducting sensors or qubits. Optimization was achieved by identifying a solution in which the mutually dependent impedances of the SIS mixers converge under given conditions. A circuit design using this method predicted an amplifier gain of approximately 20 dB and a noise temperature of approximately 2 K at 4 K operation when practical current-voltage characteristics of Nb SIS junctions are used in the simulation. To verify the validity of this method, an amplifier circuit was prepared using waveguide Nb/AlOx/Nb mixer modules. By varying the phase delay between the two SIS mixers, changes in gain were observed, resulting from different convergence conditions of their mutually dependent impedances, which closely matched the predictions made using this method. These results are promising for the development of an integrated circuit including SIS amplifiers and superconducting detector arrays, with bandwidths of 10 GHz or above. This may also enable novel nonreciprocal microwave circuits such as gyrators, isolators, and circulators.
{"title":"Optimization and Validation of the Design of Superconductor-Insulator-Superconductor Mixer-Based Amplifier Circuits","authors":"Yoshinori Uzawa;Wenlei Shan;Akira Kawakami;Yosuke Murayama;Sho Masui;Takafumi Kojima;Kazumasa Makise;Takatomi Kumagai","doi":"10.1109/TASC.2025.3646187","DOIUrl":"https://doi.org/10.1109/TASC.2025.3646187","url":null,"abstract":"We propose an optimization method for a superconductor-insulator-superconductor (SIS) mixer-based amplifier circuit that employs SIS up- and down-converters. Such a novel amplifier configuration could enable superior low-noise performance for future broadband amplifier systems, such as those for large arrays of superconducting sensors or qubits. Optimization was achieved by identifying a solution in which the mutually dependent impedances of the SIS mixers converge under given conditions. A circuit design using this method predicted an amplifier gain of approximately 20 dB and a noise temperature of approximately 2 K at 4 K operation when practical current-voltage characteristics of Nb SIS junctions are used in the simulation. To verify the validity of this method, an amplifier circuit was prepared using waveguide Nb/AlOx/Nb mixer modules. By varying the phase delay between the two SIS mixers, changes in gain were observed, resulting from different convergence conditions of their mutually dependent impedances, which closely matched the predictions made using this method. These results are promising for the development of an integrated circuit including SIS amplifiers and superconducting detector arrays, with bandwidths of 10 GHz or above. This may also enable novel nonreciprocal microwave circuits such as gyrators, isolators, and circulators.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145929429","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 : 2025-12-23DOI: 10.1109/TASC.2025.3646171
Yahao Wu;Wenjuan Song;Mohammad Yazdani-Asrami
Fast and reliable quench detection is critical for protecting high temperature superconducting coils, magnets, and devices, yet experimental datasets remain limited due to cryogenic constraints and risk of conductor damage. This limitation is one of the key challenges in developing machine learning (ML) techniques for predicting quench through regression-based forecasting of voltage signals. To address this, we propose a framework that combines Time-series Generative Adversarial Networks (TimeGAN) for artificial sequence generation with Long Short-Term Memory (LSTM) predictors. From 36 measured voltage sequences, TimeGAN generated 90 artificial sequences to expand the dataset and mitigate overfitting. Augmenting the LSTM improved quench prediction accuracy to ∼3% mean relative error. This study demonstrates the first application of TimeGAN to superconducting quench signals and highlights the benefit of ML-driven augmentation for improving quench prediction robustness.
{"title":"Machine Learning Prediction for Experimental Quench Voltage of HTS Coils Using a Combined Framework With Time-Series Generative Adversarial Network and Long Short-Term Memory Techniques","authors":"Yahao Wu;Wenjuan Song;Mohammad Yazdani-Asrami","doi":"10.1109/TASC.2025.3646171","DOIUrl":"https://doi.org/10.1109/TASC.2025.3646171","url":null,"abstract":"Fast and reliable quench detection is critical for protecting high temperature superconducting coils, magnets, and devices, yet experimental datasets remain limited due to cryogenic constraints and risk of conductor damage. This limitation is one of the key challenges in developing machine learning (ML) techniques for predicting quench through regression-based forecasting of voltage signals. To address this, we propose a framework that combines Time-series Generative Adversarial Networks (TimeGAN) for artificial sequence generation with Long Short-Term Memory (LSTM) predictors. From 36 measured voltage sequences, TimeGAN generated 90 artificial sequences to expand the dataset and mitigate overfitting. Augmenting the LSTM improved quench prediction accuracy to ∼3% mean relative error. This study demonstrates the first application of TimeGAN to superconducting quench signals and highlights the benefit of ML-driven augmentation for improving quench prediction robustness.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886665","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 : 2025-12-23DOI: 10.1109/TASC.2025.3647434
Yasuhiro H. Matsuda;Yuto Ishii;Xu-Guang Zhou;Hiroaki Hayashi;Hironobu Sawabe
An ultrahigh magnetic field in the multi-megagauss field (mMGF) range (100–1000 T) is a potential tool to explore undeveloped science disciplines. The recent development of measurement techniques in material science in the mMGF is considerable. It implies that the development of ultrahigh magnetic field science can expand not only for materials but also for other subjects, such as chemical reactions or biological systems. Destruction of the coil during the mMGF production makes the measurement a single-shot measurement. Reproducibility of the magnetic field waveform on the microsecond time scale is the key technology that ensures the high reliability of the experimental results. The current status of the waveform reproducibility of the mMGF generated by the single-turn coil and the electromagnetic flux compression is reported. The current status of the available measurements for material science in the mMGF is also introduced.
{"title":"Production of Multi-Megagauss Ultrahigh Magnetic Fields Using Destructive Magnets for Material Science","authors":"Yasuhiro H. Matsuda;Yuto Ishii;Xu-Guang Zhou;Hiroaki Hayashi;Hironobu Sawabe","doi":"10.1109/TASC.2025.3647434","DOIUrl":"https://doi.org/10.1109/TASC.2025.3647434","url":null,"abstract":"An ultrahigh magnetic field in the multi-megagauss field (<italic>m</i>MGF) range (100–1000 T) is a potential tool to explore undeveloped science disciplines. The recent development of measurement techniques in material science in the <italic>m</i>MGF is considerable. It implies that the development of ultrahigh magnetic field science can expand not only for materials but also for other subjects, such as chemical reactions or biological systems. Destruction of the coil during the <italic>m</i>MGF production makes the measurement a single-shot measurement. Reproducibility of the magnetic field waveform on the microsecond time scale is the key technology that ensures the high reliability of the experimental results. The current status of the waveform reproducibility of the <italic>m</i>MGF generated by the single-turn coil and the electromagnetic flux compression is reported. The current status of the available measurements for material science in the <italic>m</i>MGF is also introduced.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 3","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11313525","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145929362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-23DOI: 10.1109/TASC.2025.3646984
Nicolas Rotheudt;Jean-François Fagnard;Tomas Hlasek;Jan Plechacek;Philippe Vanderbemden
Combining high-temperature superconducting bulks and jointless closed-loop coated conductors recently demonstrated promising magnetic shielding/screening properties when they are zero-field cooled andsubjected to an inhomogeneous applied field. The present work focuses on studying how their screening properties evolve if several magnetic field excitation cycles are applied, as it is the case in practical applications. This study is carried out both experimentally and numerically. The main result is that more than 95% of the field attenuation (screening factor SF) obtained after the first ramp still remain after 300 cycles. This result is explained by using the numerically computed current density distribution in the bulk alone. The slight decrease in SF after several cycles is found to be smaller than the field attenuation arising from conventional current relaxation (or flux creep) if the magnetic field is kept constant after the first increasing ramp. These results demonstrate the potential of such superconducting screens for practical applications with a large number of excitation applied field cycles.
{"title":"Magnetic Screening Behavior of Hybrid High-Temperature Superconducting Screens Subjected to Successive Excitation Cycles: Experiments and Numerical Study","authors":"Nicolas Rotheudt;Jean-François Fagnard;Tomas Hlasek;Jan Plechacek;Philippe Vanderbemden","doi":"10.1109/TASC.2025.3646984","DOIUrl":"https://doi.org/10.1109/TASC.2025.3646984","url":null,"abstract":"Combining high-temperature superconducting bulks and jointless closed-loop coated conductors recently demonstrated promising magnetic shielding/screening properties when they are zero-field cooled andsubjected to an inhomogeneous applied field. The present work focuses on studying how their screening properties evolve if several magnetic field excitation cycles are applied, as it is the case in practical applications. This study is carried out both experimentally and numerically. The main result is that more than 95% of the field attenuation (screening factor SF) obtained after the first ramp still remain after 300 cycles. This result is explained by using the numerically computed current density distribution in the bulk alone. The slight decrease in SF after several cycles is found to be smaller than the field attenuation arising from conventional current relaxation (or flux creep) if the magnetic field is kept constant after the first increasing ramp. These results demonstrate the potential of such superconducting screens for practical applications with a large number of excitation applied field cycles.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982287","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}
Voltage taps remain the standard and reliable diagnostic tool for detecting quenches in superconducting magnets. However, they identify a quench only at the time of voltage rise and do not provide information on earlier physical precursors. In this work, we investigate whether acoustic emission data can reveal precursor activity that occurs before conventional voltage detection using machine learning techniques. We introduce an event selection method and a weakly supervised machine learning procedure to learn data-driven criteria for identifying potential acoustic precursors to quenches. Two Convolutional Neural Network (CNN) architectures are trained: one on acoustic sensor events from our selection procedure and one on the Fast Fourier Transforms (FFTs) of these events. Both networks are trained iteratively using confidence-weighted loss functions to associate certain subsets of training data with a precursor label. We evaluate the performance of these models by examining the time distribution of events classified as potential precursors relative to the quench onset. Results indicate that the proposed approach can possibly distinguish acoustic emission events occurring closer to the quench from earlier acoustic activity during ramping, suggesting the potential for flagging quench precursors in acoustic data.
{"title":"A Weakly Supervised Machine Learning Procedure for Acoustic Emission Quench Diagnostics","authors":"Maira Khan;Steven Krave;Vittorio Marinozzi;Jennifer Ngadiuba;Stoyan Stoynev;Nhan Tran","doi":"10.1109/TASC.2025.3647009","DOIUrl":"https://doi.org/10.1109/TASC.2025.3647009","url":null,"abstract":"Voltage taps remain the standard and reliable diagnostic tool for detecting quenches in superconducting magnets. However, they identify a quench only at the time of voltage rise and do not provide information on earlier physical precursors. In this work, we investigate whether acoustic emission data can reveal precursor activity that occurs before conventional voltage detection using machine learning techniques. We introduce an event selection method and a weakly supervised machine learning procedure to learn data-driven criteria for identifying potential acoustic precursors to quenches. Two Convolutional Neural Network (CNN) architectures are trained: one on acoustic sensor events from our selection procedure and one on the Fast Fourier Transforms (FFTs) of these events. Both networks are trained iteratively using confidence-weighted loss functions to associate certain subsets of training data with a precursor label. We evaluate the performance of these models by examining the time distribution of events classified as potential precursors relative to the quench onset. Results indicate that the proposed approach can possibly distinguish acoustic emission events occurring closer to the quench from earlier acoustic activity during ramping, suggesting the potential for flagging quench precursors in acoustic data.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 3","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982158","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}
Epitaxial iron chalcogenide (FeCh, Ch = Se, Te) film deposited by pulsed laser deposition (PLD) represents the gold standard to obtain high superconducting performances. (100) CaF2 single crystal represents the ideal substrate due to structural compatibility, low lattice mismatch and chemical compatibility with FeCh. Epitaxial thin FeCh films grown on CaF2 show optimal performances, with zero-resistance critical temperature Tc0 as high as 9.2 K and 17 K for FeSe and Fe(Se,Te), respectively. Higher Tc up to 20 K can be obtained using a seed layer in Fe(Se,Te).However, film buckling and delamination sometimes occur. Furthermore, the presence of submicrometric wrinkles arranged in graticule pattern was occasionally observed. In this contribution, we provide information on extended defect formation in epitaxial FeCh thin films deposited on (100) CaF2 single crystal by PLD, and their influence on the superconducting properties of such films.
脉冲激光沉积（PLD）外延硫系铁（FeCh, Ch = Se, Te）薄膜是获得高超导性能的金标准。（100） CaF2单晶与FeCh具有结构相容性、低晶格失配和化学相容性，是理想的衬底材料。在CaF2上生长的外延薄膜表现出最佳性能，FeSe和Fe（Se,Te）的零电阻临界温度Tc0分别高达9.2 K和17 K。在Fe（Se,Te）中使用种子层可以获得高达20 K的较高Tc。然而，有时会发生薄膜屈曲和分层。此外，偶尔观察到以网格模式排列的亚微米皱纹的存在。在这篇文章中，我们提供了PLD沉积在（100）CaF2单晶上的外延FeCh薄膜的扩展缺陷形成的信息，以及它们对这种薄膜超导性能的影响。
{"title":"Epitaxial Fe(Se,Te) Film Deposited on CaF2 Single Crystal Substrate: Defect Generation and Film Stability","authors":"Angelo Vannozzi;Antonella Mancini;Andrea Masi;Laura Piperno;Valentina Galluzzi;Alessandro Rufoloni;Giuseppe Celentano","doi":"10.1109/TASC.2025.3645747","DOIUrl":"https://doi.org/10.1109/TASC.2025.3645747","url":null,"abstract":"Epitaxial iron chalcogenide (FeCh, Ch = Se, Te) film deposited by pulsed laser deposition (PLD) represents the gold standard to obtain high superconducting performances. (100) CaF<sub>2</sub> single crystal represents the ideal substrate due to structural compatibility, low lattice mismatch and chemical compatibility with FeCh. Epitaxial thin FeCh films grown on CaF<sub>2</sub> show optimal performances, with zero-resistance critical temperature <italic>T</i><sub>c0</sub> as high as 9.2 K and 17 K for FeSe and Fe(Se,Te), respectively. Higher <italic>T</i><sub>c</sub> up to 20 K can be obtained using a seed layer in Fe(Se,Te).However, film buckling and delamination sometimes occur. Furthermore, the presence of submicrometric wrinkles arranged in graticule pattern was occasionally observed. In this contribution, we provide information on extended defect formation in epitaxial FeCh thin films deposited on (100) CaF<sub>2</sub> single crystal by PLD, and their influence on the superconducting properties of such films.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-4"},"PeriodicalIF":1.8,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886630","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 : 2025-12-22DOI: 10.1109/TASC.2025.3645709
X. Y. Tan;S. Y. Gao;X. S. Yang;H. Zhang;J. Jiang;J. M. Zhu
Stacked high-temperature superconducting (HTS) cables, with their high current-carrying capacity and high structural strength, show significant advantages in strong electric applications. However, in an alternating magnetic field environment, the conductors will generate AC losses, which can cause local overheating. Filamentary technology can effectively reduce the AC losses. This work investigates the magnetization and transport losses of stacked HTS cables based on multi-filamentary REBCO tapes. Results directly demonstrates the fact of the multi-filamentary structure in reducing magnetization loss. As the twist angle increased, magnetization losses first decreased and then stabilized. At low magnetic fields, the difference in magnetization loss between the original cable and the multi-filamentary cable is relatively small. Under higher magnetic fields, the magnetization loss of the original cable is significantly higher than that of the multi-filamentary cable. The transport losses of the multi-filamentary cable are always lower than those of the original cable. The optimization effect of filamentization on magnetization losses is significantly stronger than that on transport losses.
{"title":"AC Losses in Striated REBCO Stacked Tape Cables","authors":"X. Y. Tan;S. Y. Gao;X. S. Yang;H. Zhang;J. Jiang;J. M. Zhu","doi":"10.1109/TASC.2025.3645709","DOIUrl":"https://doi.org/10.1109/TASC.2025.3645709","url":null,"abstract":"Stacked high-temperature superconducting (HTS) cables, with their high current-carrying capacity and high structural strength, show significant advantages in strong electric applications. However, in an alternating magnetic field environment, the conductors will generate AC losses, which can cause local overheating. Filamentary technology can effectively reduce the AC losses. This work investigates the magnetization and transport losses of stacked HTS cables based on multi-filamentary REBCO tapes. Results directly demonstrates the fact of the multi-filamentary structure in reducing magnetization loss. As the twist angle increased, magnetization losses first decreased and then stabilized. At low magnetic fields, the difference in magnetization loss between the original cable and the multi-filamentary cable is relatively small. Under higher magnetic fields, the magnetization loss of the original cable is significantly higher than that of the multi-filamentary cable. The transport losses of the multi-filamentary cable are always lower than those of the original cable. The optimization effect of filamentization on magnetization losses is significantly stronger than that on transport losses.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886628","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 : 2025-12-19DOI: 10.1109/TASC.2025.3645158
R. Konishi;Y. Emori;R. Ozumi;H. Handa;H. Miyazaki;S. Miura;H. Sasa;M. Iwakuma
To reduce carbon dioxide emissions from aircraft, superconducting electric propulsion systems are attracting attention. For aircraft, high power density is particularly important, and increasing the power density requires higher rotational speed. Therefore, we are studying a saddle-shaped field coil made with REBa2Cu3O7-δ (REBCO) tape. This coil can be fixed directly to the shaft, which helps provide the mechanical strength needed for high-speed rotation. However, because of the shape characteristics of the REBCO tape, the coil ends tend to become long, increasing the axial length of the motor. In addition, excessive bending or twisting can damage the tape; thus, careful design is necessary. In this study, we developed a design method to shorten the saddle-shaped field coil and evaluated its electromagnetic performance. We introduced a generalized flatwise curvature to represent bending and twisting and set the allowable curvature of the REBCO tape to 0.1 mm-1 based on its mechanical limits. Using this condition, we designed two types of shortened coils. Model A arranges the coils based on the curvature of the innermost coil, while Model B equalizes the curvature of all coils to prevent interference at the coil ends. Three-dimensional finite-element analysis revealed that the axial gap flux density distribution of both models is almost the same. However, Model B has a slightly larger high-flux-density region because its straight part is longer, resulting in better output performance. The obtained torque also exhibits a strong proportional relationship with the axial integral of the gap flux density, confirming that the coil ends are important regions that contribute to motor output.
{"title":"Design of Shortened REBa2Cu3O7-δ Saddle-Shaped Field Coil Ends for Fully Superconducting Synchronous Motors Using Generalized Flatwise Curvature","authors":"R. Konishi;Y. Emori;R. Ozumi;H. Handa;H. Miyazaki;S. Miura;H. Sasa;M. Iwakuma","doi":"10.1109/TASC.2025.3645158","DOIUrl":"https://doi.org/10.1109/TASC.2025.3645158","url":null,"abstract":"To reduce carbon dioxide emissions from aircraft, superconducting electric propulsion systems are attracting attention. For aircraft, high power density is particularly important, and increasing the power density requires higher rotational speed. Therefore, we are studying a saddle-shaped field coil made with REBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> (REBCO) tape. This coil can be fixed directly to the shaft, which helps provide the mechanical strength needed for high-speed rotation. However, because of the shape characteristics of the REBCO tape, the coil ends tend to become long, increasing the axial length of the motor. In addition, excessive bending or twisting can damage the tape; thus, careful design is necessary. In this study, we developed a design method to shorten the saddle-shaped field coil and evaluated its electromagnetic performance. We introduced a generalized flatwise curvature to represent bending and twisting and set the allowable curvature of the REBCO tape to 0.1 mm<sup>-1</sup> based on its mechanical limits. Using this condition, we designed two types of shortened coils. Model A arranges the coils based on the curvature of the innermost coil, while Model B equalizes the curvature of all coils to prevent interference at the coil ends. Three-dimensional finite-element analysis revealed that the axial gap flux density distribution of both models is almost the same. However, Model B has a slightly larger high-flux-density region because its straight part is longer, resulting in better output performance. The obtained torque also exhibits a strong proportional relationship with the axial integral of the gap flux density, confirming that the coil ends are important regions that contribute to motor output.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145830802","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 : 2025-12-19DOI: 10.1109/TASC.2025.3645151
Keith Krause;Michael C. Hamilton;Mark Adams
Josephson parametric amplifiers (JPAs) have become an important component of superconducting applications. Simulating these circuits is vital for optimizing their performance, including their gain and stability. Previously, simulating JPAs has been inefficient due to the limits of using SPICE-based simulators that work in the time domain. JPAs are better suited to frequency domain simulations over a broad frequency range and parameter space. We present JPA simulations using the recently released flux-aware Josephson junction (JJ) and inductor models in Keysight Advanced Design Systems (ADS). We simulate two different flux-driven JPAs: one based on an RF SQUID, and another based on a DC SQUID. We efficiently run harmonic balance simulations over a wide range of circuit parameters. We compare the use of RF and DC SQUIDs in these JPAs by analyzing their simulation results. This work provides a foundation for future SQUID-based JPA simulations in Keysight ADS.
约瑟夫森参量放大器（JPAs）已成为超导应用的重要组成部分。模拟这些电路对于优化它们的性能至关重要，包括它们的增益和稳定性。以前，由于使用基于spice的在时域工作的模拟器的限制，模拟jpa的效率很低。jpa更适合于宽频率范围和参数空间的频域模拟。我们使用Keysight Advanced Design Systems （ADS）中最近发布的磁通感知Josephson结（JJ）和电感模型进行JPA模拟。我们模拟了两种不同的磁通驱动jpa：一种基于RF SQUID，另一种基于DC SQUID。我们在广泛的电路参数范围内有效地运行谐波平衡模拟。通过分析仿真结果，比较了RF和DC squid在这些jpa中的使用情况。这项工作为Keysight ADS中未来基于squid的JPA模拟提供了基础。
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