IEEE Transactions on Applied Superconductivity最新文献

{"title":"JSNPE: A Digital Superconducting Spiking Neural Processing Element","authors":"Huilong Jiang;Zhongqi Wang;Junying Huang;Gang Chen;Zhimin Zhang;Xiaochun Ye;Dongrui Fan;Lixing You","doi":"10.1109/TASC.2025.3561667","DOIUrl":"https://doi.org/10.1109/TASC.2025.3561667","url":null,"abstract":"Superconducting electronic devices are considered a compelling candidate for designing neuromorphic hardware due to their similar behavioral characteristics. Previous works have shown high potential for applying them to design spiking neural networks. However, convincing schemes remain lacking. This article proposes a Josephson junction (JJ)–based spiking neural processing element, JSNPE, a digital scheme composed of a neural and synaptic module. The neuron is a concise quasidigital circuit with three JJs. It operates asynchronously and realizes the integrate-and-fire model. The synapse is a digital circuit constructed with superconducting rapid single flux quantum devices. Compared to previous designs, JSNPE facilitates network scalability, exhibits higher computational resolution, and enables easier weight configuration. To validate the design, we conducted inference tasks on the IRIS and MNIST datasets using WRspice simulation, with inference parameters obtained through software-based training. The analysis indicates that the inference network can achieve a classification accuracy of 96.7% on IRIS, while for MNIST, the classification accuracy for digit “0” reached 94%. We also evaluated the performance and energy efficiency of JSNPE, demonstrating that JSNPE could achieve significant improvements in both metrics compared to complementary metal oxide semiconductor designs.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 4","pages":"1-12"},"PeriodicalIF":1.7,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143943951","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 Calculation of High Temperature Superconducting Coils Based on a Surrogate Model","authors":"Linjie Zhou;Yihan Wang;Qi Yuan;Xiaowei Song;Liang Li;Qiuliang Wang","doi":"10.1109/TASC.2025.3561097","DOIUrl":"https://doi.org/10.1109/TASC.2025.3561097","url":null,"abstract":"AC losses have a significant impact on the design and operation of superconducting power devices. Therefore, fast and accurate estimation of AC losses is essential. However, calculating AC losses in high-temperature superconducting (HTS) coils often requires considerable computational resources. To address this, a time-series surrogate model based on a convolutional neural network (CNN) is proposed. The model is trained using sample points <italic>X</i> (e.g., HTS coil parameters and current profiles) and corresponding AC loss responses <italic>Y</i> obtained from finite element analysis (FEA). It integrates a self-attention hybrid convolution module and a current change perception mechanism to extract deep temporal features, and employs an adaptive threshold to enhance open-set recognition and prediction robustness. The model's accuracy is validated against COMSOL simulation results, demonstrating that it significantly improves computational efficiency while maintaining high prediction accuracy.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143908386","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":"Numerical Simulations in Stand-Alone REBCO Coils Under Rotating Magnetic Fields","authors":"Yuan Wang;James G. Storey;Jin Fang;Timothy J. Haugan;Zhenan Jiang","doi":"10.1109/TASC.2025.3561042","DOIUrl":"https://doi.org/10.1109/TASC.2025.3561042","url":null,"abstract":"Large ac loss in the high-temperature superconducting (HTS) armature windings carrying ac under a rotating magnetic field poses a significant challenge for high power-to-weight ratio all-HTS rotating machines. Understanding the loss behavior of HTS coils in rotating magnetic fields and exploring methods for loss reduction are essential. This study numerically investigates the total ac loss (<italic>Q</i>_tot) (with current) and magnetization loss (<italic>Q</i>_m) (without current) in HTS coils under nonuniform rotating magnetic field. The losses of three 4-turn HTS coils are compared, which are designed with a 4 mm wide tape, a striated tape with two 2 mm filaments, and a striated tape with four 1 mm filaments, respectively. In addition, ac loss in the coils at 77 and 65 K is calculated and evaluated. Simulation results show that, under rotating magnetic fields, the striated structure of the coils significantly reduces both <italic>Q</i>_tot and <italic>Q_m</i>. At high fields (e.g., above 200 mT for <italic>Q_m</i> at 77 K), compared to the loss in the un-striated coil, the loss in the coil designed with the two-filament striated tape decreased by almost half, and the loss in the coil designed with the four-filament striated tape was reduced to nearly a quarter. Interestingly, we also show that under rotating magnetic fields, <italic>Q_m</i> and <italic>Q</i>_tot can be effectively scaled with the critical current of either the coil or the tape. This suggests that losses at different temperatures can potentially be estimated using their respective critical currents.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 4","pages":"1-8"},"PeriodicalIF":1.7,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143896408","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":"High-Order Dual-Band High-Temperature Superconducting Bandpass Filter Using Asymmetric Input/Output (I/O) Feeding Technique","authors":"Zhe Wu;Haiwen Liu;Ruolin Wang;Hongliang Tian;Sidong Wang;Wen Liu;Qinlong Li","doi":"10.1109/TASC.2025.3560670","DOIUrl":"https://doi.org/10.1109/TASC.2025.3560670","url":null,"abstract":"In this article, a high-order dual-band high-temperature superconducting (HTS) bandpass filter (BPF) is proposed, integrating a novel dual-mode hairpin ring resonator (HRR) and an asymmetric input/output (I/O) feeding technique. The proposed HRR features two independently controllable resonant modes, providing enhanced design flexibility for precise frequency and bandwidth control. By leveraging the dual-mode HRRs and optimized coupling schemes, a miniaturized high-isolation sixth-order dual-band HTS BPF is designed. The two passbands are centered at 1.42 GHz with a 7.04% fractional bandwidth for deep space exploration and 1.9625 GHz with a 3.31% fractional bandwidth for 5G mobile communication. To further improve filter performance, an asymmetric I/O feeding technique is introduced, enabling independent control over transmission zeros (TZs). This approach results in a more compact design, greater flexibility, and eliminates the need for additional space. In addition, this technique allows independent tuning of the external quality factors for both passbands, providing greater design flexibility in optimizing filter performance. Four TZs are excited, i.e., two between the two bands, one in the lower stopband, and one in the upper stopband, improving the skirt selectivity and stopband performance of the HTS filter. The working mechanisms of TZs are analyzed in detail. Finally, the designed filter is fabricated on an MgO substrate with YBa2Cu3O7 (YBCO) thin films. The measured results agree well with the simulated ones, demonstrating maximum insertion losses of 0.25 and 0.21 dB in the two passbands, respectively.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 4","pages":"1-9"},"PeriodicalIF":1.7,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143896543","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":"Delay Balancing With Clock-Follow-Data: Optimizing Area Delay Tradeoffs for Robust Rapid Single Flux Quantum Circuits","authors":"Robert S. Aviles;Phalgun G K;Peter A. Beerel","doi":"10.1109/TASC.2025.3561036","DOIUrl":"https://doi.org/10.1109/TASC.2025.3561036","url":null,"abstract":"This article proposes an algorithm for synthesis of clock-follow-data designs that provide robustness against timing violations for rapid single-flux quantum (RSFQ) circuits, minimizing area costs subject to a given performance constraint. Since all RSFQ logic gates must be clocked, properly sequencing the data flow is a challenging problem that often requires the insertion of many path balancing D flip-flops (DFFs), leading to a substantial increase in area. To address this challenge, we present an approach to insert DFFs and schedule their clock arrival times, partially balancing the delays within the circuit. Our algorithm achieves a target throughput while minimizing area overhead. Our algorithm can account for expected timing variations and, by adjusting the bias of the clock network and clock frequency, the resulting circuits can adjust for unexpected timing violations postfabrication. Quantifying the benefits of our approach with a benchmark suite with nominal delays, we yield an average 1.48x improvement in area delay product (ADP) over high frequency full path balancing designs and a 2.07x improvement in ADP over the state-of-the-art (SOTA) robust circuits provided by SOTA multiphase clocking solutions.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 4","pages":"1-9"},"PeriodicalIF":1.7,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143908364","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":"Suppression of Flux Jumps in High-$J_{c}$ Nb$_{3}$Sn Conductors by Ferromagnetic Layer","authors":"Cun Xue;Kai-Wei Cao;Tian He;Chong Wei;Wei Liu;Jun-Yi Ge","doi":"10.1109/TASC.2025.3560069","DOIUrl":"https://doi.org/10.1109/TASC.2025.3560069","url":null,"abstract":"Flux jumps observed in high-<inline-formula><tex-math>$J_{c}$</tex-math></inline-formula> Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn conductors are urgent problems to construct high field superconducting magnets. The low-field instabilities usually reduce the current-carrying capability and thus cause the premature quench of Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn coils at low magnetic field. In this article, we explore suppressing the flux jumps by ferromagnetic (FM) layer. First, we experimentally and theoretically investigate the flux jumps of Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn/FM hybrid wires exposed to a magnetic field loop with constant sweeping rate. Comparing with bare Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn and Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn/Cu (Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn wire wound by copper layer) wires, we reveal two underlying mechanisms. For lower field-ramping rate, the thermal effect of the FM layer primarily suppresses flux jumps. However, for higher field-ramping rate, both thermal and electromagnetic effects play a crucial role to suppress the flux jumps. Furthermore, we explore the flux jumps of Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn/FM hybrid wires exposed to ac magnetic fields with amplitude <inline-formula><tex-math>$B_{a0}$</tex-math></inline-formula> and frequency <inline-formula><tex-math>$omega$</tex-math></inline-formula>. We build up the phase diagrams of flux jumps in the plane <inline-formula><tex-math>$omega$</tex-math></inline-formula>-<inline-formula><tex-math>$B_{a0}$</tex-math></inline-formula> for bare Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn wire, Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn/Cu wire, and Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn/FM wire, respectively. We find that the region of flux jumps of Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn/FM wire is much smaller than the other two wires, which indicates that the Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn/FM wire has significant advantage over merely increasing the heat capacity. The findings shed light on suppression of the flux jumps by utilizing FM materials, which is useful for developing new type of high-<inline-formula><tex-math>$J_{c}$</tex-math></inline-formula> Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn conductors.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 4","pages":"1-12"},"PeriodicalIF":1.7,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144123350","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":"Densification Effects on Critical-Current Dependence on Longitudinal Strain in Bi2Sr2CaCu2O8+x Wires","authors":"Najib Cheggour;Emsley L. Marks;Jianyi Jiang;Ernesto Bosque;David C. Larbalestier","doi":"10.1109/TASC.2025.3559406","DOIUrl":"https://doi.org/10.1109/TASC.2025.3559406","url":null,"abstract":"There is undoubted new interest in applying Bi₂Sr₂CaCu₂O₈₊<italic>_x</i> (Bi-2212) superconducting round wires for ultra-high fields above 20 T. We investigated effects of filament densification in a high-quality Bi-2212 wire made with fine Engi-Mat powder by comparing critical-current <italic>I_c</i> dependence on longitudinal strain <italic>ϵ</i> among samples reacted under 5- and 50-bar overpressure during the partial-melt process. The Walters spring apparatus we used for transport <italic>I_c</i>(<italic>ϵ</i>) measurements had a high sensitivity that helps detect the first onset of irreversible damage, as well as determine other characteristic strains that describe the transition of <italic>I_c</i>(<italic>ϵ</i>) from weak to steeper dependences. Results show a noticeable improvement of all the tensile characteristic strains as a result of densification. For example, average value of the irreversible strain limit <italic>ϵ</i>_irr increased from 0.3% for 5-bar samples to 0.4% for 50-bar specimens. Moreover, the response of densified samples to strain was significantly more homogeneous along the sample length, independent of the measurement mode used. These improvements, which happened in conjunction with an increase of <italic>I_c</i> by a factor 2.5 at 16 T and 4.2 K, are plausibly due to the elimination of pores that can concentrate stress in strained, nondensified samples where they act as crack initiators. Sensitivity of densified samples to longitudinal compression, on the other hand, increased for strain values beyond −0.28% . In this case, we believe that the continuum of Bi-2212 material in densified samples facilitates the propagation of strain-induced buckling defects as compared to nondensified samples where pores may slow this propagation and keep damage more localized. The benefits of densification, nevertheless, largely outweigh this increase of sensitivity at high compression as <italic>I_c</i> remained significantly higher than that of nondensified samples. These results reveal very positive effects of filament densification on the conductor's strain properties that add to the significant boost of <italic>I_c</i> it induces.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 6","pages":"1-11"},"PeriodicalIF":1.7,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143929708","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":"Heat Treatment of Large Nb3Sn Coil for CRAFT TF","authors":"Yifei Wu;Min Yu;Ming Deng;Weijie Gu;Bin Hu;Baozhu Zhang;ZhongRen Li;Ying Wang;Wei Wen;Yu Wu;Jinggang Qin;Weijun Wang","doi":"10.1109/TASC.2025.3558800","DOIUrl":"https://doi.org/10.1109/TASC.2025.3558800","url":null,"abstract":"The fabrication of a prototype toroidal field (TF) coil for the Comprehensive Research Facility for Fusion Technology (CRAFT) represents a critical component of the China Fusion Engineering Test Reactor project. The CRAFT TF coil, characterized by its distinctive “D” shape, measures approximately 19.5 m in length, 11.5 m in width, and 1.1 m in height. The coil incorporates Nb₃Sn cable-in-conduit conductors in both its high-field and medium-field windings. Owing to the intense sensitivity of Nb₃Sn superconductors to stress and strain, the manufacturing process will adhere to the established “wind and react” methodology. Among the various manufacturing stages, heat treatment emerges as a pivotal step in the production of TF Nb₃Sn coil. We have engineered China's largest superconducting coil heat treatment facility, incorporating a fully argon-purged oven environment. This investigation primarily addresses the computational modeling and experimental validation of thermal gradients and fluid dynamics within the system. The design specifications, structural configuration, and processing parameters of the CRAFT TF heat treatment system have been experimentally validated. System performance evaluation demonstrates compliance with technical specifications, particularly in maintaining temperature uniformity within ±5 °C during the critical 650 °C stabilization phase.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 4","pages":"1-7"},"PeriodicalIF":1.7,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143875082","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":"Influence of Coil Structure and Operating Frequency on Performance of Superconducting Wireless Power Transfer","authors":"Dongxu Wang;Wenhao Li;Jinxing Zheng;Xiaotong Cui;Sisi Peng;Difan Zhou;Yanqun Guo;Chuanbing Cai","doi":"10.1109/TASC.2025.3558332","DOIUrl":"https://doi.org/10.1109/TASC.2025.3558332","url":null,"abstract":"High-temperature superconducting (HTS) coil magnets possess extremely high quality factors, therefore having unique advantages when applied to wireless power transfer (WPT) systems especially under low-frequency conditions. The dependence of peak output power and transfer efficiency of an HTS WPT system on the operating frequency varies with the design of the coils because the structure of the coils significantly affects the resonant frequency and ac loss of the HTS WPT system. In this work, a high-power HTS WPT system, including the transfer characteristics under different coil structures, current-carrying conditions, and operating frequencies, has been investigated based on the finite-element simulation to find the optimized operating frequency band and coil structure. It has been found that the change of the inner radius and turn gap in both the solenoid and pancake coils induces a predictable transition frequency change. As the gap is varied, the transfer efficiency remains relatively constant for both coil types. However, for solenoids, reducing the gap value enhances the transferred power, whereas for pancake coils, increasing the gap value augments the transferred power. A transfer efficiency as high as 98.86% or more can be achieved under the optimal conditions.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 4","pages":"1-9"},"PeriodicalIF":1.7,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892533","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":"The Electromagnetic and Structural Design of a 10 kA-Class Full-Wave HTS Transformer-Rectifier","authors":"Zaixing Yang;Yi Lin;Changhao Hu;Jianzhao Geng","doi":"10.1109/TASC.2025.3557375","DOIUrl":"https://doi.org/10.1109/TASC.2025.3557375","url":null,"abstract":"High-temperature superconducting (HTS) magnets operating in persistent current mode suffer from current decay. The footprint and energy requirements of a solid-state power supply and multi-kA current leads impose significant constraints on the size and efficiency of a fusion device. The transformer-rectifier flux pump is emerging as a novel method of supplying current, which eliminates heat leakage caused by traditional current leads and offers relatively high efficiency. In this paper, we introduce a new electromagnetic design and structural design for a 10 kA transformer-rectifier flux pump to power and maintain HTS magnets. The flux pump is powered by an iron-core transformer, which has a copper primary winding and a HTS secondary winding. <inline-formula><tex-math>$J_{mathrm{c}B}$</tex-math></inline-formula> switch is used as a rectifier to charge the magnet. The principle is validated through simulation, and the corresponding mechanical structure design is conducted based on the simulation results.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892409","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}