IEEE Transactions on Applied Superconductivity最新文献

{"title":"Toward a Reduced Helium Content Cryogenic Cooling Scheme at 4.5 K for CERN’s FCC-hh Accelerator","authors":"Patricia Borges de Sousa;Ximo Gallud;Anita Petrovic;Laurent Delprat;Benjamin Bradu;Rob van Weelderen;Laurent Tavian;Dimitri Delikaris","doi":"10.1109/TASC.2025.3604763","DOIUrl":"https://doi.org/10.1109/TASC.2025.3604763","url":null,"abstract":"A conceptual design for cooling superconducting accelerator magnets operating at 4.5 K is proposed for the hadron-hadron configuration of the Future Circular Collider (FCC-hh). This is motivated by efforts to reduce helium inventory and energy costs, while ensuring compatibility with the tunnel structure envisaged for FCC-ee, and providing a technically viable solution for the magnets. The study is carried out for the latest configuration of the FCC-hh machine, the so-called F14 scenario, that uses Nb<inline-formula><tex-math>$_{3}$</tex-math></inline-formula>Sn superconducting magnets with an operational magnetic field of 14 T, for a centre-of-mass energy of 85 TeV with a magnetic filling scheme of 83%. The updated heat loads are presented, along with expected longitudinal and radial temperature gradients in the magnet structure. The move from 1.9 K operation, which makes extensive use of He II, towards 4.5 K using single-phase helium significantly reduces the overall cryogenic power consumption by 30%, and the machine’s helium inventory by 50%.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 3","pages":"1-7"},"PeriodicalIF":1.8,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11154962","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141736","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}

{"title":"Detection of Low-Energy Fluxons From Discrete Long Josephson Junctions for Ballistic Computing","authors":"Han Cai;Liuqi Yu;Waltraut Wustmann;Ryan Clarke;Kevin D. Osborn","doi":"10.1109/TASC.2025.3607768","DOIUrl":"https://doi.org/10.1109/TASC.2025.3607768","url":null,"abstract":"Single-flux quantum (SFQ) digital logic is typically energy efficient and fast, and logic that uses ballistic and reversible principles will provide a new platform for efficient computing. We are studying long Josephson junctions (LJJs), SFQs within them, and an SFQ detector, all intended for future ballistic logic gate experiments. Specifically, we launch low-energy SFQ into discrete LJJs, made from an array of 80 Josephson junctions (JJs) and connecting inductors. The component JJs have critical currents (<inline-formula><tex-math>$I_{c}$</tex-math></inline-formula>) of only 7.5 <inline-formula><tex-math>$mu text{A}$</tex-math></inline-formula>. Measurements of the discrete inductors from our LJJs indicate that the LJJ operates in the continuous regime of the Josephson transmission line, giving dynamics similar to continuous LJJs. The Josephson penetration depth is approximately 2.4 unit cells, and the rest energy of the SFQ in the LJJ is <inline-formula><tex-math>$approx$</tex-math></inline-formula>47 zJ. While the SFQ launcher is fairly standard, the SFQ detector uses JJ critical currents of only <inline-formula><tex-math>$approx$</tex-math></inline-formula> 16 <inline-formula><tex-math>$mu text{A}$</tex-math></inline-formula>. To understand the effects of noise in the circuit, we measured it in two systems: 1) at 4.2 K using a helium dunk probe; and 2) at 3.5 K in a cryogen-free refrigerator. Data show that SFQ detection events are synchronous with SFQ launch events in both systems. The additional jitter in one system over the other is predominantly attributed to noise in the detector. The traversal of the SFQ is consistent with ballistic propagation. This study shows the creation of low-energy SFQs in LJJs composed of discrete components and a method to detect these SFQs, as a step toward achieving ballistic reversible gates.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 8","pages":"1-10"},"PeriodicalIF":1.8,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141767","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":"Rutherford-in-Copper-Channel Conductor for the MARCO Solenoidal Detector Magnet","authors":"Francesco Stacchi;Christophe Berriaud;Valerio Calvelli;P. Ghoshal;S. Gopinath;Francois-Paul Juster;Jean-Pierre Lottin;Lionel Quettier;Hugo Reymond;Michel Segreti;Damien Simon;Eric Sun;D. Young;Renuka Rajput-Ghoshal","doi":"10.1109/TASC.2025.3607770","DOIUrl":"https://doi.org/10.1109/TASC.2025.3607770","url":null,"abstract":"MARCO will be a superconducting solenoid for a new particle physics detector of the upcoming electron ion collider at Brookhaven National Laboratory (NY, USA). The design field at the interaction point is 2.0 T with a nominal current of about 4 kA at 4.5 K. For this magnet, an aluminum-stabilized conductor was considered at the very preliminary design phase. After that, due to the lack of manufacturers able to deal with aluminum extrusion, copper has been chosen as a stabilizer. Thanks to a dedicated design effort, the copper stabilizer and accompanying material choices provided acceptable hadronic interaction length. The conductor is based on an NbTi Rutherford cable that is soldered in a U-shaped copper profile. This article goes through the definition of the conductor cross section according to the project requirements and the supplier capabilities. Its characteristics will be detailed and discussed, in particular the RRR and the yield strength of the copper channel needed for protection and mechanics, respectively. Finally, a proposal on how to make the joint between two conductors is presented.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 8","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145223704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a Helium-Free 1.5 T Extremity MRI Magnet","authors":"S. Je;J. Han;Y. Ra;S. Chae;S. Jeong;Y. Jung;H. Park","doi":"10.1109/TASC.2025.3607279","DOIUrl":"https://doi.org/10.1109/TASC.2025.3607279","url":null,"abstract":"We report the design, fabrication, and testing of a 1.5 tesla extremity magnetic resonance imaging (MRI) magnet that operates without liquid helium, and cooled entirely by conduction. The magnet employs an 8-coil NbTi superconducting winding on a high-conductivity aluminum former, actively shielded and supported in a cryostat by three stainless steel cantilever tubes for thermal isolation. Thermal links of high-purity aluminum foil ensure efficient heat transfer from the coils to a 1 W cryocooler. Finite element simulations guided the design, predicting a homogeneous field (≈5 ppm peak-to-peak) over a 15 cm field of view and acceptable mechanical stresses in the coils. The fabricated magnet was successfully cooled below 5 K and energized to 1.5 T. After minimal training quenches, it achieved stable operation with a measured field drift on the order of 0.1–0.2 ppm/h. Passive shimming brought the field homogeneity to within 8 ppm peak-to-peak over a 150 mm diameter volume, meeting clinical MRI requirements. These results demonstrate the viability of a helium-free, compact MRI magnet for extremity imaging, representing a significant step toward more accessible and low-maintenance MRI systems.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 8","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141770","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":"Impact of Core Air-Gap Design on Electromagnetic Behavior and Loss Performance in High-Temperature Superconducting Transformer","authors":"Zhu Zhu;Nannan Hu;Jingfan Fu;Jiancong Lv;Huige Zhang;Yingdun Hei","doi":"10.1109/TASC.2025.3607379","DOIUrl":"https://doi.org/10.1109/TASC.2025.3607379","url":null,"abstract":"Introducing air gaps into the magnetic core of high-temperature superconducting (HTS) transformers can help mitigate magnetic saturation to some extent and influence both electromagnetic performance and losses. To investigate this effect in detail, this article develops a 3-D finite element model of a 9 kVA three-phase HTS transformer. The study examines how variations in air-gap length and position affect the main magnetic flux path, leakage field distribution, and associated losses. The results show that increasing the air-gap length effectively alleviates local magnetic saturation in the core, resulting in a significant reduction in core loss. However, this also leads to a notable increase in leakage field intensity near the gap edges. When the air-gap percentage increases from 0% to below 6%, the ac loss remains under 100 W; beyond 8%, the ac loss rises sharply. Furthermore, placing the air gap at the center of the core limb minimizes both ac loss and core loss. These findings offer theoretical support for optimizing core air-gap design in HTS transformers to improve electromagnetic performance and suppress energy loss.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 8","pages":"1-9"},"PeriodicalIF":1.8,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073203","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":"Annealing-Induced Conductivity Enhancement of Electroplated Bismuth for Transition-Edge Sensors","authors":"Lingmei Zhang;Haoyu Li;Lin Zhu;Weiwei Xu;He Gao;Zhouhui Liu;Yifei Zhang;Mengqi Jiang;Qinglei Xiu;Congzhan Liu;Jiamin Sun;Daikang Yan","doi":"10.1109/TASC.2025.3606868","DOIUrl":"https://doi.org/10.1109/TASC.2025.3606868","url":null,"abstract":"Transition-edge sensors (TESs) as a sensitive low-temperature superconducting detector have gained increasing popularity in hard X-ray detection applications, prompting extensive research on suitable absorber materials. Bismuth (Bi) has emerged as a promising candidate for hard X-ray detection due to its low specific heat capacity, good thermal conductivity, high quantum efficiency, and easiness to be handled with microfabrication methods. Previous studies have demonstrated that electroplating generally yields larger grain sizes in the Bi films compared to evaporation methods, effectively mitigating energy trapping events. Furthermore, there have also been reports that annealing improves the thermal conductivity of Bi. In this study, we electroplate 5-<inline-formula><tex-math>$mu$</tex-math></inline-formula>m Bi films on 140-nm gold (Au) seed layers and conduct analysis on samples that are annealed with different durations. The comparison reveals that annealing at 230 <inline-formula><tex-math>$^{circ }$</tex-math></inline-formula>C for several hours can increase the Bi grain size by 3–4 times and enhance the residual resistivity ratio of the Au–Bi absorber nearly three times. This discovery will help us understand the performances of the annealed electroplated Bi films and provide guidance for future X-ray superconducting TES microfabrication and optimization.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 8","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AC Loss Reduction in HTS Magnets by Applying Superconducting Shielding Coils and Magnetic Flux Diverters","authors":"Yueming Sun;Shuangrong You;Taotao Huang;Zhenan Jiang","doi":"10.1109/TASC.2025.3605198","DOIUrl":"https://doi.org/10.1109/TASC.2025.3605198","url":null,"abstract":"A 10 T fast-ramping high-temperature superconducting (HTS) magnet is being designed to characterize new rare-earth permanent magnet materials. However, AC loss associated with the fast-ramping process is one of the key technical challenges. This study focuses on evaluating the effectiveness of loss-reduction strategies—superconducting shielding coils (SSC) and magnetic flux diverters (MFD)—both individually and in combination. As the first step of the project, AC loss in a small-scale magnet was numerically studied, resulting in loss reduction of approximately 32%, 71%, and 90% with SSC, MFD, and their combination, respectively. By analyzing the correlation between critical current and AC loss, we found that the frequency and amplitude of the transport current significantly influence the effectiveness of SSC. In the subsequent simulation for the 10-T magnet, AC loss reduction is up to 34%, 57%, and 71% when using SSC, MFD and both. The simulation results indicate that the effectiveness of SSC is less sensitive to high magnetic fields than that of MFD; MFD is still effective for the 10-T magnet, even beyond its saturation field; the combined configuration of SSC and MFD is the most efficient method for AC loss reduction.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 8","pages":"1-9"},"PeriodicalIF":1.8,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141771","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 Simulation of Quench of MgB2 Superconducting Magnet in 0.3 T MRI System","authors":"Cheng Li;Shunzhong Chen;Junsheng Cheng;Qiuliang Wang","doi":"10.1109/TASC.2025.3605368","DOIUrl":"https://doi.org/10.1109/TASC.2025.3605368","url":null,"abstract":"In this article, the quench characteristics of the magnesium diboride (MgB₂) superconducting magnet in a magnetic resonance imaging system are studied. The magnet generates a central magnetic field of 0.3 T, operates at 20 K with a current of 90 A, and stores an energy of 26.25 kJ. A coupled electromagnetic-thermal multiphysics quench model for the MgB₂ magnet was established based on the finite difference method. To accurately represent magnet quench behavior, a current-sharing model applicable for low <italic>n-</i>values was employed. Computational efficiency was enhanced by utilizing a modified integral method for solving the magnetic field equations. To explore the self-protection characteristics of a magnet operating in persistent current mode, the influence of copper (Cu) content and Cu purity grade within the MgB₂ wire on the quench characteristics of the magnet was studied. The results reveal that both the peak temperature and peak voltage during a quench event decrease with increasing Cu content within the MgB₂ wire. Crucially, self-protection capability was achieved for this magnet when the Cu content exceeded a specific threshold. At the same time, increasing the purity of the Cu stabilizer was found to elevate the peak quench temperature and reduce the peak voltage. This occurs because high-purity Cu tends to confine the quench process within a smaller spatial region. Furthermore, a quench protection scheme based on a dump resistor was specifically designed for the MgB₂ superconducting magnet operating in driven mode. Simulation results confirm that this protection scheme effectively prevents damage to the magnet during quench.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 8","pages":"1-7"},"PeriodicalIF":1.8,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141772","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":"Design and Modeling of Double-Fold Superconducting High-Q Coplanar Waveguide Resonators for Quantum Applications","authors":"Jagmohan Singh;Hongxiang Shen;Nobuyuki Yoshikawa;Praveenkumar Suggisetti;Darshak Bhatt","doi":"10.1109/TASC.2025.3605024","DOIUrl":"https://doi.org/10.1109/TASC.2025.3605024","url":null,"abstract":"In this article, we present a novel design of a compact, double-fold half-wave superconducting coplanar waveguide resonator, specifically optimized for quantum readout. The geometry offers advantages in terms of scalability and allows for a more compact integration of qubits per unit area. The superconducting resonators are designed to operate within a fundamental frequency range of 1.9–1.95 GHz, utilizing both gap and finger coupling schemes. The devices are fabricated using thin aluminum films deposited on high-resistivity sapphire substrates. The proposed resonators exhibit quality factor (Q<inline-formula><tex-math>$_{L}$</tex-math></inline-formula>) of <inline-formula><tex-math>$text{2.9}times text{10}^{text{5}}$</tex-math></inline-formula> and <inline-formula><tex-math>$text{1.58}times text{10}^{text{3}}$</tex-math></inline-formula> for gap coupled and finger coupled, respectively, during experimental measurements. The simulated Q<inline-formula><tex-math>$_{L}$</tex-math></inline-formula> of single-folded meander line resonators are found to be <inline-formula><tex-math>$text{4.65}times text{10}^{text{5}}$</tex-math></inline-formula> and 258.42, for gap coupled and finger coupled, respectively, and for comparison purpose at similar operating frequency. A comprehensive analysis of the microwave transmission spectra was conducted at cryogenic temperatures near 10 mK, across very high input drive powers (<inline-formula><tex-math>$-$</tex-math></inline-formula>30 to <inline-formula><tex-math>$-$</tex-math></inline-formula>10 dBm). Experimental results show a good agreement with simulations and the equivalent lumped circuit model. Notably, the proposed design reduces the physical footprint of the resonator devices up to 28.2<inline-formula><tex-math>$%$</tex-math></inline-formula> compared to conventional single-fold meandered structures. The resonators demonstrate strong potential for integrating qubits with readout and control buses in quantum information processing, which require a Q<inline-formula><tex-math>$_{L}$</tex-math></inline-formula> between 10⁴–10⁵. They also being well-suited for cryogenic detector applications that utilize microwave kinetic inductance detector arrays in frequency multiplexing for different coupling schemes.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 8","pages":"1-11"},"PeriodicalIF":1.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145078688","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":"Simulation Framework for Thermal Quasi-Particle Microwave Loss in Multimaterial Superconducting Quantum Circuit Elements","authors":"Haoran Duan;Ritika Dhundhwal;Gabriel Cadilha Marques;Dirk Fuchs;Ioan M. Pop;Thomas Reisinger;Jasmin Aghassi-Hagmann","doi":"10.1109/TASC.2025.3604329","DOIUrl":"https://doi.org/10.1109/TASC.2025.3604329","url":null,"abstract":"Superconducting quantum circuits constitute one of the most advanced and promising platforms for building fault-tolerant quantum computers. However, the associated relatively short coherence times remain a major challenge. Therefore quantifying the various responsible loss mechanisms is key, which can be achieved effectively by refined loss modeling. An important source of dissipation is thermal quasi-particles, for which many simulation tools exist. Here, we improve on these by integrating two of them in a self-consistent manner into an automated workflow for a circuit composed of two materials. Namely, the workflow consists of a numerical simulation of the Mattis–Bardeen surface impedance and electromagnetic finite-element simulation using <italic>Ansys HFSS</i> to predict temperature-dependent quasi-particle loss from normal state material properties. As a test, we use it to simulate the quality factors as a function of the temperature of superconducting resonators composed of tantalum. Tantalum resonators are often found to be dominated by quasi-particle loss at a significantly lower temperature (less than 1 K) than what would be expected from the bulk critical temperature (4.4 K) observed to good approximation in dc transport measurements. A likely cause is a defect phase with a low critical temperature, potentially associated with the tantalum beta phase. By fitting the temperature-dependent loss data to the workflow results, we estimate the concentration of the defect phase. This is an important step forward in correlating material design and microwave loss.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 8","pages":"1-11"},"PeriodicalIF":1.8,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141766","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}