Pub Date : 2025-02-24DOI: 10.1109/TASC.2025.3544687
Zeshi Liu;Shuo Chen;Peiyao Qu;Guangming Tang;Haihang You
Current artificial intelligence faces challenges in improving computational efficiency due to increasing scale and complexity. Superconducting circuit, as one of the most promising technologies in the post-Moore era, offers ultrahigh-speed computation and ultralow power consumption. Superconducting circuits are driven by pulses, which enables direct execution of pulse-based neuromorphic computing. Consequently, superconducting circuits hold the potential to facilitate higher efficiency and larger scale neuromorphic chips. However, existing efforts neglect the limitations and constraints of superconducting circuits, such as the extra overhead of pulse-based logic, the lack of superconducting memory, and low integration. Hence, their work cannot be utilized in fabricating real superconducting neuromorphic chips. This article introduces superconducting spiking neural network (SSNN), which aims to enable full neuromorphic computing on superconducting circuits. The design of SSNN addresses key issues including a superconducting circuit-based neuron model, weight processing methods suitable for superconducting pulses, and superconducting neuromorphic on-chip networks. SSNN enables complete neuromorphic computing on superconducting circuits. We validate the feasibility and accuracy of SSNN using a standard cell library of superconducting circuits and successfully fabricate the world's first superconducting neuromorphic chip. Our evaluation demonstrates a remarkable $50times$ increase in power efficiency compared to state-of-the-art semiconductor designs.
{"title":"Toward Superconducting Neuromorphic Computing Using Single-Flux-Quantum Circuits","authors":"Zeshi Liu;Shuo Chen;Peiyao Qu;Guangming Tang;Haihang You","doi":"10.1109/TASC.2025.3544687","DOIUrl":"https://doi.org/10.1109/TASC.2025.3544687","url":null,"abstract":"Current artificial intelligence faces challenges in improving computational efficiency due to increasing scale and complexity. Superconducting circuit, as one of the most promising technologies in the post-Moore era, offers ultrahigh-speed computation and ultralow power consumption. Superconducting circuits are driven by pulses, which enables direct execution of pulse-based neuromorphic computing. Consequently, superconducting circuits hold the potential to facilitate higher efficiency and larger scale neuromorphic chips. However, existing efforts neglect the limitations and constraints of superconducting circuits, such as the extra overhead of pulse-based logic, the lack of superconducting memory, and low integration. Hence, their work cannot be utilized in fabricating real superconducting neuromorphic chips. This article introduces superconducting spiking neural network (SSNN), which aims to enable full neuromorphic computing on superconducting circuits. The design of SSNN addresses key issues including a superconducting circuit-based neuron model, weight processing methods suitable for superconducting pulses, and superconducting neuromorphic on-chip networks. SSNN enables complete neuromorphic computing on superconducting circuits. We validate the feasibility and accuracy of SSNN using a standard cell library of superconducting circuits and successfully fabricate the world's first superconducting neuromorphic chip. Our evaluation demonstrates a remarkable <inline-formula> <tex-math>$50times$</tex-math></inline-formula> increase in power efficiency compared to state-of-the-art semiconductor designs.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 3","pages":"1-14"},"PeriodicalIF":1.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143645159","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 : 2025-02-24DOI: 10.1109/TASC.2025.3544568
Yukai Qiao;Nicholas M. Strickland;Zhenan Jiang
Conductor on round core (CORC) cables carry a dc current under ac magnetic fields when applied onto the field windings of rotating machines, high-field magnets, and maglev systems. The resulting total loss, consisting of magnetization loss from external ac field and dynamic loss due to the interactions between the dc current and the ac field, will cause power dissipations in the cryogenic system. In this work, the dynamic resistance ($R_{text{dyn}}$) and total loss in a spiral tape and two CORC cables assembled with 4-mm wide REBCO coated conductors are numerically obtained under ac field amplitudes up to 500 mT and temperatures ranging from 30 K to 77.5 K, with dc current levels i ($I_{text{dc}}$/$I_{c0}$) from 0.05 to 0.9 where $I_{text{dc}}$ is the transport current value and $I_{c0}$ is the self-field critical current at each temperature. Simulation results show the effective penetration field $B_{text{eff}}$, where the peaks of the normalized magnetization loss without current, $Q_{m,0}$/$B_{mathrm{m}^{2}}$, of the spiral tape, one-layer Cable A, and two-layer Cable B, shifts to a large value with decreasing temperatures due to the increase of critical currents. In addition, the threshold field $B_{text{th}}$ together with the normalized $B_{text{th}}$/$I_{c0}$ at three temperatures of the spiral tape and Cable A can be estimated using the equation for a superconducting strip, while that of values for Cable B are higher than the analytical curves due to the shielding effect. A finite dynamic loss $Q_{text{dyn}}$ below $B_{text{th}}$ for three models at all temperatures is observed and this is due to a nonzero electric field caused by flux creep. The total loss at higher fields increases as temperature decreases from 77.5 K to 30 K except for i ≥ 0.5 at 77.5 K and i = 0.9 at 50 K where the occurrence of flux flow loss leads to a surge in total loss.
{"title":"3D Simulations of Dynamic Resistance and Total Loss on HTS CORC Cables at Various Temperatures","authors":"Yukai Qiao;Nicholas M. Strickland;Zhenan Jiang","doi":"10.1109/TASC.2025.3544568","DOIUrl":"https://doi.org/10.1109/TASC.2025.3544568","url":null,"abstract":"Conductor on round core (CORC) cables carry a dc current under ac magnetic fields when applied onto the field windings of rotating machines, high-field magnets, and maglev systems. The resulting total loss, consisting of magnetization loss from external ac field and dynamic loss due to the interactions between the dc current and the ac field, will cause power dissipations in the cryogenic system. In this work, the dynamic resistance (<inline-formula><tex-math>$R_{text{dyn}}$</tex-math></inline-formula>) and total loss in a spiral tape and two CORC cables assembled with 4-mm wide REBCO coated conductors are numerically obtained under ac field amplitudes up to 500 mT and temperatures ranging from 30 K to 77.5 K, with dc current levels <italic>i</i> (<inline-formula><tex-math>$I_{text{dc}}$</tex-math></inline-formula>/<inline-formula><tex-math>$I_{c0}$</tex-math></inline-formula>) from 0.05 to 0.9 where <inline-formula><tex-math>$I_{text{dc}}$</tex-math></inline-formula> is the transport current value and <inline-formula><tex-math>$I_{c0}$</tex-math></inline-formula> is the self-field critical current at each temperature. Simulation results show the effective penetration field <inline-formula><tex-math>$B_{text{eff}}$</tex-math></inline-formula>, where the peaks of the normalized magnetization loss without current, <inline-formula><tex-math>$Q_{m,0}$</tex-math></inline-formula>/<inline-formula><tex-math>$B_{mathrm{m}^{2}}$</tex-math></inline-formula>, of the spiral tape, one-layer Cable A, and two-layer Cable B, shifts to a large value with decreasing temperatures due to the increase of critical currents. In addition, the threshold field <inline-formula><tex-math>$B_{text{th}}$</tex-math></inline-formula> together with the normalized <inline-formula><tex-math>$B_{text{th}}$</tex-math></inline-formula>/<inline-formula><tex-math>$I_{c0}$</tex-math></inline-formula> at three temperatures of the spiral tape and Cable A can be estimated using the equation for a superconducting strip, while that of values for Cable B are higher than the analytical curves due to the shielding effect. A finite dynamic loss <inline-formula><tex-math>$Q_{text{dyn}}$</tex-math></inline-formula> below <inline-formula><tex-math>$B_{text{th}}$</tex-math></inline-formula> for three models at all temperatures is observed and this is due to a nonzero electric field caused by flux creep. The total loss at higher fields increases as temperature decreases from 77.5 K to 30 K except for <italic>i</i> ≥ 0.5 at 77.5 K and <italic>i</i> = 0.9 at 50 K where the occurrence of flux flow loss leads to a surge in total loss.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 3","pages":"1-10"},"PeriodicalIF":1.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143583254","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 : 2025-02-24DOI: 10.1109/TASC.2025.3544617
Emilio Manzo;William A. Touza;Gage Bednarz;Nagaraju Guvvala;Arup Kumar Das;Peter Cheetham;Sastry V. Pamidi
Polyethylene (PE) was studied as electrical insulation materials for high temperature superconducting (HTS) power cables using lapped tape electrical insulation design. Gaseous Helium (GHe) cooled HTS cables for electric transport applications were the focus of the study. Electric field distribution was modeled using finite element methods (FEM) for both AC and DC conditions. The partial discharge inception voltage (PDIV) measurements of two test cables were performed under AC and DC conditions at cryogenic temperature. A 3-hour DC soak test was also performed to assess partial discharge behavior under transient DC electric field. The implications of the results were discussed in the context of the electrical insulation system design for GHe-cooled HTS cables in electric transport applications.
{"title":"Evaluation of Polyethylene as Lapped Tape Electrical Insulation for Helium Gas Cooled HTS Power Cables","authors":"Emilio Manzo;William A. Touza;Gage Bednarz;Nagaraju Guvvala;Arup Kumar Das;Peter Cheetham;Sastry V. Pamidi","doi":"10.1109/TASC.2025.3544617","DOIUrl":"https://doi.org/10.1109/TASC.2025.3544617","url":null,"abstract":"Polyethylene (PE) was studied as electrical insulation materials for high temperature superconducting (HTS) power cables using lapped tape electrical insulation design. Gaseous Helium (GHe) cooled HTS cables for electric transport applications were the focus of the study. Electric field distribution was modeled using finite element methods (FEM) for both AC and DC conditions. The partial discharge inception voltage (PDIV) measurements of two test cables were performed under AC and DC conditions at cryogenic temperature. A 3-hour DC soak test was also performed to assess partial discharge behavior under transient DC electric field. The implications of the results were discussed in the context of the electrical insulation system design for GHe-cooled HTS cables in electric transport applications.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655092","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 : 2025-02-24DOI: 10.1109/TASC.2025.3540835
Xinghang Zhou;Yixue Fu;Zhiyong Liu;Rongtie Huang;Jing Chen;Minjuan Li;Chuanbing Cai
This article utilizes a fluorine-free metal organic deposition method (FF-MOD) combined with transient liquid-assisted growth (TLAG) technology to prepare $text{YBa}_{2}text{Cu}_{3}text{O}_{7-delta }$ (YBCO) superconducting thin films, achieving growth rates exceeding 60 nm/s on metallic substrates. A bilayer coating method was employed, introducing a layer of fluorine-containing material of varying thickness before applying the fluorine-free layer. This approach allowed the adjustment of carbon content in the FF layer through the diffusion of fluorine. Ultimately, different $text{BaCuO}_{2}-text{CuO}$ ratio bilayer films were obtained during the crystallization process to study their effects on the generation of Ba-Cu-O liquid phase, as well as the growth rate, orientation, and texture of YBCO. This research contributes to a deeper understanding of the reaction processes and mechanisms for achieving rapid growth of YBCO films based on the Ba-Cu-O liquid phase, addressing gaps in the field and providing valuable guidance.
{"title":"Investigating the Impact of BaCuO2-CuO Ratio on YBCO Thin Film Growth via Transient Liquid-Assisted Fluorine-Free Metal Organic Deposition","authors":"Xinghang Zhou;Yixue Fu;Zhiyong Liu;Rongtie Huang;Jing Chen;Minjuan Li;Chuanbing Cai","doi":"10.1109/TASC.2025.3540835","DOIUrl":"https://doi.org/10.1109/TASC.2025.3540835","url":null,"abstract":"This article utilizes a fluorine-free metal organic deposition method (FF-MOD) combined with transient liquid-assisted growth (TLAG) technology to prepare <inline-formula><tex-math>$text{YBa}_{2}text{Cu}_{3}text{O}_{7-delta }$</tex-math></inline-formula> (YBCO) superconducting thin films, achieving growth rates exceeding 60 nm/s on metallic substrates. A bilayer coating method was employed, introducing a layer of fluorine-containing material of varying thickness before applying the fluorine-free layer. This approach allowed the adjustment of carbon content in the FF layer through the diffusion of fluorine. Ultimately, different <inline-formula><tex-math>$text{BaCuO}_{2}-text{CuO}$</tex-math></inline-formula> ratio bilayer films were obtained during the crystallization process to study their effects on the generation of Ba-Cu-O liquid phase, as well as the growth rate, orientation, and texture of YBCO. This research contributes to a deeper understanding of the reaction processes and mechanisms for achieving rapid growth of YBCO films based on the Ba-Cu-O liquid phase, addressing gaps in the field and providing valuable guidance.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143594291","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 : 2025-02-24DOI: 10.1109/TASC.2025.3544588
Kexing Li;Ke Li;Yutong Fu;Liang Zou;Longhao Yang;Weihang Peng;Yawei Wang
The use of liquid hydrogen ($text{LH}_{2}$) in fuel cell-powered ships has been studied. However, directly heating $text{LH}_{2}$ to the operating temperature of the fuel cell requires considerable energy consumption. The heat generated from AC losses in superconducting magnetic energy storage (SMES) during operation must be promptly removed by the refrigeration system. $text{LH}_{2}$ is considered a promising superconducting refrigeration medium. Therefore, this paper establishes a $text{LH}_{2}$ -fuel cell-SMES electric-thermal integrated system, wherein $text{LH}_{2}$ is utilized for SMES refrigeration and as a fuel supply for the fuel cell. The system's refrigeration and fuel supply demands were determined by calculating the SMES AC losses and the fuel cell hydrogen consumption under three different energy management strategies. The preliminary heating of $text{LH}_{2}$ is achieved through SMES refrigeration, followed by expansion work and heat generated by the fuel cell to meet the operational conditions required by the fuel cell. Results indicate that under the equivalent consumption minimization strategy (ECMS), the fuel cell achieves the lowest hydrogen consumption, albeit with the highest overall system energy consumption. The AC loss optimization Strategy A minimizes SMES AC losses, reducing the load on the refrigeration system but increasing hydrogen consumption. Strategy B optimally balances SMES AC losses and fuel cell hydrogen consumption, resulting in fuel cell hydrogen consumption nearly identical to that under ECMS, significantly lower than under Strategy A, and with overall system energy consumption lower than that under ECMS.
{"title":"Thermal Energy Consumption of a SMES Cooled by Liquid Hydrogen in a Fuel Cell-Battery System","authors":"Kexing Li;Ke Li;Yutong Fu;Liang Zou;Longhao Yang;Weihang Peng;Yawei Wang","doi":"10.1109/TASC.2025.3544588","DOIUrl":"https://doi.org/10.1109/TASC.2025.3544588","url":null,"abstract":"The use of liquid hydrogen (<inline-formula><tex-math>$text{LH}_{2}$</tex-math></inline-formula>) in fuel cell-powered ships has been studied. However, directly heating <inline-formula><tex-math>$text{LH}_{2}$</tex-math></inline-formula> to the operating temperature of the fuel cell requires considerable energy consumption. The heat generated from AC losses in superconducting magnetic energy storage (SMES) during operation must be promptly removed by the refrigeration system. <inline-formula><tex-math>$text{LH}_{2}$</tex-math></inline-formula> is considered a promising superconducting refrigeration medium. Therefore, this paper establishes a <inline-formula><tex-math>$text{LH}_{2}$</tex-math></inline-formula> -fuel cell-SMES electric-thermal integrated system, wherein <inline-formula><tex-math>$text{LH}_{2}$</tex-math></inline-formula> is utilized for SMES refrigeration and as a fuel supply for the fuel cell. The system's refrigeration and fuel supply demands were determined by calculating the SMES AC losses and the fuel cell hydrogen consumption under three different energy management strategies. The preliminary heating of <inline-formula><tex-math>$text{LH}_{2}$</tex-math></inline-formula> is achieved through SMES refrigeration, followed by expansion work and heat generated by the fuel cell to meet the operational conditions required by the fuel cell. Results indicate that under the equivalent consumption minimization strategy (ECMS), the fuel cell achieves the lowest hydrogen consumption, albeit with the highest overall system energy consumption. The AC loss optimization Strategy A minimizes SMES AC losses, reducing the load on the refrigeration system but increasing hydrogen consumption. Strategy B optimally balances SMES AC losses and fuel cell hydrogen consumption, resulting in fuel cell hydrogen consumption nearly identical to that under ECMS, significantly lower than under Strategy A, and with overall system energy consumption lower than that under ECMS.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-7"},"PeriodicalIF":1.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629577","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 : 2025-02-24DOI: 10.1109/TASC.2025.3540733
Justin J. Scheidler;Thomas F. Tallerico;Erik J. Stalcup;Kirsten P. Duffy
NASA is developing the high efficiency megawatt motor (HEMM), a 1.4 MW partially superconducting machine, to address the need for highly efficient, lightweight, MW-class machines to support aviation sustainability efforts. This paper presents progress on the thermal, structural, and rotordynamics aspects of HEMM's superconducting rotor. A thermal model of the rotor is correlated to existing data from a thermo-electrical test of the rotor using emissivity measurements of gold-coated rotor parts. Sources of error in the uncorrelated thermal model and lessons learned from the correlated model are presented. An updated structural design of the HEMM rotor is presented and compared to the prior design. Finite element analysis demonstrates that the updated design improves stress margins while reducing magnetic flux leakage and retaining thermal performance. The key conclusions of the rotordynamics design are presented.
{"title":"Thermal, Structural, and Rotordynamics Refinements to the Superconducting Rotor of a 1.4 MW Partially Superconducting Machine for Electrified Aircraft","authors":"Justin J. Scheidler;Thomas F. Tallerico;Erik J. Stalcup;Kirsten P. Duffy","doi":"10.1109/TASC.2025.3540733","DOIUrl":"https://doi.org/10.1109/TASC.2025.3540733","url":null,"abstract":"NASA is developing the high efficiency megawatt motor (HEMM), a 1.4 MW partially superconducting machine, to address the need for highly efficient, lightweight, MW-class machines to support aviation sustainability efforts. This paper presents progress on the thermal, structural, and rotordynamics aspects of HEMM's superconducting rotor. A thermal model of the rotor is correlated to existing data from a thermo-electrical test of the rotor using emissivity measurements of gold-coated rotor parts. Sources of error in the uncorrelated thermal model and lessons learned from the correlated model are presented. An updated structural design of the HEMM rotor is presented and compared to the prior design. Finite element analysis demonstrates that the updated design improves stress margins while reducing magnetic flux leakage and retaining thermal performance. The key conclusions of the rotordynamics design are presented.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143553481","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 : 2025-02-21DOI: 10.1109/TASC.2025.3540833
Ruben Keijzer;Gerard Willering;Piotr Rogacki;Lucio Fiscarelli;Stephan Russenschuck;Marc Dhallé;Herman Ten Kate
Accelerator magnets are equipped with voltage taps and, on the test bench, with so-called quench antenna's to monitor the transient effects occurring during a magnet quench. Proper identification and localization of a quench origin is vital for understanding performance issues in Nb3Sn accelerator magnets. In this paper, we describe the physical phenomena that occur during the first few milliseconds of a developing quench and how they affect the signals as intercepted with the diagnostic tools. A better understanding of these phenomena allows for better resolution on determination of the quench start location. Measurements from Nb3Sn accelerator magnets are compared with a 3D thermal-electric PEEC-FEM model of a Rutherford cable. The voltage measured over the cable shows an accelerating build-up attributed to the transverse quench propagation in the cable cross-section, which is dominated by inductive effects that results in an avalanche of quenching strands. A slow-down in the voltage build-up then indicates the point at which all strands in the cable cross-section have quenched. This phase of the quench involves a significant current redistribution that creates a magnetic dipole moment picked up by a quench antenna. The harmonic quench antenna used in this work is used to reconstruct the location, magnitude, and direction of this dipole moment, which strongly depends on the start location of the quench in the cable cross-section, on the inter-strand contact resistances and on the magneto-resistance of the copper. It is shown how the quench start location in the cable cross-section can be determined from the time integral of the reconstructed dipole moment.
{"title":"Measurement and Modeling of Initial Quench Development in Nb3Sn Accelerator Magnets","authors":"Ruben Keijzer;Gerard Willering;Piotr Rogacki;Lucio Fiscarelli;Stephan Russenschuck;Marc Dhallé;Herman Ten Kate","doi":"10.1109/TASC.2025.3540833","DOIUrl":"https://doi.org/10.1109/TASC.2025.3540833","url":null,"abstract":"Accelerator magnets are equipped with voltage taps and, on the test bench, with so-called quench antenna's to monitor the transient effects occurring during a magnet quench. Proper identification and localization of a quench origin is vital for understanding performance issues in Nb<sub>3</sub>Sn accelerator magnets. In this paper, we describe the physical phenomena that occur during the first few milliseconds of a developing quench and how they affect the signals as intercepted with the diagnostic tools. A better understanding of these phenomena allows for better resolution on determination of the quench start location. Measurements from Nb<sub>3</sub>Sn accelerator magnets are compared with a 3D thermal-electric PEEC-FEM model of a Rutherford cable. The voltage measured over the cable shows an accelerating build-up attributed to the transverse quench propagation in the cable cross-section, which is dominated by inductive effects that results in an avalanche of quenching strands. A slow-down in the voltage build-up then indicates the point at which all strands in the cable cross-section have quenched. This phase of the quench involves a significant current redistribution that creates a magnetic dipole moment picked up by a quench antenna. The harmonic quench antenna used in this work is used to reconstruct the location, magnitude, and direction of this dipole moment, which strongly depends on the start location of the quench in the cable cross-section, on the inter-strand contact resistances and on the magneto-resistance of the copper. It is shown how the quench start location in the cable cross-section can be determined from the time integral of the reconstructed dipole moment.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-7"},"PeriodicalIF":1.7,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143521491","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 : 2025-02-20DOI: 10.1109/TASC.2025.3543798
Marco Breschi;Antonio Macchiagodena;Pier Luigi Ribani;Andrea Musso;Giuliano Angeli;Marco Bocchi
The no-insulation high-temperature superconducting (NI-HTS) coil technology is a promising field of application of HTS tapes, which has gained popularity in recent years. Compared to conventional insulated coils, NI-HTS coils have a better ability to cope with quenches, given the possibility for current and heat to redistribute towards adjacent turns in presence of a hot-spot. In recent years, the authors developed a nonlinear circuit model to compute current distribution and AC losses in NI-HTS coils (named CALYPSO). This model describes the currents flowing from turn to turn due to the NI configuration, as well as the magnetization currents arising in each tape. However, applying this model to coils composed of a large number of turns results in a high computational burden. This work presents an in-depth discussion of the reasons for the long computation time and the solutions and code improvements implemented to tackle this issue. Additionally, a comparison between the losses predicted by the code and those measured on straight REBCO tapes is presented. The model is then applied to investigate the electrodynamics of a NI pancake coil including both magnetization currents and radial currents. The impact of surface contact resistivity between turns on the delay between the magnetic field along the coil axis and the transport current is analyzed, showing the details of the current distribution between turns and inside individual tapes.
{"title":"Improvement of the Circuit Analyzer Problem Solver CALYPSO","authors":"Marco Breschi;Antonio Macchiagodena;Pier Luigi Ribani;Andrea Musso;Giuliano Angeli;Marco Bocchi","doi":"10.1109/TASC.2025.3543798","DOIUrl":"https://doi.org/10.1109/TASC.2025.3543798","url":null,"abstract":"The no-insulation high-temperature superconducting (NI-HTS) coil technology is a promising field of application of HTS tapes, which has gained popularity in recent years. Compared to conventional insulated coils, NI-HTS coils have a better ability to cope with quenches, given the possibility for current and heat to redistribute towards adjacent turns in presence of a hot-spot. In recent years, the authors developed a nonlinear circuit model to compute current distribution and AC losses in NI-HTS coils (named CALYPSO). This model describes the currents flowing from turn to turn due to the NI configuration, as well as the magnetization currents arising in each tape. However, applying this model to coils composed of a large number of turns results in a high computational burden. This work presents an in-depth discussion of the reasons for the long computation time and the solutions and code improvements implemented to tackle this issue. Additionally, a comparison between the losses predicted by the code and those measured on straight REBCO tapes is presented. The model is then applied to investigate the electrodynamics of a NI pancake coil including both magnetization currents and radial currents. The impact of surface contact resistivity between turns on the delay between the magnetic field along the coil axis and the transport current is analyzed, showing the details of the current distribution between turns and inside individual tapes.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143583164","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}
The Super-X facility for testing large size superconducting conductors is making significant progress. However, the magnetic force between two coils arises when the centers of their respective magnetic fields do not coincide. Coil misalignment is nearly unavoidable during the installation of magnets which will lead to this eccentric force. In particular, for suspended background magnet in Super-X facility, the eccentric force amplifies the stress on structural components, thereby potentially compromising the magnet's safe operation. Therefore, it is imperative to evaluate its impact on the structural components of the magnet. The pull rope structure of the background magnet is elaborated upon in this article, followed by the analysis of the electromagnetic force generated under different eccentricities of the magnet. Subsequently, the stresses on the structural components of the magnet with and without the pull rope structure are analyzed separately. The results demonstrate that the presence of a pull rope structure is crucial for withstanding magnet eccentricity. Thus far, it can be concluded that the mechanical performance of the magnet still meets the design requirements, taking into account coil misalignment.
{"title":"Misaligned Analysis of the 15 T Magnet in Super-X Facility","authors":"Yongsheng Wu;Houxiang Han;Lei Wu;Yi Shi;Yu Wu;Jinggang Qin","doi":"10.1109/TASC.2025.3543771","DOIUrl":"https://doi.org/10.1109/TASC.2025.3543771","url":null,"abstract":"The Super-X facility for testing large size superconducting conductors is making significant progress. However, the magnetic force between two coils arises when the centers of their respective magnetic fields do not coincide. Coil misalignment is nearly unavoidable during the installation of magnets which will lead to this eccentric force. In particular, for suspended background magnet in Super-X facility, the eccentric force amplifies the stress on structural components, thereby potentially compromising the magnet's safe operation. Therefore, it is imperative to evaluate its impact on the structural components of the magnet. The pull rope structure of the background magnet is elaborated upon in this article, followed by the analysis of the electromagnetic force generated under different eccentricities of the magnet. Subsequently, the stresses on the structural components of the magnet with and without the pull rope structure are analyzed separately. The results demonstrate that the presence of a pull rope structure is crucial for withstanding magnet eccentricity. Thus far, it can be concluded that the mechanical performance of the magnet still meets the design requirements, taking into account coil misalignment.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 3","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601875","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}
In this article, we present advancements of our submicrometer cross-type $text{Nb}/ text{AlO}_{x}/ text{Nb}$ Josephson junction technology by implementing an additional highly conductive resistive layer, e.g., for thermalization structures. This allows for shifting the typically observed thermal decoupling of shunt resistors of highly sensitive dc superconducting quantum interference devices (SQUIDs) and SQUID arrays down to temperatures in the millikelvin range. We show results on the technological integration, device design of series SQUID arrays, and their characterization at 4.2 K down to 65 mK. Measurements were performed in an adiabatic demagnetization refrigerator. As an application scenario, we have successfully implemented them as readout circuitry for optical transition edge sensors operated at 150 mK requiring both low-noise and large bandwidth of the readout implemented in a flux-locked loop configuration.
{"title":"Highly Sensitive DC SQUID Arrays for the Readout of Optical TES at mK Temperatures","authors":"Matthias Schmelz;Vitaliy Shvab;Katja Peiselt;Jürgen Kunert;Vyacheslav Zakosarenko;Thomas Stöhlker;Gregor Oelsner;Ronny Stolz","doi":"10.1109/TASC.2025.3543941","DOIUrl":"https://doi.org/10.1109/TASC.2025.3543941","url":null,"abstract":"In this article, we present advancements of our submicrometer cross-type <inline-formula><tex-math>$text{Nb}/ text{AlO}_{x}/ text{Nb}$</tex-math></inline-formula> Josephson junction technology by implementing an additional highly conductive resistive layer, e.g., for thermalization structures. This allows for shifting the typically observed thermal decoupling of shunt resistors of highly sensitive dc superconducting quantum interference devices (SQUIDs) and SQUID arrays down to temperatures in the millikelvin range. We show results on the technological integration, device design of series SQUID arrays, and their characterization at 4.2 K down to 65 mK. Measurements were performed in an adiabatic demagnetization refrigerator. As an application scenario, we have successfully implemented them as readout circuitry for optical transition edge sensors operated at 150 mK requiring both low-noise and large bandwidth of the readout implemented in a flux-locked loop configuration.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 3","pages":"1-4"},"PeriodicalIF":1.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143570680","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}
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