Pub Date : 2026-02-13DOI: 10.1109/TASC.2026.3664832
A. Zampa;Y. Tsuchiya;A. Matsuo;K. Kindo;K. Mizuno;Y. Kohama
One key element in designing coils using High Temperature Superconducting (HTS) ReBCO (Rare earth BaCuO) tapes as the base material is the critical current (Ic). Beyond the magnetic fields available in DC magnets, there is a lack of practical data on the magnetic field dependence of Ic. However, several world-class projects are currently aiming to develop high field user magnets using HTS tapes in the 30 T-40 T range. We propose combining a flat-top pulsed magnet with a rapid Ic measurement system to access the critical current across full-width HTS tapes in this high-field regime. A dedicated plastic-based probe was developed and tested under different magnetic field strengths and temperatures. To withstand the mechanical stress resulting from strong Lorentz forces and enable variable temperature operation, the HTS tape was immersed at room temperature into mineral oil and subsequently fixed by the oil solidification upon cooling. The critical current of a full-width HTS ReBCO tape was successfully measured under a magnetic field of 38.7 T at 26 K. Temperature monitoring was necessary to account for the temperature rise caused by eddy currents in the normal-conducting layers of the HTS tape.
{"title":"Critical Current Measurement Over Full-Width HTS Tapes Under Flat-top Pulsed Magnetic Field Up to 38.7 T","authors":"A. Zampa;Y. Tsuchiya;A. Matsuo;K. Kindo;K. Mizuno;Y. Kohama","doi":"10.1109/TASC.2026.3664832","DOIUrl":"https://doi.org/10.1109/TASC.2026.3664832","url":null,"abstract":"One key element in designing coils using High Temperature Superconducting (HTS) ReBCO (Rare earth BaCuO) tapes as the base material is the critical current (<italic>I<sub>c</sub></i>). Beyond the magnetic fields available in DC magnets, there is a lack of practical data on the magnetic field dependence of <italic>I<sub>c</sub></i>. However, several world-class projects are currently aiming to develop high field user magnets using HTS tapes in the 30 T-40 T range. We propose combining a flat-top pulsed magnet with a rapid <italic>I<sub>c</sub></i> measurement system to access the critical current across full-width HTS tapes in this high-field regime. A dedicated plastic-based probe was developed and tested under different magnetic field strengths and temperatures. To withstand the mechanical stress resulting from strong Lorentz forces and enable variable temperature operation, the HTS tape was immersed at room temperature into mineral oil and subsequently fixed by the oil solidification upon cooling. The critical current of a full-width HTS ReBCO tape was successfully measured under a magnetic field of 38.7 T at 26 K. Temperature monitoring was necessary to account for the temperature rise caused by eddy currents in the normal-conducting layers of the HTS tape.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147362410","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 : 2026-02-12DOI: 10.1109/TASC.2026.3664063
Jin Lu;Pai Peng;Jianye Chen;Shutong Deng;Shengnan Zou;Yawei Wang;Yue Zhao;Zhijian Jin
Accurate condition monitoring of high-temperature superconducting (HTS) cables in ultra-high-field magnets requires precise current measurement at cryogenic temperatures. Direct-Current Current Transformer (DCCT), a current measuring device based on zero-flux principle, is widely used as a high-precision measurement scheme. However, commercial DCCTs employing copper compensation coils exhibit significant operational losses at high currents, limiting their performance and range in low-temperature environments. To overcome this limitation, this paper proposes a conceptual design of an HTS compensated DCCT, an innovative approach to cryogenic current sensing. A comparative analysis of the loss characteristics between conventional copper and the proposed HTS compensation coil is conducted through finite element method (FEM) simulations. The results demonstrate that the copper coil generates losses 103 to 105 times greater than the HTS coil under high-current conditions. Consequently, the HTS compensated DCCT achieves a superior current range of up to 70 kA at 20 K, with virtually no steady-state loss and significantly reduced ramping loss. These findings confirm that the minimal loss characteristics of the HTS winding establish a promising solution for high-precision, high-current measurement in cryogenic applications.
{"title":"Comparative Analysis of Loss Characteristics in DCCTs at Cryogenic Temperature With HTS and Copper Compensation Windings","authors":"Jin Lu;Pai Peng;Jianye Chen;Shutong Deng;Shengnan Zou;Yawei Wang;Yue Zhao;Zhijian Jin","doi":"10.1109/TASC.2026.3664063","DOIUrl":"https://doi.org/10.1109/TASC.2026.3664063","url":null,"abstract":"Accurate condition monitoring of high-temperature superconducting (HTS) cables in ultra-high-field magnets requires precise current measurement at cryogenic temperatures. Direct-Current Current Transformer (DCCT), a current measuring device based on zero-flux principle, is widely used as a high-precision measurement scheme. However, commercial DCCTs employing copper compensation coils exhibit significant operational losses at high currents, limiting their performance and range in low-temperature environments. To overcome this limitation, this paper proposes a conceptual design of an HTS compensated DCCT, an innovative approach to cryogenic current sensing. A comparative analysis of the loss characteristics between conventional copper and the proposed HTS compensation coil is conducted through finite element method (FEM) simulations. The results demonstrate that the copper coil generates losses 10<sup>3</sup> to 10<sup>5</sup> times greater than the HTS coil under high-current conditions. Consequently, the HTS compensated DCCT achieves a superior current range of up to 70 kA at 20 K, with virtually no steady-state loss and significantly reduced ramping loss. These findings confirm that the minimal loss characteristics of the HTS winding establish a promising solution for high-precision, high-current measurement in cryogenic applications.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147440501","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 : 2026-02-12DOI: 10.1109/TASC.2026.3664193
Stephen J. Smith;Paul van der Hulst;Nicholas A. Wakeham;Edoardo Cucchetti;W. Bertrand Doriese;Malcolm Durkin;Christian Kirsch;Joel N. Ullom;Joseph S. Adams;Simon R. Bandler;James A. Chervenak;Tannaz Farrahi;Fred M. Finkbeiner;Joshua D. Fuhrman;Samuel V. Hull;Richard L. Kelley;Caroline A. Kilbourne;Haruka Muramatsu;Frederick S. Porter;Kazuhiro Sakai;Ambarish C. Venkatasubraman;Edward J. Wassell;Michael C. Witthoeft;Sang H. Yoon
The X-ray Integral Field Unit (X-IFU) on the NewAthena X-ray telescope will use a 1504-pixel array of transition-edge sensor (TES) microcalorimeters, read out via time division multiplexing. To allow testing of multiplexer chips before TES integration, each unit cell includes a “TES-bypass” resistor that substitutes for a TES during characterization. After integration, this resistor remains as a high-resistance shunt: minimal for DC operation, but it can influence the frequency response due to its placement with the Nyquist inductor. We modeled the modified bias circuit, derived the small-signal response, and evaluated noise contributions, including Johnson noise from the bypass resistor. We analyzed the effects on pulse height, slew rate, and energy resolution. Simulations were compared with measurements from prototype X-IFU microcalorimeters. Our results indicate that as long as the resistor value exceeds the TES dynamic resistance, performance is largely unaffected.
{"title":"Transition-Edge Sensor Characteristics in a Modified Bias Circuit for Multiplexed Readout","authors":"Stephen J. Smith;Paul van der Hulst;Nicholas A. Wakeham;Edoardo Cucchetti;W. Bertrand Doriese;Malcolm Durkin;Christian Kirsch;Joel N. Ullom;Joseph S. Adams;Simon R. Bandler;James A. Chervenak;Tannaz Farrahi;Fred M. Finkbeiner;Joshua D. Fuhrman;Samuel V. Hull;Richard L. Kelley;Caroline A. Kilbourne;Haruka Muramatsu;Frederick S. Porter;Kazuhiro Sakai;Ambarish C. Venkatasubraman;Edward J. Wassell;Michael C. Witthoeft;Sang H. Yoon","doi":"10.1109/TASC.2026.3664193","DOIUrl":"https://doi.org/10.1109/TASC.2026.3664193","url":null,"abstract":"The X-ray Integral Field Unit (X-IFU) on the NewAthena X-ray telescope will use a 1504-pixel array of transition-edge sensor (TES) microcalorimeters, read out via time division multiplexing. To allow testing of multiplexer chips before TES integration, each unit cell includes a “TES-bypass” resistor that substitutes for a TES during characterization. After integration, this resistor remains as a high-resistance shunt: minimal for DC operation, but it can influence the frequency response due to its placement with the Nyquist inductor. We modeled the modified bias circuit, derived the small-signal response, and evaluated noise contributions, including Johnson noise from the bypass resistor. We analyzed the effects on pulse height, slew rate, and energy resolution. Simulations were compared with measurements from prototype X-IFU microcalorimeters. Our results indicate that as long as the resistor value exceeds the TES dynamic resistance, performance is largely unaffected.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 6","pages":"1-7"},"PeriodicalIF":1.8,"publicationDate":"2026-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147362423","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 : 2026-02-11DOI: 10.1109/TASC.2026.3657176
R. Basei;F. Pase;F. Lucchini;R. Torchio;F. Toso
Efficient modeling of high-temperature superconductors (HTSs) is crucial for real-time quench monitoring; however, full-order electromagnetic simulations remain prohibitively costly due to the strong nonlinearities. Conventional projection-based reduced-order modeling pipelines for nonlinear problems, such as proper orthogonal decomposition (POD)-discrete empirical interpolation method (DEIM), alleviate this cost but often require intrusive access to the full-order model operators and a substantial number of interpolation points for hyperreduction. This work investigates reduced-order strategies for the integral equation method (IEM) of HTS systems. We present the first application of POD-DEIM to IEM-based HTS models and introduce a Structured Neural ordinary differential equation (Neural ODE) approach that learns nonlinear dynamics directly in the reduced space. The benchmark results show that Neural ODE outperforms POD-DEIM both in efficiency and accuracy, highlighting its potential for real-time simulations of superconductors.
{"title":"A Structured Neural ODE Approach for Real-Time Evaluation of AC Losses in 3-D Superconducting Tapes","authors":"R. Basei;F. Pase;F. Lucchini;R. Torchio;F. Toso","doi":"10.1109/TASC.2026.3657176","DOIUrl":"https://doi.org/10.1109/TASC.2026.3657176","url":null,"abstract":"Efficient modeling of high-temperature superconductors (HTSs) is crucial for real-time quench monitoring; however, full-order electromagnetic simulations remain prohibitively costly due to the strong nonlinearities. Conventional projection-based reduced-order modeling pipelines for nonlinear problems, such as proper orthogonal decomposition (POD)-discrete empirical interpolation method (DEIM), alleviate this cost but often require intrusive access to the full-order model operators and a substantial number of interpolation points for hyperreduction. This work investigates reduced-order strategies for the integral equation method (IEM) of HTS systems. We present the first application of POD-DEIM to IEM-based HTS models and introduce a Structured Neural ordinary differential equation (Neural ODE) approach that learns nonlinear dynamics directly in the reduced space. The benchmark results show that Neural ODE outperforms POD-DEIM both in efficiency and accuracy, highlighting its potential for real-time simulations of superconductors.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 7","pages":"1-14"},"PeriodicalIF":1.8,"publicationDate":"2026-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223846","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 : 2026-02-11DOI: 10.1109/TASC.2026.3663314
Benjamin J. Vaughan;Yuhan Wang;Cody J. Duell;Jason Austermann;James R. Burgoyne;Scott Chapman;Steve K. Choi;Abigail T. Crites;Eliza Gazda;Ben Keller;Michael D. Niemack;Darshan A. Patel;Anna Vaskuri;Eve M. Vavagiakis;Michael Vissers;Samantha Walker;Jordan Wheeler;Ruixuan Xie
The Cerro Chajnantor Atacama Telescope (CCAT) Observatory is a ground-based submillimeter to millimeter experiment located on Cerro Chajnantor in the Atacama Desert, at an altitude of 5600 m. CCAT features the 6-m Fred Young Submillimeter Telescope, which will cover frequency bands from 210 to 850 GHz using its first-generation science instrument, Prime-Cam. The detectors used in Prime-Cam are feedhorn-coupled, lumped-element superconducting microwave kinetic inductance detectors (KIDs). The telescope will perform wide-area surveys at speeds on the order of degrees per second. During telescope operation, the KIDs are exposed to changes in the magnetic field caused by the telescope’s movement through Earth’s magnetic field and internal sources within the telescope. We present and compare measurements of the magnetic sensitivity of three different CCAT KID designs at 100 mK. The measurements are conducted in a dilution refrigerator (DR) with a set of room temperature Helmholtz coils positioned around the DR. We discuss the implications of these results for CCAT field operations.
{"title":"CCAT: Magnetic Sensitivity Measurements of Kinetic Inductance Detectors","authors":"Benjamin J. Vaughan;Yuhan Wang;Cody J. Duell;Jason Austermann;James R. Burgoyne;Scott Chapman;Steve K. Choi;Abigail T. Crites;Eliza Gazda;Ben Keller;Michael D. Niemack;Darshan A. Patel;Anna Vaskuri;Eve M. Vavagiakis;Michael Vissers;Samantha Walker;Jordan Wheeler;Ruixuan Xie","doi":"10.1109/TASC.2026.3663314","DOIUrl":"https://doi.org/10.1109/TASC.2026.3663314","url":null,"abstract":"The Cerro Chajnantor Atacama Telescope (CCAT) Observatory is a ground-based submillimeter to millimeter experiment located on Cerro Chajnantor in the Atacama Desert, at an altitude of 5600 m. CCAT features the 6-m Fred Young Submillimeter Telescope, which will cover frequency bands from 210 to 850 GHz using its first-generation science instrument, Prime-Cam. The detectors used in Prime-Cam are feedhorn-coupled, lumped-element superconducting microwave kinetic inductance detectors (KIDs). The telescope will perform wide-area surveys at speeds on the order of degrees per second. During telescope operation, the KIDs are exposed to changes in the magnetic field caused by the telescope’s movement through Earth’s magnetic field and internal sources within the telescope. We present and compare measurements of the magnetic sensitivity of three different CCAT KID designs at 100 mK. The measurements are conducted in a dilution refrigerator (DR) with a set of room temperature Helmholtz coils positioned around the DR. We discuss the implications of these results for CCAT field operations.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 6","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147362424","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 : 2026-02-11DOI: 10.1109/TASC.2026.3663729
Koichi Matsuda;Xueying Ma
The acceleration and heat loss of superconducting linear motors are the main limitations in their development. The electromagnetic and thermal design methods of a partially high-temperature superconducting linear motor (HTSLM) are proposed to increase acceleration and reduce heat loss. The electromagnetic design is based on a 2-D analytical model and a 3-D finite element model (FEM), whereas the thermal design is performed using a thermal network model (TNM) and a 3-D FEM, under steady-state conditions. In this article, both the mover and the stator are placed in a cryostat to reduce the air gap and increase the acceleration up to 9 g. After the proposed HTSLM system reaches thermal equilibrium, the stator operates at 52 K. The electromagnetic thrust is analytically derived and decomposed into the fundamental and ripple components. The harmonic analysis indicates that the ripple originates from the coupling between the AC and the (6i$pm$ 1)-order harmonics of the air-gap field. The TNM and the 3-D FEM are used to analyze the heat flow paths and to calculate the heat losses. The parametric effects of the mover temperature and the heat loss are studied. The parameters of the TNM and the 3-D FEM are then improved to optimize the thermal design and to guide the selection of a cryocooler. The 2-D model proposed in this article for electromagnetic design, as well as the TNM for thermal design, have certain generality and can be used in the design of planar and rotary motor systems.
{"title":"Electromagnetic and Thermal Design of Partially HTS Linear Motor: Analysis of Thrust Ripple Harmonics and Thermal Optimization","authors":"Koichi Matsuda;Xueying Ma","doi":"10.1109/TASC.2026.3663729","DOIUrl":"https://doi.org/10.1109/TASC.2026.3663729","url":null,"abstract":"The acceleration and heat loss of superconducting linear motors are the main limitations in their development. The electromagnetic and thermal design methods of a partially high-temperature superconducting linear motor (HTSLM) are proposed to increase acceleration and reduce heat loss. The electromagnetic design is based on a 2-D analytical model and a 3-D finite element model (FEM), whereas the thermal design is performed using a thermal network model (TNM) and a 3-D FEM, under steady-state conditions. In this article, both the mover and the stator are placed in a cryostat to reduce the air gap and increase the acceleration up to 9 g. After the proposed HTSLM system reaches thermal equilibrium, the stator operates at 52 K. The electromagnetic thrust is analytically derived and decomposed into the fundamental and ripple components. The harmonic analysis indicates that the ripple originates from the coupling between the AC and the (6i<inline-formula><tex-math>$pm$</tex-math></inline-formula> 1)-order harmonics of the air-gap field. The TNM and the 3-D FEM are used to analyze the heat flow paths and to calculate the heat losses. The parametric effects of the mover temperature and the heat loss are studied. The parameters of the TNM and the 3-D FEM are then improved to optimize the thermal design and to guide the selection of a cryocooler. The 2-D model proposed in this article for electromagnetic design, as well as the TNM for thermal design, have certain generality and can be used in the design of planar and rotary motor systems.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 7","pages":"1-13"},"PeriodicalIF":1.8,"publicationDate":"2026-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147362571","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 : 2026-02-09DOI: 10.1109/TASC.2026.3662810
Ao Feng;Yi Zhu;Yanbing Yang;Gang He;Wei You;Guangquan Chen;Biaokun Bai;Weiyu Qiao;Qi Yang;Wenjie Yang
When constructing high-field magnets with nonmetallic formers, quench protection of slot-type magnets such as discrete-cosine-theta and canted-cosine-theta becomes particularly challenging, as nonmetallic structures cannot provide the quench-back effect. To address this issue, a 6+1 cable (six superconducting wires and one center cooper wire) configuration has been proposed. During a quench, the central copper strand acts as an internal heater, inducing the quench-back effect. However, the presence of the copper strand reduces the available slot space, thereby limiting the effective engineering current density. To further improve both the current density and protection performance, the coupling-loss induced quench (CLIQ) method has been introduced and applied to seven-strand superconducting cables without a central copper strand. In this study, an electro-thermal coupling model is employed to first validate, through experiment–simulation comparison, the effectiveness of quench-back protection in 6+1 cables. The same model is then extended to analyze and predict the quench protection performance of seven-strand cables under CLIQ. The results demonstrate that CLIQ can effectively trigger uniform quenching, significantly reducing the quench integral and hot-spot temperature, thereby ensuring the reliable protection of the magnet.
{"title":"Electro-Thermal Modeling of Quench-Back and CLIQ Protection for Multistrand Superconducting Magnets","authors":"Ao Feng;Yi Zhu;Yanbing Yang;Gang He;Wei You;Guangquan Chen;Biaokun Bai;Weiyu Qiao;Qi Yang;Wenjie Yang","doi":"10.1109/TASC.2026.3662810","DOIUrl":"https://doi.org/10.1109/TASC.2026.3662810","url":null,"abstract":"When constructing high-field magnets with nonmetallic formers, quench protection of slot-type magnets such as discrete-cosine-theta and canted-cosine-theta becomes particularly challenging, as nonmetallic structures cannot provide the quench-back effect. To address this issue, a 6+1 cable (six superconducting wires and one center cooper wire) configuration has been proposed. During a quench, the central copper strand acts as an internal heater, inducing the quench-back effect. However, the presence of the copper strand reduces the available slot space, thereby limiting the effective engineering current density. To further improve both the current density and protection performance, the coupling-loss induced quench (CLIQ) method has been introduced and applied to seven-strand superconducting cables without a central copper strand. In this study, an electro-thermal coupling model is employed to first validate, through experiment–simulation comparison, the effectiveness of quench-back protection in 6+1 cables. The same model is then extended to analyze and predict the quench protection performance of seven-strand cables under CLIQ. The results demonstrate that CLIQ can effectively trigger uniform quenching, significantly reducing the quench integral and hot-spot temperature, thereby ensuring the reliable protection of the magnet.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 7","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147440637","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}
Impedance measurements have long been used to study superconducting magnets in their non-energized state, providing valuable insights into their electromagnetic behaviour. However, studies involving powering have primarily been conducted at low currents, due to the impact of the power converter impedance on the measurement. This paper presents a comprehensive set of impedance measurements on the powered MQXFS7 superconducting magnet, marking the first time such measurements have been performed up to its nominal operating current of I = 16.23 kA. The magnet's impedance was characterized using two distinct measurement configurations: low-frequency (f = 10 Hz-1 kHz) and high-frequency (f = 1 kHz-45 kHz). Measurements were conducted across all powering phases (ramp-up, steady state, and ramp-down) at two cryogenic temperatures T = 1.9 K and 4.5 K. Impedance variations as a function of current were observed at T = 1.9 K, with the most notable result being an impedance shift towards the impedance measured at $T={4.5},{mathrm{K}}$ as the nominal operating current was approached. We hypothesize that this may be due to the presence of superconducting (Ti–6Al–4V) magnet poles. Being able to measure the impedance of superconducting magnets in a powered state represent a significant improvement in the understanding of impedance-based diagnostics for superconducting magnets, demonstrating their potential for characterizing magnet behaviour under operating conditions.
{"title":"Impedance Characterization of a HL-LHC Nb3Sn MQXFS Model Magnet During Powered Operation at Nominal Current","authors":"Magnus BøghBorregaard Christensen;Mateusz Jakub Bednarek;Susana Izquierdo Bermudez;Reiner Denz;Jerome Feuvrier;Ariel Haziot;Marvin Janitschke;Peter Koch;Jaromir Ludwin;Franco Mangiarotti;Tomasz Podzorny;Emmanuele Ravaioli;Jens Steckert;Jan Uythoven;Gerard Willering;Mariusz Wozniak;Jan Østergaard","doi":"10.1109/TASC.2026.3660243","DOIUrl":"https://doi.org/10.1109/TASC.2026.3660243","url":null,"abstract":"Impedance measurements have long been used to study superconducting magnets in their non-energized state, providing valuable insights into their electromagnetic behaviour. However, studies involving powering have primarily been conducted at low currents, due to the impact of the power converter impedance on the measurement. This paper presents a comprehensive set of impedance measurements on the powered MQXFS7 superconducting magnet, marking the first time such measurements have been performed up to its nominal operating current of I = 16.23 kA. The magnet's impedance was characterized using two distinct measurement configurations: low-frequency (f = 10 Hz-1 kHz) and high-frequency (f = 1 kHz-45 kHz). Measurements were conducted across all powering phases (ramp-up, steady state, and ramp-down) at two cryogenic temperatures T = 1.9 K and 4.5 K. Impedance variations as a function of current were observed at T = 1.9 K, with the most notable result being an impedance shift towards the impedance measured at <inline-formula><tex-math>$T={4.5},{mathrm{K}}$</tex-math></inline-formula> as the nominal operating current was approached. We hypothesize that this may be due to the presence of superconducting (Ti–6Al–4V) magnet poles. Being able to measure the impedance of superconducting magnets in a powered state represent a significant improvement in the understanding of impedance-based diagnostics for superconducting magnets, demonstrating their potential for characterizing magnet behaviour under operating conditions.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-7"},"PeriodicalIF":1.8,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11373216","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175871","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 : 2026-02-04DOI: 10.1109/TASC.2026.3661442
Niyaz A. Madhar;Mohammed Shahabuddin;Nasser S. Alzayed;Shahid M. Ramay;Bilal Taha
This study presents the design, fabrication, and validation of a cost-effective and compact cold high-pressure densification (CHPD) system tailored for magnesium diboride (MgB2) wires. The device integrates a 5 cm hydraulic press with a precision-machined D2 tool steel die, interchangeable plungers, and a guided alignment mechanism for uniform and repeatable densification. The system may apply pressures up to 2 GPa and enables continuous pressing along wire lengths via a 5 mm incremental overlap scheme. Optical microscopy and scanning electron microscopy analysis of square MgB2 wires pressed using this system reveal substantial improvements in core density and microstructural homogeneity. Magnetization measurements confirm enhancements in JC over the entire field range at all temperatures, with up to 1.5 times improvement approximately under the pressure of 0.8 GPa. The results demonstrate that this CHPD setup reliably densifies MgB2 wires while preserving sheath integrity and offers comparable performance gains to more complex systems. Its modular, scalable, and low-cost design makes it an accessible tool for academic and industrial labs aiming to optimize MgB2 wire performance.
{"title":"Development of a Low-Cost CHPD System for Densification of MgB2 Wires in Superconducting Applications","authors":"Niyaz A. Madhar;Mohammed Shahabuddin;Nasser S. Alzayed;Shahid M. Ramay;Bilal Taha","doi":"10.1109/TASC.2026.3661442","DOIUrl":"https://doi.org/10.1109/TASC.2026.3661442","url":null,"abstract":"This study presents the design, fabrication, and validation of a cost-effective and compact cold high-pressure densification (CHPD) system tailored for magnesium diboride (MgB<sub>2</sub>) wires. The device integrates a 5 cm hydraulic press with a precision-machined D2 tool steel die, interchangeable plungers, and a guided alignment mechanism for uniform and repeatable densification. The system may apply pressures up to 2 GPa and enables continuous pressing along wire lengths via a 5 mm incremental overlap scheme. Optical microscopy and scanning electron microscopy analysis of square MgB<sub>2</sub> wires pressed using this system reveal substantial improvements in core density and microstructural homogeneity. Magnetization measurements confirm enhancements in <italic>J<sub>C</sub></i> over the entire field range at all temperatures, with up to 1.5 times improvement approximately under the pressure of 0.8 GPa. The results demonstrate that this CHPD setup reliably densifies MgB<sub>2</sub> wires while preserving sheath integrity and offers comparable performance gains to more complex systems. Its modular, scalable, and low-cost design makes it an accessible tool for academic and industrial labs aiming to optimize MgB<sub>2</sub> wire performance.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 7","pages":"1-10"},"PeriodicalIF":1.8,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147299697","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}
Resistive type superconducting fault current limiters are in use at operating voltages up to 220 kV, and it is expected that they will also be necessary in the future in transmission grids up to 380 kV. To limit short-circuit currents at such high voltages, long high-temperature superconductor tapes are required typically wound into bifilar coils with low inductance. The windings are usually insulated from each other by a mixed insulating system, which consists of different sheets of insulation material like polyimide and a waved spacer ensuring sufficient cooling with liquid nitrogen. In this study the influence of the spacer material was investigated in detail. For this purpose, a method had to be developed to produce waved spacers from different materials on a laboratory scale, so that spacers with two dimensions, for a tape distance of 1.4 mm and 2.0 mm, could be manufactured from four different materials. The investigations reveal that the electric strength is only slightly dependent on the used spacer material, as a flashover of the spacer occurs. The increase of the tape distance from 1.4 mm to 2.0 mm leads to an increase of the breakdown voltage from roughly 31 kV to 38 kV and enlarging the flashover length at the spacer from 9 mm to 19 mm on each side results in a further increase to approximately 46 kV.
{"title":"AC Breakdown Strength of Layered Tape Insulation Systems in Liquid Nitrogen Using Different Spacer Materials","authors":"Christof Humpert;Christopher Marks;Tobias Kreuz;André Schmid","doi":"10.1109/TASC.2026.3661482","DOIUrl":"https://doi.org/10.1109/TASC.2026.3661482","url":null,"abstract":"Resistive type superconducting fault current limiters are in use at operating voltages up to 220 kV, and it is expected that they will also be necessary in the future in transmission grids up to 380 kV. To limit short-circuit currents at such high voltages, long high-temperature superconductor tapes are required typically wound into bifilar coils with low inductance. The windings are usually insulated from each other by a mixed insulating system, which consists of different sheets of insulation material like polyimide and a waved spacer ensuring sufficient cooling with liquid nitrogen. In this study the influence of the spacer material was investigated in detail. For this purpose, a method had to be developed to produce waved spacers from different materials on a laboratory scale, so that spacers with two dimensions, for a tape distance of 1.4 mm and 2.0 mm, could be manufactured from four different materials. The investigations reveal that the electric strength is only slightly dependent on the used spacer material, as a flashover of the spacer occurs. The increase of the tape distance from 1.4 mm to 2.0 mm leads to an increase of the breakdown voltage from roughly 31 kV to 38 kV and enlarging the flashover length at the spacer from 9 mm to 19 mm on each side results in a further increase to approximately 46 kV.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147362326","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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