Pub Date : 2026-02-02DOI: 10.1109/TASC.2026.3659992
Chenxi Tian;Yueming Sun;Jin Fang;Zhenan Jiang
Reducing AC loss is a critical issue in the design of high-temperature superconducting (HTS) transformers. Owing to the diamagnetism of superconductors, superconducting shielding coils (SSCs) provide an effective means of reducing the perpendicular magnetic field component and AC loss. This work systematically investigates the influence of the SSCs on AC loss in a 1 MVA HTS transformer, using two-dimensional T-A homogenization method. The effects of key parameters are analyzed, including the SSC turn number (up to 12), tape width (4, 6, 12 mm, including combination of different widths), vertical distance h above the top of the transformer windings (0.1–4 mm), and the radial gap g between the SSCs and the transformer windings (0.5–5 mm). The AC loss in the 1 MVA HTS transformer is calculated under these configurations. The simulation results indicate that incorporating SSCs significantly reduces AC loss. For example, employing four 12 mm wide turns of SSCs for both the LV and HV windings at rated current achieves a reduction of 35.2%. This effectiveness arises from the suppression of perpendicular magnetic field component to the end parts of the transformer windings.
{"title":"Superconducting Shielding Coils Influence on AC Loss Reduction of 3-Phase HTS 1 MVA Transformer","authors":"Chenxi Tian;Yueming Sun;Jin Fang;Zhenan Jiang","doi":"10.1109/TASC.2026.3659992","DOIUrl":"https://doi.org/10.1109/TASC.2026.3659992","url":null,"abstract":"Reducing AC loss is a critical issue in the design of high-temperature superconducting (HTS) transformers. Owing to the diamagnetism of superconductors, superconducting shielding coils (SSCs) provide an effective means of reducing the perpendicular magnetic field component and AC loss. This work systematically investigates the influence of the SSCs on AC loss in a 1 MVA HTS transformer, using two-dimensional T-A homogenization method. The effects of key parameters are analyzed, including the SSC turn number (up to 12), tape width (4, 6, 12 mm, including combination of different widths), vertical distance <italic>h</i> above the top of the transformer windings (0.1–4 mm), and the radial gap <italic>g</i> between the SSCs and the transformer windings (0.5–5 mm). The AC loss in the 1 MVA HTS transformer is calculated under these configurations. The simulation results indicate that incorporating SSCs significantly reduces AC loss. For example, employing four 12 mm wide turns of SSCs for both the LV and HV windings at rated current achieves a reduction of 35.2%. This effectiveness arises from the suppression of perpendicular magnetic field component to the end parts of the transformer windings.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 2","pages":"1-8"},"PeriodicalIF":1.8,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175778","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 : 2026-02-02DOI: 10.1109/TASC.2026.3659580
M. Bracco;J. Bijlsma;J. Baumann;T. Boutboul;S. Farinon;E. Gautheron;S. C. Hopkins
Particle accelerator magnets mainly use Nb-Ti ($T_{C}$ = 9 K, $B_{c2}$ = 14 T), but future machines like FCC-hh will require fields near 14 T. This drives a shift to higher-performance superconductors, with Nb$_{text{3}}$Sn as the baseline choice. Nb$_{text{3}}$Sn high-field magnets are fabricated by winding Rutherford cables made from wires containing Nb$_{text{3}}$Sn precursor materials. During the cabling process, these wires undergo deformation, which increases the likelihood of degradation of their transport properties after reaction. Understanding how unreacted wires behave during uniaxial rolling is essential to optimize and validate designs of Nb$_{text{3}}$Sn wires and cables. To investigate this, a collaboration between the Genoa branch of INFN and CERN is developing a finite element model to simulate the behavior of these wires. This study will focus on the impact of deformation during cabling on unreacted wires. Two-dimensional models of wire cross-sections, some idealized and symmetrical, and others based on SEM images of commercial RRP wires, will be presented. The study will explore differences between these models and quantitatively compare simulation results for the deformed geometry and stress and strain state with data obtained from image analysis of wire cross-sections.
{"title":"Numerical Analysis of Unreacted Nb$_{text{3}}$Sn Wires Under Compression","authors":"M. Bracco;J. Bijlsma;J. Baumann;T. Boutboul;S. Farinon;E. Gautheron;S. C. Hopkins","doi":"10.1109/TASC.2026.3659580","DOIUrl":"https://doi.org/10.1109/TASC.2026.3659580","url":null,"abstract":"Particle accelerator magnets mainly use Nb-Ti (<inline-formula><tex-math>$T_{C}$</tex-math></inline-formula> = 9 K, <inline-formula><tex-math>$B_{c2}$</tex-math></inline-formula> = 14 T), but future machines like FCC-hh will require fields near 14 T. This drives a shift to higher-performance superconductors, with Nb<inline-formula><tex-math>$_{text{3}}$</tex-math></inline-formula>Sn as the baseline choice. Nb<inline-formula><tex-math>$_{text{3}}$</tex-math></inline-formula>Sn high-field magnets are fabricated by winding Rutherford cables made from wires containing Nb<inline-formula><tex-math>$_{text{3}}$</tex-math></inline-formula>Sn precursor materials. During the cabling process, these wires undergo deformation, which increases the likelihood of degradation of their transport properties after reaction. Understanding how unreacted wires behave during uniaxial rolling is essential to optimize and validate designs of Nb<inline-formula><tex-math>$_{text{3}}$</tex-math></inline-formula>Sn wires and cables. To investigate this, a collaboration between the Genoa branch of INFN and CERN is developing a finite element model to simulate the behavior of these wires. This study will focus on the impact of deformation during cabling on unreacted wires. Two-dimensional models of wire cross-sections, some idealized and symmetrical, and others based on SEM images of commercial RRP wires, will be presented. The study will explore differences between these models and quantitatively compare simulation results for the deformed geometry and stress and strain state with data obtained from image analysis of wire cross-sections.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-4"},"PeriodicalIF":1.8,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11370189","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175834","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 : 2026-01-30DOI: 10.1109/TASC.2026.3659823
Yukai Qiao;Yueming Sun;Mark Ainslie;Matt Rindfleisch;Rodney A. Badcock;Nick M. Strickland;Zhenan Jiang
In future electric aircraft applications employing all-superconducting rotating machines, round multifilamentary magnesium diboride (MgB2) wires are a preferrable material for lowering AC loss, due to their small filaments at the macron level and tight twist pitch. Our previous work has investigated AC loss behavior in a 54-filament MgB2 wire with a filament radius of 12.5 μm, where the filament size was found not ideal for loss reduction. In this work, 3-D AC loss simulations of a twisted, nonmagnetic 114-filament MgB2 wire with a 5 μm filament radius at 20 K are performed using H-formulation. Three types of AC losses are studied: 1) Transport loss only (Qt0, with current levels up to 90% of its self-field critical current Ic0), 2) magnetization loss only (Qm0, with AC field amplitudes and frequencies up to 2 T and 200 Hz, respectively), 3) total AC loss carrying AC current exposed to AC field (Qtotal, with AC field also up to 2 T and current levels up to 40% of Ic0). Simulation results show that, for the Qm0, the simulated hysteresis loss Qh of a 5-mm twist pitch, 114-filament wire at 50 Hz, and 200 Hz matches the analytical hysteresis loss equation for a cylindrical superconductor, scaled by 114 (the number of filaments), when Bm ≤ 0.5 T. Increasing the twist pitch (5 mm versus 10 mm) and filament size (5 μm in the 114-filament wire versus 12.5 μm in the 54-filament wire) leads to a higher Qm0 due to the coupling effect. Moreover, the simulated Qtotal of the 114-filament wire range from 0.22 to 7.48 W/cm3 for i ≤ 0.4 and Bm ≤ 0.5 T operated at 200 Hz.
{"title":"3-D Simulation of AC Loss in a 114-Filament MgB2 Wire at 20 K","authors":"Yukai Qiao;Yueming Sun;Mark Ainslie;Matt Rindfleisch;Rodney A. Badcock;Nick M. Strickland;Zhenan Jiang","doi":"10.1109/TASC.2026.3659823","DOIUrl":"https://doi.org/10.1109/TASC.2026.3659823","url":null,"abstract":"In future electric aircraft applications employing all-superconducting rotating machines, round multifilamentary magnesium diboride (MgB<sub>2</sub>) wires are a preferrable material for lowering AC loss, due to their small filaments at the macron level and tight twist pitch. Our previous work has investigated AC loss behavior in a 54-filament MgB<sub>2</sub> wire with a filament radius of 12.5 <italic>μ</i>m, where the filament size was found not ideal for loss reduction. In this work, 3-D AC loss simulations of a twisted, nonmagnetic 114-filament MgB<sub>2</sub> wire with a 5 <italic>μ</i>m filament radius at 20 K are performed using <italic>H</i>-formulation. Three types of AC losses are studied: 1) Transport loss only (<italic>Q</i><sub>t0</sub>, with current levels up to 90% of its self-field critical current <italic>I</i><sub>c0</sub>), 2) magnetization loss only (<italic>Q</i><sub>m0</sub>, with AC field amplitudes and frequencies up to 2 T and 200 Hz, respectively), 3) total AC loss carrying AC current exposed to AC field (<italic>Q</i><sub>total</sub>, with AC field also up to 2 T and current levels up to 40% of <italic>I</i><sub>c0</sub>). Simulation results show that, for the <italic>Q</i><sub>m0</sub>, the simulated hysteresis loss <italic>Q</i><sub>h</sub> of a 5-mm twist pitch, 114-filament wire at 50 Hz, and 200 Hz matches the analytical hysteresis loss equation for a cylindrical superconductor, scaled by 114 (the number of filaments), when <italic>B</i><sub>m</sub> ≤ 0.5 T. Increasing the twist pitch (5 mm versus 10 mm) and filament size (5 <italic>μ</i>m in the 114-filament wire versus 12.5 <italic>μ</i>m in the 54-filament wire) leads to a higher <italic>Q</i><sub>m0</sub> due to the coupling effect. Moreover, the simulated <italic>Q</i><sub>total</sub> of the 114-filament wire range from 0.22 to 7.48 W/cm3 for <italic>i</i> ≤ 0.4 and <italic>B</i><sub>m</sub> ≤ 0.5 T operated at 200 Hz.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 7","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223826","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 : 2026-01-29DOI: 10.1109/TASC.2026.3659448
S. Kume;Y. Tsuchiya;S. Awaji
The electro-mechanical properties of REBCO tapes with Cu stabilizing layer were evaluated over a wide temperature range from 30 to 77 K under self-field conditions using the pulsed current method. This approach enabled stable critical current measurements in the kiloampere range while effectively suppressing Joule heating, thereby allowing the simultaneous acquisition of the relationships among tensile strain, critical current, and stress. The results showed that the irreversible strain, ϵirr, defined by a 2% degradation in the critical current, remained nearly constant at approximately 0.4% throughout the temperature range of 30–77 K, indicating negligible temperature dependence. Moreover, since ϵirr was smaller than the yield strain, ϵy, it was clarified that electrical degradation occurred prior to the onset of plastic deformation in the metallic substrate. The effective Young's modulus, E0.3%, determined from the slope in the initial elastic region (0–0.3%), increased with decreasing temperature, exhibiting a parabolic temperature dependence. These results indicate that while the elastic properties of REBCO tapes are sensitive to temperature, their electro-mechanical limit, represented by ϵirr, is essentially temperature-independent. The findings suggest that the value of ϵirr obtained at 77 K can be directly applied as a design parameter for high-field REBCO magnets operating at lower temperatures (30–50 K). This study contributes to improving the mechanical reliability and establishing precise design criteria for REBCO-based high-field superconducting magnets.
{"title":"Electro-Mechanical Characteristics of REBCO Tapes Over a Wide Temperature Using Pulsed Current","authors":"S. Kume;Y. Tsuchiya;S. Awaji","doi":"10.1109/TASC.2026.3659448","DOIUrl":"https://doi.org/10.1109/TASC.2026.3659448","url":null,"abstract":"The electro-mechanical properties of REBCO tapes with Cu stabilizing layer were evaluated over a wide temperature range from 30 to 77 K under self-field conditions using the pulsed current method. This approach enabled stable critical current measurements in the kiloampere range while effectively suppressing Joule heating, thereby allowing the simultaneous acquisition of the relationships among tensile strain, critical current, and stress. The results showed that the irreversible strain, <italic>ϵ</i><sub>irr</sub>, defined by a 2% degradation in the critical current, remained nearly constant at approximately 0.4% throughout the temperature range of 30–77 K, indicating negligible temperature dependence. Moreover, since <italic>ϵ</i><sub>irr</sub> was smaller than the yield strain, <italic>ϵ</i><sub>y</sub>, it was clarified that electrical degradation occurred prior to the onset of plastic deformation in the metallic substrate. The effective Young's modulus, <italic>E</i><sub>0.3%</sub>, determined from the slope in the initial elastic region (0–0.3%), increased with decreasing temperature, exhibiting a parabolic temperature dependence. These results indicate that while the elastic properties of REBCO tapes are sensitive to temperature, their electro-mechanical limit, represented by <italic>ϵ</i><sub>irr</sub>, is essentially temperature-independent. The findings suggest that the value of <italic>ϵ</i><sub>irr</sub> obtained at 77 K can be directly applied as a design parameter for high-field REBCO magnets operating at lower temperatures (30–50 K). This study contributes to improving the mechanical reliability and establishing precise design criteria for REBCO-based high-field superconducting magnets.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147362353","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}
We report on the fabrication and study of NbN/F/NbN trilayers with NbN films of 80-nm thickness, which is much larger than the coherence length but significantly smaller than the London penetration depth, and 50-nm-thick ferromagnetic (F = Ni or NiCu alloy) interlayers, along with 160-nm-thick single layers of NbN as a reference. The heterostructures were patterned into square shapes to enable nonlocal four-probe resistive measurements. This technique, previously applied to single-layer NbN films, allows for the simultaneous and independent probing of surface and bulk superconducting transitions in one measurement run. By comparing NbN and NbN/F/NbN trilayers, we demonstrate that the inclusion of a ferromagnetic interlayer leads to a significant shift in the onset of the superconducting transition, particularly in the near-surface region of the trilayer, and increases the overall transition width. This behavior is consistent with the concept of the electromagnetic proximity effect, predicted theoretically and, thanks to a new measurement strategy that distinguishes between surface and bulk contributions, provides evidence for its presence. The work provides insights into the delicate interplay between superconductivity and magnetism and opens pathways for engineering related interface-sensitive spintronic devices.
{"title":"Mesoscopic S/F/S Trilayers in Parallel Magnetic Fields","authors":"Mikhail Belogolovskii;Magdaléna Poláčková;Elena Zhitlukhina;Branislav Grančič;Leonid Satrapinskyy;Pavol Ďurina;Maroš Gregor;Tomáš Plecenik","doi":"10.1109/TASC.2026.3659452","DOIUrl":"https://doi.org/10.1109/TASC.2026.3659452","url":null,"abstract":"We report on the fabrication and study of NbN/F/NbN trilayers with NbN films of 80-nm thickness, which is much larger than the coherence length but significantly smaller than the London penetration depth, and 50-nm-thick ferromagnetic (F = Ni or NiCu alloy) interlayers, along with 160-nm-thick single layers of NbN as a reference. The heterostructures were patterned into square shapes to enable nonlocal four-probe resistive measurements. This technique, previously applied to single-layer NbN films, allows for the simultaneous and independent probing of surface and bulk superconducting transitions in one measurement run. By comparing NbN and NbN/F/NbN trilayers, we demonstrate that the inclusion of a ferromagnetic interlayer leads to a significant shift in the onset of the superconducting transition, particularly in the near-surface region of the trilayer, and increases the overall transition width. This behavior is consistent with the concept of the electromagnetic proximity effect, predicted theoretically and, thanks to a new measurement strategy that distinguishes between surface and bulk contributions, provides evidence for its presence. The work provides insights into the delicate interplay between superconductivity and magnetism and opens pathways for engineering related interface-sensitive spintronic devices.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175690","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 : 2026-01-28DOI: 10.1109/TASC.2026.3658272
Hongbo Yang;Sijian Wang;Huadong Yong
The critical current is a key factor for the stable operation of superconducting structures. Therefore, it is imperative to employ precise and efficient numerical methods for evaluating the critical current in complex superconducting structures, thereby ensuring their operational safety and reliability. Several numerical approaches based on the finite element method have been proposed by researchers. However, when evaluating the critical current, the computational demand of the time-dependent calculation method is exceedingly high. Therefore, it is necessary to adopt a quasi-static methodology for the computation of superconducting critical currents. In this paper, it is assumed that the current in the superconductor is stable and the induced current caused by magnetic field variation has been fully dissipated. The critical current is predicted in different structures based on the quasi-static A-ϕ formulation and E-J constitutive law. The numerical results are compared between the quasi-static A-ϕ formulation and experimental data as well as the H formulation. Due to its significant computational efficiency, the quasi-static A-ϕ formulation holds potential as an effective method for optimizing superconductor structures.
{"title":"Numerical Simulation of Critical Current in Superconducting Structures Based on Quasi-Static A-ϕ Formulation","authors":"Hongbo Yang;Sijian Wang;Huadong Yong","doi":"10.1109/TASC.2026.3658272","DOIUrl":"https://doi.org/10.1109/TASC.2026.3658272","url":null,"abstract":"The critical current is a key factor for the stable operation of superconducting structures. Therefore, it is imperative to employ precise and efficient numerical methods for evaluating the critical current in complex superconducting structures, thereby ensuring their operational safety and reliability. Several numerical approaches based on the finite element method have been proposed by researchers. However, when evaluating the critical current, the computational demand of the time-dependent calculation method is exceedingly high. Therefore, it is necessary to adopt a quasi-static methodology for the computation of superconducting critical currents. In this paper, it is assumed that the current in the superconductor is stable and the induced current caused by magnetic field variation has been fully dissipated. The critical current is predicted in different structures based on the quasi-static A-<italic>ϕ</i> formulation and <italic>E</i>-<italic>J</i> constitutive law. The numerical results are compared between the quasi-static A-<italic>ϕ</i> formulation and experimental data as well as the H formulation. Due to its significant computational efficiency, the quasi-static A-<italic>ϕ</i> formulation holds potential as an effective method for optimizing superconductor structures.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-10"},"PeriodicalIF":1.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223664","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 : 2026-01-28DOI: 10.1109/TASC.2026.3657828
Yaxiong Tan;Junhao Guo;Qi Wei;Weigen Chen;Jian Li
High-temperature superconducting (HTS) cables are considered an ideal transmission solution for space solar power stations owing to their low-loss characteristics. However, the vacuum and strong irradiation conditions in space can cause external heat sources and heat dissipation problems for HTS cables. Although thermal management of HTS cables for Earth-based applications is well researched, the cables are currently unsuitable for space-based applications because of deficiencies in their electro-thermal characteristics, heat balance mechanism, and lightweight and efficient structural design. In this article, a segmented self-cooling direct current (DC) HTS cable structure was proposed. Using a finite element simulation model of the HTS cable, its thermal fields in steady and transient states were investigated. The primary steady-state heat source in space is solar irradiation, and radial heat transfer is the primary route to dissipate heat in HTS cables. The process of temperature rise in the superconducting layer exhibits lag and nonlinearity. The heat can be directly dissipated through the heat sink. In the transient state, the main heat sources are metallic heat and superconducting quench heat, and the temperature response is rapid. Owing to its multilayer high heat capacity structure and thermal radiation effect, the proposed HTS cable is resistant to short-term thermal disturbances. Therefore, the cable need not be installed with a refrigeration unit. The HTS cable was compared with the conventional metallic cables. The HTS cable achieved a mass reduction of 79.2% compared with the conventional metallic cables under identical operating conditions and a 99.9% reduction in heat generation in steady-state conditions. In the transient state, under 10 and 20 kA fault currents, heat generation was reduced by 42.9% and 44.1%, respectively. The current transmission efficiency was improved by 3.1% . This study provides a novel thermal management method for HTS cables in space-based applications.
{"title":"A DC High-Temperature Superconducting Cable With Self-Sinking Structure for Space Solar Power Station","authors":"Yaxiong Tan;Junhao Guo;Qi Wei;Weigen Chen;Jian Li","doi":"10.1109/TASC.2026.3657828","DOIUrl":"https://doi.org/10.1109/TASC.2026.3657828","url":null,"abstract":"High-temperature superconducting (HTS) cables are considered an ideal transmission solution for space solar power stations owing to their low-loss characteristics. However, the vacuum and strong irradiation conditions in space can cause external heat sources and heat dissipation problems for HTS cables. Although thermal management of HTS cables for Earth-based applications is well researched, the cables are currently unsuitable for space-based applications because of deficiencies in their electro-thermal characteristics, heat balance mechanism, and lightweight and efficient structural design. In this article, a segmented self-cooling direct current (DC) HTS cable structure was proposed. Using a finite element simulation model of the HTS cable, its thermal fields in steady and transient states were investigated. The primary steady-state heat source in space is solar irradiation, and radial heat transfer is the primary route to dissipate heat in HTS cables. The process of temperature rise in the superconducting layer exhibits lag and nonlinearity. The heat can be directly dissipated through the heat sink. In the transient state, the main heat sources are metallic heat and superconducting quench heat, and the temperature response is rapid. Owing to its multilayer high heat capacity structure and thermal radiation effect, the proposed HTS cable is resistant to short-term thermal disturbances. Therefore, the cable need not be installed with a refrigeration unit. The HTS cable was compared with the conventional metallic cables. The HTS cable achieved a mass reduction of 79.2% compared with the conventional metallic cables under identical operating conditions and a 99.9% reduction in heat generation in steady-state conditions. In the transient state, under 10 and 20 kA fault currents, heat generation was reduced by 42.9% and 44.1%, respectively. The current transmission efficiency was improved by 3.1% . This study provides a novel thermal management method for HTS cables in space-based applications.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 2","pages":"1-11"},"PeriodicalIF":1.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146176022","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}
Etching a narrow bridge on REBa2Cu3O7-x (REBCO, RE = Rare Earth) tape is a widely applied procedure during transport measurements of critical current (Ic), aiming to mitigate significant Lorentz forces. However, the microbridge can influence the measurement accuracy, and understanding this influence is crucial because it can bias the extrapolation of Ic to the full tape width. In this article, we reveal that the microbridge could result in an overestimation when extrapolating the full-width Ic values from microbridge ones. We identified two primary sources of this overestimation by systematically comparing the directly measured full-width Ic values with those extrapolated from narrow bridges under varying temperatures, applied magnetic fields, and field orientations. The first source arises from inaccuracies in the assumed cross-sectional geometry and area of the narrow bridge. Specifically, assuming a rectangular cross-section when the actual geometry is trapezoidal leads to significant overestimations. The second factor is the nonuniform pinning effect across the thickness of the REBCO layer. Although this effect is negligible at low magnetic fields and higher temperatures, it becomes significant at lower temperatures, high magnetic fields, and when the field is nearly parallel to the tape surface. Based on these findings, we propose an improved procedure for transport measurements using narrow bridges to achieve more accurate determinations of Ic.
在REBa2Cu3O7-x （REBCO, RE = Rare Earth）胶带上蚀刻窄桥是一种广泛应用于临界电流（Ic）输运测量的方法，旨在减轻显著的洛伦兹力。然而，微桥会影响测量精度，了解这种影响是至关重要的，因为它会使Ic的外推偏向于整个带宽度。在本文中，我们揭示了当从微桥的值推断全宽度Ic值时，微桥可能导致高估。我们通过系统地比较直接测量的全宽Ic值与在不同温度、外加磁场和场方向下从窄桥推断的Ic值，确定了这种高估的两个主要来源。第一个原因是假定的窄桥的横截面几何形状和面积不准确。具体来说，当实际几何形状为梯形时，假设截面为矩形会导致严重的高估。第二个因素是跨REBCO层厚度的不均匀钉住效应。虽然这种效应在低磁场和高温下可以忽略不计，但在较低温度、高磁场和磁场几乎与纸带表面平行时，这种效应就会变得显著。基于这些发现，我们提出了一种改进的程序，运输测量使用窄桥，以实现更准确的测定Ic。
{"title":"Possible Overestimation of Ic Value of REBCO Tapes Due to the Narrow Bridge Fabricated by Laser Etching During Transport Measurements","authors":"Qi Yuan;Zili Zhang;Xiaowei Song;Jie Yang;Benzhe Zhou;Shuo Li;Zhen Wang;Gang Li;Jun Luo;Rui Zhou;Lei Wang;Quanliang Cao;Jinguang Cheng","doi":"10.1109/TASC.2026.3657800","DOIUrl":"https://doi.org/10.1109/TASC.2026.3657800","url":null,"abstract":"Etching a narrow bridge on REBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> (REBCO, RE = Rare Earth) tape is a widely applied procedure during transport measurements of critical current (<italic>I</i><sub>c</sub>), aiming to mitigate significant Lorentz forces. However, the microbridge can influence the measurement accuracy, and understanding this influence is crucial because it can bias the extrapolation of <italic>I<sub>c</sub></i> to the full tape width. In this article, we reveal that the microbridge could result in an overestimation when extrapolating the full-width <italic>I</i><sub>c</sub> values from microbridge ones. We identified two primary sources of this overestimation by systematically comparing the directly measured full-width <italic>I</i><sub>c</sub> values with those extrapolated from narrow bridges under varying temperatures, applied magnetic fields, and field orientations. The first source arises from inaccuracies in the assumed cross-sectional geometry and area of the narrow bridge. Specifically, assuming a rectangular cross-section when the actual geometry is trapezoidal leads to significant overestimations. The second factor is the nonuniform pinning effect across the thickness of the REBCO layer. Although this effect is negligible at low magnetic fields and higher temperatures, it becomes significant at lower temperatures, high magnetic fields, and when the field is nearly parallel to the tape surface. Based on these findings, we propose an improved procedure for transport measurements using narrow bridges to achieve more accurate determinations of <italic>I</i><sub>c</sub>.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 2","pages":"1-13"},"PeriodicalIF":1.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175767","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 : 2026-01-26DOI: 10.1109/TASC.2026.3657580
Frederick S. Porter;Gregory V. Brown;Renata S. Cumbee;Megan E. Eckart;Natalie Hell;Richard L. Kelley;Caroline A. Kilbourne;Maurice A. Leutenegger;Thomas Lockard;Makoto Sawada;Chintan D. Shah;Stephen J. Smith;Michael C. Witthoeft
Space X-ray spectrometers such as the Resolve instrument on XRISM require precise calibration in order to interpret the spectra of astrophysical objects. Key components of the calibration are the energy scale and the core line spread function, both of which vary with photon energy. A major issue in the calibration of high-resolution spectrometers is locating good calibrators with well-known and stable intrinsic line shapes. Neutral fluorescence is widely used, but inner-shell transitions in neutral atoms often exhibit complex, poorly documented line shapes that vary with excitation conditions. Here we present empirical measurements of K-shell transitions in neutral O and F below 1 keV using an engineering model XRISM calorimeter array, an electron bombardment modulated X-ray source, and an electron beam ion trap (EBIT) to provide a precise energy reference. In addition, we report measurements of the Mo Lα complex with the transition-edge microcalorimeter spectrometer (TEMS), which reveal strong satellite structure and sensitivity of the line shape to the incident exciting spectrum. Together, these results demonstrate the need for empirical line-shape models, highlight the nonstationary nature of neutral fluorescence features, and define a path toward developing transfer standards for XRISM and future precision instruments such as Athena/X-IFU.
{"title":"Measuring X-Ray Emission Line Shapes in Neutral Species for XRISM Calibration","authors":"Frederick S. Porter;Gregory V. Brown;Renata S. Cumbee;Megan E. Eckart;Natalie Hell;Richard L. Kelley;Caroline A. Kilbourne;Maurice A. Leutenegger;Thomas Lockard;Makoto Sawada;Chintan D. Shah;Stephen J. Smith;Michael C. Witthoeft","doi":"10.1109/TASC.2026.3657580","DOIUrl":"https://doi.org/10.1109/TASC.2026.3657580","url":null,"abstract":"Space X-ray spectrometers such as the Resolve instrument on XRISM require precise calibration in order to interpret the spectra of astrophysical objects. Key components of the calibration are the energy scale and the core line spread function, both of which vary with photon energy. A major issue in the calibration of high-resolution spectrometers is locating good calibrators with well-known and stable intrinsic line shapes. Neutral fluorescence is widely used, but inner-shell transitions in neutral atoms often exhibit complex, poorly documented line shapes that vary with excitation conditions. Here we present empirical measurements of K-shell transitions in neutral O and F below 1 keV using an engineering model XRISM calorimeter array, an electron bombardment modulated X-ray source, and an electron beam ion trap (EBIT) to provide a precise energy reference. In addition, we report measurements of the Mo Lα complex with the transition-edge microcalorimeter spectrometer (TEMS), which reveal strong satellite structure and sensitivity of the line shape to the incident exciting spectrum. Together, these results demonstrate the need for empirical line-shape models, highlight the nonstationary nature of neutral fluorescence features, and define a path toward developing transfer standards for XRISM and future precision instruments such as Athena/X-IFU.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 6","pages":"1-7"},"PeriodicalIF":1.8,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175894","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 : 2026-01-23DOI: 10.1109/TASC.2026.3657136
Thomas P. Satterthwaite;Zeeshan Ahmed;Cody J. Duell;Shawn W. Henderson;Tristan Pinsonneault-Marotte;Max Silva-Feaver;Yuhan Wang
Fulfilling the science goalsof the Simons Observatory, a state-of-the-art cosmic microwave background experiment, has required deploying tens of thousands of superconducting bolometers. Reading out data from the observatory’s more than 67 000 transition-edge sensor (TES) detectors while maintaining cryogenic conditions requires an effective multiplexing scheme. The SLAC microresonator radio frequency (SMuRF) electronics have been developed to provide the warm electronics for a high-density microwave frequency multiplexing readout system, and this system has been shown to achieve multiplexing factors on the order of 1000. SMuRF has recently been deployed to the Simons Observatory, which is located at 5200 m on Cerro Toco in Chile’s Atacama Desert. As the SMuRF system is exposed to the desert’s diurnal temperature swings, resulting phase drift in radio frequency (RF) transmission lines may introduce a systematic signal contamination. We present studies of phase drift in the room-temperature RF lines of the Simons Observatory’s 6 m large-aperture telescope, which hosts the largest deployment to date of TES microwave frequency multiplexing to a single telescope. We show that these phase drifts occur on time scales, which are significantly longer than sky scanning, and that their contribution to on-sky in-transition detector noise is within the readout noise budget.
{"title":"The Simons Observatory: Studies of Phase Drift in RF Transmission Lines From the First Large-Scale Deployment of Microwave Frequency Multiplexing for Cosmology","authors":"Thomas P. Satterthwaite;Zeeshan Ahmed;Cody J. Duell;Shawn W. Henderson;Tristan Pinsonneault-Marotte;Max Silva-Feaver;Yuhan Wang","doi":"10.1109/TASC.2026.3657136","DOIUrl":"https://doi.org/10.1109/TASC.2026.3657136","url":null,"abstract":"Fulfilling the science goalsof the Simons Observatory, a state-of-the-art cosmic microwave background experiment, has required deploying tens of thousands of superconducting bolometers. Reading out data from the observatory’s more than 67 000 transition-edge sensor (TES) detectors while maintaining cryogenic conditions requires an effective multiplexing scheme. The SLAC microresonator radio frequency (SMuRF) electronics have been developed to provide the warm electronics for a high-density microwave frequency multiplexing readout system, and this system has been shown to achieve multiplexing factors on the order of 1000. SMuRF has recently been deployed to the Simons Observatory, which is located at 5200 m on Cerro Toco in Chile’s Atacama Desert. As the SMuRF system is exposed to the desert’s diurnal temperature swings, resulting phase drift in radio frequency (RF) transmission lines may introduce a systematic signal contamination. We present studies of phase drift in the room-temperature RF lines of the Simons Observatory’s 6 m large-aperture telescope, which hosts the largest deployment to date of TES microwave frequency multiplexing to a single telescope. We show that these phase drifts occur on time scales, which are significantly longer than sky scanning, and that their contribution to on-sky in-transition detector noise is within the readout noise budget.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 6","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175892","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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