Pub Date : 2026-01-14DOI: 10.1109/TASC.2026.3654036
Shumin Yu;Guofeng Zhang;Haiyang Mao;Jun Wu;Jiawei Luo;Yongliang Wang;Longqing Qiu;Liangliang Rong
This article reports the wafer-scale fabrication of dc superconducting quantum interference devices (dc-SQUIDs) on 4-in silicon wafers, employing a submicron Josephson junction cross-line process that integrates i-line stepper lithography, in situ trilayer deposition, and a self-aligned insulating layer. Using a stratified regional sampling strategy, 10 SQUIDs are selected from each of the center, transition, and edge regions of the wafer (achieving a total coverage of 49.2%), and the spatial uniformity of key parameters such as critical current, voltage swing, and system flux noise is systematically evaluated. The test results show that the critical currents for the central, transition, and edge regions are (25.4±1.77) μA, (22.4±2.13) μA, and (16.2±2.81) μA, respectively; their corresponding voltage swings are (275±5.95) μV, (255±17.8) μV, and (146±44.7) μV, respectively; and the system flux noises are (1.74±0.131) μΦ0/√Hz, (1.97±0.0880) μΦ0/√Hz, and (2.70±0.452) μΦ0/√Hz, respectively. Statistical analysis shows that from the center to the edge, the critical current and voltage swing demonstrate a downward trend, whereas the system flux noise shows a trend of deterioration. The standard deviation of these parameters gradually increases from the center to the edge, which indicates poorer parameter consistency and more pronounced fluctuations in the region. Further analysis of the coefficient of variation (CV) shows that the CVs of key parameters in the central and transition regions are all below 10%. This verifies that the process route, particularly in these central and transition regions, possesses excellent spatial uniformity, providing a crucial process foundation and data support for the large-scale manufacturing of high-performance SQUIDs.
{"title":"Wafer-Scale Fabrication and Spatial Uniformity Evaluation of SQUIDs With Submicron Josephson Junctions","authors":"Shumin Yu;Guofeng Zhang;Haiyang Mao;Jun Wu;Jiawei Luo;Yongliang Wang;Longqing Qiu;Liangliang Rong","doi":"10.1109/TASC.2026.3654036","DOIUrl":"https://doi.org/10.1109/TASC.2026.3654036","url":null,"abstract":"This article reports the wafer-scale fabrication of dc superconducting quantum interference devices (dc-SQUIDs) on 4-in silicon wafers, employing a submicron Josephson junction cross-line process that integrates i-line stepper lithography, in situ trilayer deposition, and a self-aligned insulating layer. Using a stratified regional sampling strategy, 10 SQUIDs are selected from each of the center, transition, and edge regions of the wafer (achieving a total coverage of 49.2%), and the spatial uniformity of key parameters such as critical current, voltage swing, and system flux noise is systematically evaluated. The test results show that the critical currents for the central, transition, and edge regions are (25.4±1.77) μA, (22.4±2.13) μA, and (16.2±2.81) μA, respectively; their corresponding voltage swings are (275±5.95) μV, (255±17.8) μV, and (146±44.7) μV, respectively; and the system flux noises are (1.74±0.131) μΦ<sub>0</sub>/√Hz, (1.97±0.0880) μΦ<sub>0</sub>/√Hz, and (2.70±0.452) μΦ<sub>0</sub>/√Hz, respectively. Statistical analysis shows that from the center to the edge, the critical current and voltage swing demonstrate a downward trend, whereas the system flux noise shows a trend of deterioration. The standard deviation of these parameters gradually increases from the center to the edge, which indicates poorer parameter consistency and more pronounced fluctuations in the region. Further analysis of the coefficient of variation (CV) shows that the CVs of key parameters in the central and transition regions are all below 10%. This verifies that the process route, particularly in these central and transition regions, possesses excellent spatial uniformity, providing a crucial process foundation and data support for the large-scale manufacturing of high-performance SQUIDs.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 2","pages":"1-8"},"PeriodicalIF":1.8,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175902","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}
High Temperature Superconducting (HTS) cables developed for superconducting powertrains for electric aircrafts have to demonstrate their robustness, especially towards electric arcs. We propose here a methodology to evaluate HTS cable vulnerability to serial arcs following a quench. First, the arc voltage threshold of an HTS tape is measured under cryogenic temperatures. Then, a model is proposed to predict the peak of the transient voltage developed at the breaking point in case one of the HTS tapes in the cable is broken. This model depends on self and mutual inductances and on current variation dI/dt. A good correlation is obtained between the model and experiments using a simplified setup at room temperature. The comparison between the predicted transient voltage induced in representative HTS cables when one tape is broken with the arc voltage threshold will allow to assess the arcing risk in specific topologies of HTS cable.
{"title":"Serial Arc Risk Analysis in HTS Tapes for Electric Aircraft","authors":"Cécile Weulersse;Jean Rivenc;Ivan Revel;Pedro Barusco;Emelie Nilsson","doi":"10.1109/TASC.2026.3652114","DOIUrl":"https://doi.org/10.1109/TASC.2026.3652114","url":null,"abstract":"High Temperature Superconducting (HTS) cables developed for superconducting powertrains for electric aircrafts have to demonstrate their robustness, especially towards electric arcs. We propose here a methodology to evaluate HTS cable vulnerability to serial arcs following a quench. First, the arc voltage threshold of an HTS tape is measured under cryogenic temperatures. Then, a model is proposed to predict the peak of the transient voltage developed at the breaking point in case one of the HTS tapes in the cable is broken. This model depends on self and mutual inductances and on current variation <italic>dI/dt</i>. A good correlation is obtained between the model and experiments using a simplified setup at room temperature. The comparison between the predicted transient voltage induced in representative HTS cables when one tape is broken with the arc voltage threshold will allow to assess the arcing risk in specific topologies of HTS cable.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026461","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}
Superconducting transition-edge sensors (TESs) with high sensitivity can detect electromagnetic wave radiations from millimeter/submillimeter, optical to x/γ rays, and have been successfully used in many fields. To improve detection efficiency and sensitivity, large-scale TES arrays are required in combination with multiplexing readout electronics. Compared to other multiplexing schemes, microwave SQUID multiplexing (μMUX), consisting of high-quality microwave superconducting resonators and RF SQUIDs, is most suitable since it provides a wider bandwidth (GHz) and consequently higher multiplexing factor. We designed two types of circuits with different mutual inductances (${{M}_{mathrm{T}}}$) between the resonator and the RF SQUID: 2.3 pH for the weak-coupling channel and 6.5 pH for the strong-coupling channel. The resonator and RF SQUID washers made of 150 nm Nb are first fabricated by magnetron-sputtering and reactive ion etching, followed by the deposition of Nb/Al–AlOx/Nb trilayer and definition of the Josephson junctions of the RF SQUIDs. This work presents a μMUX demonstration chip with five channels with ${{Q}_{mathrm{l}}}$ values of 787 and 3626, and the measured frequency shifts ($Delta {{f}_{text{pp}}}$) of ∼500 kHz and 4 MHz for the weak- coupling and strong-coupling channels, respectively. The open-loop equivalent noise current, obtained from the measured phase noise and resonator responsivity, is $sim 80text{pA}/sqrt {text{Hz}} $ with the strong-coupling channel.
{"title":"Development of Microwave SQUID Multiplexer for Readout of Transition-Edge Sensor Array","authors":"Zhi-Fa Feng;Xian-Feng Zhou;Wen Zhang;Zheng Wang;Qing-Xiao Ma;Pei-Zhan Li;Jia-Qiang Zhong;Wei Miao;Yuan Ren;Qi-Jun Yao;Valery Koshelets;Lyudmila Filippenko;Michael Fominsky;Jing Li;Sheng-Cai Shi","doi":"10.1109/TASC.2026.3653239","DOIUrl":"https://doi.org/10.1109/TASC.2026.3653239","url":null,"abstract":"Superconducting transition-edge sensors (TESs) with high sensitivity can detect electromagnetic wave radiations from millimeter/submillimeter, optical to x/γ rays, and have been successfully used in many fields. To improve detection efficiency and sensitivity, large-scale TES arrays are required in combination with multiplexing readout electronics. Compared to other multiplexing schemes, microwave SQUID multiplexing (<italic>μ</i>MUX), consisting of high-quality microwave superconducting resonators and RF SQUIDs, is most suitable since it provides a wider bandwidth (GHz) and consequently higher multiplexing factor. We designed two types of circuits with different mutual inductances (<inline-formula><tex-math>${{M}_{mathrm{T}}}$</tex-math></inline-formula>) between the resonator and the RF SQUID: 2.3 pH for the weak-coupling channel and 6.5 pH for the strong-coupling channel. The resonator and RF SQUID washers made of 150 nm Nb are first fabricated by magnetron-sputtering and reactive ion etching, followed by the deposition of Nb/Al–AlOx/Nb trilayer and definition of the Josephson junctions of the RF SQUIDs. This work presents a <italic>μ</i>MUX demonstration chip with five channels with <inline-formula><tex-math>${{Q}_{mathrm{l}}}$</tex-math></inline-formula> values of 787 and 3626, and the measured frequency shifts (<inline-formula><tex-math>$Delta {{f}_{text{pp}}}$</tex-math></inline-formula>) of ∼500 kHz and 4 MHz for the weak- coupling and strong-coupling channels, respectively. The open-loop equivalent noise current, obtained from the measured phase noise and resonator responsivity, is <inline-formula><tex-math>$sim 80text{pA}/sqrt {text{Hz}} $</tex-math></inline-formula> with the strong-coupling channel.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 6","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146057618","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}
This study explores ternary Ag-added InSn solders to develop low-resistance, reliable, and mechanically robust joints between YBCO tapes, an essential requirement for superconducting magnets, including the magnets in the fusion industry. To investigate the impact of Ag addition to the widely used SnIn solder, several solders were made by adding small amounts of Ag (1-5wt.% ) to the eutectic In-Sn solder. Lap joints were fabricated between YBCO tapes using these solders and were characterized for electrical resistivity, microstructure, and mechanical properties. According to the results, Ag addition changes the solder bulk structure with minimum impact on the interface and mainly dissolves in the In-rich phase of the solder. The joints made with Ag-added solders show significantly higher mechanical strength and ductility, with fracture shifting from the joint to the tape outside the joint region, and reasonably low electrical resistance. The optimized 5wt.% Ag addition to the binary In-Sn solder showed the best compromised joining performance as a result of a homogenous joint microstructure, offering a promising approach towards more reliable joints for superconducting magnet applications.
{"title":"Development of Ag-Added InSn Solders for ReBCO Joints","authors":"Nooshin Goodarzi;Kévin Berger;Alexander Molodyk;Mark Ainslie;Tayebeh Mousavi","doi":"10.1109/TASC.2025.3646983","DOIUrl":"https://doi.org/10.1109/TASC.2025.3646983","url":null,"abstract":"This study explores ternary Ag-added InSn solders to develop low-resistance, reliable, and mechanically robust joints between YBCO tapes, an essential requirement for superconducting magnets, including the magnets in the fusion industry. To investigate the impact of Ag addition to the widely used SnIn solder, several solders were made by adding small amounts of Ag (1-5wt.% ) to the eutectic In-Sn solder. Lap joints were fabricated between YBCO tapes using these solders and were characterized for electrical resistivity, microstructure, and mechanical properties. According to the results, Ag addition changes the solder bulk structure with minimum impact on the interface and mainly dissolves in the In-rich phase of the solder. The joints made with Ag-added solders show significantly higher mechanical strength and ductility, with fracture shifting from the joint to the tape outside the joint region, and reasonably low electrical resistance. The optimized 5wt.% Ag addition to the binary In-Sn solder showed the best compromised joining performance as a result of a homogenous joint microstructure, offering a promising approach towards more reliable joints for superconducting magnet applications.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145982295","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 : 2026-01-12DOI: 10.1109/TASC.2026.3652981
Louis Denis;Benoît Vanderheyden;Christophe Geuzaine
The simulation of large-scale high-temperature superconducting (HTS) magnets is a computational challenge due to the multiple spatial scales involved, from the magnet to the detailed turn-to-turn geometry. To reduce the computational cost associated with finite-element (FE) simulations of insulated HTS coils, the simultaneous multi-scale homogeneous (SMSH) method can be considered. It combines a macroscopic-scale homogenized magnet model with multiple single-tape models and solves both scales monolithically. In this work, the SMSH method is reformulated using the $h$-$phi$ thin-shell (TS) approximation, where analyzed tapes are collapsed into thin surfaces, simplifying mesh generation. Moreover, the magnetic field is expressed as the gradient of the magnetic scalar potential outside the analyzed tapes. The discretized field is then described with nodal functions, further reducing the size of the FE problem compared to standard $h$ formulations. The proposed $h$-$phi$ SMSH-TS method is verified against state-of-the-art homogenization methods on a 2-D benchmark problem of stacks of HTS tapes. The results show good agreement in terms of AC losses, turn voltage and local current density, with a significant reduction in simulation time compared to reference models. All models are open-source.
{"title":"Simultaneous Multi-Scale Homogeneous H-Phi Thin-Shell Model for Efficient Simulations of Stacked HTS Coils","authors":"Louis Denis;Benoît Vanderheyden;Christophe Geuzaine","doi":"10.1109/TASC.2026.3652981","DOIUrl":"https://doi.org/10.1109/TASC.2026.3652981","url":null,"abstract":"The simulation of large-scale high-temperature superconducting (HTS) magnets is a computational challenge due to the multiple spatial scales involved, from the magnet to the detailed turn-to-turn geometry. To reduce the computational cost associated with finite-element (FE) simulations of insulated HTS coils, the simultaneous multi-scale homogeneous (SMSH) method can be considered. It combines a macroscopic-scale homogenized magnet model with multiple single-tape models and solves both scales monolithically. In this work, the SMSH method is reformulated using the <inline-formula><tex-math>$h$</tex-math></inline-formula>-<inline-formula><tex-math>$phi$</tex-math></inline-formula> thin-shell (TS) approximation, where analyzed tapes are collapsed into thin surfaces, simplifying mesh generation. Moreover, the magnetic field is expressed as the gradient of the magnetic scalar potential outside the analyzed tapes. The discretized field is then described with nodal functions, further reducing the size of the FE problem compared to standard <inline-formula><tex-math>$h$</tex-math></inline-formula> formulations. The proposed <inline-formula><tex-math>$h$</tex-math></inline-formula>-<inline-formula><tex-math>$phi$</tex-math></inline-formula> SMSH-TS method is verified against state-of-the-art homogenization methods on a 2-D benchmark problem of stacks of HTS tapes. The results show good agreement in terms of AC losses, turn voltage and local current density, with a significant reduction in simulation time compared to reference models. All models are open-source.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-7"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082166","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 present the design and testing of a prototype multiplexing kinetic inductance detector readout electronics for the PRobe far-Infrared Mission for Astrophysics (PRIMA) space mission. PRIMA is a Probe-class astrophysics mission concept that will answer fundamental questions about the formation of planetary systems, the coevolution of stars and supermassive black holes in galaxies, and the rise of heavy elements and dust over cosmic time. The readout electronics for PRIMA must be compatible with operation at Earth–Sun L2 and capable of multiplexing more than 1000 detectors over 2.5-GHz bandwidth. The electronics must also be capable of switching between the two instruments, which have different readout bands: the hyperspectral imager (PRIMAger, 2.6–4.9 GHz) and the spectrometer (Far-Infrared Enhanced Survey Spectrometer, 0.4–2.4 GHz). The PRIMA readout electronics use high-heritage SpaceCube digital electronics with a build-to-print SpaceCube Mini v3.0 board using a radiation-tolerant Kintex KU060 field programmable gate array and a custom high-speed digitizer board, along with radio frequency electronics that provide filtering and power conditioning. We present the driving requirements for the system, as well as the hardware, firmware, software, and system-level design that meets those requirements.
{"title":"Spaceflight KID Readout Electronics for PRIMA","authors":"Thomas Essinger-Hileman;C. Matt Bradford;Patrick Brown;Sean Bryan;Jesse Coldsmith;Jennifer Corekin;Sumit Dahal;Thomas Devlin;Marc Foote;Draisy Friedman;Alessandro Geist;Jason Glenn;Christopher Green;Tracee Jamison-Hooks;Kevin Horgan;Jared Lucey;Philip Mauskopf;Lynn Miles;Sanetra Bailey Newman;Gerard Quilligan;Cody Roberson;Adrian Sinclair;Salman Sheikh;Eric Weeks;Christopher Wilson;Travis Wise","doi":"10.1109/TASC.2026.3652455","DOIUrl":"https://doi.org/10.1109/TASC.2026.3652455","url":null,"abstract":"We present the design and testing of a prototype multiplexing kinetic inductance detector readout electronics for the PRobe far-Infrared Mission for Astrophysics (PRIMA) space mission. PRIMA is a Probe-class astrophysics mission concept that will answer fundamental questions about the formation of planetary systems, the coevolution of stars and supermassive black holes in galaxies, and the rise of heavy elements and dust over cosmic time. The readout electronics for PRIMA must be compatible with operation at Earth–Sun L2 and capable of multiplexing more than 1000 detectors over 2.5-GHz bandwidth. The electronics must also be capable of switching between the two instruments, which have different readout bands: the hyperspectral imager (PRIMAger, 2.6–4.9 GHz) and the spectrometer (Far-Infrared Enhanced Survey Spectrometer, 0.4–2.4 GHz). The PRIMA readout electronics use high-heritage SpaceCube digital electronics with a build-to-print SpaceCube Mini v3.0 board using a radiation-tolerant Kintex KU060 field programmable gate array and a custom high-speed digitizer board, along with radio frequency electronics that provide filtering and power conditioning. We present the driving requirements for the system, as well as the hardware, firmware, software, and system-level design that meets those requirements.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 6","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175891","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}
This study optimized the structural design of NbTi superconducting wires using the analysis method combining finite element simulation with experiments. By adjusting the matrix material of the NbTi mono-filament billet, the overall deformation uniformity of the filaments was significantly improved. Considering both the optimal structural parameters obtained from simulations and the practical requirements of assembly feasibility and processing yield, the final design has been confirmed, with the matrix material of the NbTi mono-filament billet being Cu2Mn, and the spacing-to-diameter ratio (S/D) parameter and filament spacing of the NbTi multi-filament billet being 0.50 and 5.20 mm, respectively. Based on this design, NbTi multi-filament wire with 24 filaments and a copper-to-non-copper ratio of 7 was fabricated using conventional drawing and aging heat treatment processes. The wire was finally drawn to a diameter of 1.0 mm and subjected to superconducting performance tests. The results showed that, under 4.2 K and 4 T, the optimized design achieved a critical current density (Jc) of 3804 A/mm2, representing an 11.8% improvement compared with 3400 A/mm2 for the existing structure.
本研究采用有限元模拟与实验相结合的分析方法对NbTi超导导线的结构设计进行了优化。通过调整NbTi单丝坯的基体材料，可以显著提高单丝坯的整体变形均匀性。综合考虑模拟得到的最优结构参数以及装配可行性和加工良率的实际要求，确定了最终设计方案，即NbTi单长丝坯的基体材料为Cu2Mn， NbTi多长丝坯的间距/直径比（S/D）参数为0.50 mm，长丝间距为5.20 mm。在此基础上，采用常规拉伸和时效热处理工艺制备了24根铜非铜比为7的NbTi多丝丝。最后将钢丝拉制成直径1.0 mm，并进行超导性能测试。结果表明，在4.2 K和4 T条件下，优化设计的临界电流密度（Jc）为3804 a /mm2，比现有结构的3400 a /mm2提高了11.8%。
{"title":"Optimization of Filament Structure in NbTi Superconducting Wires in WST","authors":"Zhang Kailin;Guo Qiang;Jiang Longtao;Han Luyang;Wang Han;Zhao Jiajun;Li Hengchao;Zhu Yanmin;Yan Lingxiao;Wang Ruilong;Zhou Zijing;Wang Shuai;Liu Xianghong;Feng Yong;Li Jianfeng;Zhang Pingxiang","doi":"10.1109/TASC.2026.3652108","DOIUrl":"https://doi.org/10.1109/TASC.2026.3652108","url":null,"abstract":"This study optimized the structural design of NbTi superconducting wires using the analysis method combining finite element simulation with experiments. By adjusting the matrix material of the NbTi mono-filament billet, the overall deformation uniformity of the filaments was significantly improved. Considering both the optimal structural parameters obtained from simulations and the practical requirements of assembly feasibility and processing yield, the final design has been confirmed, with the matrix material of the NbTi mono-filament billet being Cu2Mn, and the spacing-to-diameter ratio (S/D) parameter and filament spacing of the NbTi multi-filament billet being 0.50 and 5.20 mm, respectively. Based on this design, NbTi multi-filament wire with 24 filaments and a copper-to-non-copper ratio of 7 was fabricated using conventional drawing and aging heat treatment processes. The wire was finally drawn to a diameter of 1.0 mm and subjected to superconducting performance tests. The results showed that, under 4.2 K and 4 T, the optimized design achieved a critical current density (<italic>J<sub>c</sub></i>) of 3804 A/mm<sup>2</sup>, representing an 11.8% improvement compared with 3400 A/mm<sup>2</sup> for the existing structure.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026580","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 : 2026-01-12DOI: 10.1109/TASC.2026.3652458
Matthew A. Koc;Jason Austermann;James Beall;Johannes Hubmayr;Joel N. Ullom;Michael Vissers;Jordan Wheeler
Development of high-speed, spatial-mapping spectrometers in the millimeter and far-infrared frequencies would enable entirely new research avenues in astronomy and cosmology. An “on-chip” spectrometer is one such technology that could enable Line Intensity Mapping. Recent work has shown the promise of high-speed imaging; however, a limiting factor is that many of these devices suffer from low optical efficiency. Here we present the fabrication of a metalized, Si waveguide filter-bank fabricated using deep reactive ion etching for use in millimeter spectroscopy. Our design simultaneously provides high-density pixel packing, high optical efficiency, high spectral resolution, and is readily compatible with simple and multiplexable MKID arrays. Gold plated test waveguide and filter show excellent match to simulations with a measured resolving power of 263 and a loss quality factor of 1116 at room temperature. The results show promise for extending the measurements to larger, multiwavelength designs.
{"title":"Development of Silicon Micromachined Waveguide Filter-Banks for On-Chip Spectrometers","authors":"Matthew A. Koc;Jason Austermann;James Beall;Johannes Hubmayr;Joel N. Ullom;Michael Vissers;Jordan Wheeler","doi":"10.1109/TASC.2026.3652458","DOIUrl":"https://doi.org/10.1109/TASC.2026.3652458","url":null,"abstract":"Development of high-speed, spatial-mapping spectrometers in the millimeter and far-infrared frequencies would enable entirely new research avenues in astronomy and cosmology. An “on-chip” spectrometer is one such technology that could enable Line Intensity Mapping. Recent work has shown the promise of high-speed imaging; however, a limiting factor is that many of these devices suffer from low optical efficiency. Here we present the fabrication of a metalized, Si waveguide filter-bank fabricated using deep reactive ion etching for use in millimeter spectroscopy. Our design simultaneously provides high-density pixel packing, high optical efficiency, high spectral resolution, and is readily compatible with simple and multiplexable MKID arrays. Gold plated test waveguide and filter show excellent match to simulations with a measured resolving power of 263 and a loss quality factor of 1116 at room temperature. The results show promise for extending the measurements to larger, multiwavelength designs.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 6","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146082223","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 : 2026-01-12DOI: 10.1109/TASC.2026.3653352
Wenhao Li;Zhenan Jiang;Difan Zhou;Chuanbing Cai
AC loss is a critical consideration in the design of high temperature superconducting (HTS) magnets. REBCO coils exhibit excellent current-carrying capabilities and are popular choices for applications such as fusion magnets and superconducting magnetic energy storage. However, there is currently a lack of research on the AC loss of REBCO coils under low temperature and high field conditions. A quantitative understanding of AC loss over wide temperature and magnetic field ranges is urgently needed. This paper investigates the dynamic resistance, magnetization loss, and total loss of a small double-pancake coil (DPC) based on a 2D axisymmetric H-formulation, at temperatures of 25 K, 50 K, and 77 K in perpendicular AC magnetic fields up to 5 T. The results show that at different temperatures, the dynamic resistance, total loss, and loss components of the DPC can all be scaled by its critical current, ${{I}_{{rm{c, coil}}}}$. This implies that results from the high-temperature, low-field regime can be used to predict the loss values in the low-temperature, high-field regime. In addition, these scaling behaviors are quantitatively explained by the extended equations. This study is expected to provide a valuable reference for the estimation of losses in high-field magnets.
{"title":"AC Loss Scaling of a REBCO Double-Pancake Coil Over Wide Temperature and Magnetic Field Regimes","authors":"Wenhao Li;Zhenan Jiang;Difan Zhou;Chuanbing Cai","doi":"10.1109/TASC.2026.3653352","DOIUrl":"https://doi.org/10.1109/TASC.2026.3653352","url":null,"abstract":"AC loss is a critical consideration in the design of high temperature superconducting (HTS) magnets. REBCO coils exhibit excellent current-carrying capabilities and are popular choices for applications such as fusion magnets and superconducting magnetic energy storage. However, there is currently a lack of research on the AC loss of REBCO coils under low temperature and high field conditions. A quantitative understanding of AC loss over wide temperature and magnetic field ranges is urgently needed. This paper investigates the dynamic resistance, magnetization loss, and total loss of a small double-pancake coil (DPC) based on a 2D axisymmetric <italic>H</i>-formulation, at temperatures of 25 K, 50 K, and 77 K in perpendicular AC magnetic fields up to 5 T. The results show that at different temperatures, the dynamic resistance, total loss, and loss components of the DPC can all be scaled by its critical current, <inline-formula><tex-math>${{I}_{{rm{c, coil}}}}$</tex-math></inline-formula>. This implies that results from the high-temperature, low-field regime can be used to predict the loss values in the low-temperature, high-field regime. In addition, these scaling behaviors are quantitatively explained by the extended equations. This study is expected to provide a valuable reference for the estimation of losses in high-field magnets.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-6"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026357","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 : 2026-01-12DOI: 10.1109/TASC.2026.3651413
Bin Feng;Jun Ma;Zhixuan Zhang;Hanlin Zhu;Huaqian Xiao;Xuezhi Luo;Yingjie Guan;Phil Mellor;Nick Simpson
When a perpendicular AC magnetic field is applied to type-II high-temperature superconductors carrying direct current (DC), a DC voltage will be induced, which is called the dynamic resistance effect. This work investigates the dynamic resistance of REBCO coated conductors under various operating conditions. An experimental platform was developed to measure the dynamic resistance of a high-temperature superconducting (HTS) tape under different DC current ratios, magnetic field amplitudes, and frequencies. A finite element model based on H-formulation was built using COMSOL Multiphysics to simulate the dynamic resistance behaviors. The simulation results agree well with experimental measurements results and empirical formulas, supporting the accuracy of the numerical model. The results indicate that dynamic resistance will increase with the rise of DC current and the amplitude of the applied AC magnetic field. Furthermore, we compared the dynamic resistance of multi-filamentary REBCO tapes with those of standard REBCO tapes. The multifilament design can effectively reduce dynamic resistance. These results will help design and develop low-loss HTS excitation windings for high temperature superconducting electrical machines.
{"title":"Experimental Study on the Dynamic Resistance of HTS REBCO Coated Conductor Tape","authors":"Bin Feng;Jun Ma;Zhixuan Zhang;Hanlin Zhu;Huaqian Xiao;Xuezhi Luo;Yingjie Guan;Phil Mellor;Nick Simpson","doi":"10.1109/TASC.2026.3651413","DOIUrl":"https://doi.org/10.1109/TASC.2026.3651413","url":null,"abstract":"When a perpendicular AC magnetic field is applied to type-II high-temperature superconductors carrying direct current (DC), a DC voltage will be induced, which is called the dynamic resistance effect. This work investigates the dynamic resistance of REBCO coated conductors under various operating conditions. An experimental platform was developed to measure the dynamic resistance of a high-temperature superconducting (HTS) tape under different DC current ratios, magnetic field amplitudes, and frequencies. A finite element model based on <italic>H</i>-formulation was built using COMSOL Multiphysics to simulate the dynamic resistance behaviors. The simulation results agree well with experimental measurements results and empirical formulas, supporting the accuracy of the numerical model. The results indicate that dynamic resistance will increase with the rise of DC current and the amplitude of the applied AC magnetic field. Furthermore, we compared the dynamic resistance of multi-filamentary REBCO tapes with those of standard REBCO tapes. The multifilament design can effectively reduce dynamic resistance. These results will help design and develop low-loss HTS excitation windings for high temperature superconducting electrical machines.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 5","pages":"1-7"},"PeriodicalIF":1.8,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026367","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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