Pub Date : 2025-10-20DOI: 10.1109/TASC.2025.3623985
Kazuya Yokoyama;S. Shiina;T. Oka
This paper proposes a new pulsed-field magnetization (PFM) technique that adds a new method—FAVS (First Applying a Very Small magnetic field)—immediately before the application of a pulsed field of the desired magnitude. Applying a low magnetic field causes a small amount of heat to be generated in areas with low properties of bulk material, which reduces the superconducting properties of those areas and weakens the magnetic shield. As a result, those areas become a path for the magnetic flux. By applying a magnetic field of the desired magnitude with no time allowed between the first and second application of the magnetic field, the magnetic flux can be expected to efficiently penetrate through the pathway and be trapped inside the sample. To confirm the effectiveness of the proposed method, PFM experiments were conducted using a ϕ60 mm × t20 mm GdBCO bulk. The temperature was set to 20 and 30 K, and a magnetic field of 5.0 or 5.4 T was applied immediately after the first application of 0.8 to 3.1 T. The trapped field distribution on the magnetic pole surface was measured after magnetization, and the total magnetic flux was calculated from the measured data. As a result, it was confirmed that applying a magnetic field of about 0.8 to 1.6 T for the first time improves the total magnetic flux as compared to applying a single pulsed field of 5.0 or 5.4 T, demonstrating the effectiveness of the proposed FAVS method. This method has the advantage of being versatile because it takes advantage of slight differences in sample characteristics.
{"title":"Proposal for a New Pulsed-Field Magnetization With the Addition of the FAVS Method (First Applying a Very Small Magnetic Field)","authors":"Kazuya Yokoyama;S. Shiina;T. Oka","doi":"10.1109/TASC.2025.3623985","DOIUrl":"https://doi.org/10.1109/TASC.2025.3623985","url":null,"abstract":"This paper proposes a new pulsed-field magnetization (PFM) technique that adds a new method—FAVS (First Applying a Very Small magnetic field)—immediately before the application of a pulsed field of the desired magnitude. Applying a low magnetic field causes a small amount of heat to be generated in areas with low properties of bulk material, which reduces the superconducting properties of those areas and weakens the magnetic shield. As a result, those areas become a path for the magnetic flux. By applying a magnetic field of the desired magnitude with no time allowed between the first and second application of the magnetic field, the magnetic flux can be expected to efficiently penetrate through the pathway and be trapped inside the sample. To confirm the effectiveness of the proposed method, PFM experiments were conducted using a ϕ60 mm × t20 mm GdBCO bulk. The temperature was set to 20 and 30 K, and a magnetic field of 5.0 or 5.4 T was applied immediately after the first application of 0.8 to 3.1 T. The trapped field distribution on the magnetic pole surface was measured after magnetization, and the total magnetic flux was calculated from the measured data. As a result, it was confirmed that applying a magnetic field of about 0.8 to 1.6 T for the first time improves the total magnetic flux as compared to applying a single pulsed field of 5.0 or 5.4 T, demonstrating the effectiveness of the proposed FAVS method. This method has the advantage of being versatile because it takes advantage of slight differences in sample characteristics.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 3","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145456032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-20DOI: 10.1109/TASC.2025.3623195
Mustafa Altay Karamuftuoglu;Beyza Zeynep Ucpinar;Sasan Razmkhah;Massoud Pedram
We present a scalable, asynchronous up-down counter architecture implemented using single-flux quantum logic to enable efficient state management in superconductor digital systems. The proposed design eliminates the reliance on clocked storage elements by introducing the Josephson trapping line. This bidirectional pulse-trapping structure enables persistent, nonvolatile state storage without clocking. The counter integrates $alpha$-cells with a splitter element to make bidirectional data propagation possible and support multifanout connectivity. The design supports increment, decrement, and read operations and includes a control unit that guarantees correct output behavior across all valid state transitions. Circuit-level simulations based on SPICE models demonstrate robust bidirectional functionality across a 3-bit state range [−4 to +4] at an operating frequency of 4 GHz. The proposed counter offers a modular and scalable solution suitable for integration into larger superconducting systems targeting quantum computing, neuromorphic processing, and cryogenic sensing applications.
{"title":"Scalable Asynchronous Single Flux Quantum Up-Down Counter Using Josephson Trapping Lines and $alpha$-Cells","authors":"Mustafa Altay Karamuftuoglu;Beyza Zeynep Ucpinar;Sasan Razmkhah;Massoud Pedram","doi":"10.1109/TASC.2025.3623195","DOIUrl":"https://doi.org/10.1109/TASC.2025.3623195","url":null,"abstract":"We present a scalable, asynchronous up-down counter architecture implemented using single-flux quantum logic to enable efficient state management in superconductor digital systems. The proposed design eliminates the reliance on clocked storage elements by introducing the Josephson trapping line. This bidirectional pulse-trapping structure enables persistent, nonvolatile state storage without clocking. The counter integrates <inline-formula><tex-math>$alpha$</tex-math></inline-formula>-cells with a splitter element to make bidirectional data propagation possible and support multifanout connectivity. The design supports increment, decrement, and read operations and includes a control unit that guarantees correct output behavior across all valid state transitions. Circuit-level simulations based on SPICE models demonstrate robust bidirectional functionality across a 3-bit state range [−4 to +4] at an operating frequency of 4 GHz. The proposed counter offers a modular and scalable solution suitable for integration into larger superconducting systems targeting quantum computing, neuromorphic processing, and cryogenic sensing applications.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 9","pages":"1-8"},"PeriodicalIF":1.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145510210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work we measured the magnetization and AC loss of two kinds of ReBCO cables, CORC and Tape Stack. We compared these cables both “as received” as well as after a soldering meant to encourage the presence of coupling current loss. Our objective was to separate out the hysteretic and coupling loss components observed in cables exposed to time changing applied external fields and then and describe them. We performed two types of measurements. Our first was a DC susceptibility measurement at 4.2 K and ramp rates of 5–10 T/min up to 30 T, as relevant to High Energy Physics accelerator magnets. The second was a boiloff calorimetric measurement at 77 K, in an applied field of amplitude 0.56 T at frequencies up to 120 Hz. These latter measurements were used because they had much higher dB/dt excitations, and would be expected to bring out any coupling current loss clearly. DC susceptibility measurements at our modest ramp rates showed no evidence of coupling currents in either of the CORC or the tape stack cables. However, the higher dB/dt measurements of the calorimeter showed modest coupling loss components in both conductors. The results are compared to simple models for coupling currents and current path modified effective resistivities in these composites.
{"title":"Measurement and Analysis of External Field Losses in CORC and Tape Stack Conductors Including Hysteretic and Coupling Loss","authors":"M.D. Sumption;T. Garg;C. Ebbing;T. Haugan;E.W. Collings","doi":"10.1109/TASC.2025.3622547","DOIUrl":"https://doi.org/10.1109/TASC.2025.3622547","url":null,"abstract":"In this work we measured the magnetization and AC loss of two kinds of ReBCO cables, CORC and Tape Stack. We compared these cables both “as received” as well as after a soldering meant to encourage the presence of coupling current loss. Our objective was to separate out the hysteretic and coupling loss components observed in cables exposed to time changing applied external fields and then and describe them. We performed two types of measurements. Our first was a DC susceptibility measurement at 4.2 K and ramp rates of 5–10 T/min up to 30 T, as relevant to High Energy Physics accelerator magnets. The second was a boiloff calorimetric measurement at 77 K, in an applied field of amplitude 0.56 T at frequencies up to 120 Hz. These latter measurements were used because they had much higher <italic>dB/dt</i> excitations, and would be expected to bring out any coupling current loss clearly. DC susceptibility measurements at our modest ramp rates showed no evidence of coupling currents in either of the CORC or the tape stack cables. However, the higher <italic>dB/dt</i> measurements of the calorimeter showed modest coupling loss components in both conductors. The results are compared to simple models for coupling currents and current path modified effective resistivities in these composites.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 3","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145455827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-20DOI: 10.1109/TASC.2025.3623588
Seiya Tarumizu;Ryota Ishii;Osuke Miura
In this study, we aimed to enhance the critical current density (JC)–magnetic field (B) properties of GdBa2Cu3O7-δ (Gd123) high-temperature superconducting thin films by co-doping Gd2CuO4-x (Gd214) and Sm2CuO4-x (Sm214) as artificial pinning centers (APCs) to promote the refinement and dispersion of the APCs. The Gd123 films were fabricated by the fluorine-free metal-organic decomposition (FF-MOD) method, and co-doped films with total volume fractions of 2, 3, and 4 vol% were compared with those doped with a single APC. X-ray diffraction (XRD) revealed that the co-doped films maintained high c-axis orientation and crystallinity, and analysis of the full width at half maximum (FWHM) suggested that co-doping suppressed APC crystal coarsening compared to single-doped films. The co-doped film with 3 vol% of APC exhibited maximum JC values of 2.603 MA/cm2 at 3 T, 4.2 K and 0.871 MA/cm2 at 3 T, 30 K corresponding to improvements of approximately 1.9 times over the non-doped film and 1.4 times over the Gd214-doped film. These results indicate that co-doping with two kinds of RE2CuO4-x (RE = Gd, Sm) compounds having different lattice constants promotes APC refinement and dispersion, thereby enhancing the flux-pinning effect.
{"title":"Co-Doping Strategy of RE2CuO4-x (RE = Gd, Sm) Artificial Pinning Centers for Enhancing Critical Current Density in FF-MOD GdBa2Cu3O7-δFilms","authors":"Seiya Tarumizu;Ryota Ishii;Osuke Miura","doi":"10.1109/TASC.2025.3623588","DOIUrl":"https://doi.org/10.1109/TASC.2025.3623588","url":null,"abstract":"In this study, we aimed to enhance the critical current density (<italic>J</i><sub>C</sub>)–magnetic field (B) properties of GdBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> (Gd123) high-temperature superconducting thin films by co-doping Gd<sub>2</sub>CuO<sub>4-x</sub> (Gd214) and Sm<sub>2</sub>CuO<sub>4-x</sub> (Sm214) as artificial pinning centers (APCs) to promote the refinement and dispersion of the APCs. The Gd123 films were fabricated by the fluorine-free metal-organic decomposition (FF-MOD) method, and co-doped films with total volume fractions of 2, 3, and 4 vol% were compared with those doped with a single APC. X-ray diffraction (XRD) revealed that the co-doped films maintained high c-axis orientation and crystallinity, and analysis of the full width at half maximum (FWHM) suggested that co-doping suppressed APC crystal coarsening compared to single-doped films. The co-doped film with 3 vol% of APC exhibited maximum <italic>J</i><sub>C</sub> values of 2.603 MA/cm<sup>2</sup> at 3 T, 4.2 K and 0.871 MA/cm<sup>2</sup> at 3 T, 30 K corresponding to improvements of approximately 1.9 times over the non-doped film and 1.4 times over the Gd214-doped film. These results indicate that co-doping with two kinds of <italic>RE</i><sub>2</sub>CuO<sub>4-x</sub> (<italic>RE</i> = Gd, Sm) compounds having different lattice constants promotes APC refinement and dispersion, thereby enhancing the flux-pinning effect.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 3","pages":"1-4"},"PeriodicalIF":1.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145455986","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 paper describes the design, construction, and test results of the conduction cooling-type HTS module testing system. The constructed conduction cooling-type HTS module testing system uses two two-stage GM cryo-coolers as the primary cooling source. The 1st stage cold head of the cryo-cooler is responsible for cooling the metal current leads and radiation shields, and the bottom side of the HTS leads. The 2nd stage temperature section is responsible for cooling the Oxygen Free Copper (OFCu) cooling plate and top-side of the HTS leads. The HTS test module is cooled through the OFCu cooling plate. The HTS module testing system controls the temperature of the HTS module under testing from 4 K to 30 K and can supply an operating current of up to 800 A. All operating parameters of the HTS module test system are controlled and recorded using a Data Acquisition (DAQ) system based on LabVIEW.
{"title":"Design Construction and Operation of a Conduction Cooling-Type HTS Module Testing System","authors":"Kwangmin Kim;Erick Arroyo;Kurtis Cantrell;John Rogers","doi":"10.1109/TASC.2025.3622553","DOIUrl":"https://doi.org/10.1109/TASC.2025.3622553","url":null,"abstract":"This paper describes the design, construction, and test results of the conduction cooling-type HTS module testing system. The constructed conduction cooling-type HTS module testing system uses two two-stage GM cryo-coolers as the primary cooling source. The 1st stage cold head of the cryo-cooler is responsible for cooling the metal current leads and radiation shields, and the bottom side of the HTS leads. The 2nd stage temperature section is responsible for cooling the Oxygen Free Copper (OFCu) cooling plate and top-side of the HTS leads. The HTS test module is cooled through the OFCu cooling plate. The HTS module testing system controls the temperature of the HTS module under testing from 4 K to 30 K and can supply an operating current of up to 800 A. All operating parameters of the HTS module test system are controlled and recorded using a Data Acquisition (DAQ) system based on LabVIEW.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 3","pages":"1-4"},"PeriodicalIF":1.8,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145456014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-16DOI: 10.1109/TASC.2025.3622549
Heonhwan Kim;Sinhye Na;Yangjin Jung;Young-Kyoung Kim;Sanghyeun Je
In developing high-Jc Nb3Sn superconducting wires, optimizing superconducting properties along with mechanical and thermal stability is critical (Godeke, 2006), (Sumption et al., 2013). This study investigates a SnCuTi ternary alloy spacer for Distributed Barrier Strands (DBS) (Je et al., 2025), designed to supply Sn, strengthen the internal alloy for improved drawability, and reduce void formation during heat treatment, thereby enhancing thermal conductivity from the filament region. The alloy was fabricated via powder metallurgy to ensure uniform particle distribution below 2 μm, enabling the successful drawing of over 200 meters of wire without breakage. This length was determined by the shorter billet size assembled for experimental purposes, not by wire fracture. Compared with SnTi strands, the SnCuTi strand exhibited equally good workability and stable drawability. Despite a slight reduction in Ti and Sn due to 5 wt% Cu additions, the wires exhibited comparable critical current (Ic) values to those using conventional SnTi spacers. Moreover, the Quench Voltage (QV) exceeded 50 μV at 12 T and 16 T, indicating improved thermal stability (Ghosh et al., 2011). Post-heat-treatment analysis revealed a more uniform Nb3Sn microstructure with fewer voids. Preliminary mechanical evaluations also suggest increased hardness and potentially improved tensile strength, though further validation is ongoing. These results highlight SnCuTi as a promising spacer alloy for advanced high-Jc Nb3Sn strands.
在开发高jc Nb3Sn超导导线时，优化超导性能以及机械和热稳定性至关重要（Godeke, 2006）， （Sumption et al., 2013）。本研究研究了一种用于分布式屏障股（DBS）的SnCuTi三元合金隔离剂（Je et al., 2025），旨在提供Sn，强化内部合金以提高拉伸性，并减少热处理过程中的空洞形成，从而提高长丝区域的导热性。该合金采用粉末冶金技术制备，确保了2 μm以下的颗粒分布均匀，能够成功拉丝200米以上而不断裂。这个长度是由为实验目的组装的较短的坯料尺寸决定的，而不是由钢丝断裂决定的。与SnTi链相比，SnCuTi链具有良好的可加工性和稳定的拉伸性。尽管由于添加了5wt %的Cu，导致Ti和Sn的含量略有降低，但与使用传统SnTi间隔片的导线相比，该导线的临界电流（Ic）值相当。此外，在12 T和16 T时，淬灭电压（QV）超过50 μV，表明热稳定性得到改善（Ghosh et al., 2011）。热处理后的分析表明，Nb3Sn的显微组织更均匀，空洞更少。初步的力学评估也表明硬度和抗拉强度有所提高，但进一步的验证仍在进行中。这些结果表明SnCuTi是一种很有前途的用于高级高jc Nb3Sn链的间隔合金。
{"title":"Diffusion Behavior and Investigation of the Properties of High Jc Nb3Sn Wires With SnCuTi Alloy Application","authors":"Heonhwan Kim;Sinhye Na;Yangjin Jung;Young-Kyoung Kim;Sanghyeun Je","doi":"10.1109/TASC.2025.3622549","DOIUrl":"https://doi.org/10.1109/TASC.2025.3622549","url":null,"abstract":"In developing high-<italic>J<sub>c</sub></i> Nb<sub>3</sub>Sn superconducting wires, optimizing superconducting properties along with mechanical and thermal stability is critical (Godeke, 2006), (Sumption et al., 2013). This study investigates a SnCuTi ternary alloy spacer for Distributed Barrier Strands (DBS) (Je et al., 2025), designed to supply Sn, strengthen the internal alloy for improved drawability, and reduce void formation during heat treatment, thereby enhancing thermal conductivity from the filament region. The alloy was fabricated via powder metallurgy to ensure uniform particle distribution below 2 μm, enabling the successful drawing of over 200 meters of wire without breakage. This length was determined by the shorter billet size assembled for experimental purposes, not by wire fracture. Compared with SnTi strands, the SnCuTi strand exhibited equally good workability and stable drawability. Despite a slight reduction in Ti and Sn due to 5 wt% Cu additions, the wires exhibited comparable critical current (<italic>I<sub>c</sub></i>) values to those using conventional SnTi spacers. Moreover, the Quench Voltage (QV) exceeded 50 μV at 12 T and 16 T, indicating improved thermal stability (Ghosh et al., 2011). Post-heat-treatment analysis revealed a more uniform Nb<sub>3</sub>Sn microstructure with fewer voids. Preliminary mechanical evaluations also suggest increased hardness and potentially improved tensile strength, though further validation is ongoing. These results highlight SnCuTi as a promising spacer alloy for advanced high-<italic>J<sub>c</sub></i> Nb<sub>3</sub>Sn strands.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 3","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145455905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-14DOI: 10.1109/TASC.2025.3620785
Jun Lu;Jeremy Levitan;Yu Suetomi;Iain Dixon;Jan Jaroszynski
REBCO coated conductor has great potential to be used in ultra-high field magnets. Commercial REBCO tapes are strong in the longitudinal direction but prone to delamination by tensile stress in the thickness direction. For high field magnet applications, it is crucial to characterize delamination strength of REBCO conductor and better manage the electromagnetic stress. In this work, the electromagnetic stress in high magnetic fields by screening current is used to study the delamination behavior of commercial REBCO tapes. Screening currents are induced in REBCO by either ramping field or rotating sample in magnetic fields up to 35 T. The results of delamination strength are presented. The prospect of using this method for quality assurance in large magnet projects is discussed.
{"title":"REBCO Delamination by Electromagnetic Stress due to Screening Current in Magnetic Field","authors":"Jun Lu;Jeremy Levitan;Yu Suetomi;Iain Dixon;Jan Jaroszynski","doi":"10.1109/TASC.2025.3620785","DOIUrl":"https://doi.org/10.1109/TASC.2025.3620785","url":null,"abstract":"REBCO coated conductor has great potential to be used in ultra-high field magnets. Commercial REBCO tapes are strong in the longitudinal direction but prone to delamination by tensile stress in the thickness direction. For high field magnet applications, it is crucial to characterize delamination strength of REBCO conductor and better manage the electromagnetic stress. In this work, the electromagnetic stress in high magnetic fields by screening current is used to study the delamination behavior of commercial REBCO tapes. Screening currents are induced in REBCO by either ramping field or rotating sample in magnetic fields up to 35 T. The results of delamination strength are presented. The prospect of using this method for quality assurance in large magnet projects is discussed.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 3","pages":"1-4"},"PeriodicalIF":1.8,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145455903","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}
MgB2 is one of the practical superconductors that has been widely studied over the past two decades. The internal magnesium diffusion (IMD) method serves as a promising method because it can enhance the grain connectivity of MgB2 phase and thereby improve the superconducting current of MgB2 wires. Here, we present the fabrication of 30-filament MgB2 wires using the IMD method. The wires have a diameter of 1.00 mm and length more than 1 km. The filling factor of MgB2 is around 10% and the superconducting current ${{I}_c}$(4.2K, 3T) reaches 650 A. The highest layer-superconducting current density ${{J}_c}$(4.2K, 3T) is 8.9 × 103 A mm−2 and engineering superconducting current density ${{J}_e}$ (4.2K, 3T) is 8.3 × 102 A mm−2. Meanwhile, the percentage of copper in the MgB2 wire is 28% and the residual resistivity ratio RRR(300K/40K) is 60. This can enhance the thermal stability for the low-temperature application. All of these indicate the great potential for the application of our MgB2 wires in the future.
MgB2是在过去二十年中被广泛研究的实用超导体之一。镁内扩散（IMD）法可以增强MgB2相的晶粒连通性，从而提高MgB2导线的超导电流，是一种很有前途的方法。在这里，我们提出了用IMD方法制造30丝的MgB2丝。电线直径为1.00毫米，长度超过1公里。MgB2填充系数约为10%，超导电流${{I}_c}$（4.2K, 3T）达到650 A。最高超导层电流密度${{J}_c}$（4.2K, 3T）为8.9 × 103 A mm−2，工程超导层电流密度${{J}_e}$ （4.2K, 3T）为8.3 × 102 A mm−2。同时，MgB2导线中铜的含量为28%，剩余电阻率RRR（300K/40K）为60。这可以提高低温应用的热稳定性。所有这些都表明我们的MgB2线在未来的应用潜力巨大。
{"title":"Fabrication of km-Class 30-Filament MgB2 Wires by the Internal Magnesium Diffusion Method","authors":"Wei Xie;Qiang Guo;Mingjiang Wang;Wenlong Yuan;Yanming Zhu;Bo Wu;Guo Yan;Xianghong Liu;Yong Feng;Jianfeng Li;Pingxiang Zhang","doi":"10.1109/TASC.2025.3620767","DOIUrl":"https://doi.org/10.1109/TASC.2025.3620767","url":null,"abstract":"MgB<sub>2</sub> is one of the practical superconductors that has been widely studied over the past two decades. The internal magnesium diffusion (IMD) method serves as a promising method because it can enhance the grain connectivity of MgB<sub>2</sub> phase and thereby improve the superconducting current of MgB<sub>2</sub> wires. Here, we present the fabrication of 30-filament MgB<sub>2</sub> wires using the IMD method. The wires have a diameter of 1.00 mm and length more than 1 km. The filling factor of MgB<sub>2</sub> is around 10% and the superconducting current <inline-formula><tex-math>${{I}_c}$</tex-math></inline-formula>(4.2K, 3T) reaches 650 A. The highest layer-superconducting current density <inline-formula><tex-math>${{J}_c}$</tex-math></inline-formula>(4.2K, 3T) is 8.9 × 10<sup>3</sup> A mm<sup>−2</sup> and engineering superconducting current density <inline-formula><tex-math>${{J}_e}$</tex-math></inline-formula> (4.2K, 3T) is 8.3 × 10<sup>2</sup> A mm<sup>−2</sup>. Meanwhile, the percentage of copper in the MgB<sub>2</sub> wire is 28% and the residual resistivity ratio RRR(300K/40K) is 60. This can enhance the thermal stability for the low-temperature application. All of these indicate the great potential for the application of our MgB<sub>2</sub> wires in the future.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 3","pages":"1-4"},"PeriodicalIF":1.8,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145455829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-14DOI: 10.1109/TASC.2025.3621176
Zongwei Liu;Mingyang Wang;Minhui Li;Haolan Chen;Xueliang Wang;Zhijian Jin
REBCO magnets generate unavoidable screening currents during operation. The screening current effect causes severe damage to both the structural integrity and electromagnetic performance of the coil. Specifically, the screening current induced field (SCIF) leads to distortion and drift in the central magnetic field of the coil. The multifilamentary REBCO stack is a viable structure for suppressing SCIF. However, its complex internal striated architecture incurs high manufacturing challenges and costs. Based on the finite element models proposed with T-A formulation solving the vector potential of current and magnetic, the effect of stacking process and multifilamentary structure are firstly discussed in this research. Then we analyzed the influence of groove layouts on SCIF of multifilamentary stacks. The relevant results show that grooves in high current density regions can interrupt screening current loop and show superior suppressing effect. However, complex groove layout shows significant impact on the distribution of high current density areas under external magnetic field. In this study, we uncovered a phenomenon that adjacent grooves in multifilamentary HTS stack can exhibit an electromagnetic coupling effect. This effect may affect the optimization of groove layout for suppression effect on SCIF and manufacturing costs.
{"title":"Influence of Groove Layout on Screening Current Induced Field in Multifilamentary REBCO Stacks","authors":"Zongwei Liu;Mingyang Wang;Minhui Li;Haolan Chen;Xueliang Wang;Zhijian Jin","doi":"10.1109/TASC.2025.3621176","DOIUrl":"https://doi.org/10.1109/TASC.2025.3621176","url":null,"abstract":"REBCO magnets generate unavoidable screening currents during operation. The screening current effect causes severe damage to both the structural integrity and electromagnetic performance of the coil. Specifically, the screening current induced field (SCIF) leads to distortion and drift in the central magnetic field of the coil. The multifilamentary REBCO stack is a viable structure for suppressing SCIF. However, its complex internal striated architecture incurs high manufacturing challenges and costs. Based on the finite element models proposed with T-A formulation solving the vector potential of current and magnetic, the effect of stacking process and multifilamentary structure are firstly discussed in this research. Then we analyzed the influence of groove layouts on SCIF of multifilamentary stacks. The relevant results show that grooves in high current density regions can interrupt screening current loop and show superior suppressing effect. However, complex groove layout shows significant impact on the distribution of high current density areas under external magnetic field. In this study, we uncovered a phenomenon that adjacent grooves in multifilamentary HTS stack can exhibit an electromagnetic coupling effect. This effect may affect the optimization of groove layout for suppression effect on SCIF and manufacturing costs.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 3","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145352119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-10DOI: 10.1109/TASC.2025.3617918
Yubin Kim;Jeongmin Mun;Jangdon Kim;Jiho Son;Seokho Kim
Multi-Layer Insulation (MLI) is essential for reducing radiative heat transfer in cryogenic systems, particularly in hydrogen-based superconducting applications operating at temperatures below 30 K. However, conventional empirical models such as the Lockheed equation often misestimate thermal loads due to variations in stacking density and material configurations. In this study, we experimentally evaluated MLI performance by varying stacking densities within a confined 5 mm space, using a conduction-based setup with a two-stage GM cryocooler. The results reveal the existence of an optimal stacking density where thermal insulation is maximized. Beyond this point, excessive stacking leads to performance degradation due to increased solid conduction between layers. These findings underscore the need to refine classical models to account for density- and spacer-dependent behavior in practical applications.
{"title":"Study on the Optimization of MLI Stacking Density in the Limited Gap of Superconducting Rotating Machinery","authors":"Yubin Kim;Jeongmin Mun;Jangdon Kim;Jiho Son;Seokho Kim","doi":"10.1109/TASC.2025.3617918","DOIUrl":"https://doi.org/10.1109/TASC.2025.3617918","url":null,"abstract":"Multi-Layer Insulation (MLI) is essential for reducing radiative heat transfer in cryogenic systems, particularly in hydrogen-based superconducting applications operating at temperatures below 30 K. However, conventional empirical models such as the Lockheed equation often misestimate thermal loads due to variations in stacking density and material configurations. In this study, we experimentally evaluated MLI performance by varying stacking densities within a confined 5 mm space, using a conduction-based setup with a two-stage GM cryocooler. The results reveal the existence of an optimal stacking density where thermal insulation is maximized. Beyond this point, excessive stacking leads to performance degradation due to increased solid conduction between layers. These findings underscore the need to refine classical models to account for density- and spacer-dependent behavior in practical applications.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"36 3","pages":"1-5"},"PeriodicalIF":1.8,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145405356","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：