Flexible PCB quench antennas have been very useful in providing high-quality high-resolution data in low temperature superconducting magnet tests. Similar multi-sensor arrays have been employed recently to cover a high temperature superconductor magnet tested at FNAL. In the present work, data taking conditions and magnet features to support the analysis framework are discussed. Then observations made during complete magnet powering cycles are described and analysis of quench antenna data are presented. Based on results, improvements to instrumentation and data taking are debated. Views on the future of flexible quench antenna sensors for HTS magnet diagnostics and operational support are shared.
{"title":"Application of Flex-QA Arrays in HTS Magnet Testing","authors":"Stoyan Stoynev;Vadim V. Kashikhin;Sean Cohan;Joe DiMarco;Oliver Kiemschies;Steve Krave;Nghia Mai;Umesh Sambangi;Venkat Selvamanickam","doi":"10.1109/TASC.2025.3534179","DOIUrl":"https://doi.org/10.1109/TASC.2025.3534179","url":null,"abstract":"Flexible PCB quench antennas have been very useful in providing high-quality high-resolution data in low temperature superconducting magnet tests. Similar multi-sensor arrays have been employed recently to cover a high temperature superconductor magnet tested at FNAL. In the present work, data taking conditions and magnet features to support the analysis framework are discussed. Then observations made during complete magnet powering cycles are described and analysis of quench antenna data are presented. Based on results, improvements to instrumentation and data taking are debated. Views on the future of flexible quench antenna sensors for HTS magnet diagnostics and operational support are shared.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The high-temperature superconducting (HTS) tape can bring significant improvement to the performance of electric vertical take-off and landing (eVTOL) aircraft's propulsion motor. However, it requires cryogenic environment to function normally, which causes a huge amount of cryogenic loss. Meanwhile, the motor outputs different levels of torque during a flight mission and the difference can be up to tens of time. In this paper, permanent magnet auxiliary excitation structure (PMAES) is investigated for eVTOL aircraft's propulsion motor. In the proposed design, superconducting magnet (SM) is utilized as main excitation unit to achieve a higher torque density while permanent magnet (PM) is adopted to form PMAES. SM and PMAES operate during machine's high-load condition, and SM is shut off during the low-load condition to eliminate loss caused by the operation of SM's current lead. With such a structure, the HTS material can be utilized to extract the optimal performance of the machine while reducing the cryogenic losses when possible. Four topologies with PMAES are studied, and it is found axial flux superconducting machine (AFSCM) with radial permanent magnet auxiliary excitation structure (RPMAES) has the best performance and ability to significantly reduces the energy consumption of the motor during a complete flight mission.
{"title":"A Novel Topology With the Combination of Superconducting Magnet and Permanent Magnet for the Propulsion Motor of eVTOL Aircraft","authors":"Xinhong Gao;Yuanzhi Zhang;Haiyang Fang;Dawei Li;Yi Cheng;Ronghai Qu","doi":"10.1109/TASC.2025.3537066","DOIUrl":"https://doi.org/10.1109/TASC.2025.3537066","url":null,"abstract":"The high-temperature superconducting (HTS) tape can bring significant improvement to the performance of electric vertical take-off and landing (eVTOL) aircraft's propulsion motor. However, it requires cryogenic environment to function normally, which causes a huge amount of cryogenic loss. Meanwhile, the motor outputs different levels of torque during a flight mission and the difference can be up to tens of time. In this paper, permanent magnet auxiliary excitation structure (PMAES) is investigated for eVTOL aircraft's propulsion motor. In the proposed design, superconducting magnet (SM) is utilized as main excitation unit to achieve a higher torque density while permanent magnet (PM) is adopted to form PMAES. SM and PMAES operate during machine's high-load condition, and SM is shut off during the low-load condition to eliminate loss caused by the operation of SM's current lead. With such a structure, the HTS material can be utilized to extract the optimal performance of the machine while reducing the cryogenic losses when possible. Four topologies with PMAES are studied, and it is found axial flux superconducting machine (AFSCM) with radial permanent magnet auxiliary excitation structure (RPMAES) has the best performance and ability to significantly reduces the energy consumption of the motor during a complete flight mission.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-04DOI: 10.1109/TASC.2025.3538517
Jeongwoo Seo;Jiyoung Yoon;Seungyong Hahn;Jonghoon Yoon;Wonseok Jang;Seokho Kim;Kihwan Kim;Kideok Sim;Jongho Choi;Jingeun Kim;Byung Ho Min;Young Jin Hwang
This article presents a partial-depth impregnation method using electrically conductive epoxy composites in high-temperature superconductor (HTS) coils. In a previous study, we proposed a wet winding technique using electrically-conductive epoxy composites to control the contact resistance of no-insulation (NI) HTS coils. In that method, the epoxy composites were applied across the entire contact surface between winding turns, allowing the contact resistance to be controlled by adjusting the mixing ratio of electrically-conductive powder. However, this approach led to significant current degradation due to delamination caused by thermal contraction mismatch between the epoxy composites and the HTS tape. The partial-depth impregnation method addresses this issue by allowing the epoxy composites to penetrate only partway between winding turns, thereby minimizing critical current degradation. In this study, HTS coils were dry-wound with 4.1 mm-wide HTS tape and insulated with 3 mm-wide polyimide tape on each turn. By applying the electrically-conductive epoxy composites to the edge of the HTS coil, the epoxy composite penetrated to a depth of 1.1 mm. This configuration allows the current to bypass through the edge of the insulated coil, providing self-protection characteristics. Additionally, the contact resistance can be controlled by adjusting the mixing ratio of the electrically-conductive powders. The feasibility of the proposed impregnation technique was demonstrated through over-current and sudden-discharge tests on the partial-depth impregnated coils with different mixing ratios of electrically conductive powders.
{"title":"Application of Electrically-Conductive Epoxy in No-Insulation Coils for Controlling Contact Resistance","authors":"Jeongwoo Seo;Jiyoung Yoon;Seungyong Hahn;Jonghoon Yoon;Wonseok Jang;Seokho Kim;Kihwan Kim;Kideok Sim;Jongho Choi;Jingeun Kim;Byung Ho Min;Young Jin Hwang","doi":"10.1109/TASC.2025.3538517","DOIUrl":"https://doi.org/10.1109/TASC.2025.3538517","url":null,"abstract":"This article presents a partial-depth impregnation method using electrically conductive epoxy composites in high-temperature superconductor (HTS) coils. In a previous study, we proposed a wet winding technique using electrically-conductive epoxy composites to control the contact resistance of no-insulation (NI) HTS coils. In that method, the epoxy composites were applied across the entire contact surface between winding turns, allowing the contact resistance to be controlled by adjusting the mixing ratio of electrically-conductive powder. However, this approach led to significant current degradation due to delamination caused by thermal contraction mismatch between the epoxy composites and the HTS tape. The partial-depth impregnation method addresses this issue by allowing the epoxy composites to penetrate only partway between winding turns, thereby minimizing critical current degradation. In this study, HTS coils were dry-wound with 4.1 mm-wide HTS tape and insulated with 3 mm-wide polyimide tape on each turn. By applying the electrically-conductive epoxy composites to the edge of the HTS coil, the epoxy composite penetrated to a depth of 1.1 mm. This configuration allows the current to bypass through the edge of the insulated coil, providing self-protection characteristics. Additionally, the contact resistance can be controlled by adjusting the mixing ratio of the electrically-conductive powders. The feasibility of the proposed impregnation technique was demonstrated through over-current and sudden-discharge tests on the partial-depth impregnated coils with different mixing ratios of electrically conductive powders.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430552","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 primarily reports on the fabrication and testing results of a 16 T all-REBCO no-insulation (NI) magnet. The magnet is composed of 28 stacked double pancake (DP) coils, with a winding inner diameter of 112 mm and a cold bore diameter of 100 mm. Due to the length limitations of the REBCO tape, joints are required within the DP coils. The maximum stress on the coils reaches 399 MPa. The top and bottom DP coil of the magnet are wound with two REBCO tapes simultaneously to improve the electromagnetic margin. To prevent degradation of the joints under stress, we have designed the joint to be located in the low-stress regions on the outer turns of the coils. The magnet contains a total of 76 joints, of which 49 are lap joints located internally within the DP coils, while 27 are splice joints situated between the DP coils. Finally, the magnet was tested under 4.2 K conditions. When the operating current (Iop) reached 252.3 A, the measured central magnetic field of the magnet reached 16.2 T and maintained stable operation for 30 minutes.
{"title":"Design, Fabrication, and Test of a 16 T 100 mm all-REBCO Superconducting Magnet","authors":"Shuai Hu;Huajun Liu;Fang Liu;Zhaoran Wang;Wenzhe Hong;Shuowei Gao;Liang Guo;Hongjun Ma;Shenquan Xue;Shuqing Zhang;Dongshen Yang;Liangjun Shao;Timing Qu;Jiamin Zhu;Xintao Zhang","doi":"10.1109/TASC.2025.3530331","DOIUrl":"https://doi.org/10.1109/TASC.2025.3530331","url":null,"abstract":"This paper primarily reports on the fabrication and testing results of a 16 T all-REBCO no-insulation (NI) magnet. The magnet is composed of 28 stacked double pancake (DP) coils, with a winding inner diameter of 112 mm and a cold bore diameter of 100 mm. Due to the length limitations of the REBCO tape, joints are required within the DP coils. The maximum stress on the coils reaches 399 MPa. The top and bottom DP coil of the magnet are wound with two REBCO tapes simultaneously to improve the electromagnetic margin. To prevent degradation of the joints under stress, we have designed the joint to be located in the low-stress regions on the outer turns of the coils. The magnet contains a total of 76 joints, of which 49 are lap joints located internally within the DP coils, while 27 are splice joints situated between the DP coils. Finally, the magnet was tested under 4.2 K conditions. When the operating current (<italic>I<sub>op</sub></i>) reached 252.3 A, the measured central magnetic field of the magnet reached 16.2 T and maintained stable operation for 30 minutes.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143360971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The upcoming enhancement for the Large Hadron Collider (LHC), known as the High-Luminosity LHC, is designed to increase the collision rate of the accelerator by a factor of ten. This ambitious objective entails the replacement of the dipole and quadrupole magnets situated before and after the interaction region of the ATLAS and CMS experiments. Among these, the separation-recombination dipole MBRD (Main Bending Recombination Dipole, also known as D2) stands out, featuring a target integral magnetic field of 35 Tm within a double aperture of 105 mm. Following the successful testing of the full-length prototype MBRDP in 2022–23, the first magnet in the series, MBRD1, has been finalized, delivered to CERN in October 2023. During the acceptance tests at CERN, a damage in one quench heater wire was found and the magnet was sent back to ASG Superconductors for repairing in July 2024. The foreseen delivery date of the fixed MBRD1 is at the end of October 2024. The MBRD2 has been built in ASG, delivered to CERN in April 2024 and accepted in June after all the compliance tests. This magnet is now under integration in the cold mass with the multipole correctors and will be cold tested in January 2025. While the other four magnets of the series production are being built in industry and the end of the construction phase is expected in January 2026. Due to significant cross-talk between the two apertures and the high sensitivity of the field to the as-built size of the coils, a revised cross-section for the series magnets has been devised compared to the prototype. For each coil, a dedicated and optimized insulation scheme has been identified to achieve the most favorable and consistently reproducible field harmonics, guided by measurements performed on the prototype at cold and on the series at room temperature (RT). This contribution provides an update on the construction progress at ASG Superconductors, details the enhancements made to the coil cross-section to meet the stringent requirements for field quality in this dipole, and discusses the current status of testing for MBRD2 at CERN.
{"title":"Design Enhancements of the MBRD Magnet for the High Luminosity LHC: The Ongoing Status of the Series Production","authors":"A. Pampaloni;S. Angius;A. Bersani;B. Caiffi;P. Fabbricatore;S. Farinon;L. Fiscarelli;A. Foussat;F. Levi;D. Novelli;E. Todesco;N. Valle;A. Verardo","doi":"10.1109/TASC.2025.3537598","DOIUrl":"https://doi.org/10.1109/TASC.2025.3537598","url":null,"abstract":"The upcoming enhancement for the Large Hadron Collider (LHC), known as the High-Luminosity LHC, is designed to increase the collision rate of the accelerator by a factor of ten. This ambitious objective entails the replacement of the dipole and quadrupole magnets situated before and after the interaction region of the ATLAS and CMS experiments. Among these, the separation-recombination dipole MBRD (Main Bending Recombination Dipole, also known as D2) stands out, featuring a target integral magnetic field of 35 Tm within a double aperture of 105 mm. Following the successful testing of the full-length prototype MBRDP in 2022–23, the first magnet in the series, MBRD1, has been finalized, delivered to CERN in October 2023. During the acceptance tests at CERN, a damage in one quench heater wire was found and the magnet was sent back to ASG Superconductors for repairing in July 2024. The foreseen delivery date of the fixed MBRD1 is at the end of October 2024. The MBRD2 has been built in ASG, delivered to CERN in April 2024 and accepted in June after all the compliance tests. This magnet is now under integration in the cold mass with the multipole correctors and will be cold tested in January 2025. While the other four magnets of the series production are being built in industry and the end of the construction phase is expected in January 2026. Due to significant cross-talk between the two apertures and the high sensitivity of the field to the as-built size of the coils, a revised cross-section for the series magnets has been devised compared to the prototype. For each coil, a dedicated and optimized insulation scheme has been identified to achieve the most favorable and consistently reproducible field harmonics, guided by measurements performed on the prototype at cold and on the series at room temperature (RT). This contribution provides an update on the construction progress at ASG Superconductors, details the enhancements made to the coil cross-section to meet the stringent requirements for field quality in this dipole, and discusses the current status of testing for MBRD2 at CERN.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430382","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 : 2025-01-31DOI: 10.1109/TASC.2025.3537056
Takanobu Mato;So Noguchi
No-insulation (NI) rare-earth barium copper oxide (REBCO) pancake coils are a leading candidate for high-field generation due to their high performances under high fields. However, the need for active quench protection has begun arising because the high energy density makes it difficult to protect REBCO magnets only by adopting the NI techniques. One of the challenging parts of the protection is the quench detection difficult for the NI REBCO pancake coil. The slow normal-zone propagation speed and the low coil resistance lead to delayed quench detection and frequent protection failures of the NI REBCO coils system. To address the problem in the local-normal-zone detection of NI REBCO pancake coils, we have been focusing on a deep-learning technology to detect any anomalous voltage rise of the REBCO pancake coils. The deep learning has a high potential for the quench detection of the REBCO pancake coil since it can flexibly learn the characteristics of objects that people cannot recognize. In this paper, we build a CNN-based (convolutional-neural-network-based) voltage predictor to detect steep voltage rises during the normal-state transition of NI REBCO pancake coils. The CNN model is trained with the numerous quench data generated with the well-established partial equivalent element method (PEEC) simulation coupled with thermal finite element analysis. The test results of the trained CNN are presented.
{"title":"Predicting Voltage of NI REBCO Pancake Coils to Detect Normal-State Transition Using Convolutional Neural Network","authors":"Takanobu Mato;So Noguchi","doi":"10.1109/TASC.2025.3537056","DOIUrl":"https://doi.org/10.1109/TASC.2025.3537056","url":null,"abstract":"No-insulation (NI) rare-earth barium copper oxide (REBCO) pancake coils are a leading candidate for high-field generation due to their high performances under high fields. However, the need for active quench protection has begun arising because the high energy density makes it difficult to protect REBCO magnets only by adopting the NI techniques. One of the challenging parts of the protection is the quench detection difficult for the NI REBCO pancake coil. The slow normal-zone propagation speed and the low coil resistance lead to delayed quench detection and frequent protection failures of the NI REBCO coils system. To address the problem in the local-normal-zone detection of NI REBCO pancake coils, we have been focusing on a deep-learning technology to detect any anomalous voltage rise of the REBCO pancake coils. The deep learning has a high potential for the quench detection of the REBCO pancake coil since it can flexibly learn the characteristics of objects that people cannot recognize. In this paper, we build a CNN-based (convolutional-neural-network-based) voltage predictor to detect steep voltage rises during the normal-state transition of NI REBCO pancake coils. The CNN model is trained with the numerous quench data generated with the well-established partial equivalent element method (PEEC) simulation coupled with thermal finite element analysis. The test results of the trained CNN are presented.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430593","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 : 2025-01-30DOI: 10.1109/TASC.2025.3536439
Di Wu;Dmitry Sotnikov;Mohsen Haajari;Tiina Salmi
Minimizing conductor cost is one of the goals in high-field HTS magnet design. Optimization of magnet design to minimize conductor length is one way to approach the problem. HTS tapes have anisotropic material properties and non-uniform current density within the tape width during operation, which must be accounted in modeling HTS tapes. Finite element method (FEM) based simulations can be used to obtain accurate magnetic field distribution and critical current in an HTS magnet, but these simulations are typically time consuming. For example, a detailed simulation for a 2 T HTS solenoid may take several hours. As a result, it is not efficient to implement the traditional optimization algorithms, which directly use the simulation results to obtain the response of the cost function. To overcome this challenge, a novel optimization algorithm was developed by the authors, namely L-ANN-GWO to reduce the time cost of optimization (L stands for LASSO, ANN stands for artificial neural network, and GWO stands for grey wolf optimizer). In this approach, ANN is trained by FEA set of HTS solenoid designs to approximate the time-consuming simulations of magnetic field distribution based on solenoid geometry. Instead of using the approximation model in a static way, ANN is first trained with a small number of samples and updated adaptively in L-ANN-GWO along with the optimization process. In this contribution, we present application of the L-ANN-GWO optimization algorithm to ReBCO solenoid coils to optimize magnet design to minimize conductor use. The design constraints come from field homogeneity and critical surface. We demonstrate that as a multi-objective optimization, L-ANN-GWO can output the minimized superconductor consumption in different peak magnetic fields from a single optimization run. Future developments foresee adding quench protection requirements into the design optimization as this is another aspect potentially impacting the conductor use.
{"title":"Minimizing Conductor Consumption in High-Field HTS Solenoid Design Using Adaptive ANN-Based Optimization Algorithm","authors":"Di Wu;Dmitry Sotnikov;Mohsen Haajari;Tiina Salmi","doi":"10.1109/TASC.2025.3536439","DOIUrl":"https://doi.org/10.1109/TASC.2025.3536439","url":null,"abstract":"Minimizing conductor cost is one of the goals in high-field HTS magnet design. Optimization of magnet design to minimize conductor length is one way to approach the problem. HTS tapes have anisotropic material properties and non-uniform current density within the tape width during operation, which must be accounted in modeling HTS tapes. Finite element method (FEM) based simulations can be used to obtain accurate magnetic field distribution and critical current in an HTS magnet, but these simulations are typically time consuming. For example, a detailed simulation for a 2 T HTS solenoid may take several hours. As a result, it is not efficient to implement the traditional optimization algorithms, which directly use the simulation results to obtain the response of the cost function. To overcome this challenge, a novel optimization algorithm was developed by the authors, namely L-ANN-GWO to reduce the time cost of optimization (L stands for LASSO, ANN stands for artificial neural network, and GWO stands for grey wolf optimizer). In this approach, ANN is trained by FEA set of HTS solenoid designs to approximate the time-consuming simulations of magnetic field distribution based on solenoid geometry. Instead of using the approximation model in a static way, ANN is first trained with a small number of samples and updated adaptively in L-ANN-GWO along with the optimization process. In this contribution, we present application of the L-ANN-GWO optimization algorithm to ReBCO solenoid coils to optimize magnet design to minimize conductor use. The design constraints come from field homogeneity and critical surface. We demonstrate that as a multi-objective optimization, L-ANN-GWO can output the minimized superconductor consumption in different peak magnetic fields from a single optimization run. Future developments foresee adding quench protection requirements into the design optimization as this is another aspect potentially impacting the conductor use.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10858328","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422840","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 : 2025-01-30DOI: 10.1109/TASC.2025.3536437
M. Janitschke;M. Bednarek;J. Ludwin;E. Ravaioli;A.P. Verweij;U. van Rienen
Measuring a superconducting magnet's complex impedance as a function of the frequency is a promising diagnostic tool to investigate its electrical integrity and the potential presence of electrical nonconformities. Such transfer function measurements (TFM) were performed for the first time on a large number of magnets in the Large Hadron Collider (LHC). During this measurement campaign, the impedances of all 1232 superconducting main dipoles installed in the LHC were measured at cold in the frequency range from 1 Hz to 100 kHz. This letter presents the measurement set-up and provides a comparative data analysis of all complex impedance measurements. Distinct groups of magnets showing similar behavior are analyzed, and frequency ranges showing significant impedance variations are identified. Variations in TFM are shown to be correlated to individual features of each magnet, such as manufacturing tolerances in the magnets' beam screens, different materials used in their coil-protection sheets, and variations in the critical current of their superconductors. Moreover, measurements are compared to the simulation results obtained by a recently developed and validated lumped-element network model and show good agreement. Finally, a few magnets are identified as outliers as their measured impedances deviate significantly from the impedances of the other magnets and differ from the simulated values.
{"title":"Analyzing the Complex Impedances of All LHC Main Dipole Magnets","authors":"M. Janitschke;M. Bednarek;J. Ludwin;E. Ravaioli;A.P. Verweij;U. van Rienen","doi":"10.1109/TASC.2025.3536437","DOIUrl":"https://doi.org/10.1109/TASC.2025.3536437","url":null,"abstract":"Measuring a superconducting magnet's complex impedance as a function of the frequency is a promising diagnostic tool to investigate its electrical integrity and the potential presence of electrical nonconformities. Such transfer function measurements (TFM) were performed for the first time on a large number of magnets in the Large Hadron Collider (LHC). During this measurement campaign, the impedances of all 1232 superconducting main dipoles installed in the LHC were measured at cold in the frequency range from 1 Hz to 100 kHz. This letter presents the measurement set-up and provides a comparative data analysis of all complex impedance measurements. Distinct groups of magnets showing similar behavior are analyzed, and frequency ranges showing significant impedance variations are identified. Variations in TFM are shown to be correlated to individual features of each magnet, such as manufacturing tolerances in the magnets' beam screens, different materials used in their coil-protection sheets, and variations in the critical current of their superconductors. Moreover, measurements are compared to the simulation results obtained by a recently developed and validated lumped-element network model and show good agreement. Finally, a few magnets are identified as outliers as their measured impedances deviate significantly from the impedances of the other magnets and differ from the simulated values.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10858385","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430554","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}
REBCO high-temperature superconductors (HTS) provide a technical possibility for a high current density operation of a superconducting magnet. The intra-Layer No-insulation (LNI) method, one of the No-Insulation (NI) schemes, can be a promising solution for improving thermal stability and quench protection characteristics, which are vital to high current density operations. We previously proposed the concept of a resistance-controlled (RC) interface for controlling bypass resistance inside a coil winding and showed its electrical properties related to quench protection. In the present work, we measured the thermal conductive properties of an RC interface with a conduction cooling experiment on NI single pancake coils and numerically evaluated the characteristics of an LNI-REBCO coil implemented with the RC interface. The experimental and numerical results showed that the RC interface has high thermal conductive properties, which can be expected to contribute to the thermal stability of a coil under Joule heat dissipation as well as to cooling characteristics.
{"title":"Thermal Conductive Properties of a Resistance-Controlled (RC) Interface for No-Insulation (NI) Scheme Coils","authors":"Yuya Tanaka;Yu Suetomi;Mizuho Kawahata;Tomoaki Takao;Kazuya Nakamura;Kensuke Kobayashi;Renzhong Piao;Toshio Yamazaki;Yoshinori Yanagisawa","doi":"10.1109/TASC.2025.3534189","DOIUrl":"https://doi.org/10.1109/TASC.2025.3534189","url":null,"abstract":"REBCO high-temperature superconductors (HTS) provide a technical possibility for a high current density operation of a superconducting magnet. The intra-Layer No-insulation (LNI) method, one of the No-Insulation (NI) schemes, can be a promising solution for improving thermal stability and quench protection characteristics, which are vital to high current density operations. We previously proposed the concept of a resistance-controlled (RC) interface for controlling bypass resistance inside a coil winding and showed its electrical properties related to quench protection. In the present work, we measured the thermal conductive properties of an RC interface with a conduction cooling experiment on NI single pancake coils and numerically evaluated the characteristics of an LNI-REBCO coil implemented with the RC interface. The experimental and numerical results showed that the RC interface has high thermal conductive properties, which can be expected to contribute to the thermal stability of a coil under Joule heat dissipation as well as to cooling characteristics.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422865","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 : 2025-01-29DOI: 10.1109/TASC.2025.3535851
Shuma Kawabata;Tadashi Hirayama
In order to develop high temperature superconducting (HTS) tapes with excellent low-loss characteristics, it is indispensable to have a measurement system capable of measuring the AC loss characteristics of HTS tapes with high sensitivity at 77 K. We have developed a measurement system using the pickup coil method, which can measure the AC loss characteristics of short straight HTS tapes under AC transverse magnetic fields with high sensitivity. In the pickup coil method, pickup coils consist of a main pickup coil for measuring the specimen signal voltage and a compensation coil used to extract only the magnetization signal voltage of the specimen contained in the main pickup coil voltage. In order to increase the sensitivity of AC loss measurement systems using the pickup coil method, background losses, which are apparent losses that occur even when there is no sample in the main pickup coil, must be reduced as much as possible. To reduce background losses, first, a magnet was designed and manufactured to apply external transverse magnetic fields so that a main pickup coil and a compensation coil could be arranged symmetrically. This makes it possible to reduce the phase difference between the main pickup coil voltage and the compensation coil voltage, which is one of the main causes of background losses. Next, background losses were measured using several kinds of pickup coils with different parameters. Furthermore, based on the measurement results, the optimum parameters of the pickup coils were investigated. Finally, background losses could be successfully reduced, and the sensitivity of the AC loss measurement system increased.
{"title":"Highly Sensitive Measurement of AC Loss Characteristics of Short and Straight HTS Tapes Under Transverse Magnetic Field by Pickup Coil Method","authors":"Shuma Kawabata;Tadashi Hirayama","doi":"10.1109/TASC.2025.3535851","DOIUrl":"https://doi.org/10.1109/TASC.2025.3535851","url":null,"abstract":"In order to develop high temperature superconducting (HTS) tapes with excellent low-loss characteristics, it is indispensable to have a measurement system capable of measuring the AC loss characteristics of HTS tapes with high sensitivity at 77 K. We have developed a measurement system using the pickup coil method, which can measure the AC loss characteristics of short straight HTS tapes under AC transverse magnetic fields with high sensitivity. In the pickup coil method, pickup coils consist of a main pickup coil for measuring the specimen signal voltage and a compensation coil used to extract only the magnetization signal voltage of the specimen contained in the main pickup coil voltage. In order to increase the sensitivity of AC loss measurement systems using the pickup coil method, background losses, which are apparent losses that occur even when there is no sample in the main pickup coil, must be reduced as much as possible. To reduce background losses, first, a magnet was designed and manufactured to apply external transverse magnetic fields so that a main pickup coil and a compensation coil could be arranged symmetrically. This makes it possible to reduce the phase difference between the main pickup coil voltage and the compensation coil voltage, which is one of the main causes of background losses. Next, background losses were measured using several kinds of pickup coils with different parameters. Furthermore, based on the measurement results, the optimum parameters of the pickup coils were investigated. Finally, background losses could be successfully reduced, and the sensitivity of the AC loss measurement system increased.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-4"},"PeriodicalIF":1.7,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430419","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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