A simple method is proposed for the establishment of resistance-controlled (RC) interfaces to control bypass resistance inside windings for no-insulation (NI) scheme coils. The method uses stainless steel mesh impregnated with epoxy to create current bypass paths between REBCO tape turns or between a REBCO tape turn and a copper sheet. Short samples for an RC interface are evaluated for bypass resistance using the four-terminal method at 77 K. Each sample is composed of two REBCO tapes between which a 30 μm-thick SS mesh which is impregnated with epoxy to keep the contacts between the surfaces of the REBCO tapes and SS mesh. Most samples show bypass resistances of the order of 100–1000 mΩ·cm2; such high values are of importance from the viewpoint of achieving self-protection of NI scheme coils, via management of both overheating and overstressing. Issues related to variations in bypass resistances must be addressed before the proposed method can be implemented in coils.
{"title":"Resistance-Controlled (RC) Interface With Metal Mesh for Managing Current Bypassing in No-Insulation (NI) Scheme Coils","authors":"Mizuho Kawahata;Yuya Tanaka;Yu Suetomi;Syouon Imanishi;Kazuya Nakamura;Tomoaki Takao;Renzhong Piao;Kensuke Kobayashi;Toshio Yamazaki;Yoshinori Yanagisawa","doi":"10.1109/TASC.2025.3538672","DOIUrl":"https://doi.org/10.1109/TASC.2025.3538672","url":null,"abstract":"A simple method is proposed for the establishment of resistance-controlled (RC) interfaces to control bypass resistance inside windings for no-insulation (NI) scheme coils. The method uses stainless steel mesh impregnated with epoxy to create current bypass paths between REBCO tape turns or between a REBCO tape turn and a copper sheet. Short samples for an RC interface are evaluated for bypass resistance using the four-terminal method at 77 K. Each sample is composed of two REBCO tapes between which a 30 μm-thick SS mesh which is impregnated with epoxy to keep the contacts between the surfaces of the REBCO tapes and SS mesh. Most samples show bypass resistances of the order of 100–1000 mΩ·cm<sup>2</sup>; such high values are of importance from the viewpoint of achieving self-protection of NI scheme coils, via management of both overheating and overstressing. Issues related to variations in bypass resistances must be addressed before the proposed method can be implemented in coils.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143489260","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 : 2025-02-05DOI: 10.1109/TASC.2025.3538533
Jihan Sun;Yawei Wang;Weihang Peng;Yutong Fu;Yue Zhao;Longbiao Wang;Yuguang Chen;Zhijian Jin
The fast growth of semiconductor Integrated Circuit industry gains a significant focus on producing high-quality silicon wafers with larger diameters. High temperature superconductor (HTS) magnets can generate high static magnetic fields at high operating temperature, which can be used to improve the quality of single silicon crystal. The No-Insulation (NI) and Metal-Insulated (MI) HTS coils show great advantages on enhanced thermal stability and are the best candidates for high-quality silicon wafer production. However, these HTS coils face challenges related to the slow propagation speed of quench events, leading to the occurrence of local hot-spot quench while other sections continue to operate in the superconducting state. Recent studies reveal that local hot spots in NI and MI HTS coils cause central magnetic field reductions, making magnetic field-based quench detection an effective method, particularly suitable for single silicon growth systems that require magnetic field monitoring. Therefore, this study aims to experimentally investigate and analyze the local hot-spot quench in NI HTS coils, as well as in metal-insulated and insulated HTS coils. Distributed voltage taps and Hall sensors are used to monitor quench signals created by heater. The experiment measured the voltage and magnetic field characteristics of these coils during the quench, showing that the magnetic field based quench detection method is effective. This study provides data support for understanding the local hot-spot quench properties of HTS coil, offering reference for its design and optimization in applications for high-strength magnetic fields.
{"title":"Local Hot-Spot Quench Test and Analysis on High Temperature Superconductor Coils for a Single Silicon Crystal Growth System","authors":"Jihan Sun;Yawei Wang;Weihang Peng;Yutong Fu;Yue Zhao;Longbiao Wang;Yuguang Chen;Zhijian Jin","doi":"10.1109/TASC.2025.3538533","DOIUrl":"https://doi.org/10.1109/TASC.2025.3538533","url":null,"abstract":"The fast growth of semiconductor Integrated Circuit industry gains a significant focus on producing high-quality silicon wafers with larger diameters. High temperature superconductor (HTS) magnets can generate high static magnetic fields at high operating temperature, which can be used to improve the quality of single silicon crystal. The No-Insulation (NI) and Metal-Insulated (MI) HTS coils show great advantages on enhanced thermal stability and are the best candidates for high-quality silicon wafer production. However, these HTS coils face challenges related to the slow propagation speed of quench events, leading to the occurrence of local hot-spot quench while other sections continue to operate in the superconducting state. Recent studies reveal that local hot spots in NI and MI HTS coils cause central magnetic field reductions, making magnetic field-based quench detection an effective method, particularly suitable for single silicon growth systems that require magnetic field monitoring. Therefore, this study aims to experimentally investigate and analyze the local hot-spot quench in NI HTS coils, as well as in metal-insulated and insulated HTS coils. Distributed voltage taps and Hall sensors are used to monitor quench signals created by heater. The experiment measured the voltage and magnetic field characteristics of these coils during the quench, showing that the magnetic field based quench detection method is effective. This study provides data support for understanding the local hot-spot quench properties of HTS coil, offering reference for its design and optimization in applications for high-strength magnetic fields.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465679","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 : 2025-02-05DOI: 10.1109/TASC.2025.3538641
L. Brouwer;C. Messe;K. Amm;Y. Bai;J. S. Berg;A. Drees;P. Ferracin;K. Hamdi;S. Prestemon;G. Sabbi;G. Vallone;H. Witte
We present the initial design of the matching dipole B2PF, a large aperture cosine-theta magnet for the Electron-Ion Collider (EIC). First we share an optimized 2D magnet cross-section based on a double-layer design with Nb-Ti Rutherford cable. This cross-section is optimized to meet the required field quality in the 120 mm coil aperture both at the nominal operating current and considering iron saturation effects during the ramp. Next, we share a first design of the 3D coil ends optimized for windability, field quality, and minimizing the conductor peak field. Based on the resulting peak field, we evaluate the short-sample margin of the design for an operating target of 6.3 T dipole field at 1.9 K. Finally, we share an initial mechanical design study which utilizes a key-and-bladder support structure capable of adjusting magnet preload.
{"title":"Design of B2PF: A Large Aperture Nb-Ti Dipole Magnet for the Electron-Ion Collider","authors":"L. Brouwer;C. Messe;K. Amm;Y. Bai;J. S. Berg;A. Drees;P. Ferracin;K. Hamdi;S. Prestemon;G. Sabbi;G. Vallone;H. Witte","doi":"10.1109/TASC.2025.3538641","DOIUrl":"https://doi.org/10.1109/TASC.2025.3538641","url":null,"abstract":"We present the initial design of the matching dipole B2PF, a large aperture cosine-theta magnet for the Electron-Ion Collider (EIC). First we share an optimized 2D magnet cross-section based on a double-layer design with Nb-Ti Rutherford cable. This cross-section is optimized to meet the required field quality in the 120 mm coil aperture both at the nominal operating current and considering iron saturation effects during the ramp. Next, we share a first design of the 3D coil ends optimized for windability, field quality, and minimizing the conductor peak field. Based on the resulting peak field, we evaluate the short-sample margin of the design for an operating target of 6.3 T dipole field at 1.9 K. Finally, we share an initial mechanical design study which utilizes a key-and-bladder support structure capable of adjusting magnet preload.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-7"},"PeriodicalIF":1.7,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465799","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.2025.3538673
Thomas J. Bennett IV;Eric M. Taleff;Pashupati Dhakal;Shreyas Balachandran;Peter J. Lee;Thomas R. Bieler;Philip Eisenlohr
A fully recrystallized microstructure with a fine grain size can improve the performance of superconducting radio-frequency cavities produced from high-purity Nb (ASTM B393–18 Type 5 Nb) while providing mechanical strength. Recrystallization depends on impurity content, initial microstructure, deformation state, and annealing conditions. To better understand how fine-grained, fully recrystallized microstructures may be produced, the recrystallization behaviors of Type 5 and Type 2 Nb materials were studied. Type 5 Nb specimens were produced with both fine and coarse initial grain sizes. All were cold rolled and then annealed under vacuum for one hour to determine the rolling reductions and temperatures required for recrystallization. The recrystallized fraction exceeded 95% in fine-grained Type 5 Nb rolled to a 30% or greater thickness reduction and then annealed at 800°C or higher. The coarse-grained Type 5 Nb required greater rolling reductions to produce any recrystallized grains at 800°C. The higher interstitial content of the Type 2 Nb required a temperature of 1000°C or higher to reach a recrystallized fraction greater than 95% in specimens rolled to a 60% reduction. Recrystallization is more easily achieved during annealing at a given temperature for a set time by increasing rolling reduction, decreasing interstitial content, and decreasing initial grain size prior to cold rolling. To avoid grain growth following recrystallization, which increases grain size, the minimum time and temperature necessary for complete recrystallization should be applied.
{"title":"Effects of Grain Size and Interstitial Content on Recrystallization in Nb After Cold Rolling","authors":"Thomas J. Bennett IV;Eric M. Taleff;Pashupati Dhakal;Shreyas Balachandran;Peter J. Lee;Thomas R. Bieler;Philip Eisenlohr","doi":"10.1109/TASC.2025.3538673","DOIUrl":"https://doi.org/10.1109/TASC.2025.3538673","url":null,"abstract":"A fully recrystallized microstructure with a fine grain size can improve the performance of superconducting radio-frequency cavities produced from high-purity Nb (ASTM B393–18 Type 5 Nb) while providing mechanical strength. Recrystallization depends on impurity content, initial microstructure, deformation state, and annealing conditions. To better understand how fine-grained, fully recrystallized microstructures may be produced, the recrystallization behaviors of Type 5 and Type 2 Nb materials were studied. Type 5 Nb specimens were produced with both fine and coarse initial grain sizes. All were cold rolled and then annealed under vacuum for one hour to determine the rolling reductions and temperatures required for recrystallization. The recrystallized fraction exceeded 95% in fine-grained Type 5 Nb rolled to a 30% or greater thickness reduction and then annealed at 800°C or higher. The coarse-grained Type 5 Nb required greater rolling reductions to produce any recrystallized grains at 800°C. The higher interstitial content of the Type 2 Nb required a temperature of 1000°C or higher to reach a recrystallized fraction greater than 95% in specimens rolled to a 60% reduction. Recrystallization is more easily achieved during annealing at a given temperature for a set time by increasing rolling reduction, decreasing interstitial content, and decreasing initial grain size prior to cold rolling. To avoid grain growth following recrystallization, which increases grain size, the minimum time and temperature necessary for complete recrystallization should be applied.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465776","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}
While the ITER assembly is progressing, a Magnet Cold Test Bench (MCTB) is also under preparation to test some of the ITER superconducting coils at 4 K up to nominal current before their installation in the pit. In this context transient Electro-Magnetic (EM) calculations were performed to estimate the impact of AC losses and eddy currents on the cryogenic and mechanical performance of the coils and other components of the MCTB. In particular the case of a fast exponential discharge is investigated, which represents the most severe transient operation expected for MCTB. Although different types of ITER coils are considered for the tests (several Toroidal Field Coils and Poloidal Field Coil number 1), the following discussion will be limited to the operation of a single Toroidal Field (TF) coil. Detailed results of the EM analysis, such as field maps, AC losses and QD voltages will be presented.
{"title":"EM Simulations for the ITER Magnet Cold Test Bench – TF Coil Fast Discharge","authors":"P. Bauer;F. Auricane;A. Bonito-Oliva;C. Fichera;J. Lorenzo;N. Koizumi;A. Louzguiti;A. Portone;G. Rubinacci;T. Schild;S. Ventre","doi":"10.1109/TASC.2025.3538671","DOIUrl":"https://doi.org/10.1109/TASC.2025.3538671","url":null,"abstract":"While the ITER assembly is progressing, a Magnet Cold Test Bench (MCTB) is also under preparation to test some of the ITER superconducting coils at 4 K up to nominal current before their installation in the pit. In this context transient Electro-Magnetic (EM) calculations were performed to estimate the impact of AC losses and eddy currents on the cryogenic and mechanical performance of the coils and other components of the MCTB. In particular the case of a fast exponential discharge is investigated, which represents the most severe transient operation expected for MCTB. Although different types of ITER coils are considered for the tests (several Toroidal Field Coils and Poloidal Field Coil number 1), the following discussion will be limited to the operation of a single Toroidal Field (TF) coil. Detailed results of the EM analysis, such as field maps, AC losses and QD voltages will be presented.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465612","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.2025.3538616
Kwangmin Kim;Yu Suetomi;Brnesto Bosque;Brent Jarvis;William S. Marshall
This study presents experimental results on the fatigue characteristics of a REBCO coil and crossover joint, aiming to determine whether they can withstand cyclic loading up to the condition of the 40 T superconducting magnet's design fatigue limit. A pair of REBCO coils were wound with SP (SuperPower) 1013, using copper and stainless steel tape as co-winding materials. The crossover sample, designed to the 40 T superconducting magnet baseline specifications and composed of four Bi2223 (Sumitomo Type H) tape conductors soldered to a stainless steel foil, was mounted to the outermost turn of the REBCO coil. Both the coil and crossover were subjected to cyclic loading by ramping the current up and down in a 7 T background magnetic (BM) field at 4.2 K, with over 25,000 cycles applied. The electromagnetic strain between the outermost turn of the REBCO coil and the crossover joint was estimated numerically, considering the screening current distribution.
{"title":"Report on Over 25 000 Cycles Fatigue Test Results of a REBCO HTS Coil and Crossover Joint in a 7 T Background Magnetic Field at 4.2 K","authors":"Kwangmin Kim;Yu Suetomi;Brnesto Bosque;Brent Jarvis;William S. Marshall","doi":"10.1109/TASC.2025.3538616","DOIUrl":"https://doi.org/10.1109/TASC.2025.3538616","url":null,"abstract":"This study presents experimental results on the fatigue characteristics of a REBCO coil and crossover joint, aiming to determine whether they can withstand cyclic loading up to the condition of the 40 T superconducting magnet's design fatigue limit. A pair of REBCO coils were wound with SP (SuperPower) 1013, using copper and stainless steel tape as co-winding materials. The crossover sample, designed to the 40 T superconducting magnet baseline specifications and composed of four Bi2223 (Sumitomo Type H) tape conductors soldered to a stainless steel foil, was mounted to the outermost turn of the REBCO coil. Both the coil and crossover were subjected to cyclic loading by ramping the current up and down in a 7 T background magnetic (BM) field at 4.2 K, with over 25,000 cycles applied. The electromagnetic strain between the outermost turn of the REBCO coil and the crossover joint was estimated numerically, considering the screening current distribution.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-4"},"PeriodicalIF":1.7,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465684","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}
An organic olefin-based thermosetting dicyclopentadiene (DCP) resin, C10H12, commercially available in Japan as TELENE from RIMTEC Corporation, has a viscosity less than one tenth of that of the CTD-101K epoxy resin. The TELENE can tolerate larger strains than CTD-101K and can have a higher heat capacity by mixing it with ceramic powder. Using the TELENE as the impregnation resin is expected to reduce the number of quench training of Nb3Sn magnets. In this paper, the flexural properties of the pure and mixed TELENE was measured before and after gamma-ray irradiation and compared to that of the CTD-101K. Three powders of Gd2O3, Gd2O2S, and HoCu2 were mixed with the pure TELENE, respectively. The gamma-ray irradiation was performed using Cobalt-60 source at the Takasaki Advanced Radiation Research Institute, Japan, up to 25 MGy at room temperature. The pure TELENE exhibits plastic deformation before irradiation and increases in strength up to 2 MGy irradiation. The flexural modulus of pure and mixed TELENE increased continuously up to 25 MGy irradiation.
{"title":"Flexural Properties of an Organic Olefin-Based Thermosetting Dicyclopentadiene Resin for Superconducting Magnet Impregnation","authors":"Xudong Wang;Akihiro Kikuchi;Masaki Takeuchi;Tatsushi Nakamoto;Kiyosumi Tsuchiya","doi":"10.1109/TASC.2025.3537947","DOIUrl":"https://doi.org/10.1109/TASC.2025.3537947","url":null,"abstract":"An organic olefin-based thermosetting dicyclopentadiene (DCP) resin, C<sub>10</sub>H<sub>12</sub>, commercially available in Japan as TELENE from RIMTEC Corporation, has a viscosity less than one tenth of that of the CTD-101K epoxy resin. The TELENE can tolerate larger strains than CTD-101K and can have a higher heat capacity by mixing it with ceramic powder. Using the TELENE as the impregnation resin is expected to reduce the number of quench training of Nb3Sn magnets. In this paper, the flexural properties of the pure and mixed TELENE was measured before and after gamma-ray irradiation and compared to that of the CTD-101K. Three powders of Gd<sub>2</sub>O<sub>3</sub>, Gd<sub>2</sub>O<sub>2</sub>S, and HoCu<sub>2</sub> were mixed with the pure TELENE, respectively. The gamma-ray irradiation was performed using Cobalt-60 source at the Takasaki Advanced Radiation Research Institute, Japan, up to 25 MGy at room temperature. The pure TELENE exhibits plastic deformation before irradiation and increases in strength up to 2 MGy irradiation. The flexural modulus of pure and mixed TELENE increased continuously up to 25 MGy irradiation.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-4"},"PeriodicalIF":1.7,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465805","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}
Compact cyclotrons are required for the production of radiopharmaceuticals used in targeted alpha-particle therapy, which is a promising treatment for patients with intractable cancers. To realize a compact cyclotron, we have proposed the Skeleton Cyclotron—an air-core compact cyclotron using high-temperature superconducting (HTS) technology. This cyclotron consists of circular and non-circular coils, all wound with REBCO tape using a no-insulation (NI) winding technique. To verify the feasibility of superconducting technology in NI coil systems with such an air-core cyclotron structure, we have fabricated a half-scale coil system of the Skeleton Cyclotron called the Ultra-Baby Cyclotron, which has a diameter of 0.7 m (the full-scale Skeleton Cyclotron has a diameter of 1.6 m). Experiments are currently in progress. In previous experiments, the strain gauge readings showed large values. The cause is currently under investigation, and one possible explanation may be screening currents. In this study, numerical simulations of the additional stresses due to screening currents in the non-circular coils of the Ultra-Baby Cyclotron reproduce the stresses observed experimentally.
{"title":"Local Stress Due to Screening Current of No-Insulation Non-Circular REBCO Coil in Half-Scale Coil System of Skeleton Cyclotron","authors":"Hiroshi Ueda;Aoi Yamashita;Ryota Inoue;SeokBeom Kim;So Noguchi;Tomonori Watanabe;Mitsuhiro Fukuda;Atsushi Ishiyama","doi":"10.1109/TASC.2025.3537951","DOIUrl":"https://doi.org/10.1109/TASC.2025.3537951","url":null,"abstract":"Compact cyclotrons are required for the production of radiopharmaceuticals used in targeted alpha-particle therapy, which is a promising treatment for patients with intractable cancers. To realize a compact cyclotron, we have proposed the Skeleton Cyclotron—an air-core compact cyclotron using high-temperature superconducting (HTS) technology. This cyclotron consists of circular and non-circular coils, all wound with REBCO tape using a no-insulation (NI) winding technique. To verify the feasibility of superconducting technology in NI coil systems with such an air-core cyclotron structure, we have fabricated a half-scale coil system of the Skeleton Cyclotron called the Ultra-Baby Cyclotron, which has a diameter of 0.7 m (the full-scale Skeleton Cyclotron has a diameter of 1.6 m). Experiments are currently in progress. In previous experiments, the strain gauge readings showed large values. The cause is currently under investigation, and one possible explanation may be screening currents. In this study, numerical simulations of the additional stresses due to screening currents in the non-circular coils of the Ultra-Baby Cyclotron reproduce the stresses observed experimentally.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465803","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.2025.3538651
Tejumadejesu Oluwadamilare;Eby G. Friedman
A multiplexer is a digital structure that controls signal flow, selecting among multiple inputs to produce a single output. A two-input to one output (2:1) multiplexer is commonly used in single flux quantum (SFQ) systems. When three or more inputs to one output are required, 2:1 SFQ multiplexers are typically cascaded to create a multiplexer tree. A multi-input SFQ multiplexer comprising both a three-input (3:1) and four-input (4:1) to one output SFQ multiplexer is presented. These multiplexers require fewer control signals without cascading multiple 2:1 multiplexers. This SFQ circuit function is achieved using an XOR gate, AND gate, NOR gate, non-destructive read out cells, splitters, and confluence buffers for the 3:1 multiplexer. The XOR gate in the 3:1 multiplexer is replaced with two gates that distinguish between the 01 and 10 control signals. The circuit topologies are presented, and the performance and control signals are compared with a conventional 2:1 multiplexer tree and an individual input control multi-input multiplexer. A combination of 2:1, 3:1, and 4:1 multiplexers is proposed to achieve higher performance, leveraging the advantages of each type of multiplexer. A speed increase of 36% and an 83.6% reduction in the number of control signals in a 54:1 multi-input SFQ multiplexer are demonstrated using the combined multiplexer tree.
{"title":"Multi-Input SFQ Multiplexers","authors":"Tejumadejesu Oluwadamilare;Eby G. Friedman","doi":"10.1109/TASC.2025.3538651","DOIUrl":"https://doi.org/10.1109/TASC.2025.3538651","url":null,"abstract":"A multiplexer is a digital structure that controls signal flow, selecting among multiple inputs to produce a single output. A two-input to one output (2:1) multiplexer is commonly used in single flux quantum (SFQ) systems. When three or more inputs to one output are required, 2:1 SFQ multiplexers are typically cascaded to create a multiplexer tree. A multi-input SFQ multiplexer comprising both a three-input (3:1) and four-input (4:1) to one output SFQ multiplexer is presented. These multiplexers require fewer control signals without cascading multiple 2:1 multiplexers. This SFQ circuit function is achieved using an XOR gate, AND gate, NOR gate, non-destructive read out cells, splitters, and confluence buffers for the 3:1 multiplexer. The XOR gate in the 3:1 multiplexer is replaced with two gates that distinguish between the 01 and 10 control signals. The circuit topologies are presented, and the performance and control signals are compared with a conventional 2:1 multiplexer tree and an individual input control multi-input multiplexer. A combination of 2:1, 3:1, and 4:1 multiplexers is proposed to achieve higher performance, leveraging the advantages of each type of multiplexer. A speed increase of 36% and an 83.6% reduction in the number of control signals in a 54:1 multi-input SFQ multiplexer are demonstrated using the combined multiplexer tree.","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":"143489261","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.
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