The demand for stronger magnetic fields in fusion devices necessitates robust conductors capable of withstanding greater loads. High-temperature superconducting (HTS) cables using REBCO tapes have demonstrated practicality by carrying high currents even in magnetic fields up to 20 T. Several projects have been initiated to demonstrate the feasibility of using HTS twisted stacked-tape cable (TSTC) conductors. However, these challenges, particularly those associated with soldering defects leading to cavities, failures, and cable cracking, have been effectively addressed, significantly enhancing load resistance and structural reliability when making REBCO tapes into cables. In this study, we conducted experiments on a double casing cable (DCC), a round HTS strand designed following the TSTC approach. We improved soldering quality using vacuum pressure impregnation: an inner casing provides additional tape support, reducing mechanical issues from weak solder strength, while an outer casing facilitates solder flow channels, preventing inner casing cracking under direct stress. Direct current (DC) tests on transverse electromagnetic characteristics demonstrate the DCC strand's potential for high-current cables and fusion magnet applications. Notably, the strand sustained transverse load amplitudes up to 1250 kN/m without degradation of critical current (I$_{c}$). We present experimental results and discuss structural optimizations based on visual inspection and analysis.
{"title":"Double Casing Conductor Designed for High Mechanical Stress in Fusion Devices","authors":"Xianfeng Xu;Shu Tao;Yi Shi;Hongjun Ma;Houxiang Han;Huajun Liu;Fang Liu;Jinggang Qin","doi":"10.1109/TASC.2025.3530904","DOIUrl":"https://doi.org/10.1109/TASC.2025.3530904","url":null,"abstract":"The demand for stronger magnetic fields in fusion devices necessitates robust conductors capable of withstanding greater loads. High-temperature superconducting (HTS) cables using REBCO tapes have demonstrated practicality by carrying high currents even in magnetic fields up to 20 T. Several projects have been initiated to demonstrate the feasibility of using HTS twisted stacked-tape cable (TSTC) conductors. However, these challenges, particularly those associated with soldering defects leading to cavities, failures, and cable cracking, have been effectively addressed, significantly enhancing load resistance and structural reliability when making REBCO tapes into cables. In this study, we conducted experiments on a double casing cable (DCC), a round HTS strand designed following the TSTC approach. We improved soldering quality using vacuum pressure impregnation: an inner casing provides additional tape support, reducing mechanical issues from weak solder strength, while an outer casing facilitates solder flow channels, preventing inner casing cracking under direct stress. Direct current (DC) tests on transverse electromagnetic characteristics demonstrate the DCC strand's potential for high-current cables and fusion magnet applications. Notably, the strand sustained transverse load amplitudes up to 1250 kN/m without degradation of critical current (I<inline-formula><tex-math>$_{c}$</tex-math></inline-formula>). We present experimental results and discuss structural optimizations based on visual inspection and analysis.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143360930","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 : 2025-01-17DOI: 10.1109/TASC.2025.3530329
Weihang Peng;Yawei Wang;Yutong Fu;Jinke Guo;Siqi Hu;Yue Zhao;Zhijian Jin
The joint is one of the core components of high temperature superconducting (HTS) magnet, responsible for enabling the current transmission, and it is a key factor in evaluating the performance of HTS magnets. HTS parallel-wound (PW) coils, formed by parallelly stacking tapes, have been minimally studied in terms of joint manufacturing and measurement. The current shunting introduced by joints is one of the important parameters affecting the electrothermal performance of PW coils. This study investigates two manufacturing methods suitable for joints of PW coil and measures each joint resistance between HTS tape and copper terminal. The current distribution and heat loss caused by joint are analyzed by testing and simulation. The results indicate that the joint-distributed method is the preferred solution for manufacturing multi-joint connections on the same terminal. A 3-tape PW coil is wound using this method for both inner and outer joints. Further analysis shows that greater non-uniformity in joint resistance results in a more uneven current distribution among parallel tapes and increased heat generation during steady-state operation. The addition of parallel tape-to-tape shunt can reduce losses, especially during high current operation.
{"title":"Study on Terminal Joint Resistance and Current Distribution in Parallel-Wound HTS Coil","authors":"Weihang Peng;Yawei Wang;Yutong Fu;Jinke Guo;Siqi Hu;Yue Zhao;Zhijian Jin","doi":"10.1109/TASC.2025.3530329","DOIUrl":"https://doi.org/10.1109/TASC.2025.3530329","url":null,"abstract":"The joint is one of the core components of high temperature superconducting (HTS) magnet, responsible for enabling the current transmission, and it is a key factor in evaluating the performance of HTS magnets. HTS parallel-wound (PW) coils, formed by parallelly stacking tapes, have been minimally studied in terms of joint manufacturing and measurement. The current shunting introduced by joints is one of the important parameters affecting the electrothermal performance of PW coils. This study investigates two manufacturing methods suitable for joints of PW coil and measures each joint resistance between HTS tape and copper terminal. The current distribution and heat loss caused by joint are analyzed by testing and simulation. The results indicate that the joint-distributed method is the preferred solution for manufacturing multi-joint connections on the same terminal. A 3-tape PW coil is wound using this method for both inner and outer joints. Further analysis shows that greater non-uniformity in joint resistance results in a more uneven current distribution among parallel tapes and increased heat generation during steady-state operation. The addition of parallel tape-to-tape shunt can reduce losses, especially during high current operation.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143184018","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 : 2025-01-17DOI: 10.1109/TASC.2025.3530908
C. Fiamozzi Zignani;G. De Marzi;A. Di Zenobio;L. Muzzi;M. Ortino;R. Bonifetto;G. Campana;G. Drago;F. Fabbri;D. Magrassi;P.L.P. Martello;G.M. Polli;G. Ramogida;R. Repetto;K. Sedlak;S. Turtù
The Divertor Tokamak Test (DTT) facility is a challenging high-field and compact tokamak, currently under construction at the Frascati ENEA Research Center. Its purpose is to significantly contribute to the exploration, design and assessment of systems intended for the management of heat exhaust. Its superconducting magnetic system consists of 18 Toroidal Field (TF) coils, 6 Poloidal Field (PF) coils and a Central Solenoid (CS). This work is focused on the superconducting praying-hands joint, manufactured by ASG-Superconductors for the DTT TF coils terminations and for the connection among the adjacent double-pancakes constituting the TF winding pack. The joint has been tested and fully characterized by dedicated 2-weeks cryogenic tests in the SULTAN facility at Swiss Plasma Centre (SPC, EPFL) in November 2023. The tests included 3000 EM cycles at the maximum foreseen operative load of 8.1 T–21 kA and two Warm-Up-Cool-Down (WUCD) cycles, while reference DC measurements were done in normal and reversed polarity up to 42.5 kA and to 4 T, before, during and after cyclic loading and WUCDs. Assessment of AC losses, performed through bipolar sinusoidal pulsing at frequencies up to 2 Hz, and pressure drop measurements as a function of He mass flow rate, were conducted on the virgin sample and after full cyclic loading. The Minimum Quench Energy (MQE) has also been measured at different temperatures under nominal current conditions. All the conducted tests confirmed the efficacy and goodness of the joint design, with its resistance at self-field consistently remaining below the nominal allowable value of 2 nΩ.
{"title":"Characterization of the Full-Size Superconducting ASG Joint Designed for the DTT Toroidal Field Coils","authors":"C. Fiamozzi Zignani;G. De Marzi;A. Di Zenobio;L. Muzzi;M. Ortino;R. Bonifetto;G. Campana;G. Drago;F. Fabbri;D. Magrassi;P.L.P. Martello;G.M. Polli;G. Ramogida;R. Repetto;K. Sedlak;S. Turtù","doi":"10.1109/TASC.2025.3530908","DOIUrl":"https://doi.org/10.1109/TASC.2025.3530908","url":null,"abstract":"The Divertor Tokamak Test (DTT) facility is a challenging high-field and compact tokamak, currently under construction at the Frascati ENEA Research Center. Its purpose is to significantly contribute to the exploration, design and assessment of systems intended for the management of heat exhaust. Its superconducting magnetic system consists of 18 Toroidal Field (TF) coils, 6 Poloidal Field (PF) coils and a Central Solenoid (CS). This work is focused on the superconducting praying-hands joint, manufactured by ASG-Superconductors for the DTT TF coils terminations and for the connection among the adjacent double-pancakes constituting the TF winding pack. The joint has been tested and fully characterized by dedicated 2-weeks cryogenic tests in the SULTAN facility at Swiss Plasma Centre (SPC, EPFL) in November 2023. The tests included 3000 EM cycles at the maximum foreseen operative load of 8.1 T–21 kA and two Warm-Up-Cool-Down (WUCD) cycles, while reference DC measurements were done in normal and reversed polarity up to 42.5 kA and to 4 T, before, during and after cyclic loading and WUCDs. Assessment of AC losses, performed through bipolar sinusoidal pulsing at frequencies up to 2 Hz, and pressure drop measurements as a function of He mass flow rate, were conducted on the virgin sample and after full cyclic loading. The Minimum Quench Energy (MQE) has also been measured at different temperatures under nominal current conditions. All the conducted tests confirmed the efficacy and goodness of the joint design, with its resistance at self-field consistently remaining below the nominal allowable value of 2 nΩ.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143369906","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 second-generation high-temperature superconducting REBCO coated conductors with very high critical current density under high fields exhibit considerable potential for ultra-high-field applications, including accelerator magnets, high-field magnets for thermonuclear fusion reactors, and MRI machines. However, the current carrying capacity of a single-strip REBCO coated conductor, typically ranging from 600 A to 1000 A at 4.2 K, 20 T, is generally insufficient to fulfill the requirements exceeding 40 kA, 20 T for conductors employed in these applications. A qualified REBCO cabling method that enhances current-carrying capacity and reduces AC losses is generally essential to bridge the existing gap. This article introduces a 100-kA class REBCO Rutherford cable, which offers advantages in high current-carrying capacity, low AC loss characteristics, and robust mechanical behavior. The current-carrying capacity, magnetic behavior, and AC loss characteristics of the REBCO Rutherford cable were evaluated using a bench-marked two-dimensional axisymmetric electro-thermal-mechanical coupling model based on finite element methods. The comparative evaluation of its current-carrying capacity and AC loss characteristics shows that it has a current-carrying capacity of 100 kA at 4.2 K, self-field. In addition, AC losses in the REBCO Rutherford cable are estimated to be lower within the scope of REBCO cables, suggesting significant potential for high-field applications, especially for the central solenoid coils of high-field thermonuclear fusion reactors.
{"title":"Elaboration of a 100-kA Class HTS REBCO Rutherford Cable for High-Field Applications","authors":"Xiaodong Li;Jinggang Qin;Wenjiang Yang;Rafael Macián-Juan","doi":"10.1109/TASC.2025.3530907","DOIUrl":"https://doi.org/10.1109/TASC.2025.3530907","url":null,"abstract":"The second-generation high-temperature superconducting REBCO coated conductors with very high critical current density under high fields exhibit considerable potential for ultra-high-field applications, including accelerator magnets, high-field magnets for thermonuclear fusion reactors, and MRI machines. However, the current carrying capacity of a single-strip REBCO coated conductor, typically ranging from 600 A to 1000 A at 4.2 K, 20 T, is generally insufficient to fulfill the requirements exceeding 40 kA, 20 T for conductors employed in these applications. A qualified REBCO cabling method that enhances current-carrying capacity and reduces AC losses is generally essential to bridge the existing gap. This article introduces a 100-kA class REBCO Rutherford cable, which offers advantages in high current-carrying capacity, low AC loss characteristics, and robust mechanical behavior. The current-carrying capacity, magnetic behavior, and AC loss characteristics of the REBCO Rutherford cable were evaluated using a bench-marked two-dimensional axisymmetric electro-thermal-mechanical coupling model based on finite element methods. The comparative evaluation of its current-carrying capacity and AC loss characteristics shows that it has a current-carrying capacity of 100 kA at 4.2 K, self-field. In addition, AC losses in the REBCO Rutherford cable are estimated to be lower within the scope of REBCO cables, suggesting significant potential for high-field applications, especially for the central solenoid coils of high-field thermonuclear fusion reactors.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10844535","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430483","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 : 2025-01-17DOI: 10.1109/TASC.2025.3530903
Riki Sakakibara;So Noguchi
High-temperature superconducting (HTS) applications are researched worldwide; such as MRI, NMR, particle accelerator, and compact fusion reactor. Especially, rare-earth barium copper oxide (REBCO), known as the second-generation HTS, is attract a lot of attentions because REBCO shows high performances under a high temperature and a high magnetic field. The NI winding technique can significantly improve the thermal stability of REBCO magnets, and it brings out the performance of REBCO conductors even more. One of the structures used to create magnets is the multi-bundled (MB) structure. It is now known that the use of the MB structure improves the excitation delay that originates from the NI winding structure. For bundled coils, the stress distribution in the coil has not yet been fully investigated. For further improving REBCO magnet technology, a few of the important research topics are the critical current deteriorations and the REBCO tape damages due to large hoop stresses. Since REBCO magnets are often used under high magnetic fields, strong electromagnetic forces are inevitably generated in the radial direction of REBCO pancake coils. As a dry winding is commonly employed for NI REBCO magnets, the REBCO-tape displacement in the circumferential direction occurs. That is, the hoop force acts to extend the REBCO tape in the winding direction. In the extended REBCO tapes, the deterioration of the superconducting properties and the damage of REBCO tapes would occur. In this study, the stress distribution of NI REBCO coils with MB structure was investigated considering the tape deformation.
{"title":"Numerical Investigation on Stress Distribution of Multi-Bundled NI REBCO Pancake Coils","authors":"Riki Sakakibara;So Noguchi","doi":"10.1109/TASC.2025.3530903","DOIUrl":"https://doi.org/10.1109/TASC.2025.3530903","url":null,"abstract":"High-temperature superconducting (HTS) applications are researched worldwide; such as MRI, NMR, particle accelerator, and compact fusion reactor. Especially, rare-earth barium copper oxide (REBCO), known as the second-generation HTS, is attract a lot of attentions because REBCO shows high performances under a high temperature and a high magnetic field. The NI winding technique can significantly improve the thermal stability of REBCO magnets, and it brings out the performance of REBCO conductors even more. One of the structures used to create magnets is the multi-bundled (MB) structure. It is now known that the use of the MB structure improves the excitation delay that originates from the NI winding structure. For bundled coils, the stress distribution in the coil has not yet been fully investigated. For further improving REBCO magnet technology, a few of the important research topics are the critical current deteriorations and the REBCO tape damages due to large hoop stresses. Since REBCO magnets are often used under high magnetic fields, strong electromagnetic forces are inevitably generated in the radial direction of REBCO pancake coils. As a dry winding is commonly employed for NI REBCO magnets, the REBCO-tape displacement in the circumferential direction occurs. That is, the hoop force acts to extend the REBCO tape in the winding direction. In the extended REBCO tapes, the deterioration of the superconducting properties and the damage of REBCO tapes would occur. In this study, the stress distribution of NI REBCO coils with MB structure was investigated considering the tape deformation.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-4"},"PeriodicalIF":1.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143183930","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 : 2025-01-17DOI: 10.1109/TASC.2025.3531253
Jingyi Liu;Zhen Lu;Lezhe Wang;Weihang Peng;Yutong Fu;Yawei Wang
A high temperature superconductor (HTS) magnet is an attractive solution for reducing energy consumption to generate a major-diameter, high-quality single silicon crystal. However, quench has been an urgent problem for the application of HTS coils. Rapidly discharging the current in the coil is a crucial part of quench protection. Previous studies have shown that the copper plates initially intended for support and cooling can accelerate the coil current discharging rate during fast energy extraction. However, it's unclear how the copper plates influence the discharging process of the large scale HTS magnet with a low magnetic field for a single silicon crystal growth system. This paper designs a HTS magnet for a single silicon crystal growth system and a detailed study of the electromagnetic thermal characteristics of the magnet coupled with copper plates and rings has been conducted through simulations. The results show that both the copper plates and the copper rings can absorb energy from the HTS coil through electromagnetic coupling and the copper plates perform better than the copper rings. The copper frame combined with the copper plates and rings shows the best performance in accelerating the current discharging rate as well as decreasing the hot spot temperature of the HTS coil. This copper frame is a promising structure for the quench protection of HTS magnets for a single silicon crystal growth system.
{"title":"Fast Current Discharging of High Temperature Superconductor Magnets for a Single Silicon Crystal Growth System by Self-Coupling Energy Absorption","authors":"Jingyi Liu;Zhen Lu;Lezhe Wang;Weihang Peng;Yutong Fu;Yawei Wang","doi":"10.1109/TASC.2025.3531253","DOIUrl":"https://doi.org/10.1109/TASC.2025.3531253","url":null,"abstract":"A high temperature superconductor (HTS) magnet is an attractive solution for reducing energy consumption to generate a major-diameter, high-quality single silicon crystal. However, quench has been an urgent problem for the application of HTS coils. Rapidly discharging the current in the coil is a crucial part of quench protection. Previous studies have shown that the copper plates initially intended for support and cooling can accelerate the coil current discharging rate during fast energy extraction. However, it's unclear how the copper plates influence the discharging process of the large scale HTS magnet with a low magnetic field for a single silicon crystal growth system. This paper designs a HTS magnet for a single silicon crystal growth system and a detailed study of the electromagnetic thermal characteristics of the magnet coupled with copper plates and rings has been conducted through simulations. The results show that both the copper plates and the copper rings can absorb energy from the HTS coil through electromagnetic coupling and the copper plates perform better than the copper rings. The copper frame combined with the copper plates and rings shows the best performance in accelerating the current discharging rate as well as decreasing the hot spot temperature of the HTS coil. This copper frame is a promising structure for the quench protection of HTS magnets for a single silicon crystal growth system.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143360951","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 : 2025-01-17DOI: 10.1109/TASC.2025.3530379
Tim Mulder;Gianluca Vernassa;Leon Teichröb;Bernardo Bordini;Patricia Borges de Sousa;Alexey Dudarev;Mariusz Wozniak;Arjan Verweij;Luca Bottura
The final stage of the cooling channel of a muon collider contains several cooling cells, each requiring a very high-field solenoid. Such a so-called ‘final cooling’ solenoid is key in strongly reducing the emittance of the beam during pre-acceleration and subsequent injection of the beam into the collider ring. In the muon collider design, about 12 to 14 final cooling solenoids of different lengths are foreseen. The conceptual design of the final cooling solenoid that is currently pursued has a homogeneous ($sim$1%) magnetic field of $>$40 T over a length of approximately 0.5 m and features a stack of 52 No-Insulation (NI) High-Temperature Superconductor (HTS) pancake coils. Its ramp scheme has been investigated and a ramp profile has been derived for a constant dissipation of 200 W during the majority of the ramp, while keeping the overall magnet characteristic time at 2700 s. Protection calculations have been performed and show that these solenoids require active quench protection at nominal field to limit the Lorentz forces and thus tape tensile and magnet radial stress during a quench. This contribution provides an overview of the current state of the thermo-electromagnetic design, operational aspects, and several simulated quench and protection scenarios for our design of a final cooling solenoid for a muon collider.
{"title":"Thermo-Electromagnetic Design, Operation, and Protection Simulations of a 40 T HTS NI Final Cooling Solenoid for a Muon Collider","authors":"Tim Mulder;Gianluca Vernassa;Leon Teichröb;Bernardo Bordini;Patricia Borges de Sousa;Alexey Dudarev;Mariusz Wozniak;Arjan Verweij;Luca Bottura","doi":"10.1109/TASC.2025.3530379","DOIUrl":"https://doi.org/10.1109/TASC.2025.3530379","url":null,"abstract":"The final stage of the cooling channel of a muon collider contains several cooling cells, each requiring a very high-field solenoid. Such a so-called ‘final cooling’ solenoid is key in strongly reducing the emittance of the beam during pre-acceleration and subsequent injection of the beam into the collider ring. In the muon collider design, about 12 to 14 final cooling solenoids of different lengths are foreseen. The conceptual design of the final cooling solenoid that is currently pursued has a homogeneous (<inline-formula><tex-math>$sim$</tex-math></inline-formula>1%) magnetic field of <inline-formula><tex-math>$>$</tex-math></inline-formula>40 T over a length of approximately 0.5 m and features a stack of 52 No-Insulation (NI) High-Temperature Superconductor (HTS) pancake coils. Its ramp scheme has been investigated and a ramp profile has been derived for a constant dissipation of 200 W during the majority of the ramp, while keeping the overall magnet characteristic time at 2700 s. Protection calculations have been performed and show that these solenoids require active quench protection at nominal field to limit the Lorentz forces and thus tape tensile and magnet radial stress during a quench. This contribution provides an overview of the current state of the thermo-electromagnetic design, operational aspects, and several simulated quench and protection scenarios for our design of a final cooling solenoid for a muon collider.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10845151","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143360960","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}
The inner triplet (or low-β) quadrupole magnets are among the components to be upgraded in LHC interaction regions for the HL-LHC project. The new quadrupole magnets, called MQXF, are based on Nb3Sn superconducting magnet technology, with a conductor peak field of 11.3 T. CERN is in charge of the fabrication of the MQXFB variant, the longest Nb3Sn accelerator magnets designed and manufactured up to now, with a magnetic length of 7.2 m. Two magnets, MQXFBP3 and MQXFB02, reached the HL-LHC project requirements. However, they still exhibited a limitation at 4.5 K with a phenomenology similar to the one observed on the first two prototypes. After improvements on the cold mass (longitudinal welding) and magnet assembly (elimination of overstress on the conductor during loading) procedures, a series of modifications were implemented in MQXFB03 at the level of the coil fabrication to address and/or reduce weaknesses in the coils. The magnet was tested and was the first to achieve performance requirements at both 1.9 K and 4.5 K, with no signs of conductor limitation at 4.5 K. MQXFB is now in the series production phase, with around 2/3 of the coils completed and half of the magnets assembled. We provide in this paper an overview of the MQXFB program, with a summary of the main recent achievements and an overall status of the fabrication.
{"title":"Status and Challenges in the MQXFB Nb3Sn Quadrupoles for the HL-LHC","authors":"Susana Izquierdo Bermudez;Giorgio Ambrosio;Jerome Axensalva;Amalia Ballarino;Lucie Baudin;Christian Barth;Nicolas Bourcey;Thierry Boutboul;Delio Duarte Ramos;Arnaud Devred;Sandor Feher;Paolo Ferracin;Jose Ferradas Troitino;Lucio Fiscarelli;Jerome Fleiter;Ludovic Grand-Clement;Michael Guinchard;Simon Hopkins;Nicholas Lusa;Franco Mangiarotti;Attilio Milanese;Francois-Olivier Pincot;Rosario Principe;Mariano Pentella;Juan Carlos Perez;Carlo Petrone;Penelope Quassolo;Piotr Rogacki;Simon Staarup;Herve Prin;Stephan Russenschuck;Ezio Todesco;Gerard Willering","doi":"10.1109/TASC.2025.3530911","DOIUrl":"https://doi.org/10.1109/TASC.2025.3530911","url":null,"abstract":"The inner triplet (or low-β) quadrupole magnets are among the components to be upgraded in LHC interaction regions for the HL-LHC project. The new quadrupole magnets, called MQXF, are based on Nb<sub>3</sub>Sn superconducting magnet technology, with a conductor peak field of 11.3 T. CERN is in charge of the fabrication of the MQXFB variant, the longest Nb<sub>3</sub>Sn accelerator magnets designed and manufactured up to now, with a magnetic length of 7.2 m. Two magnets, MQXFBP3 and MQXFB02, reached the HL-LHC project requirements. However, they still exhibited a limitation at 4.5 K with a phenomenology similar to the one observed on the first two prototypes. After improvements on the cold mass (longitudinal welding) and magnet assembly (elimination of overstress on the conductor during loading) procedures, a series of modifications were implemented in MQXFB03 at the level of the coil fabrication to address and/or reduce weaknesses in the coils. The magnet was tested and was the first to achieve performance requirements at both 1.9 K and 4.5 K, with no signs of conductor limitation at 4.5 K. MQXFB is now in the series production phase, with around 2/3 of the coils completed and half of the magnets assembled. We provide in this paper an overview of the MQXFB program, with a summary of the main recent achievements and an overall status of the fabrication.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-7"},"PeriodicalIF":1.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143369953","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 : 2025-01-17DOI: 10.1109/TASC.2025.3531344
Yujie Chen;Yutong Fu;Pai Peng;Jingyi Liu;Yawei Wang
High temperature superconducting (HTS) magnets have shown great potential on the development of high-field applications. However, non-uniform current margin inside the multi-pancake HTS magnet significantly limits its application on ultra-high field magnets, with a particularly higher quench risk for pancakes on both ends. Enhanced-homogeneous (EH) HTS magnets are a novel type of magnets that are composed of series-connected pancakes wound with graded numbers of parallel-stacked tapes, which offer a promising approach to improve the overall current-carrying capacity based on reduced tape consumption by homogenizing the safety transport current margin $I_{op}/ I_{c}$ (where $I_{op}$ is the transport current) distribution. However, this homogeneous transport current margin technique leads to a new magnetic field distribution and changes the screening effect of the magnet, which have not been studied. This work is to study the screening current and the induced magnetic field of high-field EH HTS magnets. A 2D-axisymmetric FEM model based on T-A formulation is used to calculate the electromagnetic behaviors of the magnet. A 3.3 T DEMO EH HTS magnet and its single-wound (SW) counterpart operating at 30 K are developed and analyzed. Results demonstrate that EH technique exacerbates the non-uniformity of the magnetic field. It also leads to an increase in screening current of the middle coils and remnant screening current induced field (SCIF).
{"title":"Screening Current and Induced Magnetic Field of High Temperature Superconducting Magnet With Enhanced Uniformity of Transport Current Margin","authors":"Yujie Chen;Yutong Fu;Pai Peng;Jingyi Liu;Yawei Wang","doi":"10.1109/TASC.2025.3531344","DOIUrl":"https://doi.org/10.1109/TASC.2025.3531344","url":null,"abstract":"High temperature superconducting (HTS) magnets have shown great potential on the development of high-field applications. However, non-uniform current margin inside the multi-pancake HTS magnet significantly limits its application on ultra-high field magnets, with a particularly higher quench risk for pancakes on both ends. Enhanced-homogeneous (EH) HTS magnets are a novel type of magnets that are composed of series-connected pancakes wound with graded numbers of parallel-stacked tapes, which offer a promising approach to improve the overall current-carrying capacity based on reduced tape consumption by homogenizing the safety transport current margin <inline-formula><tex-math>$I_{op}/ I_{c}$</tex-math></inline-formula> (where <inline-formula><tex-math>$I_{op}$</tex-math></inline-formula> is the transport current) distribution. However, this homogeneous transport current margin technique leads to a new magnetic field distribution and changes the screening effect of the magnet, which have not been studied. This work is to study the screening current and the induced magnetic field of high-field EH HTS magnets. A 2D-axisymmetric FEM model based on T-A formulation is used to calculate the electromagnetic behaviors of the magnet. A 3.3 T DEMO EH HTS magnet and its single-wound (SW) counterpart operating at 30 K are developed and analyzed. Results demonstrate that EH technique exacerbates the non-uniformity of the magnetic field. It also leads to an increase in screening current of the middle coils and remnant screening current induced field (SCIF).","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143183910","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}
No-Insulation (NI) REBCO coils are being considered for application in high-field whole-body magnetic resonance imaging (MRI). In such applications, the magnetic field generated by the coil must exhibit high spatial accuracy and temporal stability. However, in NI-REBCO coils, two key factors can compromise magnetic field accuracy: (1) irregular magnetic fields caused by screening currents induced in the REBCO tape and (2) excitation delays due to radial current flow during coil energization, which occur in the NI coil winding. To address issue 1, the “overshoot method”—in which the current is initially raised above the operating level before being reduced to the target operating value—has been confirmed to improve temporal magnetic field stability. However, the effectiveness of this method may be affected by issue 2, the excitation delay specific to NI coils. In this study, we explore the two electromagnetic phenomena unique to NI-REBCO coils, investigate the effects of both the overshoot method and a modified version incorporating a plateau, and ultimately determine the optimal current waveform for improving performance.
{"title":"Energization Current Waveform to Reduce Irregular Magnetic Fields in Multi-Stacked No-Insulation REBCO Coil Systems","authors":"Muku Yoshifuji;Ao Shimada;Atsushi Ishiyama;So Noguchi;Hiroshi Ueda","doi":"10.1109/TASC.2025.3531347","DOIUrl":"https://doi.org/10.1109/TASC.2025.3531347","url":null,"abstract":"No-Insulation (NI) REBCO coils are being considered for application in high-field whole-body magnetic resonance imaging (MRI). In such applications, the magnetic field generated by the coil must exhibit high spatial accuracy and temporal stability. However, in NI-REBCO coils, two key factors can compromise magnetic field accuracy: (1) irregular magnetic fields caused by screening currents induced in the REBCO tape and (2) excitation delays due to radial current flow during coil energization, which occur in the NI coil winding. To address issue 1, the “overshoot method”—in which the current is initially raised above the operating level before being reduced to the target operating value—has been confirmed to improve temporal magnetic field stability. However, the effectiveness of this method may be affected by issue 2, the excitation delay specific to NI coils. In this study, we explore the two electromagnetic phenomena unique to NI-REBCO coils, investigate the effects of both the overshoot method and a modified version incorporating a plateau, and ultimately determine the optimal current waveform for improving performance.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403812","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：