Pub Date : 2024-12-16DOI: 10.1109/TASC.2024.3514594
Mikko Kiviranta;Leif Grönberg
Biasing arrangements in multi-channel multi-stage SQUID amplifier systems, such as Transition Edge Sensor matrices for astronomical observation (Barrett et al., 2023) or quantum science (Hummatov et al., 2023), typically require a large number of wires. This is due to the need for two or more cascaded SQUID stages to obtain sufficiently large power gain over a sufficient bandwidth, and due to moderate obtainable multiplexing factors, which forces implementation of many parallel readout chains to serve all the sensor pixels. We suggest an arrangement where one bias line and one flux setpoint line are shared by two cascaded SQUID stages on a single chip, halving the number of lines two cascaded stages would ordinarily require. The stages are connected in series, sharing a single supply current , dual to ordinary integrated transistor circuits in which many transistor stages are connected in parallel and share a single supply voltage . We show experimental results at T = 4.2 K for a proof-of-concept amplifier chip, fabricated in the VTT Micronova foundry, using SWAPS Josephson junctions (Grönberg et al., 2017) at JC = 20 μA/(μm) 2 critical current density. The device shows larger than 3 kΩ transresistance, when operating from LIN = 29 nH input inductance to RD < 150 Ω output dynamic resistance.
{"title":"Two-Stage SQUID Amplifier With Bias Current Re-Use","authors":"Mikko Kiviranta;Leif Grönberg","doi":"10.1109/TASC.2024.3514594","DOIUrl":"https://doi.org/10.1109/TASC.2024.3514594","url":null,"abstract":"Biasing arrangements in multi-channel multi-stage SQUID amplifier systems, such as Transition Edge Sensor matrices for astronomical observation (Barrett et al., 2023) or quantum science (Hummatov et al., 2023), typically require a large number of wires. This is due to the need for two or more cascaded SQUID stages to obtain sufficiently large power gain over a sufficient bandwidth, and due to moderate obtainable multiplexing factors, which forces implementation of many parallel readout chains to serve all the sensor pixels. We suggest an arrangement where one bias line and one flux setpoint line are shared by two cascaded SQUID stages on a single chip, halving the number of lines two cascaded stages would ordinarily require. The stages are connected in series, sharing a single supply \u0000<italic>current</i>\u0000, dual to ordinary integrated transistor circuits in which many transistor stages are connected in parallel and share a single supply \u0000<italic>voltage</i>\u0000. We show experimental results at \u0000<italic>T</i>\u0000 = 4.2 K for a proof-of-concept amplifier chip, fabricated in the VTT Micronova foundry, using SWAPS Josephson junctions (Grönberg et al., 2017) at \u0000<italic>J<sub>C</sub></i>\u0000 = 20 μA/(μm)\u0000<sup>2</sup>\u0000 critical current density. The device shows larger than 3 kΩ transresistance, when operating from \u0000<italic>L<sub>IN</sub></i>\u0000 = 29 nH input inductance to \u0000<italic>R<sub>D</sub></i>\u0000 < 150 Ω output dynamic resistance.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-4"},"PeriodicalIF":1.7,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10804585","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142880377","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 : 2024-12-16DOI: 10.1109/TASC.2024.3518454
Antonio Bianchi
Niobium thin film radio-frequency (RF) cavities have historically shown performance degradation as the RF field progressively increases, posing limitations on their use in particle accelerators where the real-estate gradient has to be maximized. This issue, often referred to as the medium-field Q -slope problem, has not yet been fully understood and is the subject of ongoing research. This study analyzed the RF performance of several niobium thin film cavities reported in the literature. These cavities, with resonance frequencies ranging from 100 MHz to 1.5 GHz, were produced using a variety of coating techniques and manufacturing processes. Despite these notable differences, the field-dependent increase in surface resistance, when normalized by the resonance frequency, is consistently similar across all the niobium thin film cavities analyzed. Consequently, the Q -slope problem might not be strictly influenced by the specific treatments or coating techniques applied. Instead, it appears to be intrinsically associated with the interaction between the RF field and the superconductor, with the frequency of the field playing a significant role.
{"title":"A Comprehensive Analysis of Performance Degradation in Niobium Thin Film Radio-Frequency Cavities","authors":"Antonio Bianchi","doi":"10.1109/TASC.2024.3518454","DOIUrl":"https://doi.org/10.1109/TASC.2024.3518454","url":null,"abstract":"Niobium thin film radio-frequency (RF) cavities have historically shown performance degradation as the RF field progressively increases, posing limitations on their use in particle accelerators where the real-estate gradient has to be maximized. This issue, often referred to as the medium-field \u0000<italic>Q</i>\u0000-slope problem, has not yet been fully understood and is the subject of ongoing research. This study analyzed the RF performance of several niobium thin film cavities reported in the literature. These cavities, with resonance frequencies ranging from 100 MHz to 1.5 GHz, were produced using a variety of coating techniques and manufacturing processes. Despite these notable differences, the field-dependent increase in surface resistance, when normalized by the resonance frequency, is consistently similar across all the niobium thin film cavities analyzed. Consequently, the \u0000<italic>Q</i>\u0000-slope problem might not be strictly influenced by the specific treatments or coating techniques applied. Instead, it appears to be intrinsically associated with the interaction between the RF field and the superconductor, with the frequency of the field playing a significant role.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142912406","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}
Shorter period undulators typically require a higher on-axis magnetic field in order to achieve a practical deflection parameter, K . Recent simulations and experiments have demonstrated that high-temperature superconducting (HTS) undulators, constructed from staggered-array bulk superconductors, can generate high undulator fields with period length as short as 10 mm. This advanced HTS technology has the potential to significantly enhance the photon energy range of synchrotron radiation light sources and free electron laser facilities. This paper reports on the progress made in developing of a 50-period bulk HTS undulator with period length of 12 mm for Shanghai soft x-ray free electron laser facility. It details the engineering design of the undulator prototype, thermal and mechanical analysis of the HTS variable temperature insert, and the current status of the system.
{"title":"Progress in the Development of a 50-Period HTS Undulator for SXFEL","authors":"Kai Zhang;Dabin Wei;Zhuangwei Chen;Chan Liu;Yimin Tong;Difan Zhou;Chao Li;Marco Calvi;Anthony Dennis;John Durrell;Haixiao Deng;Zhentang Zhao","doi":"10.1109/TASC.2024.3519086","DOIUrl":"https://doi.org/10.1109/TASC.2024.3519086","url":null,"abstract":"Shorter period undulators typically require a higher on-axis magnetic field in order to achieve a practical deflection parameter, \u0000<italic>K</i>\u0000. Recent simulations and experiments have demonstrated that high-temperature superconducting (HTS) undulators, constructed from staggered-array bulk superconductors, can generate high undulator fields with period length as short as 10 mm. This advanced HTS technology has the potential to significantly enhance the photon energy range of synchrotron radiation light sources and free electron laser facilities. This paper reports on the progress made in developing of a 50-period bulk HTS undulator with period length of 12 mm for Shanghai soft x-ray free electron laser facility. It details the engineering design of the undulator prototype, thermal and mechanical analysis of the HTS variable temperature insert, and the current status of the system.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142912481","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 : 2024-12-16DOI: 10.1109/TASC.2024.3517669
Runar Mellerud;Matteo Leandro;Casper Leonard Klop;Christian Hartmann;Jonas Kristiansen Nøland
Accurate estimation of ac losses is crucial to successfully implement high-temperature superconductors (HTS) in the armature of electric machines. In this estimation, a purely sinusoidal current is often assumed. However, the connection to power electronic converters will introduce harmonics in the transport current, generally leading to higher losses. In this article, four separate distorted current waveforms produced by space vector modulation were implemented to assess how harmonics from power electronics influence the HTS ac losses in a 2.5 MW superconducting aviation motor. By varying the switching frequency between 5 and 40 kHz, the amount of harmonic distortion was varied between the four cases. The ReBCO and copper layers were both modeled using a multilayer H-A-formulated model. While the harmonic distortion was found to have a minor impact on ReBCO layer hysteresis losses, it increased eddy current losses in the copper stabilizer by between 250% and 471%, depending on the amount of distortion. Consequently, the total losses increased by between 60% and 123%, with a higher copper loss fraction.
{"title":"Influence of Harmonic Distortion on AC Losses in Converter-Fed Superconducting Electrical Machines","authors":"Runar Mellerud;Matteo Leandro;Casper Leonard Klop;Christian Hartmann;Jonas Kristiansen Nøland","doi":"10.1109/TASC.2024.3517669","DOIUrl":"https://doi.org/10.1109/TASC.2024.3517669","url":null,"abstract":"Accurate estimation of ac losses is crucial to successfully implement high-temperature superconductors (HTS) in the armature of electric machines. In this estimation, a purely sinusoidal current is often assumed. However, the connection to power electronic converters will introduce harmonics in the transport current, generally leading to higher losses. In this article, four separate distorted current waveforms produced by space vector modulation were implemented to assess how harmonics from power electronics influence the HTS ac losses in a 2.5 MW superconducting aviation motor. By varying the switching frequency between 5 and 40 kHz, the amount of harmonic distortion was varied between the four cases. The ReBCO and copper layers were both modeled using a multilayer H-A-formulated model. While the harmonic distortion was found to have a minor impact on ReBCO layer hysteresis losses, it increased eddy current losses in the copper stabilizer by between 250% and 471%, depending on the amount of distortion. Consequently, the total losses increased by between 60% and 123%, with a higher copper loss fraction.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 2","pages":"1-7"},"PeriodicalIF":1.7,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142890181","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 : 2024-12-16DOI: 10.1109/TASC.2024.3513288
Michael B. De Leon;Richard Pascua;Hyung-Seop Shin
In high-performance applications, the REBCO-coated conductor (CC) tapes are frequently pushed to their limits, resulting in fatigue-related failures, particularly at the vulnerable CC joint—a critical weak point in the structure of REBCO coils and magnets. This study investigates the influence of stress ratio ( R ) on the electromechanical durability of ultrasonically welded (UW) joints in two commercially available REBCO CC tapes. Employing a systematic approach, the research investigates fatigue behavior and cumulative damage under varied R values (0.1 and 0.5). Low-cycle fatigue (LCF) tests at 0.02 Hz provide in-depth insights into the fatigue behavior of each CC tape joint. Utilizing a flux-free hybrid welding approach, the study analyzes joint enhancement, electromechanical properties at varying R under LCF. Results reveal a clear R dependence of fatigue behavior in REBCO CC joints. Specifically, at a particular R , employing R = 0.1 results in a gradual degradation of critical current ( I c ), while R = 0.5 induces a considerably faster and less recoverable I c decline. The results highlight the interaction between R and fatigue cycles in REBCO joints, emphasizing the need for additional investigation across a broader spectrum of materials to comprehensively understand and optimize their performance in CC coils and magnets.
{"title":"Effects of Stress Ratio on Low-Cycle Fatigue Performance of Various REBCO CC Lap Joints at 77 K","authors":"Michael B. De Leon;Richard Pascua;Hyung-Seop Shin","doi":"10.1109/TASC.2024.3513288","DOIUrl":"https://doi.org/10.1109/TASC.2024.3513288","url":null,"abstract":"In high-performance applications, the REBCO-coated conductor (CC) tapes are frequently pushed to their limits, resulting in fatigue-related failures, particularly at the vulnerable CC joint—a critical weak point in the structure of REBCO coils and magnets. This study investigates the influence of stress ratio (\u0000<italic>R</i>\u0000) on the electromechanical durability of ultrasonically welded (UW) joints in two commercially available REBCO CC tapes. Employing a systematic approach, the research investigates fatigue behavior and cumulative damage under varied \u0000<italic>R</i>\u0000 values (0.1 and 0.5). Low-cycle fatigue (LCF) tests at 0.02 Hz provide in-depth insights into the fatigue behavior of each CC tape joint. Utilizing a flux-free hybrid welding approach, the study analyzes joint enhancement, electromechanical properties at varying \u0000<italic>R</i>\u0000 under LCF. Results reveal a clear \u0000<italic>R</i>\u0000 dependence of fatigue behavior in REBCO CC joints. Specifically, at a particular \u0000<italic>R</i>\u0000, employing \u0000<italic>R</i>\u0000 = 0.1 results in a gradual degradation of critical current (\u0000<italic>I</i>\u0000<sub>c</sub>\u0000), while \u0000<italic>R</i>\u0000 = 0.5 induces a considerably faster and less recoverable \u0000<italic>I</i>\u0000<sub>c</sub>\u0000 decline. The results highlight the interaction between \u0000<italic>R</i>\u0000 and fatigue cycles in REBCO joints, emphasizing the need for additional investigation across a broader spectrum of materials to comprehensively understand and optimize their performance in CC coils and magnets.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142918209","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}
Accurate estimation of AC losses is crucial for designing superconducting motors with high output power, lightweight, and safety, particularly for aircraft applications. This study examined the AC losses in a horizontal array of REBa 2 Cu 3 O y tapes to develop an accurate method for estimating AC losses in motors. The AC losses of the short tape samples and coil samples were measured. The characteristic parameters included the number of tapes/coils, n , and the distance between the tapes/coils normalized by the width of the superconducting layer, g / w . For small amplitudes of the applied field, the AC loss was found to be influenced by n and g / w . As n increased or g / w decreased, the AC loss increased. In addition, the applicability of the proposed AC loss estimation method is verified.
{"title":"AC Loss Property of Horizontal Array of Isolated REBCO Superconducting Tapes and Pancake Coils","authors":"Hiromasa Sasa;Ryoma Oishi;Yuji Nishida;Yuuki Himeno;Takaemi Suenaga;Shun Miura;Hiroshi Miyazaki;Masataka Iwakuma","doi":"10.1109/TASC.2024.3518453","DOIUrl":"https://doi.org/10.1109/TASC.2024.3518453","url":null,"abstract":"Accurate estimation of AC losses is crucial for designing superconducting motors with high output power, lightweight, and safety, particularly for aircraft applications. This study examined the AC losses in a horizontal array of REBa\u0000<sub>2</sub>\u0000Cu\u0000<sub>3</sub>\u0000O\u0000<italic><sub>y</sub></i>\u0000 tapes to develop an accurate method for estimating AC losses in motors. The AC losses of the short tape samples and coil samples were measured. The characteristic parameters included the number of tapes/coils, \u0000<italic>n</i>\u0000, and the distance between the tapes/coils normalized by the width of the superconducting layer, \u0000<italic>g</i>\u0000/\u0000<italic>w</i>\u0000. For small amplitudes of the applied field, the AC loss was found to be influenced by \u0000<italic>n</i>\u0000 and \u0000<italic>g</i>\u0000/\u0000<italic>w</i>\u0000. As \u0000<italic>n</i>\u0000 increased or \u0000<italic>g</i>\u0000/\u0000<italic>w</i>\u0000 decreased, the AC loss increased. In addition, the applicability of the proposed AC loss estimation method is verified.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142912479","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 : 2024-12-16DOI: 10.1109/TASC.2024.3517552
Lorenzo Balconi;Gabriele Crespi;Danilo Pedrini;Lucio Rossi;Carlo Santini;Stefano Sorti;Marco Statera
REBCO tapes stand out as the most promising conductors for various applications, spanning physics experiments and societal use. Manufactured through a now-consolidated yet intricate process, these tapes yield continuous pieces reaching hundreds of meters. However, this process limits the length of tape that can be wound into a coil without requiring internal splicing. Splices are inherently the weakest points in the coil due to heat generation and reduced current-carrying performance. While small non-insulated coils naturally self-protect against splice-related risks through current bypassing, larger coils, conduction-cooled, or partially insulated ones often experience a diminished self-protecting behaviour, necessitating careful consideration of splices in the coil design. Moreover, larger magnets often relies on multiple cable co-winding, making this issue more challenging to explore and to understand. To this purpose, this study aims at investigating various joint layouts for double tape HTS cable through electrical experiments. The manufacturing procedure, along with the measured performances of the different splice geometries produced using various brazing alloys and fluxes, is discussed. Finally, numerical models with lumped elements are utilized to analyse experimental results and to describe the joint behaviour. This work serves as an initial step toward a splice-inclusive design approach for magnets.
{"title":"Optimization of Internal Splicing for Non-Insulated HTS Magnets","authors":"Lorenzo Balconi;Gabriele Crespi;Danilo Pedrini;Lucio Rossi;Carlo Santini;Stefano Sorti;Marco Statera","doi":"10.1109/TASC.2024.3517552","DOIUrl":"https://doi.org/10.1109/TASC.2024.3517552","url":null,"abstract":"REBCO tapes stand out as the most promising conductors for various applications, spanning physics experiments and societal use. Manufactured through a now-consolidated yet intricate process, these tapes yield continuous pieces reaching hundreds of meters. However, this process limits the length of tape that can be wound into a coil without requiring internal splicing. Splices are inherently the weakest points in the coil due to heat generation and reduced current-carrying performance. While small non-insulated coils naturally self-protect against splice-related risks through current bypassing, larger coils, conduction-cooled, or partially insulated ones often experience a diminished self-protecting behaviour, necessitating careful consideration of splices in the coil design. Moreover, larger magnets often relies on multiple cable co-winding, making this issue more challenging to explore and to understand. To this purpose, this study aims at investigating various joint layouts for double tape HTS cable through electrical experiments. The manufacturing procedure, along with the measured performances of the different splice geometries produced using various brazing alloys and fluxes, is discussed. Finally, numerical models with lumped elements are utilized to analyse experimental results and to describe the joint behaviour. This work serves as an initial step toward a splice-inclusive design approach for magnets.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938164","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 : 2024-12-16DOI: 10.1109/TASC.2024.3519072
Yuanhang Pan;Jiangtao Yang;Qing Li;Shoudao Huang;Jun Ma
The high temperature superconducting homopolar inductor alternator (HTS-HIA) connected with a high-speed gas turbine can achieve higher efficiency and higher power density. However, limited by the insulation and quench of the HTS winding, the HTS-HIA cannot change excitation current quickly to meet the requirements of output voltage regulation. To satisfy the load demand of multiple voltage levels, a novel hybrid excitation HTS-HIA (HEHTS-HIA) is proposed in this paper. Its excitation windings include a HTS winding and an adjusting winding made of copper wire. In steady-state operation, only the HTS winding carries the excitation current, while the adjusting winding only operates when the output voltage needs to be regulated. Firstly, the structure and operation principle of the proposed HEHTS-HIA is illustrated. To describe the principle of voltage regulation, the equivalent circuits of HTS winding and adjusting winding are established. Then, the electromagnetic performance of HEHTS-HIA is analyzed, including adjusting characteristics, response speed, transient characteristics and output performance. The results show that the proposed HEHTS-HIA can achieve a full range of voltage regulation under the premise of ensuring the safety of HTS winding, indicating that the proposed HEHTS-HIA is a promising candidate for the application of aviation turbo-electric system.
{"title":"Novel Hybrid Excitation High Temperature Superconducting Homopolar Inductor Alternator for Aviation Turbo-Electric System","authors":"Yuanhang Pan;Jiangtao Yang;Qing Li;Shoudao Huang;Jun Ma","doi":"10.1109/TASC.2024.3519072","DOIUrl":"https://doi.org/10.1109/TASC.2024.3519072","url":null,"abstract":"The high temperature superconducting homopolar inductor alternator (HTS-HIA) connected with a high-speed gas turbine can achieve higher efficiency and higher power density. However, limited by the insulation and quench of the HTS winding, the HTS-HIA cannot change excitation current quickly to meet the requirements of output voltage regulation. To satisfy the load demand of multiple voltage levels, a novel hybrid excitation HTS-HIA (HEHTS-HIA) is proposed in this paper. Its excitation windings include a HTS winding and an adjusting winding made of copper wire. In steady-state operation, only the HTS winding carries the excitation current, while the adjusting winding only operates when the output voltage needs to be regulated. Firstly, the structure and operation principle of the proposed HEHTS-HIA is illustrated. To describe the principle of voltage regulation, the equivalent circuits of HTS winding and adjusting winding are established. Then, the electromagnetic performance of HEHTS-HIA is analyzed, including adjusting characteristics, response speed, transient characteristics and output performance. The results show that the proposed HEHTS-HIA can achieve a full range of voltage regulation under the premise of ensuring the safety of HTS winding, indicating that the proposed HEHTS-HIA is a promising candidate for the application of aviation turbo-electric system.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142905736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have proposed a high-temperature superconducting (HTS) air-core cyclotron for cancer therapy, called the Skeleton Cyclotron. The design of a full-scale Skeleton Cyclotron is currently underway. The magnetic field in the acceleration plane of the cyclotron requires both an isochronous field and an azimuthally varying field (AVF). Particles deviating from the orbit and the median plane are focused and defocused, respectively. In conventional cyclotrons using copper wire and iron cores, the iron poles are machined into a spiral shape to ensure a focusing force. Our proposed Skeleton Cyclotron is an air-core design, consisting of several circular-shaped main coils and triangular-shaped sector coils wound with REBCO tape. In this design, the iron sectors are replaced by triangular HTS sector coils. The axial focusing force for accelerated particles is generated by the flutter produced by these triangular-shaped sector coils. However, winding REBCO wire into the spiral sector-type coil with negative bend curvatures is technically challenging. Therefore, we considered the use of multiple straight sector coils wound with REBCO tape. Moreover, by independently adjusting the operating currents in the sector coils, we can freely manipulate the generated magnetic field, enabling the acceleration of various types of beams within a single cyclotron. In this study, we designed multiple sector coils, evaluated the reproduction of the AVF for variable energy, and conducted orbital simulations of accelerating particles.
{"title":"Design of Multiple REBCO Sector Coils for Improving Focusing Force in Skeleton Cyclotron for Cancer Therapy","authors":"Aoi Yamashita;Ryota Inoue;SeokBeom Kim;So Noguchi;Tomonori Watanabe;Mitsuhiro Fukuda;Atsushi Ishiyama;Hiroshi Ueda","doi":"10.1109/TASC.2024.3514595","DOIUrl":"https://doi.org/10.1109/TASC.2024.3514595","url":null,"abstract":"We have proposed a high-temperature superconducting (HTS) air-core cyclotron for cancer therapy, called the Skeleton Cyclotron. The design of a full-scale Skeleton Cyclotron is currently underway. The magnetic field in the acceleration plane of the cyclotron requires both an isochronous field and an azimuthally varying field (AVF). Particles deviating from the orbit and the median plane are focused and defocused, respectively. In conventional cyclotrons using copper wire and iron cores, the iron poles are machined into a spiral shape to ensure a focusing force. Our proposed Skeleton Cyclotron is an air-core design, consisting of several circular-shaped main coils and triangular-shaped sector coils wound with REBCO tape. In this design, the iron sectors are replaced by triangular HTS sector coils. The axial focusing force for accelerated particles is generated by the flutter produced by these triangular-shaped sector coils. However, winding REBCO wire into the spiral sector-type coil with negative bend curvatures is technically challenging. Therefore, we considered the use of multiple straight sector coils wound with REBCO tape. Moreover, by independently adjusting the operating currents in the sector coils, we can freely manipulate the generated magnetic field, enabling the acceleration of various types of beams within a single cyclotron. In this study, we designed multiple sector coils, evaluated the reproduction of the AVF for variable energy, and conducted orbital simulations of accelerating particles.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142890281","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 : 2024-12-16DOI: 10.1109/TASC.2024.3516728
Panpan Chen;Yue Liu;Jiahui Zhu
Superconducting synchronous condensers have the capability of quick reactive power regulation and play an important role in maintaining the stability of renewable energy grid. In this paper, the structural and electromagnetic parameters of a 50 Mvar, 10.5 kV high temperature superconducting (HTS) synchronous condenser are designed. For the rotor, only the yoke is retained, forming an air-core superconducting rotor. The field windings are made of rare earth barium copper oxide (REBCO), cooled by helium gas and operate at the temperature of 30 K. The rated no-load field current is in consideration of the maximum magnetic field at the end of the field windings, so that quench can be suppressed. As for the stator, non-magnetic stator teeth are adopted, and the armature windings are supported by epoxy resin, which can effectively restrain the ferromagnetic teeth from saturation. The armature windings are distributed at two layers and composed of thin Litz copper wires. The internal magnetic field distribution of the superconducting synchronous condenser is preliminarily obtained by constructing a two-dimensional (2D) finite element model. It is found that the maximum magnetic flux density in the air gap is 1.6 T, and the no-load electromotive force (EMF) varies linearly with the field current. The simulation results validate the design scheme and provide a theoretical basis for manufacturing a prototype in the future.
{"title":"Structural Design and Electromagnetic Performance of 50 Mvar HTS Synchronous Condenser","authors":"Panpan Chen;Yue Liu;Jiahui Zhu","doi":"10.1109/TASC.2024.3516728","DOIUrl":"https://doi.org/10.1109/TASC.2024.3516728","url":null,"abstract":"Superconducting synchronous condensers have the capability of quick reactive power regulation and play an important role in maintaining the stability of renewable energy grid. In this paper, the structural and electromagnetic parameters of a 50 Mvar, 10.5 kV high temperature superconducting (HTS) synchronous condenser are designed. For the rotor, only the yoke is retained, forming an air-core superconducting rotor. The field windings are made of rare earth barium copper oxide (REBCO), cooled by helium gas and operate at the temperature of 30 K. The rated no-load field current is in consideration of the maximum magnetic field at the end of the field windings, so that quench can be suppressed. As for the stator, non-magnetic stator teeth are adopted, and the armature windings are supported by epoxy resin, which can effectively restrain the ferromagnetic teeth from saturation. The armature windings are distributed at two layers and composed of thin Litz copper wires. The internal magnetic field distribution of the superconducting synchronous condenser is preliminarily obtained by constructing a two-dimensional (2D) finite element model. It is found that the maximum magnetic flux density in the air gap is 1.6 T, and the no-load electromotive force (EMF) varies linearly with the field current. The simulation results validate the design scheme and provide a theoretical basis for manufacturing a prototype in the future.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938207","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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