We report the niobium titanium nitride (NbTiN) superconducting strip photon detectors (SSPDs) with strip widths ranging from 0.1 to 30 µm. The bias current dependences of the detection efficiencies at the 1550 nm wavelength and the dark count rates were systematically evaluated in the wide range of the strip widths. Single-photon detection was confirmed and a saturation trend in the bias current dependence of detection efficiency was also observed for all strip width SSPDs. In addition, we measured the physical properties of the NbTiN films and found the switching current of SSPDs gradually deviated lower from the estimated depairing current with increasing the strip width. Furthermore, the dark counts occurred at the lower bias current relative to the depairing current as the strip width increased. These results suggest that the bias current is unevenly distributed as the strip width increases and the concentrated bias current may induce the dark counts. Our results would provide valuable insights into a better understanding of SSPDs with a wide range of strip widths, the origin of dark counts, and the mechanism of photon detection in superconducting strip.
{"title":"Evaluation of NbTiN Superconducting Strip Photon Detectors With 0.1–30 µm Strip Widths","authors":"Tomohiro Haneishi;Masahiro Yabuno;Hiroki Kutsuma;Shigehito Miki;Taro Yamashita","doi":"10.1109/TASC.2024.3521901","DOIUrl":"https://doi.org/10.1109/TASC.2024.3521901","url":null,"abstract":"We report the niobium titanium nitride (NbTiN) superconducting strip photon detectors (SSPDs) with strip widths ranging from 0.1 to 30 µm. The bias current dependences of the detection efficiencies at the 1550 nm wavelength and the dark count rates were systematically evaluated in the wide range of the strip widths. Single-photon detection was confirmed and a saturation trend in the bias current dependence of detection efficiency was also observed for all strip width SSPDs. In addition, we measured the physical properties of the NbTiN films and found the switching current of SSPDs gradually deviated lower from the estimated depairing current with increasing the strip width. Furthermore, the dark counts occurred at the lower bias current relative to the depairing current as the strip width increased. These results suggest that the bias current is unevenly distributed as the strip width increases and the concentrated bias current may induce the dark counts. Our results would provide valuable insights into a better understanding of SSPDs with a wide range of strip widths, the origin of dark counts, and the mechanism of photon detection in superconducting strip.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938211","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}
A spacecraft re-entering the Earth's atmosphere must endure extremely high heat loads. These heat loads are created by the rapid deceleration of the spacecraft causing shock waves which in turn create a high-temperature plasma. Passive thermal protection based on ablative materials is the current solution for spacecraft heat shielding, but it is limited by material durability. As an alternative, magnetic heat shielding has shown great potential to deflect and redirect the plasma. However, fully understanding of the concept requires further experimental validation. Paihau-Robinson Research Institute has designed and built a high-temperature superconductor (HTS) system, which will be used to test the magnetic heat shielding concept at the German Aerospace Centre's (DLR) shock tunnel, where realistic flow conditions for hypersonic flight configurations are created. This paper reports the design of the HTS system with some preliminary experimental results on its performance. The shock wave stand-off distance is calculated based on the designed field (2T), which will be compared with the experimental data using a high-speed camera at DLR's shock tunnel in 2025.
{"title":"Investigation of Magnetic Heat Shielding During Spacecraft Re-Entry Using HTS Magnet – Preliminary Experimental Design","authors":"Xiyong Huang;Ben Parkinson;Nicholas Strickland;Steven Smart;Joseph Bailey;Vishnu Asokakumar Sreekala;Tulasi Parashar;Jakub Glowacki;Nicholas Long;Hubertus Weijers","doi":"10.1109/TASC.2024.3521904","DOIUrl":"https://doi.org/10.1109/TASC.2024.3521904","url":null,"abstract":"A spacecraft re-entering the Earth's atmosphere must endure extremely high heat loads. These heat loads are created by the rapid deceleration of the spacecraft causing shock waves which in turn create a high-temperature plasma. Passive thermal protection based on ablative materials is the current solution for spacecraft heat shielding, but it is limited by material durability. As an alternative, magnetic heat shielding has shown great potential to deflect and redirect the plasma. However, fully understanding of the concept requires further experimental validation. Paihau-Robinson Research Institute has designed and built a high-temperature superconductor (HTS) system, which will be used to test the magnetic heat shielding concept at the German Aerospace Centre's (DLR) shock tunnel, where realistic flow conditions for hypersonic flight configurations are created. This paper reports the design of the HTS system with some preliminary experimental results on its performance. The shock wave stand-off distance is calculated based on the designed field (2T), which will be compared with the experimental data using a high-speed camera at DLR's shock tunnel in 2025.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-6"},"PeriodicalIF":1.7,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938165","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 : 2024-12-24DOI: 10.1109/TASC.2024.3521900
M. de Wit;L. Gottardi;K. Nagayoshi;E. Taralli;D. Vaccaro;K. Ravensberg;M.P. Bruijn;J. van der Kuur;J.R. Gao;J.W.A. den Herder
The X-ray Integral Field Unit (X-IFU) is an imaging spectrometer based on a large array of Transition Edge Sensors (TES) measured using Time Domain Multiplexing (TDM). For the development of a backup detector array, we have designed and realized a cryogenic test setup capable of measuring 9 detectors in a single cooldown under DC bias. We have used this setup to study a small selection of low aspect ratio TES designs, intended to have a low normal resistance suitable for TDM readout. In this work we show how the different designs are affected by magnetic fields. We do this by presenting the impact on the transition shape, detector integrated Noise Equivalent Power (NEP), and sensitivity of the energy scale calibration. We find, in agreement with previous studies, that reducing the width of the TES bilayer greatly improves the detector resilience to magnetic fields, potentially by several orders of magnitude.
{"title":"Transition Edge Sensors for DC Operation and Low Magnetic Field Sensitivity","authors":"M. de Wit;L. Gottardi;K. Nagayoshi;E. Taralli;D. Vaccaro;K. Ravensberg;M.P. Bruijn;J. van der Kuur;J.R. Gao;J.W.A. den Herder","doi":"10.1109/TASC.2024.3521900","DOIUrl":"https://doi.org/10.1109/TASC.2024.3521900","url":null,"abstract":"The X-ray Integral Field Unit (X-IFU) is an imaging spectrometer based on a large array of Transition Edge Sensors (TES) measured using Time Domain Multiplexing (TDM). For the development of a backup detector array, we have designed and realized a cryogenic test setup capable of measuring 9 detectors in a single cooldown under DC bias. We have used this setup to study a small selection of low aspect ratio TES designs, intended to have a low normal resistance suitable for TDM readout. In this work we show how the different designs are affected by magnetic fields. We do this by presenting the impact on the transition shape, detector integrated Noise Equivalent Power (NEP), and sensitivity of the energy scale calibration. We find, in agreement with previous studies, that reducing the width of the TES bilayer greatly improves the detector resilience to magnetic fields, potentially by several orders of magnitude.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142940752","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 : 2024-12-24DOI: 10.1109/TASC.2024.3522067
Alexander J. Brooks;Jay C. LeFebvre;Joseph A. Forman;Sreekar Vattipalli;Alex Belianinov;Michael Titze;Shane A. Cybart
In this work, we study cobalt (Co) ion implantation into YBCO thin film, and correlate irradiation parameters with electrical transport measurements. 40 keV Co ions were implanted into patterned electrodes at fluences ranging from 1 × 10 13 to 3 × 10 14 ions/cm 2 , and we report the temperature dependence of the resistivity of the implanted regions. For the highest fluence we observe five orders of magnitude higher resistivity than in the untreated film. Stopping and Range of Ions in Matter (SRIM) ion implantation simulations show that the average range of the implant was in the center of the film. This work demonstrates a high throughput means to directly pattern YBCO films using direct write lithography platforms as an alternative to conventional photolithography and argon ion etching.
{"title":"Electrical Characterization of Co Implanted Y-Ba-Cu-O Thin Films","authors":"Alexander J. Brooks;Jay C. LeFebvre;Joseph A. Forman;Sreekar Vattipalli;Alex Belianinov;Michael Titze;Shane A. Cybart","doi":"10.1109/TASC.2024.3522067","DOIUrl":"https://doi.org/10.1109/TASC.2024.3522067","url":null,"abstract":"In this work, we study cobalt (Co) ion implantation into YBCO thin film, and correlate irradiation parameters with electrical transport measurements. 40 keV Co ions were implanted into patterned electrodes at fluences ranging from 1 × 10\u0000<sup>13</sup>\u0000 to 3 × 10\u0000<sup>14</sup>\u0000 ions/cm\u0000<sup>2</sup>\u0000, and we report the temperature dependence of the resistivity of the implanted regions. For the highest fluence we observe five orders of magnitude higher resistivity than in the untreated film. Stopping and Range of Ions in Matter (SRIM) ion implantation simulations show that the average range of the implant was in the center of the film. This work demonstrates a high throughput means to directly pattern YBCO films using direct write lithography platforms as an alternative to conventional photolithography and argon ion etching.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-3"},"PeriodicalIF":1.7,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937873","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 : 2024-12-24DOI: 10.1109/TASC.2024.3521894
Alejandro Simon;Reed Foster;Owen Medeiros;Matteo Castellani;Emma Batson;Karl K. Berggren
The scaling of superconducting nanowire detectors to larger arrays is often limited by room-temperature-readout cabling. Cryogenic integrated circuits constructed from nanowire cryotrons, or nanocryotrons, can address this limitation by performing signal processing on chip. In this study, we characterize key performance metrics of the nanocryotron to elucidate its potential as a logical element in cryogenic integrated circuits and develop an electro-thermal model to connect material parameters with device performance. We find that the performance of the nanocryotron depends on the device geometry, and trade-offs are associated with optimizing the gain, jitter, and energy dissipation. We demonstrate that nanocryotrons fabricated on niobium nitride can achieve a grey zone less than 210 nA wide for a 5 ns long input pulse corresponding to a maximum achievable gain of 48 dB, an energy dissipation of less than 20 aJ per operation, and a jitter of less than 60 ps.
{"title":"Characterizing and Modeling the Influence of Geometry on the Performance of Superconducting Nanowire Cryotrons","authors":"Alejandro Simon;Reed Foster;Owen Medeiros;Matteo Castellani;Emma Batson;Karl K. Berggren","doi":"10.1109/TASC.2024.3521894","DOIUrl":"https://doi.org/10.1109/TASC.2024.3521894","url":null,"abstract":"The scaling of superconducting nanowire detectors to larger arrays is often limited by room-temperature-readout cabling. Cryogenic integrated circuits constructed from nanowire cryotrons, or nanocryotrons, can address this limitation by performing signal processing on chip. In this study, we characterize key performance metrics of the nanocryotron to elucidate its potential as a logical element in cryogenic integrated circuits and develop an electro-thermal model to connect material parameters with device performance. We find that the performance of the nanocryotron depends on the device geometry, and trade-offs are associated with optimizing the gain, jitter, and energy dissipation. We demonstrate that nanocryotrons fabricated on niobium nitride can achieve a grey zone less than 210 nA wide for a 5 ns long input pulse corresponding to a maximum achievable gain of 48 dB, an energy dissipation of less than 20 aJ per operation, and a jitter of less than 60 ps.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938210","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 : 2024-12-24DOI: 10.1109/TASC.2024.3521917
Ben George Koshy;Konstantinos Bouloukakis;Mark Ainslie;Yueming Sun;Rodney A. Badcock;Benjamin P.P. Mallett;Zhenan Jiang
No-insulation (NI) high-temperature superconductor (HTS) coils possess inherent advantages compared with their insulated (INS) counterparts, including enhanced current density, improved mechanical integrity, thermal stability, and self-protecting properties, making them a more appealing technological choice for high-field magnets, rotating machines, and linear propulsion applications. In many such applications, the coils are exposed to time-varying magnetic fields which results in magnetization loss. This loss, which creates a heat load that could significantly impact the cryogenic system, has yet to be well characterized and understood for NI coils. In this study, magnetization loss in a double-pancake, solder-impregnated NI coil wound HTS-coated conductor is investigated both experimentally and numerically at 77 K. The amplitude of the applied ac field is varied between 10 and 100 mT with frequency varying from 72 to 145 Hz and field orientation varying between parallel to perpendicular with respect to the normal vector of the conductor surface of the coil. The experimental results showed no frequency dependence and no clear angular dependence with the loss essentially equal between parallel and perpendicular fields, in striking contrast to INS coils. Numerical analysis carried out in a 2D configuration for parallel fields was able to reproduce the relevant experimental data. The current density and magnetic field distributions calculated from the analysis show that the NI coil can completely shield its inner turns, attributed to the effective shielding provided by the radial and screening currents. As such the magnetization loss characteristics of NI coils are better understood as those of an HTS bulk, rather than of a coil.
{"title":"Magnetization Loss and Its Angular Dependence in a No-Insulation HTS REBCO Double-Pancake Coil","authors":"Ben George Koshy;Konstantinos Bouloukakis;Mark Ainslie;Yueming Sun;Rodney A. Badcock;Benjamin P.P. Mallett;Zhenan Jiang","doi":"10.1109/TASC.2024.3521917","DOIUrl":"https://doi.org/10.1109/TASC.2024.3521917","url":null,"abstract":"No-insulation (NI) high-temperature superconductor (HTS) coils possess inherent advantages compared with their insulated (INS) counterparts, including enhanced current density, improved mechanical integrity, thermal stability, and self-protecting properties, making them a more appealing technological choice for high-field magnets, rotating machines, and linear propulsion applications. In many such applications, the coils are exposed to time-varying magnetic fields which results in magnetization loss. This loss, which creates a heat load that could significantly impact the cryogenic system, has yet to be well characterized and understood for NI coils. In this study, magnetization loss in a double-pancake, solder-impregnated NI coil wound HTS-coated conductor is investigated both experimentally and numerically at 77 K. The amplitude of the applied ac field is varied between 10 and 100 mT with frequency varying from 72 to 145 Hz and field orientation varying between parallel to perpendicular with respect to the normal vector of the conductor surface of the coil. The experimental results showed no frequency dependence and no clear angular dependence with the loss essentially equal between parallel and perpendicular fields, in striking contrast to INS coils. Numerical analysis carried out in a 2D configuration for parallel fields was able to reproduce the relevant experimental data. The current density and magnetic field distributions calculated from the analysis show that the NI coil can completely shield its inner turns, attributed to the effective shielding provided by the radial and screening currents. As such the magnetization loss characteristics of NI coils are better understood as those of an HTS bulk, rather than of a coil.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 2","pages":"1-9"},"PeriodicalIF":1.7,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we report the development of a low-power single-flux-quantum (SFQ) standard cell library and experimental results, including the cell design, high-speed test of shift-registers, delay measurement using ring oscillators, and demonstration of simple demultiplexers. We fabricated the SFQ circuits using a lowered critical current density (250 A/cm $^{2}$ ) process and low-voltage design (0.5 or 0.1 mV). We reduced the power consumption to 1/50 or 1/250 from the conventional SFQ circuits operating at 4.2 K. We designed several essential SFQ cells, including wiring elements, flip-flops, and logic gates with the fabrication process using four planarized Nb layers and obtained the correct operation at 0.3 K. We tested 8-bit shift-registers aiming to evaluate the operating frequency of the developed SFQ cells. The 0.1-mV shift-registers operated up to 8.5 GHz. The experimental results of ring oscillators showed good agreement with the analog circuit simulation results. We believe that our experimentally-verified standard cell library is ready to use for SFQ-based digital control of qubits, such as demultiplexing of control signals, and the timing information and power consumption will be valuable information as the baseline to discuss future scalable quantum computer systems.
{"title":"Low-Power Single-Flux-Quantum Standard Cell Library Using 250 A/cm$^{2}$ Process for Qubit Control Applications","authors":"Masamitsu Tanaka;Yoshihiro Kitagawa;Tetsuro Satoh;Tsuyoshi Yamamoto","doi":"10.1109/TASC.2024.3521892","DOIUrl":"https://doi.org/10.1109/TASC.2024.3521892","url":null,"abstract":"In this paper, we report the development of a low-power single-flux-quantum (SFQ) standard cell library and experimental results, including the cell design, high-speed test of shift-registers, delay measurement using ring oscillators, and demonstration of simple demultiplexers. We fabricated the SFQ circuits using a lowered critical current density (250 A/cm\u0000<inline-formula><tex-math>$^{2}$</tex-math></inline-formula>\u0000) process and low-voltage design (0.5 or 0.1 mV). We reduced the power consumption to 1/50 or 1/250 from the conventional SFQ circuits operating at 4.2 K. We designed several essential SFQ cells, including wiring elements, flip-flops, and logic gates with the fabrication process using four planarized Nb layers and obtained the correct operation at 0.3 K. We tested 8-bit shift-registers aiming to evaluate the operating frequency of the developed SFQ cells. The 0.1-mV shift-registers operated up to 8.5 GHz. The experimental results of ring oscillators showed good agreement with the analog circuit simulation results. We believe that our experimentally-verified standard cell library is ready to use for SFQ-based digital control of qubits, such as demultiplexing of control signals, and the timing information and power consumption will be valuable information as the baseline to discuss future scalable quantum computer systems.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937872","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 : 2024-12-24DOI: 10.1109/TASC.2024.3522074
A. Kawagoe;M. Yoshida;S. Ando;S. Miura;H. Miyazaki;M. Iwakuma
Measurements of current distributions among tapes consisted of parallel conductors under perpendicular magnetic fields have been carried out to investigate the effect of such fields on current sharing among tapes in Bi-2223 parallel conductors at 77 K. Samples were formed into double pancake coil with the racetrack shape wound with the parallel conductors composed of three Bi-2223 tapes. Magnetic fields were applied perpendicular to the coil axis, ensuring a perpendicular orientation to the tape face in the straight sections of the coil. Experiments were conducted in liquid nitrogen; current distributions were measured by Rogowski coils. The results show that perpendicular magnetic fields enhance current uniformity between tapes. Although multiple transpositions are usually required in parallel conductors to ensure uniformity, this finding suggests that the number of transpositions required in parallel conductors can be significantly reduced, depending on the conductor design. These insights contribute to the optimization of superconducting devices by minimizing mechanical stresses and manufacturing complexity associated with frequent transpositions.
{"title":"Current Sharing in Parallel Conductors Using Bi-2223 Tapes in Perpendicular Magnetic Fields","authors":"A. Kawagoe;M. Yoshida;S. Ando;S. Miura;H. Miyazaki;M. Iwakuma","doi":"10.1109/TASC.2024.3522074","DOIUrl":"https://doi.org/10.1109/TASC.2024.3522074","url":null,"abstract":"Measurements of current distributions among tapes consisted of parallel conductors under perpendicular magnetic fields have been carried out to investigate the effect of such fields on current sharing among tapes in Bi-2223 parallel conductors at 77 K. Samples were formed into double pancake coil with the racetrack shape wound with the parallel conductors composed of three Bi-2223 tapes. Magnetic fields were applied perpendicular to the coil axis, ensuring a perpendicular orientation to the tape face in the straight sections of the coil. Experiments were conducted in liquid nitrogen; current distributions were measured by Rogowski coils. The results show that perpendicular magnetic fields enhance current uniformity between tapes. Although multiple transpositions are usually required in parallel conductors to ensure uniformity, this finding suggests that the number of transpositions required in parallel conductors can be significantly reduced, depending on the conductor design. These insights contribute to the optimization of superconducting devices by minimizing mechanical stresses and manufacturing complexity associated with frequent transpositions.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975791","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}
Commonwealth Fusion Systems (CFS) is the world leader in developing High Temperature Superconducting (HTS) magnet technology for high-field compact tokamaks, SPARC and next generation ARC. As part of these and associated energy generation related projects CFS achieved significant progress in developing, building, and testing several high-field magnets both using no-insulation winding technique and traditional winding using an insulated cable. One major takeaway is that to be quench-resilient high-field, high stored energy HTS magnets need quench detection (QD) and quench protection (QP) features. The general situation with HTS magnets indicates that traditional voltage-based QD methods are at least difficult, as for insulated magnets, or just impossible, as for the no-insulation magnets. Alternative methods of QD are considered. We are proposing an apparently universal conceptual approach to QD. It is based on voltage measurements, reliable, relatively simple, provides an exceptionally good noise rejection and can be used with all the above insulated and no-insulation magnets, as well as many other magnet designs, not only HTS but also Low Temperature Superconducting. QP is suggested but ls left mostly outside the scope of this study.
{"title":"Method of Quench Detection in HTS Magnets","authors":"Alexi Radovinsky;Nicolai Martovetsky;Sergey Kuznetsov","doi":"10.1109/TASC.2024.3520084","DOIUrl":"https://doi.org/10.1109/TASC.2024.3520084","url":null,"abstract":"Commonwealth Fusion Systems (CFS) is the world leader in developing High Temperature Superconducting (HTS) magnet technology for high-field compact tokamaks, SPARC and next generation ARC. As part of these and associated energy generation related projects CFS achieved significant progress in developing, building, and testing several high-field magnets both using no-insulation winding technique and traditional winding using an insulated cable. One major takeaway is that to be quench-resilient high-field, high stored energy HTS magnets need quench detection (QD) and quench protection (QP) features. The general situation with HTS magnets indicates that traditional voltage-based QD methods are at least difficult, as for insulated magnets, or just impossible, as for the no-insulation magnets. Alternative methods of QD are considered. We are proposing an apparently universal conceptual approach to QD. It is based on voltage measurements, reliable, relatively simple, provides an exceptionally good noise rejection and can be used with all the above insulated and no-insulation magnets, as well as many other magnet designs, not only HTS but also Low Temperature Superconducting. QP is suggested but ls left mostly outside the scope of this study.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938205","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 coupled axial and transverse currents (CATI) method was recently introduced to model the AC loss and magnetization in twisted composite superconducting strands with low computational cost and high accuracy. This method involves two-dimensional finite element (FE) models coupled with circuit equations representing the periodicity of the strand. In this paper, we propose to adapt the CATI method to Rutherford cables, which are periodic structures made of transposed superconducting strands. We focus on reproducing the interstrand coupling currents flowing across contact resistances between the strands and we analyze the associated AC loss. We show that results of a reference three-dimensional FE model are accurately reproduced with a strongly reduced computational cost.
{"title":"Simulation of Rutherford Cable AC Loss and Magnetization With the Coupled Axial and Transverse Currents Method","authors":"Julien Dular;Fredrik Magnus;Erik Schnaubelt;Arjan Verweij;Mariusz Wozniak","doi":"10.1109/TASC.2024.3520941","DOIUrl":"https://doi.org/10.1109/TASC.2024.3520941","url":null,"abstract":"The coupled axial and transverse currents (CATI) method was recently introduced to model the AC loss and magnetization in twisted composite superconducting strands with low computational cost and high accuracy. This method involves two-dimensional finite element (FE) models coupled with circuit equations representing the periodicity of the strand. In this paper, we propose to adapt the CATI method to Rutherford cables, which are periodic structures made of transposed superconducting strands. We focus on reproducing the interstrand coupling currents flowing across contact resistances between the strands and we analyze the associated AC loss. We show that results of a reference three-dimensional FE model are accurately reproduced with a strongly reduced computational cost.","PeriodicalId":13104,"journal":{"name":"IEEE Transactions on Applied Superconductivity","volume":"35 5","pages":"1-5"},"PeriodicalIF":1.7,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10812063","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142962897","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}
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