Article
Engineering, Electrical & Electronic
Satoshi Awaji, Arnaud Badel, Tatsunori Okada, Kohki Takahashi, Hiroshi Miyazaki, Satoshi Hanai, Shigeru Ioka, Shinji Fujita, Shogo Muto, Yasuhiro Iijima, Masanori Daibo, Kazuhiro Kajikawa
Summary: The upgrade project aims to increase the field strength of the 25T-CSM to 30T by replacing the existing Bi2223 insert coil with one wound using REBCO. The use of a dual-tape bundle conductor configuration has been shown to effectively mitigate risks from local defects and provide early detection and protection against hotspots in the REBCO insert. Based on successful testing, a robust REBCO insert with the potential to achieve 35T has been designed.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2021)
Article
Engineering, Electrical & Electronic
K. Takahashi, A. Badel, A. Zampa, T. Okada, S. Awaji, G. Nishijima, T. Uto, H. Takewa, S. Hanai, S. Ioka, J. Inagaki
Summary: For the next generation of high field cryogen-free superconducting user magnets, a robust coil concept is adopted, with two tapes co-wound in a face-to-back configuration, a fluorine-coated polyimide tape as the inter-bundle insulation, and thin FRP plates glued on the coil edges. The electromagnetic and current-voltage properties of 20-stacked REBCO pancake coils wound with Fujikura EuBCO tapes using the robust coil concept were investigated under a background field of 14 T and at a temperature of 4.2 K. The coil structure showed no anomalous behavior up to 25 T, indicating its advantage against large electromagnetic stress.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Engineering, Electrical & Electronic
Shin Hasegawa, Satoshi Ito, Gen Nishijima, Hidetoshi Hashizume
Summary: A quench detection method using a low-temperature superconducting quench detector (QD) has been proposed to protect rare-earth barium copper oxide (REBCO) coils in magnetic fields at temperatures below 20 K. Experimental results showed that the Nb-Ti/Cu-Ni QD could achieve quick quench detection before the thermal runaway of the REBCO tape at 0-9 T, while the Nb-Ti/Cu QD only exhibited this capability at 9 T. Numerical evaluation also confirmed the feasibility of quench detection time with Nb-Ti QDs attached to a locally degraded REBCO tape at 4.2 K in 0-9 T, with a requirement for the contact resistance to be lower than 1.0 x 10(-3) m(2)K/W for quick quench detection.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2021)
Article
Physics, Applied
Christian Lacroix, Jael Giguere, Simon-Mathieu Bergeron Hartman, Haifa Ben Saad, Anthony Martin, Thomas Leduc, Maxime Gendron-Paul, Zakaria Bellil, Jean-Hughes Fournier-Lupien, Lucile Moret, Pedro Barusco, Xavier Granados, Xavier Obradors, Marcela Pekarcikova, Fedor Gomory, Veit Grosse, Markus Bauer, Frederic Sirois
Summary: In this study, the normal zone propagation velocity (NZPV) of three different REBCO tape architectures designed for superconducting fault current limiters and high voltage direct current transmission systems was measured experimentally and numerically simulated. The results showed that the NZPV varied significantly depending on the tape architectures, and the dynamic current transfer length (CTL) was found to be the key factor determining the NZPV.
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Kohki Takahashi, Tatsunori Okada, Arnaud Badel, Satoshi Awaji, Hiroshi Miyazaki, Satoshi Hanai, Shigeru Ioka
Summary: The upgrading of the 25T cryogen-free superconducting magnet to a 30T-class magnet using REBCO coils is being considered. The strategy involves adopting a two tapes co-winding technique to increase the current density and prevent hotspot generation. Electromagnetic and mechanical properties of two bundle co-wound pancake coils were investigated as part of the R&D process for the 30T-class superconducting magnet.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2021)
Article
Physics, Applied
Xiaorong Wang, Timothy J. Bogdanof, Paolo Ferracin, William B. Ghiorso, Stephen A. Gourlay, Hugh C. Higley, Janakiram Kaushal Kadiyala, Soumen Kar, Reginald Lee, Linqing Luo, Maxwell A. Maruszewski, Robert Memmo, Cory S. Myers, Soren O. Prestemon, Jithin Sai Sandra, Venkat Selvamanickam, Reed Teyber, Marcos Turqueti, Yuxin Wu
Summary: This research presents the experimental results of dipole magnet development using star (R) wires, demonstrating the feasibility of these wires under high-field conditions and identifying further development needs.
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Shuangsong Du, Kaizhong Ding, Changle Feng, Rui Hu, Yuntao Song, YongHua Chen, Yanfang Bi, Hansheng Feng, Chunlong Zou
Summary: This study investigated the stress conditions of the coil for the 240MeV superconducting isochronous cyclotron under various conditions, with results showing that the hoop stress does not exceed the allowable limit, providing sufficient safety margin for the hoop stress compared to the previous model.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2021)
Article
Physics, Applied
Yufan Yan, Peng Song, Canjie Xin, Mingzhi Guan, Yi Li, Huajun Liu, Timing Qu
Summary: This paper investigates the mechanical strain induced by screening currents in REBCO coils, showing that moderate over-banding structures are effective in providing reinforcements for the superconductors. Additionally, a new edge-bonding method was proposed to reduce hoop strains in low applied fields.
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
(2021)
Article
Chemistry, Analytical
Tao Geng, Jihao Wang, Wenjie Meng, Jing Zhang, Qiyuan Feng, Yubin Hou, Qingyou Lu
Summary: We have developed a novel homebuilt scanning tunneling microscope (STM) integrated into a cryogen-free superconducting magnet system with a variable temperature insert. The STM head, designed as a nested structure of double piezoelectric tubes (PTs), demonstrated excellent performance in obtaining atomic-resolution images of graphite and low drift rates. The STM also showed high stability, vibration resistance, and immunity to high magnetic fields during experiments.
Article
Chemistry, Multidisciplinary
Jae Young Jang, Myung Su Kim, Young Jin Hwang, Seunghyun Song, Yojong Choi, Yeon Suk Choi
Summary: This article describes a cryogen-free portable 3T high-temperature superconducting magnet, which adopts metallic insulation and genetic algorithm for optimized design to minimize superconducting tape consumption. Through various tests, the feasibility of this magnet system for electromagnetic property measurement experiments has been proven.
APPLIED SCIENCES-BASEL
(2021)
Article
Engineering, Electrical & Electronic
Makoto Takayasu
Summary: The study investigates the initial quench pressure developments in a CICC cable of REBCO tapes by analyzing the first law of thermodynamics. It evaluates the temperature and pressure rise from a quench in a REBCO CICC conductor operating in helium gas coolant at 26 K, and proposes a MEMS sensor-in-tube array method for quench detection.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2021)
Article
Physics, Applied
Yi Li, Stefan Roe
Summary: The 14T whole-body MRI magnet designed with Bi2223 HTS wire is optimized for compact shape, with a total wire consumption of 455 km. Various stress factors such as hoopstress, thermal contraction, and Lorenz force have been calculated to ensure the magnet's performance. The reduction of screening current effect in MRI magnet application has been proven, showing promising potential for further design optimization and development of ultra-high field MRI magnets using different wire candidates like REBCO and Nb3Sn.
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
H. Yu, J. Lu, J. D. Weiss, D. C. van der Laan
Summary: This experimental work presents the critical current measurements of two different REBCO cables using a test facility at NHMFL. The critical currents were determined by measuring the voltage-current traces at 4.2 K. The results have significant implications for the development and application of REBCO cables.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2022)
Article
Instruments & Instrumentation
Saurabh Chaudhary, Janmey Jay Panda, Suman Mundlia, S. Mathimalar, Aathif Ahmedof, Karthik Raman
Summary: The article discusses the successful integration of a cryogen-free scanning tunneling microscope with a cryogen-free superconducting vector-magnet, demonstrating operation at extremely low noise levels below 30 fA/root Hz. It also presents atomic resolution imaging and spectroscopy of surfaces at cryogenic temperature and in the presence of a magnetic field. The design of the in-house customized cluster-vacuum-line assembly offers opportunities for continuous uninterrupted imaging of ultra-clean surfaces without the need for cryogenic refills.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Physics, Fluids & Plasmas
S. Ito, H. Tamura, N. Yanagi, H. Hashizume
Summary: This paper presents the progress in electrical and mechanical performances of the mechanical joints of HTS conductors and methods to evaluate their quality for segment-fabrication of HTS helical coils. R&D of joint performance has progressed over the past decade and it shows acceptable performance for the HTS helical coils. The contact-probing current transfer length method and x-ray computer tomography scanning are promising for quality assessment of the joints and HTS tapes.
Article
Engineering, Electrical & Electronic
Yutaro Doi, Ryo Teranishi, Tomohiro Miyajima, Akiyoshi Matsumoto, Valery Petrykin, Sergey Lee, Tatsunori Okada, Satoshi Awaji
Summary: This study investigates the effect of heat-treatment temperature and precursor film thickness on the crystallinity and joint rate of GdBCO coated conductors. The results show that heat treatment at around 800 degrees C with a thicker precursor film improves the crystallization of GdBCO and leads to a higher joint rate.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2022)
Article
Materials Science, Multidisciplinary
Masashi Miura, Go Tsuchiya, Takumu Harada, Keita Sakuma, Hodaka Kurokawa, Naoto Sekiya, Yasuyuki Kato, Ryuji Yoshida, Takeharu Kato, Koichi Nakaoka, Teruo Izumi, Fuyuki Nabeshima, Atsutaka Maeda, Tatsumori Okada, Satoshi Awaji, Leonardo Civale, Boris Maiorov
Summary: The addition of artificial pinning centers has greatly increased the critical current density of superconductors, allowing for breakthroughs in all-superconducting magnets and other applications. By modifying certain parameters such as carrier density and chemical pressure, the critical current density can be further enhanced.
NPG ASIA MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Zhe Cheng, Chiheng Dong, Huan Yang, Qinghua Zhang, Satoshi Awaji, Lin Gu, Hai-Hu Wen, Yanwei Ma
Summary: Researchers have finely tuned the electronic properties of grain boundaries in iron-based superconductors by doping them with different concentrations of a certain element. The study reveals that the contribution of grain boundaries to supercurrent transport is closely related to the doping concentration. The presence of a special structure at the grain boundaries and adjacent grains plays a key role in the transport of supercurrent. This study provides important insights for improving the application performance of iron-based superconductors through grain boundary engineering.
MATERIALS TODAY PHYSICS
(2022)
Article
Physics, Applied
Sunseng Pyon, Takamasa Ito, Ryosuke Sakagami, Tsuyoshi Tamegai, Satoshi Awaji, Hijiri Kito, Shigeyuki Ishida, Hiroshi Eisaki, Yoshiyuki Yoshida, Hideki Kajitani
Summary: This study reports the fabrication and systematic characterization of multi-filament (Ba,A)Fe2As2 (A: Na, K) round wires under high pressure. The transport and magnetic critical current density were found to depend on the number of cores. The study also discussed the degradation of the superconducting core, degradation of the concentric texturing, and the enhanced sausaging effect of the core as the number of cores increases. Additionally, a superconducting magnet using seven-filament (Ba,K)Fe2As2 round wires was constructed, and the generated magnetic field and critical current were measured.
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
(2023)
Article
Nanoscience & Nanotechnology
Iduru Shigeta, Shuta Oku, Takahide Kubota, Shojiro Kimura, Takeshi Seki, Bunju Shinozaki, Satoshi Awaji, Koki Takanashi, Masahiko Hiroi
Summary: Superconducting properties of NbN/CMS films were investigated. The upper critical field decreased with increasing CMS thickness, while the superconducting transition temperature had a minimum value at a thickness of around 5 nm. The experimental results suggest that the superconductivity of the NbN layer is affected by the interaction between the NbN and the CMS layers.
Article
Engineering, Electrical & Electronic
Junyi Luo, Tatsunori Okada, Satoshi Awaji, Cong Liu, Yanwei Ma
Summary: We investigated the magnetic and angular dependence of the critical current Ic(B, theta) in Ba1-xKxFe2As2 (Ba122) tapes with 7 filaments sheathed in Cu/Ag. The results showed hysteresis behaviors of Ic(B, theta) below 8T, which depended on the direction of B and the rotation of theta. Analysis revealed that Ic(up)(B) displayed a non-monotonic dependence on B, which could be explained by flux pinning. Calculations based on a spherical pin model successfully reproduced the measured Ic(B > 8T, theta) and I-c(avg)(B, theta). This suggests that controlling spherical pins may improve the characteristics of Ic(T, B, theta) in Cu/Ag-sheathed Ba122 tapes.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Engineering, Electrical & Electronic
Masahiro Sugimoto, Kiyoshige Hirose, Hiroyuki Fukushima, Ryo Taniguchi, Hisaki Sakamoto, Tomoya Kato, Hirokazu Tsubouchi, Satoshi Awaji, Hidetoshi Oguro, Hiroyasu Utoh, Yoshiteru Sakamoto
Summary: In this study, a Nb-rod-method Cu-Nb reinforced ITER-type Nb3Sn wire was developed to achieve superior superconducting properties and mitigate damage during the cable manufacturing process. The Cu-Nb/Nb3Sn wire exhibited significantly higher critical current performance under both tensile and transverse compression stress compared to conventional Cu/Nb3Sn wires. The Cu-Nb reinforcement did not have a detrimental effect on AC losses. Trial production of sub-cables confirmed the improved manufacturability of multi-stage stranded cables co-twisted with copper wires.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Engineering, Electrical & Electronic
M. Nakamoto, M. Sugano, M. Dhakarwal, T. Ogitsu, G. Nishijima, S. Awaji, S. Kawashima, S. C. Hopkins, A. Ballarino
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Engineering, Electrical & Electronic
T. Tamegai, S. Pyon, T. Ito, H. Kajitani, N. Koizumi, S. Awaji, H. Kito, S. Ishida, Y. Yoshida
Summary: Small magnets using (Ba,Na)Fe2As2 and (Ba,K)Fe2As2 round wires were constructed and evaluated. The critical current (I-c) varied significantly along the length of the wires, reaching a maximum of 160 A in the (Ba,Na)Fe2As2 wire. X-ray tomography observations revealed a severe sausaging effect in the wires. Bending strain had a modest effect on the wires, with over 60% of I-c sustained even at a strain of 0.5%.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Engineering, Electrical & Electronic
Julien Vialle, Arnaud Badel, Kohki Takahashi, Satoshi Awaji, Pascal Tixador
Summary: REBCO Coated Conductors have high tensile strength but are sensitive to delamination when subjected to traction force. Dry winding is commonly used for REBCO magnets, but it is inefficient for conduction cooling at low temperatures. This paper proposes an improved pancake structure with edge impregnation using Hastelloy tape and thin insulation coating to reinforce the winding. The mechanical behavior and insulation performance of this structure were estimated, validated, and tested under different conditions.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Engineering, Electrical & Electronic
Tatsuhiko Yoshihara, Genki Honda, Tatsuoki Nagaishi, Shinichi Kobayashi, Kiyoshi Kanie, Tatsunori Okada, Satoshi Awaji
Summary: REBCO films with BaMO3 artificial pinning centers were fabricated using a low-cost fluorine-free metal organic decomposition (FF-MOD) method. The size of BMO formation can be maintained on the nanometer order by adding preformed BMO nanoparticles, acting as effective pinning centers at low temperatures and magnetic fields. A polycrystallization sintering process enables the formation of polycrystalline REBCO films prior to REBCO orientation. By utilizing preformed BMO nanoparticles and a polycrystallization sintering process, BMO doped GdBCO over 100 m-long tapes with a thickness of more than 3 μm can be achieved, which is the first report of 120-meter-long artificial pinned REBCO tapes with I-c exceeding 200 A/4 mm width at 77 K, self-field made by the FF-MOD method.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Engineering, Electrical & Electronic
Y. Tsuchiya, I. Sakai, K. Mizuno, Y. Kohama, Y. Yoshida, S. Awaji
Summary: High-temperature superconducting (HTS) tapes have been extensively researched for various applications, including high-temperature cooling, ultra-high field magnets, fusion reactors, and rotating machines. Improvements in the critical current of HTS tapes have led to the development of test facilities with variable temperatures and high currents. This study focuses on pulsed current measurements to determine the critical currents of commercially available HTS tapes at high currents and limited spaces, using a low inductance probe and a 500 A-class pulse power supply.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Engineering, Electrical & Electronic
K. Takahashi, A. Badel, A. Zampa, T. Okada, S. Awaji, G. Nishijima, T. Uto, H. Takewa, S. Hanai, S. Ioka, J. Inagaki
Summary: For the next generation of high field cryogen-free superconducting user magnets, a robust coil concept is adopted, with two tapes co-wound in a face-to-back configuration, a fluorine-coated polyimide tape as the inter-bundle insulation, and thin FRP plates glued on the coil edges. The electromagnetic and current-voltage properties of 20-stacked REBCO pancake coils wound with Fujikura EuBCO tapes using the robust coil concept were investigated under a background field of 14 T and at a temperature of 4.2 K. The coil structure showed no anomalous behavior up to 25 T, indicating its advantage against large electromagnetic stress.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Engineering, Electrical & Electronic
Nobuya Banno, Tsuyoshi Yagai, Shinya Kawashima, Masahiro Sugimoto, Satoshi Awaji, Hiroyasu Utoh, Yoshiteru Sakamoto
Summary: This study summarizes the analysis of material properties of reinforced Nb3Sn wires for DEMO in Japan. The reinforced wires exhibit higher mechanical strength and better stress tolerance against bending load than copper, supporting their use in Japan's DEMO design.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Physics, Multidisciplinary
Yasunao Otsuki, Shojiro Kimura, Satoshi Awaji, Motohiro Nakano
Summary: This Letter demonstrates a novel mechanism to enhance the magnetoelectric (ME) coupling between electric polarization and magnetism using the dynamic Jahn-Teller (JT) effect. An electric polarization of over 100 mu C/m(2) is induced by the magnetic field through the second-order ME effect in the noncentrosymmetric transition metal complex [Mn-III(taa)], without requiring magnetic order. The electric polarization is one order larger than that induced by the second-order ME effect, originating from p-d hybridization. The alignment of the JT distortion by the magnetic field results in the observed large electric polarization. This provides a new method to achieve strong ME coupling by tuning the atomic displacement using a magnetic field.
PHYSICAL REVIEW LETTERS
(2022)
