Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Takayanagi, Tomohiro; Ueno, Tomoaki*; Horino, Koki*; Sugita, Moe; Fuwa, Yasuhiro; Shinozaki, Shinichi
IEEE Transactions on Applied Superconductivity, 36(3), p.4900905_1 - 4900905_5, 2026/05
Times Cited Count：0 Percentile：0.00(Engineering, Electrical & Electronic)Sueyoshi, Tetsuro*; Ozaki, Toshinori*; Semboshi, Satoshi*; Sakane, Hitoshi*; Nishizaki, Terukazu*; Ishikawa, Norito
IEEE Transactions on Applied Superconductivity, 35(5), p.8000205_1 - 8000205_5, 2025/08
We investigated additional pinning effect on in-field Jc properties of coated conductors including Y
O
nano-particles as artificial pinning centers (APCs), where three types of heavy-ion beams were employed. The addition of the irradiation defects enhanced the in-field Jc. Furthermore, more upward shift in the Jc was observed for the introduction of the defects with larger volume of the irradiation damage, not only in high magnetic fields but also in low magnetic fields. One factor of the irradiation effect is that the self-field Jc and the critical temperature (Tc) are relatively insensitive to the addition of the irradiation defects for the samples with APCs. Another is the glassy flux creep behavior over wide temperature region, suggesting that flux pinning by the combination of APCs and irradiation defects is strong against thermal fluctuation.
Sn wires with and without Cu-Nb reinforcementNakamoto, Mio*; Sugano, Michinaka*; Ogitsu, Toru*; Sugimoto, Masahiro*; Taniguchi, Ryo*; Hirose, Kiyoshige*; Kawasaki, Takuro; Gong, W.; Harjo, S.; Awaji, Satoshi*; et al.
IEEE Transactions on Applied Superconductivity, 34(5), p.8400806_1 - 8400806_6, 2024/08
Times Cited Count：0 Percentile：0.00(Engineering, Electrical & Electronic)Iwashita, Yoshihisa*; Kuriyama, Yasutoshi*; Fuwa, Yasuhiro
IEEE Transactions on Applied Superconductivity, 34(5), p.4904504_1 - 4904504_4, 2024/08
Times Cited Count：1 Percentile：14.99(Engineering, Electrical & Electronic)A permanent magnet can be used to generate an axisymmetric uniform magnetic field over a long distance. To satisfy Ampere's law, which states that the line-integral value of the magnetic field is zero, a magnetic field region of opposite polarity appears somewhere along the axis while maintaining uniformity in a certain range along the axis. Using this configuration, a magnetic field generator for a Faraday rotation device for laser light was fabricated. This device has a large bore of 30 mm in diameter to handle ultra-high-power lasers and can hold a large crystal disc for Faraday rotation. The irregularity in the central plane is less than 1% within the bore diameter. This configuration can also be applied to long axisymmetric beam transport magnets. This technique can be extended to control the gradient of the magnetic field distributions, such as the focusing field of a klystron.
Kuriyama, Yasutoshi*; Iwashita, Yoshihisa*; Fuwa, Yasuhiro; Terunuma, Nobuhiro*
IEEE Transactions on Applied Superconductivity, 34(5), p.4004005_1 - 4004005_5, 2024/08
Times Cited Count：1 Percentile：14.99(Engineering, Electrical & Electronic)We are developing a correction magnet for charged particle beams using permanent magnets. By rotating the rod of the permanent magnet that generates the magnetic field, the magnetic field can be changed to bipolarity. To verify the principle of this bi-polarity change, a prototype was built, and its performance was evaluated. The performance evaluation of the prototype machine revealed that the inhomogeneity of the remanent magnetization of the permanent magnet has a significant effect on the multipole component. To suppress this effect, a compensating magnet with additional anisotropic intermediate poles is being considered.
Takayanagi, Tomohiro; Sugita, Moe; Ueno, Tomoaki*; Horino, Koki*; Ono, Ayato; Yamamoto, Kazami; Kinsho, Michikazu
IEEE Transactions on Applied Superconductivity, 32(6), p.4101405_1 - 4101405_5, 2022/09
Times Cited Count：1 Percentile：6.97(Engineering, Electrical & Electronic)In order to design a pulsed electromagnet, it is necessary to consider eddy currents that depend on the pattern shape of the pulse excitation, and to design the structure and set the operating parameters considering the fluctuation of the magnetic field distribution and its effect on heat generation. Evaluation tests of a new bump magnet for the J-PARC RCS showed that the magnetic field distributions at the rising edge of the trapezoidal pattern and at the flat top are different from each other. This was also confirmed by the 3D dynamic magnetic field analysis of OPERA-3d. Since the skin-depth due to eddy currents depends on the time variation of the waveform, the effect is the same as changing the shape of the coil. The measurement of the magnetic field distribution fluctuation was verified and evaluated using a flux meter, search coil, and Hall probe with different measurement principles.
Fuwa, Yasuhiro; Takayanagi, Tomohiro; Iwashita, Yoshihisa*
IEEE Transactions on Applied Superconductivity, 32(6), p.4006705_1 - 4006705_5, 2022/09
Times Cited Count：1 Percentile：6.97(Engineering, Electrical & Electronic)Space charge compensation technique using multipole magnetic field components has been proposed to transport high intensity beam in the J-PARC linac. In order to realize this compensation technique, a compact size permanent hybrid multi-pole magnet would be suitable. A magnet system for the simultaneous production of quadrupole and adjustable octupole components using permanent magnet materials and have manufactured a first model of the magnet systems.
Fuwa, Yasuhiro; Iwashita, Yoshihisa*; Kondo, Akihiro*
IEEE Transactions on Applied Superconductivity, 32(6), p.4007304_1 - 4007304_4, 2022/06
Times Cited Count：0 Percentile：0.00(Engineering, Electrical & Electronic)High-field magnets are often demanded advanced scientific studies. Although a hybrid coil design comprising Nb-Ti, NbSn, and HTS (High-Temperature Superconductors) are potential candidates for such application, the costs of NbSn and HTS are expensive compared with Nb-Ti. By generating an additional field of about 1 T by permanent magnets, the required amounts of superconducting material may be reduced. Magnetic properties of some magnetic materials have been studied by other works at temperatures as low as 100 K. The remanent field of conventional NdFeB magnets decreases at 100 K due to spin reorientation. PrFeB magnets consisting of praseodymium (Pr) instead of neodymium (Nd) do not show such degradation and the coercivity of PrFeB at 100 K is 7 T. In this study, the B-H curve, as a primary magnetic property, of a PrFeB magnet sample was measured in the temperature range down to 4 K. As a result, no decrease in magnetization of the praseodymium magnets, and the coercivity was 10 T.
Shishido, Hiroaki*; Nishimura, Kazuma*; Vu, TheDang*; Aizawa, Kazuya; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Soyama, Kazuhiko; et al.
IEEE Transactions on Applied Superconductivity, 31(9), p.2400505_1 - 2400505_5, 2021/12
Times Cited Count：1 Percentile：5.45(Engineering, Electrical & Electronic)In this study, we employed a superconducting detector, current-biased kinetic-inductance detector (CB-KID) for neutron imaging using a pulsed neutron source. We employed the delay-line method, and high spatial resolution imaging with only four reading channels was achieved. We also performed wavelength-resolved neutron imaging by the time-of-flight method. We obtained the neutron transmission images of a Gd-Al alloy sample, inside which single crystals of GdAl were grown, using the delay-line CB-KID. Single crystals were well imaged, in both shapes and distributions, throughout the Al-Gd alloy. We identified Gd nuclei via neutron transmissions that exhibited characteristic suppression above the neutron wavelength of 0.03 nm. In addition, the 
Gd resonance dip, a dip structure of the transmission caused by the nuclear reaction between an isotope and neutrons, was observed even when the number of events was summed over a limited area of 15 
m 
12 m. Gd selective imaging was performed using the resonance dip of Gd, and it showed clear Gd distribution even with a limited neutron wavelength range of 1 pm.
Okumura, Takuma*; Azuma, Toshiyuki*; Bennet, D. A.*; Caradonna, P.*; Chiu, I.-H.*; Doriese, W. B.*; Durkin, M. S.*; Fowler, J. W.*; Gard, J. D.*; Hashimoto, Tadashi; et al.
IEEE Transactions on Applied Superconductivity, 31(5), p.2101704_1 - 2101704_4, 2021/08
Times Cited Count：3 Percentile：17.39(Engineering, Electrical & Electronic)A superconducting transition-edge sensor (TES) microcalorimeter is an ideal X-ray detector for experiments at accelerator facilities because of good energy resolution and high efficiency. To study the performance of the TES detector with a high-intensity pulsed charged-particle beam, we measured X-ray spectra with a pulsed muon beam at the Japan Proton Accelerator Research Complex (J-PARC) in Japan. We found substantial temporal shifts of the X-ray energy correlated with the arrival time of the pulsed muon beam, which was reasonably explained by pulse pileup due to the incidence of energetic particles from the initial pulsed beam.
Sueyoshi, Tetsuro*; Enokihata, Ryusei*; Yamaguchi, Hiroshi*; Fujiyoshi, Takanori*; Okuno, Yasuki*; Ishikawa, Norito
IEEE Transactions on Applied Superconductivity, 31(5), p.8000305_1 - 8000305_5, 2021/08
Angular behaviors of critical current density Jc at 77 K, 1 T were investigated in YBCO films with columnar defects (CDs) tilted at small angles to the ab-plane before and after the additional introduction of CDs at different angles, where CDs were installed by heavy-ion irradiations. The enhanced Jc at 
by the initial irradiation at 
i=
85
relative to the c-axis was reduced by the additional irradiation at i=75, whereas the Jc was increased at the intermediate angle between the two irradiation angles. The addition of CDs at i=0 also lowered the Jc around , which were enhanced by the initial irradiation angles of i=80.
Takayanagi, Tomohiro; Ueno, Tomoaki*; Horino, Koki*; Ono, Ayato; Yamamoto, Kazami; Kinsho, Michikazu
IEEE Transactions on Applied Superconductivity, 30(4), p.4901605_1 - 4901605_5, 2020/06
Times Cited Count：3 Percentile：15.75(Engineering, Electrical & Electronic)
-axis in -axis oriented YBCO thin filmsSueyoshi, Tetsuro*; Iwanaga, Yasuya*; Fujiyoshi, Takanori*; Takai, Yosuke*; Muta, Mitsuhiro*; Mukaida, Masashi*; Ichinose, Ataru*; Ishikawa, Norito
IEEE Transactions on Applied Superconductivity, 29(5), p.8003204_1 - 8003204_4, 2019/08
Times Cited Count：8 Percentile：38.27(Engineering, Electrical & Electronic)Columnar defects (CDs) along -axis were installed into an in-plane aligned -axis-oriented YBaCuO
film by using heavy-ion irradiation, in order to clarify the influence of CDs on flux pinning properties around B
. The critical current density 
at B
significantly decreases after the irradiation, since the CDs act as a channel for flux creep along their length. The magnetic field dependence of at B, on the other hand, is weakened by the introduction of CDs.
Takayanagi, Tomohiro; Yamamoto, Kazami; Kamiya, Junichiro; Saha, P. K.; Ueno, Tomoaki*; Horino, Koki*; Kinsho, Michikazu; Irie, Yoshiro*
IEEE Transactions on Applied Superconductivity, 28(3), p.4100505_1 - 4100505_5, 2018/04
Times Cited Count：6 Percentile：30.53(Engineering, Electrical & Electronic)Sn strand during coolingSuwa, Tomone*; Hemmi, Tsutomu*; Saito, Toru*; Takahashi, Yoshikazu*; Koizumi, Norikiyo*; Luzin, V.*; Suzuki, Hiroshi; Harjo, S.
IEEE Transactions on Applied Superconductivity, 28(3), p.6001104_1 - 6001104_4, 2018/04
Times Cited Count：1 Percentile：6.44(Engineering, Electrical & Electronic) in GdBCO-coated conductors with crossed columnar defects around planeSueyoshi, Tetsuro*; Iwanaga, Yasuya*; Fujiyoshi, Takanori*; Takai, Yosuke*; Mukaida, Masashi*; Kudo, Masaki*; Yasuda, Kazuhiro*; Ishikawa, Norito
IEEE Transactions on Applied Superconductivity, 27(4), p.8001305_1 - 8001305_5, 2017/06
Times Cited Count：9 Percentile：40.83(Engineering, Electrical & Electronic)We investigated in detail the flux pinning properties around B for GdBCO coated conductors with crossed columnar defects produced by heavy-ion irradiation, where the crossing angle was systematically controlled in the range from 5 to 15 relative to the ab-plane. A single peak of critical current density centered at B occurs for the crossing angle of 5, where an upward shift in can be observed compared to an unirradiated sample. As the crossing angle is larger, the peak becomes smaller and broader while maintaining the peak at B . Three peaks emerges at B and at the two irradiation angles, independently from the others.
Hashimoto, Tadashi*; Tanida, Kiyoshi; 49 of others*
IEEE Transactions on Applied Superconductivity, 27(4), p.2100905_1 - 2100905_5, 2017/06
Times Cited Count：14 Percentile：51.55(Engineering, Electrical & Electronic)Sn strands of CIC conductor using neutron diffractionHemmi, Tsutomu*; Harjo, S.; Kajitani, Hideki*; Suwa, Tomone*; Saito, Toru*; Aizawa, Kazuya; Osamura, Kozo*; Koizumi, Norikiyo*
IEEE Transactions on Applied Superconductivity, 27(4), p.4200905_1 - 4200905_5, 2017/06
Times Cited Count：2 Percentile：12.26(Engineering, Electrical & Electronic)Sakurai, Takeru; Iguchi, Masahide; Nakahira, Masataka; Saito, Toru; Koizumi, Norikiyo
IEEE Transactions on Applied Superconductivity, 26(4), p.4204705_1 - 4204705_5, 2016/06
Japan Atomic Energy Agency (JAEA) has responsibility to procure 9 Toroidal Field (TF) coils and 19 TF coil structures for ITER project. A TF coil structure consists of the main body structure having D-shape with 13.6 m of height and 9 m of width in which a superconducting winding pack is enclosed and the components to connect adjacent TF coils or other surrounding components. TF coil structures are manufactured from austenitic stainless steel having high tensile strength and fracture toughness at cryogenic temperature (4K) in order to ensure the huge electromagnetic force. As structural materials, austenitic stainless steel having high Manganese and Nitrogen which was named as JJ1 and high Nitrogen containing 316LN stainless steel are applied. These materials are welded each other by Tungsten Inert Gas (TIG) welding with FMYJJ1, which had been developed for welding material based on JJ1. The cryogenic mechanical properties of welded joints which have over 200 mm of actual thickness are limited due to less demonstration of such a heavy thick joints. In addition, destructive test specimens cannot be taken from actual TF coil structure. Hence, it is necessary to confirm actual thickness of welded joint performance by actual welding conditions mock-up. JAEA manufactured some welded joint mock-ups having the same welding thickness and combination of base materials as actual TF coil structure by applying actual welding conditions. JAEA measured mechanical properties of tensile and fracture toughness in liquid Helium environment by using test specimens taken from these welded joint mock-ups. This study reports these mechanical test results of welded joints at cryogenic temperature. "The view and opinions expressed herein do not necessarily reflect those of the ITER Organization."
Tani, Norio; Watanabe, Yasuhiro; Hotchi, Hideaki; Takayanagi, Tomohiro; Togashi, Tomohito; Horino, Koki
IEEE Transactions on Applied Superconductivity, 26(4), p.4101904_1 - 4101904_4, 2016/06
Times Cited Count：8 Percentile：39.31(Engineering, Electrical & Electronic)Field measurement was implemented in order to confirm performance of the pulse corrector quadrupole magnet (QDT) in the RCS. A result of the field measurement showed a 20% difference against the design value. We investigated the cause and made a study to restore the performance. We challenged a new approach to install shims on the pule magnet. Shims were produced with a laminating steel sheet. We found the permissible value by field calculation in as installation accuracy greatly depended on the performance. A shim has a sharp and long edge with a complicated shape. Therefore it was difficult to make a structure that can tolerate installation works. We made various trial manufactures and adopted a processing method with an adhesion steel sheet. The homogeneity of field became less than 1% by measurement and a QDT which laminated shims were installed showed a fully satisfactory performance. In this presentation I will report optimization of the pole shape and the result of the field measurement carried out afterward.
