Faculty Profiles - UEDA Hiroshi

Papers - UEDA Hiroshi

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Numerical Evaluation of Screening Current-Induced Magnetic Field Considering Variable Output Energy in REBCO Coil System of Skeleton Cyclotron for Cancer Therapy Reviewed International journal

Takamitsu Ogata, Kodai Shirai, Atsushi Ishiyama, Hiroshi Ueda, So Noguchi, Tomonori Watanabe, Shigeo Nagaya, Mitsuhiro Fukuda

IEEE Transactions on Applied Superconductivity 31 ( 5 ) 4400105 2021.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical and Electronics Engineers (IEEE)

We have been developing a new-generation accelerator named 'Skeleton Cyclotron', which is an ultra-compact and high-intensity accelerator for the stable production of 211At used for targeted alpha-particle therapy. Coil system for Skeleton Cyclotron consists of circular and noncircular high-temperature superconducting magnets and it can cause the output energy to vary without being bounded by the non-linearity of the iron core. This will enable not only the production of 211At, but also the production of radioisotopes for positron emission tomography and neutron irradiation for boron neutron capture therapy with a single accelerator. A high-precision magnetic field distribution and a high temporal stability are required for stable beam acceleration, but the screening current, which is induced in the REBa2Cu3Ox (REBCO, RE: Rare Earth) coated conductor, generates an irregular magnetic field and deteriorates the quality of the magnetic field spatially and temporally. In this study, we numerically evaluated the temporal stability and reproducibility of the screening current-induced field considering the variable energy operation for the Ultra-Baby Skeleton Cyclotron, which is a small demonstration model of Skeleton Cyclotron.

DOI： 10.1109/tasc.2021.3059725

Thermal Characteristics of REBCO Coil in a Wireless Power Transmission System for the Railway Vehicle in Liquid Nitrogen Reviewed International journal

Ryota Inoue, Hiroshi Ueda, SeokBeom Kim, Makoto Tsuda

IEEE Transactions on Applied Superconductivity 31 ( 5 ) 4700905 2021.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical and Electronics Engineers (IEEE)

A wireless power transmission (WPT) system using the high temperature superconducting (HTS) coil for a railway vehicle is required to transmit the electric power of several hundred kW in a short time (60 s). In order to design the WPT system using HTS coil with the thermal stability, and it is necessary to clarify the thermal characteristics of the HTS coil at the operating current in kHz band and the operating conditions considering thermal stability in the WPT system. We analyzed the frequency characteristics of the critical current in the HTS coil above 1 kHz and investigated the operating conditions considering thermal stability in the WPT system for the railway vehicle using HTS coil in liquid nitrogen. As a result, the critical current of the HTS coil in the kHz band decreased with the frequency. This is because the AC loss in the HTS coil increased with the frequency, and the critical current density of the HTS coil decreased with increasing the surface temperature. In order to design the HTS coil with thermal stability in the kHz band, and it is necessary to operate the HTS coil on alternating current less than about 50% of the critical current measured by direct current. We found that the thermally stable WPT system capable of fast charging for 60 seconds can be realized by operating current at the frequency of about 2 kHz.

DOI： 10.1109/tasc.2021.3059234

Numerical Evaluation of Thermal and Electromagnetic Stress in Frame-Reinforced Stacked REBCO Pancakes Coils Reviewed International journal

Keisuke Tokunaga, SeokBeom Kim, Ryota Inoue, Hiroshi Ueda

IEEE Transactions on Applied Superconductivity 31 ( 5 ) 4603505 2021.8

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical and Electronics Engineers (IEEE)

To achieve high-field rare-earth barium copper oxide (REBCO) coils, the mechanism of the deterioration of or damage to such coils needs to be clarified. A REBCO coil experiences various stresses and strains during the winding, cooling down, charging, and discharging processes. Furthermore, the additional force and stress due to a screening current has become an issue in REBCO coils. To protect REBCO coils from large electromagnetic stress in a high field, a reinforcement structure called the Y-based oxide superconductor and reinforcing outer integrated (YOROI) coil was proposed. This study numerically evaluated the effect of the YOROI coil structures against thermal and electromagnetic stress using a two-dimensional axisymmetric structural analysis. This simulation considered the following: 1) the mechanical stress induced by 10 N of winding tension, 2) thermal stress during cooling from 300 K to 10 K, and 3) electromagnetic stress, which included the additional stress due to a screening current during the charging process. The mechanical behavior due to each process was investigated, and the effect of the YOROI structures was also examined.

DOI： 10.1109/tasc.2021.3060702

Numerical Evaluation of Screening Current-Induced Magnetic Field in No-Insulation REBCO Coil Systems Reviewed International journal

Satomi Ueda, Atsushi Ishiyama, Hiroshi Ueda, So Noguchi

IEEE Transactions on Applied Superconductivity 31 ( 5 ) 4601405 2021.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical and Electronics Engineers (IEEE)

We have been developing a no-insulation (NI) REBCO coil which is expected to be applied to medical accelerators and magnetic resonance imaging as a technology that can achieve both high thermal stability and high current density. Due to the flat shape and much greater, than the thickness, width of a REBCO-coated conductor, the screening currents are remarkably induced by changing the magnetic flux that penetrates the tape vertically. For insulated (INS) coils, this screening current causes an irregular magnetic field (screening current-induced magnetic field (SCIF)). Also, in the NI coil, an excitation delay occurs because of the current flowing in the radial direction with coil excitation. Therefore, as the cause of irregular magnetic field, it is necessary to simultaneously consider the influence of both the excitation delay and SCIF. In this study, we numerically investigate the magnetic field in the NI coil. The SCIF and an excitation delay reduce magnetic accuracy in the NI coil. Thus, we propose an energization waveform that can improve the magnetic field accuracy even if there is an excitation delay. Besides, we verified its effectiveness.

DOI： 10.1109/tasc.2021.3064540

Study on the Current Bypassing and Mechanical Properties of No-Insulation HTS Coil With Protection Ring Reviewed International journal

Daisuke Nishikawa, Kohei Miyamoto, Hirotaka Kobayashi, Ryota Inoue, Hiroshi Ueda, SeokBeom Kim

IEEE Transactions on Applied Superconductivity 31 ( 5 ) 4603405 2021.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical and Electronics Engineers (IEEE)

We have been studying no-insulation (NI) high temperature superconducting (HTS) coils that do not use turn-to-turn electrical insulation. The no-insulation winding technique can provide high stability of the HTS coils against the quenching, but it cannot prevent mechanical deterioration of the HTS coil due to electromagnetic force and multiple cooling. To solve these problems, we propose the installation of metal protection ring on the outermost turn of NI HTS coil to improve thermal, mechanical, and electrical stability. In this study, the current bypass characteristics in the transverse direction within an NI test coil wound with 37 turns of REBCO wire with/without copper protection ring were experimentally investigated for various amounts of heating by a heater and various heater positions. Eight repeated cooling experiments with liquid nitrogen proved that the proposed copper protection ring was effective against shape deformation of the NI test coil and deterioration of contact resistance between turns due to thermal stress.

DOI： 10.1109/tasc.2021.3063654

Performance of Epoxy-Impregnated Intra-Layer No-Insulation (LNI) REBCO Coils at 77 K Reviewed International journal

Taisuke Yoshida, Yu Suetomi, Keisuke Takahashi, Tomoaki Takao, Yoshinori Yanagisawa, Hideaki Maeda, Hiroshi Ueda

IEEE Transactions on Applied Superconductivity 31 ( 5 ) 4602706 2021.8

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

The intra-layer no-insulation (LNI) method is effective for protecting a layer-wound REBCO coil from a quench. However, a recently reported hoop stress modification (both increase and decrease) due to screening currents is a potential problem causing conductor degradation during charging. Epoxy impregnation can suppress the hoop stress modification and in this work, we develop prototypes of epoxy-impregnated LNI-REBCO coils to be charged at 77 K. Degradation of the coil performance due to cooling down can be prevented by mechanically isolating each layer. The coil shows a reasonably short field delay and current bypassing behavior, which are major technical benefits of the LNI-REBCO coil. A structural analysis with screening current-induced electromagnetic forces qualitatively suggests that the epoxy-impregnated LNI-REBCO coil can support a compressive hoop stress which causes conductor degradation due to buckling. The tensile hoop stress, however, is still very high at the upper and lower ends of each layer, causing fracture of a superconducting layer; i.e., additional reinforcement is required.

DOI： 10.1109/TASC.2021.3065875

Numerical Analysis of the Reduction of Screening-Current-Induced Magnetic Field in Copper-Plated and Striated REBCO-Coated Conductor Wound into Pancake Coils Reviewed International journal

Hinako Ishizaki, Satomi Ueda, Takamitsu Ogata, Atsushi Ishiyama, Hiroshi Ueda, So Noguchi

IEEE Transactions on Applied Superconductivity 31 ( 5 ) 4901405 2021.8

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

We aim to develop REBCO coil systems for high-magnetic-field whole-body magnetic resonance imaging and medical cyclotron for cancer therapy. These applications require high temporal stability and spatial uniformity of the generated magnetic field. Although the magnetic field generated during excitation changes very slowly, a screening-current-induced magnetic field (SCIF) is generated, which affects the required accuracy of the magnetic field. To reduce the SCIF, we focus on two methods: 1) a current control method, and 2) the use of striated coated conductors. When adopting a striated coated conductor, it is necessary to plate copper onto it in order to maintain its thermal stability and mechanical strength. However, in the copper-plated layer, changes in the magnetic field induce a coupling current, which flows between the filaments of the REBCO coated conductor. In this study, we apply the overshoot method with a plateau as a current control to eliminate the effect of coupling currents in the copper plating layer. We numerically analyzed the effectiveness of this overshoot method by visualizing the changes in the current distributions in a model pancake coil wound with a REBCO-coated conductor separated into two filaments. For that purpose, we used a three-dimensional nonlinear transient electromagnetic field computation in which the spiral arrangement of the pancake coil windings is appropriately considered.

DOI： 10.1109/TASC.2021.3073634

Turn-to-Turn Contact Resistance Measurement of No-Insulation REBCO Pancake Coil: External Field Dependence Reviewed International journal

So Noguchi, Shunpei Mori, Takanobu Mato, Takahiro Tatsuta, Daisuke Nishikawa, Kohei Miyamoto, Ryota Inoue, Hiroshi Ueda, Seokbeom Kim

IEEE Transactions on Applied Superconductivity 31 ( 5 ) 2021.8

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

The characteristics of no-insulation high-temperature superconducting (HTS) manet is dominated by the magnitude of the turn-to-turn contact resistance. A few techniques have been proposed to increase the turn-to-turn contact resistance. The relation between the turn-to-turn contact resistance and the magnet stability has also been investigated in simulations. Although the turn-to-turn contact resistance measurement was only the sudden-discharging method before, we proposed a low-frequency-AC current (LFAC) method. Using our proposed method, it is possible to measure the turn-to-turn contact resistance under various conditions. In a previous paper, we measured it when charging DC current to a single pancake coil. In this paper, the turn-to-turn contact resistance was measured by the LFAC method when an external field of 1-3 T was applied to a single pancake coil. The coil strain was also measured, and the relation of the turn-to-turn contact resistance and the coil strain was also discussed.

DOI： 10.1109/TASC.2021.3070232

Turn-to-Turn Contact Resistance Measurement of No-Insulation REBCO Pancake Coil: External Field Dependence Reviewed International journal

So Noguchi, Shunpei Mori, Takanobu Mato, Takahiro Tatsuta, Daisuke Nishikawa, Kohei Miyamoto, Ryota Inoue, Hiroshi Ueda, SeokBeom Kim

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 31 ( 5 ) 2021.8

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Thecharacteristics of no-insulation high-temperature superconducting (HTS) manet is dominated by the magnitude of the turn-to-turn contact resistance. A few techniques have been proposed to increase the turn-to-turn contact resistance. The relation between the turn-to-turn contact resistance and the magnet stability has also been investigated in simulations. Although the turn-to-turn contact resistance measurement was only the sudden discharging method before, we proposed a low-frequency-AC current (LFAC) method. Using our proposed method, it is possible to measure the turn-to-turn contact resistance under various conditions. In a previous paper, we measured it when charging DC current to a single pancake coil. In this paper, the turn-to-turn contact resistance was measured by the LFAC method when an external field of 1-3 T was applied to a single pancake coil. The coil strain was also measured, and the relation of the turn-to-turn contact resistance and the coil strain was also discussed.

DOI： 10.1109/TASC.2021.3070232

Influence of Coil Size and Operating Temperature on the Transient Stability of a Multi-Stacked No-Insulation REBCO Pancake Coil System Reviewed International journal

Haruka Onoshita, Yuka Yoshihara, Hiroshi Ueda, So Noguchi, Atsushi Ishiyama

IEEE Transactions on Applied Superconductivity 30 ( 4 ) 4702605 2020.6

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

The no-insulation (NI) coil is a technology expected to realize both high current density and high thermal stability which are essentially trade-off relationship in REBCO coil application. This technique has been studied mainly for application to small-diameter inner coils of NMR magnets exceeding 30 T. In this case, the coil is cooled using 4.2-K liquid He. We are developing an NI-REBCO coil system for high-magnetic-field whole-body MRI, and for a medical cyclotron to be used for cancer therapy. The NI-REBCO coil which we aim for development has a diameter of similar to 1 m, a generated magnetic field is similar to 10 T, and a conduction cooling around 30 K is assumed. Because the size, operating temperature, and magnetic field differ from those of NMR coil, it is possible that the electromagnetic, thermal, and mechanical behaviors will be quite different. In this paper, we report on these behaviors when a local deterioration occurs in NI-REBCO double-pancake coils using numerical analysis considering coil size, operating temperature, and magnetic field as parameters. For the numerical simulation, we conducted a coupled analysis of current distribution analysis based on PEEC (Partial Element Equivalent Circuit) model and thermal analysis by the 2-dimensional finite element method.

DOI： 10.1109/TASC.2020.2974847

Study on the Effect of Metal Protection Rings in No-Insulation HTS Coils Reviewed International journal

SeokBeom Kim, Takahiro Tatsuta, Daisuke Nishikawa, Kohei Miyamoto, Hiroshi Ueda

IEEE Transactions on Applied Superconductivity 30 ( 4 ) 4703604 2020.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical and Electronics Engineers (IEEE)

In this study, we propose the installation of multiple metal protection rings on the outermost turn of no-insulation (NI) coils to improve thermal, mechanical, and electrical stability. The current bypass characteristics in the transverse direction within an NI test coil wound with 10 turns of GdBCO wire and wrapped with 8 turns of Cu tape around the outermost layer were experimentally investigated for various amounts of heating by a heater and various heater positions. To confirm the electrical effectiveness of the metal protection rings, 8-turn Cu tape was used as the rings. A bypass current from the outermost part of the test coils to the Cu tape was observed. The local temperature increase due to thermal disturbance was suppressed.

DOI： 10.1109/tasc.2020.2976066

Turn-to-Turn Contact Resistance Measurement of No-Insulation REBCO Pancake Coil at DC Current Operation Reviewed International journal

So Noguchi, Takahiro Tatsuta, Daisuke Nishikawa, Hiroshi Ueda, SeokBeom Kim

IEEE Transactions on Applied Superconductivity 30 ( 4 ) 9000305 2020.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical and Electronics Engineers (IEEE)

No-insulation (NI) (RE)Ba tex-math notation="LaTeX">$_3$ (REBCO) magnets are very promising for practical applications to generate high magnetic field. The NI winding technique provides high thermal stability so that quench protection is unnecessary. However, the turn-to-turn contact resistance (sometimes called characteristic resistance) is an important factor to characterize the thermal stability and charging delay of NI REBCO pancake magnets. Although the conventional sudden-discharging method is widely used to measure the turn-to-turn contact resistance, it is not applicable to various conditions; e.g., the change of DC operating current and temperature. Therefore, we have previously proposed a turn-to-turn contact resistance measurement method using a low-frequency AC (LFAC) current. In this paper, we measured the contact resistance for different DC operating currents or change of DC current to confirm the validity of LFAC method. In addition, by heating a test coil, the contact resistances were also measured during the change of DC operating current. Since the electromagnetic stress is small enough not to change the contact condition, the change in contact resistance is negligible. The measured contact resistance was unchanged, so we could conclude that the LFAC method is effective in measurement of the contact resistance when DC operating current was applied.

DOI： 10.1109/tasc.2020.2970381

Design and Trial Production of Magnetic Filter for Medical Protein Screening System using High Gradient Magnetic Separation Reviewed International journal

M. Mori, M. Kubota, T. Abe, S. B. Kim, H. Ueda

Journal of Physics: Conf. Series 1293 12081 2019.10

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：IOP PUBLISHING LTD

Biomedicine is indispensable for the treatment of various diseases such as cancer and diabetes mellitus. In particular, antibodies utilized by the immune system are believed to represent the future of medical supplies as they offer an effective treatment for diseases with minor side effects. The development of antibody drugs requires a large-scale, sequential, fast separation, and refinement process for the medical proteins. Thus, in the previous study, we proposed a medical protein screening system that is based on high-gradient magnetic separation using a superconducting magnet. In the proposed system, the protein is specifically attached to the magnetic beads and captured by the magnetic force around a magnetic filter generated by a high magnetic field. In this paper, the behaviour of the magnetic beads was investigated using particle trace simulation coupled with electromagnetic and fluid analyses for three types of commercially available magnetic filters. Simulations were performed using the filter stack intervals and number of filters as design parameters. Finally, we designed the suitable filter for capturing the magnetic beads.

DOI： 10.1088/1742-6596/1293/1/012081

Turn-to-Turn Contact Resistance Measurement of No-Insulation REBCO Pancake Coils Reviewed International journal

So Noguchi, Ryousuke Miyao, Haruyoshi Okusa, Takahiro Tatsuta, Hiroshi Ueda, Seokbeom Kim

IEEE Transactions on Applied Superconductivity 29 ( 5 ) 4601605 2019.8

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

© 2002-2011 IEEE. The turn-to-turn contact resistance (characteristic resistance) is a very important factor to a no-insulation (NI) (RE)Ba-2 Cu-3O-y (REBCO) pancake coil. It characterizes the stability and charging delay of NI REBCO pancake coils. However, the ordinary sudden-discharging method cannot measure the turn-to-turn contact resistance under different conditions, such as an operating current, a temperature, and an external magnetic field. Although the turn-to-turn contact condition is strongly affected by the pressure inside of the NI REBCO coils, the feature of the contact resistance must be clarified to estimate the stability of NI REBCO coils. In this paper, we have proposed a new method to measure the turn-to-turn contact resistance applying ac current. The theory and the measurement results are also shown. The measured turn-to-turn contact resistance is reasonable, compared with that measured by the ordinary sudden-discharging method. In near future, we will measure the turn-to-turn contact resistance under different conditions by means of the proposed method.

DOI： 10.1109/TASC.2019.2903643

A simple screening current-induced magnetic field estimation method for REBCO pancake coils Reviewed International coauthorship International journal

So Noguchi, Hiroshi Ueda, Seungyong Hahn, Atsushi Ishiyama, Yukikazu Iwasa

Superconductor Science and Technology 32 ( 4 ) 45007 2019.4

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

© 2019 IOP Publishing Ltd. The development of NMR/MRI REBa 2 Cu 3 O y (REBCO, RE = rare earth) magnets is happening all over the world. It has been found that screening current-induced magnetic fields (SCMFs) are a serious problem for NMR/MRI magnets wound with REBCO tapes. The reduction of SCMFs is strongly desired, and the estimation of SCMFs is also desired at the design stage of REBCO magnets. In order to evaluate a SCMF, a finite element method (FEM) or a boundary integration method is needed thus far, and a high-level simulation technique is required. In this paper, we develop an easy method to estimate a SCMF without a high-level simulation technique. In this method, the inductance of a winding turn is calculated and then a screening current is estimated according to the magnetic field penetrating into the winding turn. The SCMF is obtained from the estimated screening current. The SCMFs computed by the proposed method were compared with measurements and simulation results of the FEM. The results agreed well, but we can see a large difference. However, the SCMFs found by the proposed method are accurate enough to know they are at the design stage without the use of a high-level simulation technique.

DOI： 10.1088/1361-6668/aafe26

REBCOコイルにおける遮蔽電流不整磁場の抑制効果解析 ‐ 9.4 T 級ヒト全身用MRI コイルを対象として ‐ Reviewed

伊東慶太, 植田浩史, 野口聡, 石山敦士

低温工学 54 ( 2 ) 119 - 126 2019.3

無絶縁REBCOパンケーキ・コイルにおける数値解析技術 Invited Reviewed

野口聡, 植田浩史, 石山敦士

低温工学 54 ( 2 ) 103 - 110 2019.3

Numerical Simulation on Coupling Current for Multifilamentary HTS Wire Reviewed International journal

T. Koizumi, E. Morikawa, SB. Kim, H. Ueda

Journal of Physics: Conf. Series 1054 12039 - 012039 2018.6

Numerical Simulation on Behaviour of Magnetic Beads in Magnetic Filter for Medical Protein Screening System using High Gradient Magnetic Separation Reviewed International journal

M. Kubota, Y. Mori, SB. Kim, H. Ueda

Journal of Physics: Conf. Series 1054 12085 - 012085 2018.6

Development of HTS Bulk NMR Relaxometry with Ring-Shaped Iron Reviewed International journal

Seokbeom Kim, Susumu Fukada, Ryota Nomura, Hiroshi Ueda

IEEE Transactions on Applied Superconductivity 28 ( 3 ) 4301205 2018.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical and Electronics Engineers Inc.

The compact NMR magnets consisted of the stacked higherature superconducting (HTS) GdBCO bulk annuli trapped by field cooling (FC) method have been developed. The target values of strength and homogeneity of magnetic field for proposed NMR relaxometry are 1.5 T and 150 ppm/cm3, respectively, at liquid nitrogen temperature. Since last year, we have been developing a hardware and software to detect the NMR signals by ourselves. Therefore, we needed to determine the final structure of HTS bulk magnet to be used in the NMR relaxometry. We can obtain the trapped magnetic field over 1.5 T at 77.4 K experimentally. However, it is still difficult to obtain the magnetic field homogeneity under 150 ppm/cm3 experimentally, due to their different superconducting properties. Therefore, in this study, four types of HTS bulk magnets to determine the final structure of compact NMR relaxometry were designed and their field properties including the degraded HTS bulk were investigated using three-dimensional finite-element method analysis. The field properties of 10-stacked HTS bulk magnets with the ring-shaped irons for field compensation and the degraded HTS bulk were investigated experimentally.

DOI： 10.1109/TASC.2017.2785260

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