研究者詳細 - 金　錫範

MISC - 金　錫範

分割表示 288 件中 121 - 140 件目／全件表示 >>

Current bypassing properties by thermal switch for PCS application on NMR/MRI HTS magnets

S. B. Kim, M. Takahashi, R. Saito, Y. J. Park, M. W. Lee, Y. K. Oh, H. S. Ann

Proceedings of the 27th International Symposium on Superconductivity (ISS 2014) 65 149 - 152 2015年

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

We develop the compact NMR/MRI device using high temperature superconducting (HTS) wires with the persistent current mode operating. So, the joint techniques between 2G wires are very important issue and many studies have been carried out. Recently, the K.JOINS, Inc. has developed successfully the high performance superconducting joints between 2G wires by partial melting diffusion and oxygenation annealing process [1]. In this study, the current bypassing properties in a loop-shaped 2G wire are measured experimentally to develop the permanent current switch (PSC). The current bypassing properties of loop-shaped test coil wound with 2G wire (GdBCO) are evaluated by measured the self-magnetic field due to bypassed current by Hall sensors. The strain gauge was used as heater for persistent current switch, and thermal properties against various thermal inputs were investigated experimentally. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

DOI： 10.1016/j.phpro.2015.05.088

Magnetic-Thrust Flexible Electrode with Integrated Preamplifier for Neural Recording

Toshihiko Noda, Yoshiya Matsuzaka, SeokBeom Kim, Hiroaki Takehara, Kiyotaka Sasagawa, Takashi Tokuda, Hajime Mushiake, Hiroshi Onodera, Jun Ohta

SENSORS AND MATERIALS 27 ( 11 ) 1079 - 1089 2015年

記述言語：英語出版者・発行元：MYU, SCIENTIFIC PUBLISHING DIVISION

Flexible electrodes for use in recording neural activity were fabricated in this study, and their use was demonstrated. By using the mechanical force generated by a magnetic field, an electrode can be inserted into a tissue, and the position of the electrode can be controlled. The position and insertion path of the electrode can be controlled accurately with a high degree of freedom. No stiffener materials are required for the insertion process. A headstage amplifier, which is indispensable for low-noise recording, was hybrid-integrated with a flexible electrode. A miniaturized main amplifier that served as a second-stage amplifier was also fabricated. The magnetic controllability of the fabricated electrode was demonstrated using a phantom of a tissue. An in vivo experiment was also performed for the functional validation of the recording function. Local field potentials were recorded successfully as a result of the experiment.

DOI： 10.18494/SAM.2015.1145

Development of field control method and basic design of HTS magnet for MDDS

A. Nakashima, S. B. Kim, I. Eritate, T. Abe, S. Shima, M. Takahashi, N. Sanada

Proceedings of the 27th International Symposium on Superconductivity (ISS 2014) 65 237 - 240 2015年

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

The magnetic drug delivery system (MDDS) is a key technology to reduce the side effects in the medical applications. We proposed the new magnetic force control system that consists of superconducting magnet, high temperature superconductors (HTS) tapes and iron blocks. In this study, it was confirmed that the control of magnetic field gradient was possible by arranging the HTS tapes and iron blocks on the superconducting magnet. In addition, the multiple racetrack HTS magnets were proposed in order to generate the high field gradient along the longitudinal direction. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

DOI： 10.1016/j.phpro.2015.05.132

The study on the shape of 2-D stator with electromagnets and permanent magnets for 3-D superconducting actuator

S. Ozasa, S. B. Kim, H. Nakano, M. Sawae, H. Kobayashi

Proceedings of the 27th International Symposium on Superconductivity (ISS 2014) 65 257 - 260 2015年

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

The electric device applications of a high temperature superconducting (HTS) bulk magnet having stable levitation and suspension properties due to their strong flux pinning force have been proposed and developed. We have been investigating the three-dimensional (3-D) superconducting actuator using HTS bulk to develop a non-contact transportation device.
Probably, the cost of the manufactory will be increased to install the 2-D arranged electromagnets (EM) in a large area because many EMs are needed to cover the area. Therefore, we have been trying to find the method for reducing the number of EMs. In this study, all the EMs except for rotation were replaced in the 2-D arranged permanent magnets (PM), and gap length between PMs were experimentally investigated to improve the dynamic behavior of the mover and to reduce the cost of the manufacturing. As a result, we have succeeded in conveyance of the bulk and reduce the convergence time and maximum overshoot. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

DOI： 10.1016/j.phpro.2015.05.141

The Dynamic Characteristics on the Wall Traveling of the HTS Bulk Superconducting Actuator

M. Sawae, S. B. Kim, S. Ozasa, H. Nakano, H. Kobayashi

Proceedings of the 27th International Symposium on Superconductivity (ISS 2014) 65 249 - 252 2015年

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

The electric device applications of a high temperature superconducting (HTS) bulk having stable levitation and suspension properties due to their strong flux pinning force have been proposed and developed. We have been investigating the three-dimensional (3-D) superconducting actuator using HTS bulk to develop the transportation device with non-contact and moves in free space. It is expected that our proposed 3-D superconducting actuator to be useful as a transporter used in clean room which manufactures the silicon wafer where dislikes mechanical contact and dust. Proposed the actuator consists of a field-cooled HTS bulk for mover and two-dimensional arranged multiple electromagnets as a stator. In our previous study, the dynamic characteristics on the floor traveling of the HTS bulk mover had been studied. Therefore in this study, a system for the wall traveling was proposed to use the limited space effectively. It is expected that the wall traveling system is very useful to apply the transporter used in the tunnels which flammable gas may be produced. In this paper, the optimal angle between electromagnets located at floor and wall for moving to the wall traveling from the floor traveling was investigated experimentally. The position displacement on the rotating of the HTS bulk during the wall traveling was measured. As a result, the bulk with initial gap of 2 mm could move to the wall traveling from the floor traveling. Also, the position displacement on the height direction during the rotating of the HTS bulk was 18 mm from the initial position because of its gravity, but it was possible to rotate by changing the pattern NSNS of the trapped magnetic field in near the initial position. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

DOI： 10.1016/j.phpro.2015.05.138

Development of the current bypassing methods into the transverse direction in non-insulation HTS coils

K. Tanaka, S. B. Kim, H. Ikoma, D. Kanemoto

Proceedings of the 27th International Symposium on Superconductivity (ISS 2014) 65 229 - 232 2015年

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

In the case of motors and generators, the benefits of using high temperature superconducting (HTS) coils can be represented by the reduction of 50% in both losses and sizes compared to conventional machines. However, it is hard to establish quench detection and protection devices for the HTS coils applied to the rotors of motors and generators. So, the stability of the coils is lower than for the quiescent coils applied to NMR, MRI and so on. Therefore, it is important to improve the self-protection ability of HTS coils. We have studied the methods to improve the self-protection ability of HTS coils by removing the layer-to-layer insulation and inserting metal tape instead of the electrical insulation. The operating current in the non-insulated HTS coil was bypassed into the transverse direction by the generated normal region because of their electrical contact among the winding. In this study, we examined the method to control the current bypassing on layer-to-layer for controlling the inductance of the non-insulated HTS coil. The current bypassing properties on non-insulated HTS coil wound with 2G wires will be discussed. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

DOI： 10.1016/j.phpro.2015.05.129

The fundamental study to control the magnetic field for MDDS using shielding currents of HTS tapes and bulks

B. Kim, I. Eritate, T. Abe, S. Shima, M. Takahashi

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 506 27 - 32 2014年11月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

The magnetic drug delivery system (MDDS) is a key technology to reduce the side effects in the medical applications, and the magnetic force control is a very important issue in MDDS. In general, the high magnetic field along the axial direction and high magnetic field gradient along the longitudinal direction are very useful for MDDS. So, we proposed the new magnetic force control system that consists of superconducting magnet, high temperature superconductors (HTS) bulks or tapes and ferromagnetic substances. In this new system, the shielding currents in HTS bulks and tapes due to diamagnetism of the superconductor generate the magnetic field with same direction of external magnetic field, and we can control the magnetic field gradient along the longitudinal direction by the arrangement of the HTS bulks, tapes and ferromagnetic substances. In this study, the stacked GdBCO tapes without stabilizer were used in experiments and electromagnetic analysis based on finite element method (FEM) was carried out to optimize the arrangement of the superconductors and the irons. It was confirmed that the control of magnetic field gradient along the longitudinal direction was possible by arranging the HTS bulks, tapes and irons on the superconducting magnet and then it was possible to obtain a magnetic field higher than the external field. Crown Copyright (C) 2014 Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physc.2014.08.001

Study on the Remagnetization Process to Improve the Field Homogeneity of the Stacked HTS Bulk Magnets

S. B. Kim, N. Hayashi, H. Kitamura, I. Eritate

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 24 ( 3 ) 4301405 - 4301405 2014年6月

記述言語：英語出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

The compact NMR magnets consisting of stacked HTS bulk annuli trapped by a field cooling (FC) method have been developed. However, it is difficult to trap a uniform magnetic field above 4.7 T (200 MHz-class NMR magnet) and field homogeneity under 0.01 ppm/cm(3) at liquid nitrogen temperature (77.4 K) because of the low Jc-B characteristics of present HTS bulk magnets. On the other hand, the strength and homogeneity of the magnetic field required for the NMR relaxometry device are 1.5 T and 150 pprn/cm(3) respectively; these values are much lower than the conventional NMR device. It is relatively easy to generate a magnetic field over 1.5 T at 77.4 K using the stacked HTS bulk annuli, but it is still hard to obtain 150 pprn/cm(3) field homogeneity with the conventional superconducting magnet (SCM) as the magnetizing magnets. In this paper, we proposed that the homogeneity had been improved by utilizing the remagnetization process.

DOI： 10.1109/TASC.2013.2290591

Development of the Noncontact Rotating System Using Combined Ring-Shaped HTS Bulks and Permanent Magnets

S. B. Kim, T. Ikegami, Y. Fujii, M. Takahashi, H. Onodera

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 24 ( 3 ) 6800105 - 6800105 2014年6月

記述言語：英語出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

In this study, the noncontact magnetic levitation system using combined high temperature superconducting (HTS) hulk annuli and ring-shaped permanent magnet (PM) was proposed. In the suggested levitation system, the HTS bulk annuli were magnetized by ring-shaped PMs fixed between the HTS bulk annuli, so there was no more need to apply source for magnetization. In this paper, the levitation forces on the radial and axial directions were measured using 1 PM + 2 bulks (1 unit) and 2 PM + 3 bulks systems to study the optimization of levitation system. To improve the levitation property of proposed levitation system, the shape of PM and materials of the rotor shaft were studied experimentally.

DOI： 10.1109/TASC.2013.2284021

Study on the Electrical Contact Resistance Properties With Various Winding Torques for Noninsulated HTS Coils

S. B. Kim, H. Kajikawa, H. Ikoma, J. H. Joo, J. M. Jo, Y. J. Han, H. S. Jeong

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 24 ( 3 ) 4600405 - 4600405 2014年6月

記述言語：英語出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

In the case of motors and generators, the benefits of using high-temperature superconducting (HTS) coils can be represented by the reduction of 50% in both losses and sizes compared to conventional machines. However, it is hard to establish quench detection and protection devices for the HTS coils applied to the rotors of motors and generators. Therefore, the stability of the coils is lower than for the quiescent coils applied to NMR, MRI, and so on. Therefore, it is important to improve the self-protection ability of HTS coils. We have studied the methods to improve the self-protection ability of HTS coils by removing the turn-to-turn insulation and inserting metal tape instead of the electrical insulation. When the coils are energized, there are voltages generated by sweep rate of the current (di/dt) and inductance of the coil. Because noninsulated HTS coils have electrical contacts along the transverse direction, a bypass current is generated along the transverse direction and noninsulated HTS coils have a risk of Joule heating in the stabilizer and metal substrate. Furthermore, the electrical contact resistance of noninsulated HTS coils was changed by a winding torque. In this paper, we measured the electrical contact resistance along the transverse direction with various winding torques for noninsulated HTS coils.

DOI： 10.1109/TASC.2013.2283103

Passive Shimming by Eliminating Spherical Harmonics Coefficients of all Magnetic Field Components Generated by Correction Iron Pieces

So Noguchi, SeokBeom Kim, Seungyong Hahn, Yukikazu Iwasa

IEEE TRANSACTIONS ON MAGNETICS 50 ( 2 ) 7014904 - 7014904 2014年2月

記述言語：英語出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

When a magnet generating highly homogeneous magnetic field is designed, a shimming is required. The shimming is usually performed so that the magnetic field only in the axis direction is compensated by iron pieces and/or coils. The compensation is commonly achieved by eliminating the coefficients of the spherical harmonics expansion of the magnetic field generated by the main magnet. Some papers showed the coefficients of the spherical harmonics expansion in only the z-direction for passive shimming. However, recently some magnets generate a magnetic field tilted from the z-axis, such as a magic-angle-spinning nuclear magnetic resonance/MRI. It is, therefore, necessary to eliminate the coefficients of the spherical harmonics expansion in the x- and y-direction.

DOI： 10.1109/TMAG.2013.2276736

The dynamic characteristics of 3-D superconducting actuator using the magnetized HTS bulk by sandwiched electromagnets

H. Nakano, S. B. Kim, S. Ozasa, M. Sawae

PROCEEDINGS OF THE 26TH INTERNATIONAL SYMPOSIUM ON SUPERCONDUCTIVITY (ISS 2013) 58 294 - 297 2014年

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

The electric device applications of a high temperature superconducting (HTS) bulk, having stable levitation and suspension properties due to their strong flux pinning force, have been proposed and developed. We have been investigating the three-dimensional (3-D) superconducting actuator using HTS bulk to develop a non-contact transportation device. In our previous works, the overshooting of the HTS bulk mover magnetized by 2-D arranged electromagnets were observed. Therefore, the new magnetization method using sandwiched electromagnets was purposed in order to solve the overshooting problems of HTS bulk mover. In this paper, the dynamic stabilities on the rotating and horizontal moving of the HTS bulk mover magnetized by sandwiched electromagnets was investigated experimentally, and the maximum moving displacements and convergence times during the overshooting state were reduced by proposed magnetization method with small magnetizing current. (C) 2014 The Authors. Published by Elsevier B.V.

DOI： 10.1016/j.phpro.2014.09.073

Numerical study on split coil-shaped HTS bulks to improve the field homogeneity for compact NMR relaxometry magnets

D. Ishizuka, S. B. Kim, N. Hayashi, H. Kitamura, D. Miyazawa

PROCEEDINGS OF THE 26TH INTERNATIONAL SYMPOSIUM ON SUPERCONDUCTIVITY (ISS 2013) 58 290 - 293 2014年

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

We have been developing a new compact NMR magnet using stacked HTS bulks. In this paper, in order to improve the trapped magnetic field homogeneity and to obtain the enlarged sample space of HTS bulk magnet for compact NMR relaxometry, the HTS bulk magnet with 10 mm gap length in the center region of HTS bulk magnet (we call it split coil-shaped THS bulks) were proposed and studied as the functions of size and shape of HTS bulk using 3D FEM based electromagnetic analysis. The improved field homogeneity was obtained using notch coil shaped HTS bulk configuration and the field compensation by attached the coil instated of the bulks. (C) 2014 The Authors.Published by Elsevier B.V.

DOI： 10.1016/j.phpro.2014.09.072

The study to improve the field homogeneity of the HTS bulk magnets for NMR Relaxometry device by passive compensation methods

H. Kitamura, S. B. Kim, N. Hayashi, D. Ishizuka, D. Miyazawa

PROCEEDINGS OF THE 26TH INTERNATIONAL SYMPOSIUM ON SUPERCONDUCTIVITY (ISS 2013) 58 298 - 301 2014年

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

In this paper, the compensation method to obtain the high field homogeneity (150 ppm/cm(3)) of compact NMR magnet was studied analytically. In order to improve the trapped magnetic field homogeneity of HTS bulk magnet, we used the packaged HTS bulk magnet consisted of HTS bulks annuli and 3 iron rings for field compensation. We could confirm that the target homogeneity of trapped magnetic field of HTS bulk magnet was achieved by the proposed passive compensation method. (C) 2014 The Authors. Published by Elsevier B.V.

DOI： 10.1016/j.phpro.2014.09.074

The levitation characteristics of the magnetic substances using trapped HTS bulk annuli with various magnetic field distributions

S. B. Kim, T. Ikegami, J. Matsunaga, Y. Fujii, H. Onodera

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 494 270 - 275 2013年11月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

We have been investigating the levitation system without any mechanical contact which is composed of a field-cooled ring-shaped high temperature superconducting (HTS) bulks [1]. In this proposed levitation system, the trapped magnetic field distributions of stacked HTS bulk are very important. In this paper, the spherical solenoid magnet composed of seven solenoid coils with different inner and outer diameters was designed and fabricated as a new magnetic source. The fabricated spherical solenoid magnet can easily make a homogeneous and various magnetic field distributions in inner space of stacked HTS bulk annuli by controlling the emerging currents of each coil. By using this spherical solenoid magnet, we tried to make a large magnetic field gradient in inner space of HTS bulk annuli, and it is very important on the levitation of magnetic substances. In order to improve the levitation properties of magnetic substances with various sizes, the external fields were reapplied to the initially trapped HTS bulk magnets. We could generate a large magnetic field gradient along the axial direction in inner space of HTS bulk annuli, and obtain the improved levitation height of samples by the proposed reapplied field method. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physc.2013.05.020

Experimental and Analytical Studies on Non-Uniformity Properties of HTS Bulk Annuli for High Magnetic Performance Applications

S. B. Kim, Y. Yano, N. Hayashi, Jin-Hong Joo

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 23 ( 3 ) 4602804 2013年6月

記述言語：英語出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

In designing and manufacturing of a new type of compact nuclear magnetic resonance/magnetic resonance imaging magnet, which consists of a stacked high-temperature superconducting (HTS) bulk annuli, the spatial homogeneity and the temporal stability of the trapped magnetic fields are the key issues. On the other hand, there is an asymmetry problem for superconducting properties including the critical current density along the axial (thickness) direction in HTS bulks due to its manufacturing process using a seed crystal located at the top surface. Therefore, in this study, we find the nonuniformity of the critical current density of the HTS bulk along the axial direction, which probably comes from the quench-melt-growth process using a seed crystal. The measured axial positions of the maximum magnetic field were slightly shifted to the bottom direction lower than the axial center position. The critical current density and/or superconducting properties of HTS bulks are probably decreased in proportion to the distance from a seed crystal. Therefore, the superconducting properties along the thickness direction in the HTS bulk were represented as a variable J(c) - B and electrical conductivity.

DOI： 10.1109/TASC.2013.2250331

The Transient Stability of HTS Coils With and Without the Insulation and With the Insulation Being Replaced by Brass Tape

Seok Beom Kim, Takeshi Kaneko, Hiromu Kajikawa, Jin Hong Joo, Jeong-Min Jo, Young-Jae Han, Hyun-Seung Jeong

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 23 ( 3 ) 7100204 2013年6月

記述言語：英語出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

In the case of motors and generators, the benefits of using high-temperature superconducting (HTS) coils could be represented by the reduction of 50% in both losses and sizes compared to the conventional machines of the same rating. However, it is hard to establish the quench detection and protection devices for the HTS coils applied to the rotors of motors and generators. Therefore, the stability of the coils is lower than the quiescent coils applied to NMR, MRI, and so on. Therefore, it is important to improve the self-protection ability of HTS coils. We have been developing a novel self-protection method, which removes the insulation turn-turn winding and inserts various metal tapes instead of the insulation. In our previous research, the higher self-protection ability for the thermal disturbances in the HTS coils removed the insulation and inserted Cu tape has been proved. This paper presents the results of an experimental study for the quench current using the insulated, the noninsulated, and the Brass tape inserted HTS coils in liquid nitrogen and background magnetic fields. Also, the measured quench currents of each coil will be discussed.

DOI： 10.1109/TASC.2012.2234492

Study on optimization of YBCO thin film stack for compact NMR magnets

S. B. Kim, T. Kimoto, S. Hahn, Y. Iwasa, J. Voccio, M. Tomita

Physica C: Superconductivity and its Applications 484 295 - 299 2013年1月

記述言語：英語

A compact high temperature superconducting (HTS) magnet, which consists of a stack of 500 HTS thin film annuli, was constructed and tested. Each thin film annulus, manufactured by the AMSC using the Rolling Assisted Bi-axially Textured Substrate (RABiTS) method, has a square cross-section of 40 mm × 40 mm with a thickness of 80 m. It has a 25-mm center hole created by machining. This paper reports a study on the anisotropic Jc issue due to the rolling procedure of the Ni substrate direction and its impact on field homogeneity. Also, three different stacking methods with rotation angles of 22.5°, 90°, and 0° against the rolling direction have been tested to study their impacts on strength, spatial homogeneity, and temporal stability of trapped fields. Finally, the 500-annulus magnet was tested at 21 K under a cryogen-free environment using a GM cryocooler. The spatial field homogeneity and temporal stability were measured at 21 K and compared with those obtained in a bath of liquid nitrogen at 77 K.

DOI： 10.1016/j.physc.2012.02.042

The study on improving the self-protection ability of HTS coils by removing the insulation and lamination of the various metal tapes

S. B. Kim, T. Kaneko, A. Saito, H. Kajikawa, J. H. Joo, J. M. Jo, Y. J. Han, H. S. Jeong

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 484 310 - 315 2013年1月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

The high temperature superconducting (HTS) coils have very low normal zone propagation velocity (NZPV) and complicated quench behaviors. Because of these reasons, it is difficult to expect the self-protection. In this paper, two methods are suggested to improve the self-protection ability of HTS coils. One is to remove the insulation between turn-turn winding in HTS coils to enhance the thermal and electrical contacts along transverse direction and to increase the whole thermal stability of them. The other is Cu or Brass tapes are wound with HTS tape wire instead of the insulation to improve the thermal, electrical and mechanical stability of the HTS coils. To clarify the quench behaviors of the suggested coils, the normal zone propagation properties of the fabricated non-insulated HTS pancake coils were shown by measured voltage and temperature traces during the quench as a function of the operating temperature. And the characteristics of the normal transition and amount of the shared current to adjacent layers were quantitatively measured by a Hall sensor located at the center of HTS coils to measure the change of the self-magnetic field by operating current. The current sharing behaviors in the non-insulated HTS coil and the coil with Cu tape inserted were observed. The minimum quench energy (MQE) of the HTS coil with Cu tape inserted was the largest in the tested coils. It means that the HTS coil with Cu tape inserted had the highest transient stability against the thermal disturbances among the tested coils and the improvement of self protection abilities was proved. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physc.2012.03.064

Study on the characteristics of magnetic levitation for permanent magnets and ferromagnetic materials with various sizes using stacked HTS bulk annuli

S. B. Kim, J. Matsunaga, A. Doi, T. Ikegami, H. Onodera

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 484 316 - 320 2013年1月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE BV

We achieved stable levitation of cylindrical permanent magnets and irons using stacked ring-shaped high temperature superconducting (HTS) bulks with 20 mm ID, 60 mm OD and 50 mm height, and those were magnetized by field cooling method. The levitation characteristics of permanent magnets and iron samples located in the inner space of that levitation system were investigated experimentally. Iron samples with needle-shape and smaller than 1 mm diameter could not levitate stably. However, we found that the high strength of magnetized field was not necessary to levitate small needle-shaped irons. In order to levitate them, we need a uniform magnetic field in radial direction, so, a spherical solenoid magnet that can easily make a homogeneous magnetic field in inner space of HTS bulk annuli was developed. The spherical solenoid magnet, composed of seven solenoid coils with different inner and outer diameters, was designed by an electromagnetic analysis and fabricated. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physc.2012.02.030

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