M. Furuse

National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan

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Publications (66)60.46 Total impact

  • Mitsuho Furuse, Shuichiro Fuchino
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    ABSTRACT: We measured the thermal conductivity of polypropylene laminated paper (PPLP) impregnated with subcooled liquid nitrogen. PPLP is widely used for the electrical insulation of high-Tc superconducting (HTS) power transmission cables. Although the thermal conductivity of PPLP is an important factor in the design of HTS cables, there has been very limited work on its measurement in subcooled liquid nitrogen. We prepared PPLP samples and symmetrically stacked them on both sides of a heater. The stacked samples were immersed in liquid nitrogen in an open cryostat. A cryocooler mounted on the cryostat was used to maintain the subcooled temperature of the liquid nitrogen. The thermal conductivity of the stacked PPLPs was measured by the steady state method at a bath temperature of 65–75 K and was found to be 0.23–0.26 W/mK, which is about five times that measured in a vacuum as presented in available literature. We also discuss possible mechanisms for boosting the thermal conductivity of PPLP by liquid nitrogen impregnation.
    Cryogenics 09/2014; · 1.17 Impact Factor
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    ABSTRACT: Medical proteins such as monoclonal antibodies or immunoglobulin are important as medicine for cancer and other uses. Today, we can easily sort and analyze medical proteins using various types of commercially available affinity magnetic beads. However, separation systems for these medical proteins have a very low separation rate, and the cost of the product is extremely high. We successfully developed a high gradient magnetic separation system using a cryocooler-cooled low-temperature superconducting magnet and conducted experiments on separating affinity magnetic nanobeads. Our system demonstrated very high separation efficiency and can achieve low costs with a large production rate compared to systems now used in this field. The design of a filter to trap and recover the nanobeads is important to this application. In order to achieve a filter with a high trapping ratio of magnetic beads, the parameters need to be optimized because the ratio depends on the dimensions and arrangement of the filter made of fine magnetic metal fibers. In this study, we investigated the performance of filters in the high gradient magnetic separation system. The test results show 97.8% of the magnetic nanobeads in pure water were captured, and 94.1% of the total beads were collected.
    IEEE Transactions on Applied Superconductivity 06/2014; 24(3):1-5. · 1.20 Impact Factor
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    ABSTRACT: Medical proteins such as monoclonal antibodies and immunoglobulins are important substances for the manufacture of medicines for cancer, etc. However, the conventional separation system for these medical proteins has very low separation rate and the cost is extremely high. To address these issues, we have developed a high gradient magnetic separation system for medical proteins using affinity magnetic nanobeads. Our system shows very high separation efficiency and can achieve low cost owing to its large production rate compared with conventional systems. The system consists of a 3T superconducting magnet cooled by a cryocooler, a filter made of fine magnetic metal fibers of about 30 μm in diameter with demagnetization circuit and liquid circulation pump for the solvent containing the medical proteins. Reducing the size of the system entails reduction of the cryocooler size, thereby resulting in reduced cooling capacity. Therefore, the heat load on the cryocooler has been considered carefully in the design of the cryogenic system. The calculated heat load of the 1st and 2nd stages was made to satisfy the cooling capacity of the cryocooler. As a result, a magnet temperature of 4.2 K and a thermal shield temperature of 60 K have been achieved, enabling smooth operation and good performance of the HGMS separation system.
    IEEE Transactions on Applied Superconductivity 06/2014; 24(3):1-4. · 1.20 Impact Factor
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    ABSTRACT: We have successfully developed a high-gradient magnetic separation system for medical proteins using affinity magnetic nanobeads. Our system shows very high separation efficiency and can also be expected to realize lower cost due to larger production rate compared to the conventional system. The developed system consists of a 3-T superconducting magnet and a filter made of fine magnetic metal fibers. The superconducting magnet is wound with a NbTi twisted multifilamentary wire, and cooled by a 4-K Gifford-McMahon cryocooler. In order to achieve high recovery ratio of the magnetic nanobeads trapped on the filter located in a room-temperature clear bore of the cryostat, the ac degaussing system for the filter is fabricated using an inductance-capacitance resonance circuit composed of a series connection with the superconducting magnet and an additional capacitor. To perform the inductance-capacitance resonance more than a few cycles between superconducting magnet and capacitor, the superconducting magnet has a slit in the bobbin to prevent an eddy current coupled with an alternating magnetic field. It also has a control system for a high-speed switching circuit. This magnet can successfully generate a magnetic field of 3.0 T in the clear bore of the cryostat with a diameter of 30 mm in a relatively fast sweep time of 150 s due to the slit in the magnet bobbin. Using our degaussing system, a high recovery ratio of the nanobeads in pure water has been performed about 94.1%.
    IEEE Transactions on Applied Superconductivity 01/2014; 24(3):1-5. · 1.20 Impact Factor
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    ABSTRACT: A high gradient magnetic separation system for medical protein using affinity magnetic nano-beads has been developed. Medical protein such as monoclonal antibody or immunoglobulin is an important substance as a medicine for cancer etc. However; the separation system of these medical protein has very low separation rate and the cost of product is extremely high. The developed system shows very high separation efficiency and can achieve low cost by large production rate compared to the system now using in this field. The system consists of a 3T superconducting magnet cooled by a cryo-cooler, a filter made of fine magnetic metal wires of about 30μm diameter and a demagnetization circuit and a liquid circulation pump for solvent containing medical protein. Affinity magnetic nano-beads is covered with the medical protein after agitation of solvent containing the protein and nano-beads, then the solvent flows through the system and the beads are trapped in the filters by high gradient magnetic field. The beads are released and flow out of the system by the AC demagnetization of the filters using LC resonance circuits after discharge of the magnet. The test results shows 97.8% of the magnetic nano-beads in pure water were captured and 94.1% of total beads were collected.
    12/2013; 1573(1).
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    ABSTRACT: In this study, we developed a two-dimensional vector magnet with Y-Ba-Cu-O (YBCO) tape conductors for use in an X-ray magnetic circular dichroism measurement system. The characteristics of this high- Tc superconducting vector magnet are as follows: (a) it is a split magnet comprising four unit coils that enable an X-ray magnetic circular dichroism system to access the center sample space along three axes; (b) it is compact with a high magnetic field, and it exhibits a cone-shaped design to enable the split unit coils to come close together and to achieve a maximum magnetic field up to 1 T at the center; and (c) it is conduction-cooled by a cryocooler and a cryogen-free system. We fabricated four unit coils with YBCO tape conductors (manufactured by SuperPower Inc.). Two pairs of the unit coils were configured at right angles to each other in a cryostat and cooled below 30 K by the cryocooler. We confirmed that the magnetic field orientation can be controlled by adjusting the current of the unit coils. However, we observed hysteresis and drift of the magnetic field owing to the screening current induced in the YBCO tape conductors. Here, we design a high- Tc superconducting vector magnet and present its excitation test results.
    IEEE Transactions on Applied Superconductivity 01/2013; 23(3):4100704-4100704. · 1.20 Impact Factor
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    ABSTRACT: We are developing a high-Tc superconducting vector magnet for use in solid-state physics apparatus. The vector magnet features are (a) 1 T peak and two-dimensional magnetic field vector controllable (b) comprising four split magnet units enabling free access in three directions to a sample space (c) cryogen-free conduction-cooled magnet. To obtain a vector controllable magnetic field as high as 1 T using a compact magnet, we adopted a tapered design for split magnet units. We fabricated a test magnet unit with YBCO tape conductors and examined its basic performance. The magnet unit generated the rated magnetic field. This paper describes the vector magnet design, fabrication procedures, and the magnet unit test results.
    IEEE Transactions on Applied Superconductivity 01/2012; 22(3):3900504-3900504. · 1.20 Impact Factor
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    ABSTRACT: We numerically calculated the transient temperature distribution of flowing subcooled liquid nitrogen in a high- T <sub>c</sub> superconducting (HTS) model cable when faults occur. The coolant and cable core temperatures were calculated by numerically solving the heat equation using the finite difference method. In the calculation, we assume that the heat transfer coefficient between the flowing subcooled liquid nitrogen and the cable core surface is described by the Dittus-Boelter correlation. The calculation results reveal that the coolant temperature increases even after the fault has been removed and that it continues increasing until fresh coolant arrives from the inlet. The calculated temperature profile of the coolant agrees well with measured data obtained by conducting over-current tests on a model HTS cable. Using our computational code, we also evaluated the maximum HTS cable lengths that ensure that the coolant remains in the liquid phase for certain fault currents for an HTS model cable.
    IEEE Transactions on Applied Superconductivity 07/2011; · 1.20 Impact Factor
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    ABSTRACT: In plant and industrial complex, further energy saving can be realized by DC interconnection between the ends of AC radial distribution system. We fabricated a power system simulator to verify that the DC interconnection is effective for energy saving in the distribution system. An YBCO toroidal coil composed of eight double pancake coils was fabricated and adopted in the simulator as a DC reactor. Harmonic current with DC-offset component were observed in the YBCO toroidal coil and the frequency component ratio of harmonic current depended on the inductance of the toroidal coil. Energy loss in the YBCO toroidal coil during the DC interconnection in the power system simulator decreased with the inductance of the YBCO toroidal coil because the magnitude of harmonic current component decreased with the inductance. To clarify the loss characteristics in the YBCO toroidal coil, we investigated influence of the magnitude of harmonic-frequency component and DC-offset component on the transport current loss in YBCO tape conductor. The transport current lose was independent of the magnitude of DC-offset component. The energy loss characteristics in the YBCO toroidal coil were closely related to the transport current loss in the YBCO tape conductor with harmonic current.
    IEEE Transactions on Applied Superconductivity 07/2011; · 1.20 Impact Factor
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    ABSTRACT: Recently, affinity magnetic beads have been widely used in immunomagnetic cell sorting (IMCS) technology. Today, we can easily sort and analyse DNA and antibodies (immunoglobulin) using various types of affinity magnetic beads available in the market. The diameters of the affinity magnetic beads used in immunomagnetic cell sorting are above approximately 1 ??m because of the low magnetic fields induced by permanent magnets. At present, nanosized affinity magnetic beads are strongly desired to achieve high resolutions. We have been studying and attempting to develop a high-gradient magnetic separation (HGMS) system that employs a superconducting magnet to induce a considerably higher magnetic field than that induced by a permanent magnet. The objective is to trap smaller nanosized affinity magnetic beads using a filter made of fine stainless steel wool. In a previous study, we constructed a prototype of a desktop-type HGMS system using a cryocooler-cooled LTS magnet; we conducted preliminary experiments on trapping nanosized magnetic particles and investigated the magnetic field distribution and magnetic force around a magnetic wire in the filter by means of a numerical simulation. In this study, we succeeded in producing prototype nanobeads covered with the biosurfactant of a high-affinity ligand system for immunoglobulin G and M. Furthermore, we attempted to improve the recovery of nanobeads by adding a resonance circuit to the HGMS system. In practice, the trapped nanobeads attract one another and agglomerate due to their remaining magnetization when the magnetic field is decreased to 0 T. Therefore, the nanobeads and wire are demagnetized in the AC magnetic field by the resonance circuit, making good use of the superconducting magnet of the HGMS system.
    IEEE Transactions on Applied Superconductivity 07/2010; · 1.20 Impact Factor
  • M. Furuse, K. Agatsuma, S. Fuchino
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    ABSTRACT: We measured the heat flow of current leads used for high-Tc superconducting apparatuses operating at liquid nitrogen temperature by the nitrogen boil-off method. To reduce the heat flow at the cold end of the current leads, the use of commercial Bi2223 silver-sheathed (Bi2223/Ag) tape conductors for current leads above liquid nitrogen temperature was also studied. We derived average Lorenz numbers between room temperature and liquid nitrogen temperature from the measurement results to assess the performance of the current leads. We tested Bi2223/Ag-soldered oxygen-free copper leads and obtained slightly lower heat flows and average Lorenz numbers than those of solid copper leads. The average Lorenz numbers of copper alloys were measured as well.
    IEEE Transactions on Applied Superconductivity 07/2009; · 1.20 Impact Factor
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    ABSTRACT: These days, voltage stability of power system is very important for example in semiconductor industries. So, development of a device suppressing voltage sags in power system is expected. In this article, the authors propose a new voltage stabilizing device using a LC resonance circuit composed of superconducting coil and capacitor connected in parallel. This power system voltage stabilizer acts automatically against a voltage sag or a steep voltage change, and it suppresses the voltage drop for several cycles by releasing its stored energy. The authors have confirmed this principle experimentally using a small model system using a LC resonance circuit with a superconducting coil and a capacitor. The experimental results and some theoretical analyses are presented.
    IEEE Transactions on Applied Superconductivity 07/2009; · 1.20 Impact Factor
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    ABSTRACT: Recently, affinity magnetic beads have been widely used in immunomagnetic cell sorting (IMCS) technology. Today, we can easily sort and analyze DNA and antibodies (immunoglobulin) using various types of affinity magnetic beads available in the market. The diameters of these affinity magnetic beads used in immunomagnetic cell sorting are limited to above approximately 1 mum because of the low magnetic fields induced by permanent magnets. Now, nano-sized affinity magnetic beads are strongly desired to achieve high resolutions. We have been studying and attempting to develop a high-gradient magnetic separation (HGMS) system that employs a superconducting magnet to induce a considerably higher magnetic field than that induced by a permanent magnet in order to trap smaller nano-sized affinity magnetic beads by a filter made of fine stainless steel wool. In this study, we constructed a prototype of a desktop-type HGMS system using a cryocooler-cooled LTS magnet and conducted preliminary experiments on trapping the nano-sized magnetic particles. Furthermore, we investigated the magnetic field distribution and magnetic force around a magnetic wire in the filter by means of a numerical simulation.
    IEEE Transactions on Applied Superconductivity 07/2009; · 1.20 Impact Factor
  • Mitsuho Furuse, Koh Agatsuma, Shuichiro Fuchino
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    ABSTRACT: This paper evaluates the losses of current leads made of various metals used in high-Tc superconducting power apparatuses operating at liquid nitrogen temperatures. The heat flow into liquid nitrogen conducting adiabatic current leads was measured by the nitrogen boil-off method. The results were used to derive average Lorenz numbers for metals between room temperature and liquid nitrogen temperatures. The average Lorenz number is a good index of performance of current leads. A theory of loss evaluation of current leads using the average Lorenz number and a method for the optimum current lead design were described as well. In addition, the loss of current leads made of Bi2223/Ag tape conductors was evaluated above the liquid nitrogen temperature, and a higher efficiency was achieved than with pure metal current leads.
    Cryogenics 01/2009; 49(6):263-266. · 1.17 Impact Factor
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    ABSTRACT: We performed fault current limiting tests using YBCO thin films and investigated the reasons for their breakdown during current limiting. There were two patterns of film breakdown. One occurred immediately after current limiting and the other occurred during current limiting. In film breakdown, the quench propagation speed showed almost no change with increasing energy consumption per unit time, but the energy consumption per unit area increased with increasing energy consumption per unit time. Therefore, local areas of the film reached the melting point and arcing occurred.It is therefore concluded that the performance of the films can be improved by decreasing the energy consumption per unit time. Connecting a parallel capacitor to the film in order to limit the energy consumption per unit time is proposed and tested as a measure to improve the current limiting performance of thin films. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(1): 20–27, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20709
    Electrical Engineering in Japan 09/2008; 166(1):20 - 27. · 0.10 Impact Factor
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    ABSTRACT: This paper presents an optimal design method of winding cross section of high temperature superconducting coils wound by Bi2223/Ag tape based on AC loss minimization. We try to optimize the winding cross section starting from the conventional HTS coil with the rectangular cross section to minimize the AC loss. An example of the optimal cross section coil is presented. The result shows that the AC loss in the optimized coil is significantly reduced and the critical current of the optimized coil is increased compared with the rectangle cross section coil. It is verified that our optimal design method is effective to reduce the AC loss in the HTS coil. The disadvantageous points of the optimized coil are also discussed.
    IEEE Transactions on Applied Superconductivity 07/2008; · 1.20 Impact Factor
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    ABSTRACT: We have developed a high-strength Ta-reinforced conductor for high-magnetic-field magnets. In our previous work, it was demonstrated that the Ta-reinforced conductor had good characteristics against mechanical stress and strain. In this study, we made a 2-D calculation code for a stress-strain analysis, and derived the stress and strain of the magnet using some physical values such as the Young's modulus of the conductors, magnet dimensions and so on. According to the calculation results of some model magnets, the Ta-reinforced conductor could be used without extra support structures. Hence, the conductors are fit for high-magnetic-field and large-scale magnets such as NMR and SMES magnets.
    IEEE Transactions on Applied Superconductivity 07/2008; · 1.20 Impact Factor
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    ABSTRACT: We have been developing a superconducting fault current limiter (FCL), in which YBCO superconducting thin films with Au-Ag alloy shunt layers are used. We have already achieved high electric fields (>40 Vpeak/cm), which enable the total length of FCL elements to be reduced drastically, thus greatly reducing the cost of FCLs. In this paper, we report the normal zone propagation velocity in our films when over-current was applied to the films at 50 Hz for 100 ms. The velocity plotted against the root-mean square values of the normalized film current showed a common curve or curves. The data were also discussed using the adiabatic theory. As the normal zone propagation velocity was not so fast, we divided one unit film of 120 mm length into two portions, to each of which an external resistance was attached. The test result showed that a high electric field of 45 Vpeak/cm and total voltage of 450 Vpeak were achieved in the first cycle after quenching, and the film withstood the voltage for five cycles. The temperature distribution along the length of the film was also shown.
    Journal of Physics Conference Series 03/2008; 97(1):012031.
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    ABSTRACT: Using a high temperature superconductor, we proposed a model superconducting fault current limiter (SCFCL) with the high-speed commutation switch. The high-speed commutation switch consists of the parallel coil, the electromagnetic repulsion plate and the vacuum interrupter. In this SCFCL, the current in the superconductor is interrupted within 0.5 cycles. By using this equipment, the current flow time in the superconductor can be easily minimized. We studied resistive type SCFCL with the high-speed commutation switch and use YBCO thin film. For applying to high voltage, it is a problem that the superconductors in series connection don't quench immediately for the Ic variations of the various superconductors. In this paper, we conducted the series connection test using YBCO thin films without a metal layer. The research is aimed at the scalability of small models towards commercial size fault current limiter (FCL).
    IEEE Transactions on Applied Superconductivity 07/2007; · 1.20 Impact Factor
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    ABSTRACT: Switching power densities of current limiting elements consisting of metal organic deposition YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub> (MOD-YBCO) thin films with high-resistivity Au-Ag alloy shunt layers and non-inductive Manganin resistors are evaluated. Despite the non-uniform critical current density distribution in MOD-YBCO films, the use of a high-resistivity Au-Ag shunt layer allows MOD-YBCO-based elements to achieve switching power densities comparable to those obtained for elements based on co-evaporated YBCO thin films. The present MOD-YBCO-based elements are capable of withstanding electric fields of 46 V/cm with a switching power density of 2.0 kVA/cm<sup>2</sup>. These results indicate that low cost MOD-YBCO thin films are promising for practical fault current limiters. In addition, relationships between the uniformity of J<sub>c</sub> distribution and current limiting properties are also discussed.
    IEEE Transactions on Applied Superconductivity 07/2007; · 1.20 Impact Factor

Publication Stats

183 Citations
60.46 Total Impact Points

Institutions

  • 2002–2014
    • National Institute of Advanced Industrial Science and Technology
      • Advanced Manufacturing Research Institute
      Tsukuba, Ibaraki, Japan
  • 2005–2009
    • Seikei University
      Edo, Tōkyō, Japan
  • 2006–2008
    • Sophia University
      • Department of Engineering and Applied Science
      Tokyo, Tokyo-to, Japan
  • 2004
    • Niigata University
      • Graduate School of Science and Technology
      Niahi-niigata, Niigata, Japan
  • 2000–2003
    • Yokohama National University
      • Department of Physics, Electrical and Computer Engineering
      Yokohama, Kanagawa, Japan