bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plug-in Wire for 200-pixel Superconducting Tunnel Junction X-ray Detector Array for Helium-3 Cryostat
Authors: Shiki S , Fujii G , Ukibe M 
Published: October 2019

Abstract
A plug-in wire system is designed for a 200-pixel superconducting tunnel junction (STJ) X-ray detector array for a helium-3 cryostat. The STJ array and the room-temperature electronics are electrically connected by wire modules that have connectors at both ends. Two types of wire module are used to balance the electric conductance and thermal conductance under various temperature conditions. One type uses a copper-based miniature coaxial cable harness, and is utilized to electrically connect the room-temperature electronics to the 3 K stage. The other type uses woven wire looms of twisted-pairs of NbTi wire, and is used to electrically connect the 3 K stage to the helium-3 stage. With the installation of all wire modules, the temperature of the cold stage is less than 310 mK, and the holding time is more than 80 hours. The plug-in wire system is suitable for large-scale STJ X-ray detector arrays.
Effects and Design Considerations of Inserted Resonator to Improve Efficiency Including Rectifying Circuit for Superconducting Wireless Power Transfer System for Electric Vehicle
Authors: Chung Yoon Do , Lee Chang Young , Park Eun Young 
Published: October 2019

Abstract
The wireless power transfer (WPT) technology based on strongly resonance coupled method realizes large power charging without any wires through the air. Recently, the WPT systems have started to be applied to the wireless charging for electrical vehicles (EVs) because of their advantages compared with the wired counterparts, such as convenient, safety and fearless transmission of power. However, it has obstacles to commercialize such as delivery distance and efficiency. To solve the problems, we proposed the technical fusion using HTS antenna in the WPT system, it is called as, superconducting wireless power transfer for electric vehicle (SUWPT4EV) system. Since the superconducting wire has merits a larger current density and higher Q value than normal conducting wire, the HTS antenna enables to deliver a mass amount of electric energy in spite of a small scale antenna. Thus, SUWPT4EV system has been expected as a reasonable option to improve the transfer efficiency of large electric power. Authors already demonstrated the efficienct effects for inserted resonator using simply copper tube wires, which structure is helix type of multi layers. In this study, as a practical approach, authors evaluated the SUWPT4EV system with inserted copper type resonator, which structure is a rectangular shape of single layer to reduce installation volume. Based on the evaluation results, authors deduced the practically alternative structure for the inserted resonator to reduce the installation space as well as to improve transmission power, compared with non-resonator SUWPT4EV system under radio frequency (RF) power of 370 kHz below 500 W.
Power enhancement of the high-Tc superconducting terahertz emitter with a modified device structure
Authors: Minami H , Ono Y , Murayama K , Tanabe Y , Nakamura K , Kusunose S , Kashiwagi T , Tsujimoto M , Kadowaki K 
Published: October 2019

Abstract
Continuous and monochromatic terahertz electromagnetic waves can be generated with sizable power (∼30 μW) by the mesa-shaped device made of the high-T
c superconductor Bi2Sr2CaCu2O8+δ, by synchronizing the phase of the Josephson currents between multi-stacked intrinsic Josephson junctions. From the previous experimental results on the line width, spatial distribution of the emission, etc., we think that the relatively weaker power may originate from the partial failure of the phase synchronization of the Josephson currents in the mesa device. This may be improved by modifying the device structure to enhance the Josephson current density inside the mesa. In the present study, an array of four rectangle-shaped mesas with the dimensions of 80±5 μm×350 μm×3.2 μm was fabricated on a thin Bi2Sr2CaCu2O8+δ single crystal, where several slots were made around the mesas by photolithography and chemical etching techniques in order to weaken electrical connection between mesa and superconductor base. The best result of the emission power for the array so far obtained is ~80 μW at 0.42 THz, which is about 2.7 times bigger than the previous champion data in our group.
Estimation of electricity storage capacity of compact SMESs composed of stacks of Si-wafers loaded with superconducting thin film coils in spiral trenches formed by MEMS process
Authors: Ichiki Y , Ichiki A , Hioki T , Sasaki M , Noh J-H , Takai O , Honma H , Motohiro T 
Published: October 2019

Abstract
A method to estimate the electricity storage capacity of our compact superconducting magnetic energy storage system composed of stacks of Si-wafers loaded with superconducting thin film coils in spiral trenches formed by MEMS process was developed and tested for initial 6 designs of wafer coils. The results show energy storage density as low as around 6 Wh/ℓ. This is not caused by the limitation of the hoop stress but by the limitation of the maximum magnetic flux density. Further calculations for optimum wafer coil designs will be continued in which the effect of the maximum magnetic flux energy and the effect of the maximum hoop stress on the limit of the amount of the electrical energy storage come into a good balance.
Early Detection of Normal Transitions in a High Temperature Superconducting Transformer Wound with a Plurality of HTS Tapes Using the Active Power Method
Authors: Nanato N , Aoyama H 
Published: October 2019

Abstract
The authors have been developing an AC power source with a high temperature superconducting (HTS) transformer which is small in size and can supply large AC current. The HTS transformer needs a detection system of normal transitions for high reliability. The authors have reported the active power method as the detection system. However, the conventional method could not detect early the normal transition in a secondary coil of the transformer which was wound with a bundle of some HTS tapes since resistive voltage in the normal area is too small due to current sharing among the HTS tapes. In this paper, the authors propose a method to detect the normal transitions in the bundle conductor by improving the active power method. The early and correct detection can be achieved by measuring each active power of each HTS tape. In order to measure the active power, current leads are attached independently to all the HTS tapes. The current leads enable to measure the resistive voltage in each HTS tape, and each active power can be measured. The proposed method works well when even one of secondary tapes transits to the normal conducting state. Experimental results show the usefulness of the proposed method.
Numerical simulation of the fast processes in HTS tapes under the pulsed current load
Authors: Anischenko I V , Pokrovskii S V , Rudnev I A , Osipov M A , Abin D A 
Published: October 2019

Abstract
This paper presents a numerical layered 2G HTS tape model with the transport current flowing through it. The simulation is performed by using FEM H-formulation method implemented in the Comsol Multyphysics software. The model provides two cooling modes: cryocooler and liquid nitrogen. LN2 cooling mode provides for a complex hysteresis character of the liquid nitrogen boiling curve and the boiling regimes changing possibility between the stationary and the bubble boiling. The delay of the voltage rising with a transport current above the critical value pulse input is shown in the liquid nitrogen cooling case. The possibility of parameters calculating for current redistribution from the HTS to the stabilizing copper layer is shown, and the stabilizing coating thickness effect on the thermal transition critical current value is studied A comparison with experimental results is carried out.
Observation of a non-uniform current distribution in stacked high temperature superconducting tapes
Authors: Meulenbroeks T A J , Terazaki Y , Matsunaga S , Yanagi N 
Published: October 2019

Abstract
High Temperature Superconductors (HTS) improve upon low temperature superconductors in many ways and the ability to cope with a non-uniform current distribution might be one of those improvements. To put this to the test, an experimental setup is designed to force a non-uniform current upon a stack of 5 HTS tapes, using a worst case current feeding method. The experiment can help determine the potential of this conductor design and is part of the ongoing effort to develop a non-transposed stacked HTS conductor for the nuclear fusion reactor FFHR. The results clearly show that the conductor sample is able to stably conduct a current equal to its critical current, although at an elevated electric field of roughly 5 mV/m. This means non-transposed stacked tape conductors remain stable, even if a worst case nonuniform current is constantly forced upon them. A hypothesis to explain this abnormally high electric field is formulated on the basis of the results, however additional research is needed to verify it. It states that the electric field is necessary for the tapes to share current and would mean that in a properly engineered application, these losses due to the electric field, would only occur during start-up. Overall it is clear that this experiment proves the excellent stability of non-transposed stacked HTS tapes and their ability to conduct a non-uniform current.
Low voltage and large current DC superconducting power cable designs for 10 km to 100km transmission line using experimental data of Ishikari project
Authors: Yamaguchi Satarou , Yamada Takeo , Iitsuka Takashi , Sato Akio , Sawamura Toru , Sytnikov Victor 
Published: October 2019

Abstract
Main merit of the DC superconducting power transmission line is low loss even in low voltage power transmission. It should be realized when the transmission length is long. Therefore, we discuss and analyse an aspect of thermo-hydrodynamic performance of Ishikari project, and show one design of 100 km transmission line. At the same time, we also discuss the cable design and the rated voltage of the cable is lower than 50 kV for 500MW transmission. This is one of the most important advantages to make the DC power grid because we can omit an ultra-high voltage substation, the primary and the secondary substations and we can connect the power stations to the distribution stations directly. Finally, we may be able to reduce the construction and operation costs of the power grid.
A Feasibility Study of Smart High-Temperature Superconducting Cable to Improve Stability of KEPCO System
Authors: Seo Sangsoo , Lee Seung Ryul , Cho Jeonwook 
Published: October 2019

Abstract
The Korean power system is a very tightly coupled island system. The installed capacity is about 100 GW and the load demand is gradually increasing. Especially in metropolitan areas where the load is concentrated, the system fault current often exceeds the breaker capacity due to the strong connection. The system operator limits the fault current by bus split operations considering the breaker capacity but this reduces system stability. Therefore, various efforts have been made using a fault current limiter to overcome these problems. A smart superconducting (SC) cable is a type of SC power transmission cable. It has not only standard structure of the existing SC power cable but also a fault current limiter. The cable has a SC characteristic in a normal state, while when a fault occurs, it can limit a fault current through generating impedance that adjusts electrical and thermal properties of SC cable and material and cross-sectional area of SC cable. In this paper, a technique is proposed to reduce system fault current while improving the system stability using a smart high-temperature SC cable. In addition, the appropriate cable capacity and locations are selected to improve the reliability of the Korean power systems using the smart SC cables. The proposed locations and capacities will be applied to the smart SC cable development project that started in May last year
An effective design for induced current reducing of a single-phase multi-layer HTS coaxial cable with former
Authors: Kang S Y , Lee S J , Le D V , Park M 
Published: October 2019

Abstract
High temperature superconducting (HTS) cables require a former layer to bypass fault currents and support superconducting tape. The former layer of the HTS cable does not conduct current in steady-state operation due to the resistance difference with the conducting layer. However, in practice, an induced current flows through the former layer due to the mutual interaction with the conducting layer. Therefore, the current distribution in the cable should be uniform and the induced current in the former layer must be minimized. This paper deals with an effective design of a single-phase multi-layer HTS coaxial (SMHTSC) cable with former layer. The optimal combination of the pitch length and the winding direction in the conducting layer and the shield layer was selected for uniform current distribution of the SMHTSC cable and minimization of induced current in the former layer. The current distribution of the SMHTSC cable was analyzed based on the numerical calculation results obtained using the impedance matching method. The results and discussions of the current distribution on the SMHTSC cable with and without former layer were compared and presented.
Heat load to the cryogenic system in the 1000 m class superconducting DC power transmission system
Authors: Watanabe Hirofumi , Ivanov Yury V , Chikumoto Noriko , Yamaguchi Satarou , Ishiyama Kotaro , Oishi Zenji , Watanabe Michihiko , Masuda Takato 
Published: October 2019

Abstract
Long-term circulation and load cycle tests of the cooling of the 1000 m class superconducting DC power transmission system in Ishikari, Japan were performed to measure the heat load delivered to and the power consumption of the cryogenic system. The average heat load and power consumption during these tests was about 2.5 and 120 kW, respectively. To increase the efficiency of superconducting power transmission systems, the selection and composition of constituent devices of the cooling system should be optimized.
Development of Single-phase Bi2223 High Temperature Superconducting Transformer with Protection System for High Frequency and Large Current Source
Authors: Nanato N , Adachi T , Yamanishi T 
Published: October 2019

Abstract
The authors have been developing a large AC current source with a single-phase Bi2223 superconducting transformer. The authors aim to develop the source of supplying current with the maximum frequency of 1 kHz and the maximum amplitude of 1 kA. However, the conventional transformer has some leakage inductance resulting in large voltage drop, and therefore it was unable to transport the current with high frequency and large amplitude. In this paper, the authors propose a configuration of the transformer with less leakage inductance than inductance of the conventional one. Improved current source has output current with the maximum frequency of 1 kHz and the maximum amplitude of 900 A. In addition, a protection system for normal transition in the transformer is proposed. The authors have proposed the active power method to detect the normal transition. For high frequency and large current, however, the normal transition may be incorrectly detected by using the method due to large AC loss. The authors show a new method to avoid the incorrect detection by an empirical formula based on measurement results of the AC loss. From the experimental results of the normal transition, the authors show that the proposed method is more correct to detect the normal transition than the conventional method.
Numerical analysis on the influence of armature winding configuration on AC loss of 10 MW fully superconducting generators of electric aircrafts
Authors: Komiya M , Aikawa T , Yoshida K , Miura S , Iwakuma M , Yoshida T , Sasayama T , Tomioka A , Konno M , Izumi T 
Published: October 2019

Abstract
10 MW fully superconducting generators, comprising REBCO superconducting tapes with various armature winding configurations, were designed. The influences of these configurations, such as a distributed-winding and a concentrated-winding configuration, on AC loss, output power density, and output voltage waveform were evaluated. As a result, the short-pitch distributed-winding model exhibited the best properties among all the models. In particular, the AC loss of the armature winding was approximately half that of the concentrated winding. Furthermore, the distortion factor was lower than 10%.
Motor structure and mechanical output density of IPM motor using bulk superconductors as magnetic field
Authors: Akada Wataru , Terao Yutaka , Ohsaki Hiroyuki 
Published: October 2019

Abstract
Recently, means of transportation with electrical motors such as electric vehicles and ships are rapidly increasing. Various attempts have been made to reduce the size of the motors to increase the freedom of transport equipment system layouts and the energy efficiency of their transportation. Interior permanent magnet synchronous motors (IPMSMs) can realize higher torque than surface permanent magnet synchronous motors (SPMSMs) by using reluctance torque caused by magnetic saliency in addition to magnet torque. In comparison with SPMSMs, IPMSMs can have wide operation ranges by applying control methods such as maximum output control and field weakening control. Therefore, IPMSMs are expected to be used for a variety of application such as electric vehicles, ships and heavy equipment. By replacing permanent magnets with bulk superconductors in the rotors of IPMSMs, the magnet torque increases due to the stronger magnetic field of magnetized bulk superconductors. This leads to an increase in total torque density of the motors and contributes to motor size reduction. In this research, we propose an IPMSM with bulk superconductors with the goal of increasing the mechanical output density. In the proposed IPMSM, cooling space is left inside the rotor to cool the bulk superconductors to their superconducting state. Here, analysis based on finite element method was carried out to verify the utility of the proposed motor. First, the design of the motor with bulk superconductors and cooling space is discussed. It is shown that the total torque can be increased by adjusting the position of the bulk superconductor and modifying the structure of the flux barrier. The maximum total torque shown here was 22500 Nm. Then, the mechanical output density of the proposed IPMSM is compared with a conventional IPMSM. It is shown that the mechanical output density of the proposed IPMSM is 38% higher than the conventional IPMSM. Finally, the magnetic shielding effect, which might be a problem when using bulk superconductors, is discussed. By using electromagnetic analysis, it is shown that the external magnetic flux is weakened by the cooling space to several percent of the magnets’ surface and the effect of the shielding current is trivial.
Design of an HTS module coil for a 750 kW-class superconducting wind power generator
Authors: Tuvdensuren O , Go B S , Sung H J , Park M 
Published: October 2019

Abstract
Recently, high temperature superconducting (HTS) generators are being studied with the advantages of high efficiency, light weight and small volume compared with the conventional generators. However, the HTS generator requires a large vacuum vessel and has problems such as difficulties in maintenance of the HTS coil. These problems can be overcome through the modularization of the HTS field coil. This paper designs an HTS module coil for a 750 kW-class superconducting wind power generator. The HTS module coil was designed based on the electromagnetic analysis results obtained using a 3D finite element method. For detail structure of the module coil, the heat load analysis and the mechanical stress analysis were performed. As a result, the total heat load was minimized the temperature of the HTS coil could be kept below 30 K. The von Mises stress of the supports was less than the allowable stress of the glass-fiber reinforced plastic material. The design results of the HTS module coil can be effectively utilized to develop large scale the superconducting wind power generators.
Remediation of Groundwater Contaminated by Heavy Metals Using Magnetic Separation Technique
Authors: Amosse A J , Akiyama Y 
Published: October 2019

Abstract
Heavy metals pollution has become one of the most serious environmental problems nowadays. Studies on the environmental pollution indicate that water pollution by heavy metals ions has reached unprecedented levels over the past decade in many countries, with highlights to African countries. Removal of these toxic metals from contaminated water can improve human being life quality and prevent from their adverse effects. This study aims to text the ability of magnetic activated carbon (MAC) and MAC coated with wastes of colloidal silica (MACSi) for adsorption of copper, manganese and zinc ions from water and its separation from water using magnetic separation technique. The adsorption results of MAC and MACSi showed that MACSi was more effective to adsorb the ions than MAC. FT-IR spectrum and XRD pattern of MACSi indicated that silica coating onto MAC surface is in amorphous form.
Design and Trial Production of Magnetic Filter for Medical Protein Screening System using High Gradient Magnetic Separation
Authors: Mori M. , Kubota M. , Abe T. , Kim S.B. , Ueda H. 
Published: October 2019

Abstract
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.