著者

竹内 尚輝

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.52, no.5, pp.332-339, 2017-09-20 (Released:2017-10-27)

参考文献数

53

被引用文献数

1 1

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We report recent progress on adiabatic quantum-flux-parametron (AQFP) logic, which is an energy-efficient superconductor logic based on quantum flux parametron (QFP). The switching energy of an AQFP gate can be arbitrarily reduced via adiabatic switching, in which the shape of the potential energy gradually varies between single-well and double-well shapes as the result of using ac excitation magnetic fluxes. First, we show the operation principle of AQFP and explain adiabatic switching in light of potential energy shapes. We also show calculated switching energy and bit error rates to demonstrate that the switching energy of AQFP can be significantly reduced while keeping a low error rate. Then, we report recently developed AQFP subsystems, which include an 8-bit carry look-ahead adder, a register file, and a long-interconnect driver. Our demonstration reveals that AQFP technology is ready to be applied in microprocessor design.

著者

廣田 憲之

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.55, no.3, pp.185-188, 2020-05-20 (Released:2020-06-04)

参考文献数

14

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The magneto-Archimedes effect is a technique to enhance the effect of the magnetic force acting on materials by considering the influence of the surrounding medium. Application of this technique as a way of materials separation is known as the magneto-Archimedes separation. The magneto-Archimedes separation enables the separation of many different materials into each component based on the differences in their magnetic susceptibilities and densities irrespective of the particle size. In this topical review, the principle of the magneto-Archimedes effect and its application as a way to separate materials are described and some other examples applying the magneto-Archimedes effect are introduced.

著者

梅本 勝弥 柳本 俊之

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.47, no.6, pp.377-383, 2012-06-25 (Released:2013-02-16)

参考文献数

12

被引用文献数

9 5

---

Although the application of superconductivity technologies to rotating machines has been studied since the 1970s, it has not yet been made practicable. However, due to the recent rapid improvements in high-temperature superconductor performance, high-temperature superconducting motors for ship propulsion are approaching a level where they can be utilized. In this article, the current status of R&D on high-temperature superconducting motors for ship propulsion being developed by Kawasaki Heavy Industries Ltd. (KHI) and its cooperative research groups is reported. In particular, the aims, content and plans of two projects being led by KHI will be shown. The first one is the New Energy and Industrial Technology Development Organization (NEDO) energy-saving project, and the second one is the Japan Science and Technology Agency (JST) SInnovation project. Finally, a roadmap and further studies related to the practical application of high-temperature superconducting motors for ship propulsion are shown.

著者

富田 優

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.57, no.4, pp.236-240, 2022 (Released:2022-07-20)

参考文献数

8

---

Introducing a superconducting cable is expected to reduce power loss. However, it needs cooling to maintain the superconducting state. In this paper, we outline the superconducting system which consists of superconducting cables and a cooling system. Subsequently, we report the examination of the efficient refrigerant circulation methods, the construction of the cooling system, and the results of the cooling tests on the railway site.

著者

成瀬 雅人 安藤 友彦 久保田 立記 桑田 正博 田井野 徹 明連 広昭

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.54, no.3, pp.174-180, 2019-05-20 (Released:2019-07-02)

参考文献数

37

---

This paper reports how the superconducting micro-resonators work as high-sensitivity photon detectors, from millimeter-wave signals to high-energy particles. The resonators are called microwave kinetic inductance detectors and are suitable for use in a large format array. The resonators are easily fabricated applying a few photolithographic processes, and the resonator yield is more than 90%. Hundreds of superconducting resonators can be biased with a single readout line, enabling them to be read out together with frequency multiplexing. We introduce the recent progress of scientific projects relying on this technique, and summarize our results for millimeter-wave astronomy and a high-energy particle detection system. The device was made using epitaxial aluminum on a silicon wafer and its noise was as low as the background limit, approximately 6 × 10−18 W/Hz1/2 in the millimeter-wave range. For high-energy particle detection, we investigated two materials: niobium and a hightemperature superconductor, YBa2Cu3O7-δ. The niobium-based device detected the alpha line (5.4 MeV) events. The pulse decay time was approximately 5 μs and energy resolution was approximately 1 MeV.

著者

山田 一成 大関 和貴 須田 健嗣

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.56, no.4, pp.201-208, 2021 (Released:2021-07-20)

参考文献数

18

---

A helium cryogenics system for the superconducting heavy-ion linear accelerator (SRILAC) has been introduced at the RIKEN Nishina Center. The SRILAC contains a total of 10 superconducting quarter-wave-length resonators made of pure niobium materials installed in 3 cryomodules; which realizes the beam energy upgrade of the existing room-temperature linear accelerator. The refrigerator, a HELIAL MF manufactured by Air Liquide, has successfully accomplished a cooling capacity of about 730 W and a sufficient helium pressure stability with a fluctuation less than ±0.4 kPa. The cryogenic system started operation in October 2019, and the SRILAC has been supplying beams to experiments since June 2020, along with a stable operation of the cryogenics system. This article provides an overview of the cryomodule and the helium cryogenics system as well as the operational status of the helium cryogenics system.

著者

宇佐美 貴史 吉田 隆 一野 祐亮 菅野 未知央 町屋 修太郎 衣斐 顕 和泉 輝郎

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.51, no.6, pp.259-264, 2016

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<p>The strain effect of REBa₂Cu₃O<i>_y</i> (REBCO: RE = Y, Gd, Sm)-coated conductors (CCs) on critical current (<i>I</i>_c) is one of the most fundamental factors for superconducting coil applications. In this study, we aim to clarify the effect of artificial pinning center shapes on the strain effect in BHO-doped GdBCO CCs_. To achieve this, we fabricated a Pure-GdBCO CC, a BHO nanorod-doped GdBCO CC and a multilayered-GdBCO (ML-GdBCO) CC, and carried out bending tests. As the result, the strain dependence of <i>I</i>_c for each CC showed an upward convex and the<i> </i>peak strain of the BHO-doped GdBCO CC shifts towards the compressive strain independent of the BHO shapes. In addition, the strain sensitivity of <i>I</i>_c in the GdBCO CCs including BHO becomes smaller. To clarify the difference between the strain sensitivity of <i>I</i>_c and the peak strain among the CCs, we evaluated the residual strain and the slopes of the internal lattice strains against the applied tensile strain (<i>&beta;</i>). From this measurement, the residual strains for the Pure-GdBCO CC and the ML-GdBCO CC were almost the same. In addition, there was no change in the <i>&beta;</i> value between the Pure-GdBCO and ML-GdBCO CCs. These results suggest that the changes in peak strain and strain sensitivity were not related to the internal lattice strain.</p>

著者

島﨑 毅

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.56, no.1, pp.3-11, 2021-01-20 (Released:2021-01-28)

参考文献数

40

---

The temperature is one of the important parameters, both in experiments and analysis, in cryogenic research and development. Recently the definition of the unit of temperature, Kelvin, which is one of the seven basic units in the International System of Units (SI) was redefined along with three other basic SI units. An outline of the redefinition of the Kelvin and its background are presented. Despite the historic redefinition of the Kelvin, practical cryogenic thermometry is not, and will not be, affected at least for a while. Practical cryogenic thermometry is based on the International Temperature Scales (ITSs). The definitions of the ITSs were not changed after the redefinition of the Kelvin. The relationship between the ITSs and the Kelvin definition, and the characteristics of thermodynamic thermometry are also presented.

著者

白井 康之 横山 彰一

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.53, no.4, pp.210-217, 2018-07-20 (Released:2018-08-03)

参考文献数

34

---

We have been developing a conduction cooled HTS-MRI that is driven by a power supply in order to solve the long-lasting attenuation of the screening current induced on superconducting tapes at the time of initial excitation and the difficulty with REBCO tape superconducting junctions, as well as a superconducting switch for persistent current operation. A power supply system consisting of two exciters, one for charging and discharging and the other for holding the magnet current, is proposed and developed. The supply system is equipped with a control block to compensate the magnetic field deviation caused by the screening current. We carried out a magnetic field stability experiment using a 32-H HTS-MRI magnet excited by the power supply system proposed which was equipped with specially designed micro-current control.

著者

押川 巧 船越 義彦 今岡 宏志 井口 将秀 櫻井 武尊 中平 昌隆

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.54, no.6, pp.452-458, 2019-11-20 (Released:2019-11-29)

参考文献数

13

---

High nitrogen austenitic stainless steel forgings with heavy thickness and complex configuration are used for the ITER TF coil case. In the forging process for high nitrogen austenitic stainless steel, it is generally difficult to simultaneously obtain good ultrasonic attenuation, the required mechanical properties and the desired near-net shape. Accordingly, JCFC undertook development of an innovative forging method to form the near-net shape of the product, through consideration of possible methods and laboratory testing. By applying JCFC’s innovative method in trial manufacturing commissioned by QST, it was confirmed that the resulting forgings had material properties that satisfy ITER requirements and were also formed into a near-net shape. Subsequently, JCFC manufactured the actual forgings.

著者

沼澤 健則

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.55, no.1, pp.53-58, 2020-01-20 (Released:2020-01-28)

参考文献数

7

被引用文献数

1

---

A new Active Magnetic Regenerator (AMR) cycle has been proposed and tested. We developed a four-unit AMR (fAMR) driving cycle consisting of four AMR units and two magnets. f-AMR operates a pair of magnetization and demagnetization processes in an AMR cycle simultaneously, and as a result, four AMR cycles can be continuously operated. The merits of the fAMR cycle are: four times larger cooling capacity, reducing the thermal loss of heat transfer fluid, a simple mechanism to provide a larger temperature span, feasibility as a thermal device, and expandability of the AMR unit number. Experimental results at room temperatures showed unique properties of f-AMR. Using a weak 0.75 T permanent magnet, the largest temperature span reached to 20 deg. using Gd spheres with a 0.4 mm diameter and COP was larger than 1.0 for a temperature span of 10 deg. We have started to use the f-AMR cycle for a hydrogen re-condensation system at 20 K. A hybrid cooling system using f-AMR and GM cycles will be able to pursue a target of 15% Carnot for hydrogen re-condensation liquefiers.

著者

長﨑 陽 鎌田 弦 刀 友基 佐々木 修平 宮城 大輔 津田 理

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.55, no.2, pp.117-124, 2020-03-20 (Released:2020-03-27)

参考文献数

12

---

This paper discusses the demonstration of a stable levitation (SL) system for a magnetic levitation type seismic isolation device using a high-temperature superconducting (HTS) bulk. The SL system utilizes a restoring force between an HTS bulk and permanent magnet (PM) to maintain the stable levitation of a base-isolation object. We first measured the restoring force between the HTS bulk and PM, and then demonstrated the performance of the SL system using a magnetic levitation type seismic isolation model device with a radial arrangement of HTS bulks and a PM rail. The SL system with the HTS bulk can reduce small vibration and displacement during the normal period of operation without experiencing a large disturbance. We also demonstrated that, when a large disturbance was applied, the transmission of horizontal vibration to the base-isolation object via the SL system was eliminated by decoupling the magnetic coupling between the HTS bulk and PM. Furthermore, the vibration transmissibility at any vibration frequency to the base-isolation object was reduced by incorporating an HTS bulk damper and eddy current damper in the model device. These results suggest that a SL system used together with an HTS bulk can realize both the stable levitation of a base-isolation object during the normal period of operation as well as the elimination of the horizontal vibration transmission when a large vibration is applied.

著者

畑 徹

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.54, no.5, pp.392-397, 2019-09-20 (Released:2019-11-12)

参考文献数

13

著者

村上 雅人

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.42, no.12, pp.414-418, 2007-12-25 (Released:2008-10-28)

参考文献数

9

被引用文献数

2 1

---

In this article, the mechanism of stable levitation by bulk high-temperature superconductors is presented. Superconductor levitation is fascinating and thus displayed in various demonstrations. In general, superconductor levitation is explained in terms of the Meissner effect, which is not applicable in the case of levitating a permanent magnet by Y-Ba-Cu-O cooled with liquid nitrogen. For stable levitation in free space, the restoring forces must act on the levitated object in three rectangular directions, which cannot be fulfilled by simple diamagnetic levitation like that found with the Meissner effect. A pinning effect that fixes quantized fluxoids is the source of such restoring forces, and therefore, superconductor levitation is stabilized by flux pinning.

著者

門奈 五兵

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.2, no.3, pp.1-6, 1967-10-10 (Released:2010-02-26)

参考文献数

13

著者

三戸 利行

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.50, no.12, pp.566-574, 2015-12-25 (Released:2016-02-01)

参考文献数

5

被引用文献数

1 3

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The Large Helical Device (LHD) is an experimental heliotron-type fusion plasma which consisting of a complete superconducting magnet system cooled by a helium refrigerator having a total equivalent cooling capacity of 9.2 kW@4.4 K. Eighteen plasma experimental campaigns have been performed successfully since 1997, with a high reliability of 99%. Seventeen years have passed since beginning system operation. During the operational history, appropriate improvements have been implemented to prevent serious failures and to pursue further reliability. The operational history of the LHD cryogenic system is reported along with improvements that have been made to the system.

著者

齋藤 明子 加治 志織 小林 忠彦 中込 秀樹

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.50, no.2, pp.88-95, 2015-02-25 (Released:2015-04-06)

参考文献数

40

被引用文献数

1

---

The development of magnetic refrigerants and basic research on active magnetic regenerative (AMR) refrigeration at room temperature were performed. Temperature differences between the hot and cold ends of the AMR unit of more than 45 degrees, and achieving the lowest temperature of minus 10 degrees were obtained by operating the AMR cycle with a NdFeB Halbach-type permanent magnet and spherical-shaped GdY magnetic refrigerants. In the case of the La(Fe,Co,Si)13 compound, the temperature difference between the ends of the AMR unit reached only 21 degrees. This is mainly attributed to the fact that larger specific heat provides smaller temperature changes in the magnetocaloric effect even if the La(Fe,Co,Si)13 compound shows larger magnetic entropy change than Gd alloys. At the same time, large specific heat is effective for load characteristics. Model calculations indicated that multi-layered magnetic refrigerants whose magnetic transition temperatures are tailored to the temperature gradient in the AMR unit improve both temperature difference and load characteristics. Ideal design for achieving optimized heat flow and regeneration leads to the room-temperature application.

著者

青井 良文 上田 祐樹

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.43, no.12, pp.556-560, 2008 (Released:2009-03-02)

参考文献数

9

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A gas in a tube spontaneously oscillates when the temperature ratio between the tube ends exceeds a critical value. This spontaneous gas oscillation is applied to a liquid helium level finder. In the present study, to design a liquid nitrogen level finder using spontaneous gas oscillation, the critical value of the temperature ratio causing spontaneous gas oscillation for the case of nitrogen gas was numerically investigated. It was found that a tube in which an array of narrow circular tubes is located can work as a liquid nitrogen level finder. Hence, a tube with an array of narrow tubes was constructed and the liquid level of nitrogen put into a vessel was measured with the constructed tube. The measurements also demonstrated that the tube can work as a liquid nitrogen level finder.

著者

小森 彰夫

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.45, no.1, pp.1, 2010 (Released:2010-04-02)

著者

相山 義道 梅田 政一

出版者

公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)

雑誌

低温工学 (ISSN:03892441)

巻号頁・発行日

vol.36, no.10, pp.576-583, 2001

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The historic story of the superconducting (SC) magnet for MHD ETL Mark V Facility (cf. Fig. 1) is presented. This SC magnet was developed in the MHD Project (1966-75), which was one of the first MITI/AIST Large-Scale R & D Projects and the first national project for superconductor applications in Japan. This SC magnet had been the largest in Japan through 1982 when the Japanese LCT coil was made by JAERI. It was completed after many difficulties, some fatal and some trivial, because of a lack of knowledge, before it could generate maximum magnetic field 7T with stored energy 65MJ in 1973. Because technological problems had piled up and because no management know-how of national projects on technology development had been accumulated before then in the forefront of worldwide technological advances, &ldquo;step by step&rdquo; advances and &ldquo;trial and error&rdquo; attempts in the progress of the project had to be done over again. The paper is divided into three parts. Part I (Ref. 12) described the magnet design concept and the conductor tests. In this part II, the failures in exciting the magnet, the repair of the magnet system and the re-challenge with success are described.