低温工学
検索
OR
閲覧
検索
28 巻 , 1 号
選択された号の論文の8件中1~8を表示しています
    • |<
    • <
    • 1
    • >
    • >|
  • 「低温工学」編集委員会
    28 巻 (1993) 1 号 p. 1
    公開日: 2010/02/26
    ジャーナル フリー
  • 多田 栄介, 吉田 清, 柴沼 清, 奥野 清, 辻 博史, 島本 進
    28 巻 (1993) 1 号 p. 2-15
    公開日: 2010/02/26
    ジャーナル フリー
    Fusion Experimental Reactors are one of the major steps toward realization of the fusion energy and the key objectives are to demonstrate the scientific and technological feasibility prior to the Demo Fusion Reactor, ITER (International Thermonuclear Experimental Reactor) is one of experimental reactors and the conceptual design has been completed by the united efforts of USA, USSR, EC and Japan. In parallel with the conceptual design, key technology development in various areas has being conducted. This paper describes the overall design concepts and the latest technological achievements of the ITER reactor structure and superconducting magnet system.
    抄録全体を表示
  • 下川原 正博, 賀戸 久
    28 巻 (1993) 1 号 p. 16-21
    公開日: 2010/02/26
    ジャーナル フリー
    Multichannel SQUID systems for biomagnetic measurement are developed recently in the whole world. Such systems can detect the weak magnetic flux generated by the brain activity, because a magnetometer based on SQUID has high sensitivity. This paper reviews technical problems to construct more than 100 channel system and the latest development of components such as SQUIDs, pickup coils, electronics and so on.
    抄録全体を表示
  • 鈴木 光政, 三橋 説
    28 巻 (1993) 1 号 p. 22-29
    公開日: 2010/02/26
    ジャーナル フリー
    Critical current density Jc and its temperature dependence in multifilamentary NbTi wires were measured. Further their pinning behavior was examined. Used samples which have been fabricated by a double stacking method are divided into two groups. One group was heat-treated in the fabrication process in order to produce the precipitates of α-Ti and the filament diameter df of NbTi wires ranges from 0.39 to 1.53μm. For the other group, such a heat-treatment was not done and the df of some samples was reduced to the level of below 0.1μm. In this paper, the experimental results on the former group, namely heat-treated (HT) samples with Cu-CuNi mixed matrix or CuNi matrix, are given. The Jc of samples is affected by df. In case of 4.2K, these samples show a slight difference in Jc at high fields. As the temperature rises, the effect of df on Jc becomes remarkable and the Jc-B curves are very different among samples. Normally, samples with small df show low Jc values and reveal a rapid decrease in Jc with increasing magnetic field. An anomalous change in Jc at low fields of below 0.1T was seen at temperatures close to Tc for samples with sub-micron sized filaments. The pinning force Fp vs. reduced field b(=B/Bc2) curves at 4.2K for different samples coincide with each other except for the sample with df=0.39μm. The reduced pinning curves (Fp/Fp, max vs. b) obtained at various temperatures have similar shapes for each sample. The bm where the maximum of Fp takes place is around 0.35 except for the sample with df=0.39μm. The pinning properties of these samples are discussed in terms of their upper critical field Bc2 and transition temperature Tc.
    抄録全体を表示
  • 鈴木 光政, 三橋 説
    28 巻 (1993) 1 号 p. 30-39
    公開日: 2010/02/26
    ジャーナル フリー
    Experimental results on non-heat-treated (NHT) samples with CuNi matrix, whose filament diameter df ranges from 0.061 to 0.314μm, are given. In case of 4.2K, Jc values at low fields are very different among samples. As df decreases to below 0.1μm, the Jc surprisingly increases and exceeds 1×106A/cm2 at 2T. However, samples which have high Jc values at low fields show a large decrease in Jc with magnetic field. A rise in temperature causes a marked decrease in Jc, especially, for samples with finer filaments. An anomalous change in Jc around 0.1T was also seen at temperatures close to Tc for the sample with df=0.314μm. The reduced pinning curves (Fp/Fp, max vs. B/Bc2) of each sample at various temperatures coincide with each other. Values of reduced field bm indicating the position of Fp, max are lower, 0.15-0.2. The highest value of Fp, max was obtained for a sample with df=0.072μm. Its pinning exponents p and q expressed in the form of Fp={Bc2}nbp(1-b)q are ≈0.5 and ≈2.5, respectively, The critical current density and the pinning properties of these samples are compared to those of heat-treated samples.
    抄録全体を表示
  • 藤原 民也, 大西 鉄矢, 松川 倫明, 山田 弘, 能登 宏七, 杉田 慶一郎, 山本 純也
    28 巻 (1993) 1 号 p. 40-47
    公開日: 2010/02/26
    ジャーナル フリー
    Two-dimensional analysis has been made on transient stability of a strand for a large current pool-cooled superconducting cable. The strand is an aluminum stabilized NbTi/Cu composite. Results of the analysis revealed that a radial distribution of temperature, as well as a longitudinal one, is formed distinctly due to a thermal disturbance, even within a small strand diameter of 1.8mm. The profile of the radial distribution determines the necessary time for the conductor to recover from a normal state after the end of the disturbance. When a superconducting region re-appears locally within the cross section, the conductor temperature decreases to the bath temperature with a 20 times higher rate than that before the reappearance.
    抄録全体を表示
  • 十合 晋一, 伊東 一敏, 玉田 紀治, 岡野 眞
    28 巻 (1993) 1 号 p. 48-55
    公開日: 2010/02/26
    ジャーナル フリー
    A regenerative compressor equipped with 5-axis controlled magnetic bearings is manufactured on an experimental basis. Compression characteristics of the compressor are measured for air and helium of room temperature. Pressure coefficients are very large in comparison with that of centrifugal compressors and ranged 3.5-4.8 for air and 3.6-6.4 for helium. High pressure ratio can be obtained with a single stage regenerative compressor. Surging phenomena were not observed over a full range of flow rate. The efficiency of the trial compressor is very low and its maximum value is only about 6%. It is required to improve the efficiency. Escape flow from outlet to inlet port through a separator is comparable to the effective flow rate. This is thought to be one of factors that lower the efficiency. From the view of its compression characteristics, regenerative compressors are thought to be the best for stabilizing or controlling device of oil-free helium refrigerators equipped with multi-stage centrifugal compressors when their efficiency is improved.
    抄録全体を表示
  • 鈴木 光政, 三橋 説, 舟山 邦男
    28 巻 (1993) 1 号 p. 56-60
    公開日: 2010/02/26
    ジャーナル フリー
    An apparatus with a variable temperature probe has been made to measure temperature dependent critical currents in superconducting wires. In this apparatus, a ramp current with a short sweep time of 0.1s is used for determining critical currents in a sample which has been helically wounded on a Cu cylindrical block in an adiabatic cell. The sample temperature is easily controlled in the range from 4.2K to transition temperature Tc. The maximum measuring current is 20A. The construction and ability of this apparatus are given and further a typical measurement result on a NbTi multifilamentary superconducting wire is shown.
    抄録全体を表示
    • |<
    • <
    • 1
    • >
    • >|
feedback
Top