• Title/Summary/Keyword: Bi-2223/Ag tapes

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The effect of cryogenic rolling on critical current density of Bi-2223/Ag HTS tapes (Bi-2223/Ag 고온초전도선재의 Jc와 미세조직에 미는 저온압연의 영향)

  • 최정규;황선역;하동우;오상수;권영길;이세종
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2003.10a
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    • pp.142-145
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    • 2003
  • In order to investigate the effect of cryogenic rolling on the critical current density (Jc), 54 and 55-multi-filament Bi-2223/hg tapes have been fabricated using a PIT process including two different types of cooling methods. The densification of oxide filament was found to occur due to the cryogenic rolling, and this enhanced the critical current density. However, when the wire was fully immersed in liquid nitrogen used as the coolant in cryogenic rolling, Jc degradation appeared caused by the nitrogen penetration into the filament. The cryogenically rolled tape with an improved type of cooling showed approximately 10% Jc's increase.

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Analysis on Current Distribution in Bi-2223/Ag Tapes with Applied Alternating Over-critical Current

  • Yim, Seong-Woo;Kim, Hye-Rim;Hwang, Si-Dole
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.6
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    • pp.678-682
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    • 2004
  • Generally Bi-2223/Ag tapes have a broad S/N transition region and their sheath is a good electric conductor. In this study, the current distribution between superconductor and metal sheath in HTS tapes were investigated. AC with its peak value above 10 times $I_{c}$ was applied to HTS tapes for around 6 cycles and V-I characteristics were measured. Using the resistance of the sheath and V-I curves, the current distribution between superconductor and metal sheath was calculated. When 150 $A_{p}$ was applied, more than 2/3 of the current flows through superconductor. However, in the case of 304 $A_{p}$, most of the applied current came to flow through the metal sheath at the 6th cycle.e.e.e.

Influence of External Reinforcement on Strain Characteristics of Critical Current in BSCCO Superconducting Tapes

  • Shin, Hyung-Seop;Kazumune Katagiri
    • Progress in Superconductivity and Cryogenics
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    • v.5 no.3
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    • pp.15-19
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    • 2003
  • For the purpose of standardization of the critical current measurement, it is meaningful to describe how $I_{c}$ will behave as the stress/strain level changes. In this study, strain dependencies of the critical current $I_{c}$ in Ag-alloy sheathed multifilamentary Bi(2212) and Bi(2223) superconducting tapes were evaluated at 77K, 0T. The external reinforcement was accomplished by soldering AgMgNi alloy tapes onto single or both sides of the sample. With the external reinforcement to the Bi(2212) tape, the strength of the tapes increased but the critical current at the strain free state, $I_{c0}$ decreased in some cases. The strain for onset of the $I_{c}$ degradation, $\varepsilon$$_{\irr}$, increased with an increase of the reinforcing volume and then saturated to a certain value. The effect of external reinforcement on the degradation of $I_{c}$ due to the bending strain in the Bi(2223) tape was also examined. Contrary to the expectation, it showed a significant $I_{c}$ degradation even at a small strain of 0.4 %. The observations of damage morphologies gave a good explanation to the $I_{c}$ behavior.c/ behavior.r.

AC Loss Measurement and Analysis of Ag-sheathed Bi-2223 Conductors in Terms of Eddy Currents and Flux Creep

  • Jang, Mi-Hye
    • KIEE International Transactions on Electrophysics and Applications
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    • v.3C no.6
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    • pp.211-215
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    • 2003
  • Alternating current (AC) losses of two Bi-2223 ([Bi, Pb] : Sr : Ca : Cu :O = 2:2:2:3) tapes [one untwisted (Tape I, twist-pitch of $\infty$ mm) and the other with a twist-pitch of 8mm (Tape II) ] were measured and compared. These samples, produced by the powder-in-tube (PIT) method, are multi-filamentary and have a Ag/Au and Ag matrix, respectively. Susceptibility measurements were conducted while cooling in a magnetic field. Flux loss measurements were conducted as a function of ramping rate, frequency and field direction. The AC flux loss increases as the twist-pitch of the tapes decreased, in agreement with the Norris Equation.

A study on the improvements of Critical Current Density of Bi2223 Superconducting Tapes in PIT process (PIT법에 의한 Bi-2223 고온 초전도 테이프의 임계전류밀도 향상에 관한 연구)

  • 장현만;오상수;하동우;류강식;김상현
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.05a
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    • pp.198-201
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    • 1996
  • In order to investigate control factors to critical current density, Ag sheathed Bi2223 superconducting tapes were fabricated using PIT process. Optimizing the reduction ratio of rolling, critical current density 7f rolled Bi2223 tape could be improved with the value of 15,000 A/$\textrm{cm}^2$(77 K, zero field). The correlation between J$\_$c/ and work inhomogeneity was revealed as a dependence of COV of measured oxide layer thickness.

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A Study on AC Loss of Ag Sheathed Bi-2223 Superconducting Tapes (Bi계 초전도 테이프의 교류손실 연구)

  • Jeong, Jong-Man;Jang, Hyeon-Man;Sin, Jae-Hwa;Choe, Jae-Seok;Kim, Sang-Hyeon
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.1
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    • pp.29-33
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    • 1999
  • Superconducting tape is being developed for electrical equipment such as superconducting transformers and generators etc. AC loss reduction is primary concerned in the development of such high-efficiency equipment. AC losses in Bi-2223 silver-sheathed tapes, both single and multi-filamentary, were investigated by means of AC magnetization techniques when longitudinal fields are applied. The experiment resultswere compared with the hysteresis loss equation based on Bean model and the eddy current loss equation. The AC loss of the mono-filamentary tape was dominated by the hysteresis. On the contrary, the AC loss of the multi-filamentary tape was substantially dominated by the eddy current loss in the silver matrix.

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