• Title/Summary/Keyword: Critical current ratio

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Effect of Processing Factors on Critical Current Density in Bi2212/Ag Wires

  • Kim, Sang-Cheol;Ha, Dong-Woo;Oh, Sang-Soo;Han, Il-Yong;Ha, Hong-Soo;Sohn, Ho-Sang
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.1243-1244
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    • 2006
  • Five kinds of double stacked 385 (55 x7) filamentary Bi2212/Ag round wires and 55 filamentary tapes with different Ag ratios (silver area/superconductor area) have been fabricated via PIT method, and the effects of Ag ratio and processing factors on critical current density were studied. The effects of the maximum temperature and average filament diameter on critical current density were also studied. The wire of 0.74 mm diameter having Ag ratio 3.7 showed critical current density of $2,218\;A/mm^2$ at 4.2 K, 0 T.

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A Study on Joining Method of BSCCO(223) Multifilamentary Tape (BSCCO(2223) 다심 초전도 선재의 접합공정 연구)

  • 김정호;김규태;주진호;나완수
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.6
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    • pp.511-517
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    • 2001
  • We evaluated the electrical properties of 37 multifilamentary jointed tapes processed by superconducting joint. In the superconducting joining method, a lap-joint was used. Tapes were selectively etched, and exposed superconducting cores of the two tapes were brought into contact with each other and then only the joined region was uniaxially pressed in the range of 1,000 to 2,50 MPa. The critical current ratio(CCR) and n-value of the jointed tape were evaluated as a function of uniaxial pressure and number of step in the contacting region. It was observed that the CCR was dependent on the number of step, but almost independent of uniaxial pressure. The highest critical current ratio and n-value were obtained to be 58% and 26%, respectively, for the jointed tape to the tape itself.

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Experiment of harmonic components in voltage on high temperature superconducting wire carrying an AC

  • Lee, Jiho;Ko, Tae Kuk
    • Progress in Superconductivity and Cryogenics
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    • v.15 no.1
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    • pp.51-54
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    • 2013
  • This paper deals with harmonic components of the voltage on high temperature superconducting wire carrying an alternating current. HTS wire is used to manufacture superconducting power applications carrying an alternating current. Typically, international standard, IEC 61788-3 is used for critical current measurement. Thus, it is not ideal that critical current criteria in dc are adapted to superconducting power devices to decide the operating current of the devices. In this paper, we confirmed odd harmonic voltage on HTS wires carrying an AC. The ratio between harmonic components and fundamental component can be significant clues to decide the critical current criteria for HTS wire and its power applications in AC circumstance.

Energy and Inductance of a HTS Magnet with Various Aspect Ratios (마그넷 형상에 따른 고온초전도 마그넷의 에너지와 인덕턴스)

  • Kang, Myung-Hun;Kim, Young-Min;Ku, Dae-Kwan;Paik, Kyoung-Ho;Cha, Guee-Soo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.6
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    • pp.1134-1139
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    • 2011
  • When the aspect ratio of a magnet varies, the magnetic field in the magnet also varies. The critical current of a tape-shaped HTS wire varies with the direction and magnitude of applied magnetic field. Consequently when the aspect ration of a HTS magnet varies, the critical current of a HTS magnet varies. This paper shows the relation between the aspect ratio of a magnet and the energy and inductance of a HTS magnet. The critical current is also shown at various aspect ratio of the magnet. The length of the HTS wire, inner diameter of the magnet, and number of pancake are chosen to be variables which varies the shape of the magnet. For a HTS magnet consisting of pancake windings, calculation results show the number of pancake windings are the prime factor which varied the energy and inductance of the magnet. The inner diameter of the magnet varies the energy and inductance of the magnet a little.

Fabrication of Bi2212/Ag HTS Wire with Various Ag Raio (다양한 은비의 Bi2212/Ag 고온초전도 선재의 제조)

  • Kim, Sang-Cheol;Ha, Dong-Woo;Oh, Sang-Soo;Oh, Jae-Geun;Song, Kyu-Jeong;Ha, Hong-Soo;Sohn, Ho-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.11a
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    • pp.163-164
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    • 2005
  • Round shape Bi2212/Ag is isotropic and can be fabricated Rutherford cable to transport high current. Bi2212/Ag round wires with various Ag ratio were fabricated using powder-in-tube process. Double stacked 385 (55\times$7) filamentary wire of various wire diameter was heat-treated at various melting temperature. Wires which have Ag ratio of 0.3 and 0.42 of Ag tube for monofilament show similar critical current density. As average filament diameter decreases from 33 to 16 \mu$m, critical current density of wires increase, and in case of 16 ${\mu}m$ and $T_m$ 890$^{\circ}C$, critical current density was 2,062 $A/mm^2$ at 4.2 K, 0 T.

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Estimation of Magnetization loss of HTS wires with Different Current Density (전류 밀도가 다른 선재들의 자화손실 특성 평가)

  • Lim, H.;Yoon, K.;Lee, H.;Cha, G.
    • Progress in Superconductivity and Cryogenics
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    • v.9 no.1
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    • pp.72-75
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    • 2007
  • Magnetization loss of HTS wire is strongly dependent on the critical current density and the aspect ration of the HTS wire. This paper presents the magnetization loss of stacked BSCCO wire and stacked YBCO wires which had different critical current densities. Width of the BSCCO wire was 4mm and widths of two YBCO wires were 4mm and 8mm. Single wire, two stacked three stacked and four stacked wires were fabricated and tested. Ratio of magnetization loss of BSCCO wire to YBCO wire was presented at single wire. For stacked wire, ratio of magnetization loss of single wire to stacked wire was presented. Test results shows that magnetization losses of stacked wires were greater than that of single wire at large high magnetic field above critical magnetic field.

Fabrication and performance of 100 m Class Bi-2223 High Temperature Superconducting Tape (100 m급 Bi-2223 고온초전도 선재 제조 및 특성)

  • 하홍수;오상수;하동우;장현만;이남진;류강식;이준석
    • Progress in Superconductivity and Cryogenics
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    • v.1 no.2
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    • pp.15-19
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    • 1999
  • For large scale applications of high temperature superconductor (HTS) such as transmission cables, motors and generators, long length of flexible HTS conductor is required. Currently, Bi-2223 HTS tape is capable of being fabricated in longer than 100 m length by industrial processes. In this study, we fabricated 100 m 19 filamentary Bi-2223 ($Bi_{1.8}Pb_{0.4}Sr_2Ca_2O_{10+x}$) HTS tape by PIT (Power in Tube) process. Critical current(IC) of this long length tape was measured 18.5 A at 77K, self field. Critical current of 100 m length tape was mainly resulted from the increase of inhomogeneity in oxide from the increase of inhomogeneity in oxide layer. Engineering critical current (Je=Ic/total tape cross-section area) that is important factor for practical applications and fabrication cost was measured 2.2 kA/cm2.

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The comparison of critical currents measured by hall probe and transport methods for HTS coated conductor

  • Lee, Nam-Jin;Oh, Sang-Soo;Kim, Ho-Sup;Ha, Dong-Woo;Ha, Hong-Soo;Ko, Rock-Kil;Kim, Tae-Hyung;Kim, Hae-Jong;Song, Kyu-Jeong;Moon, Seung-Hyun;Youm, Do-Jun
    • Progress in Superconductivity and Cryogenics
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    • v.11 no.2
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    • pp.11-14
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    • 2009
  • We estimated the critical current distribution of the long length CCs using hall probe method, and checked the reliability by comparing with the four-probe dc transport method. The deviation ratio of $I_{c-T}$ (a measured critical current by four probe dc transport method) and $I_{c-H}$ (calculated critical current by formula (3).) was nearly smaller than 12%. The Hall probe method appeared powerful to evaluate the critical current of CCs in a reel to reel system.

Determination of Critical Chloride Content of Ordinary Portland Cement Concrete by Linear Polarization Technique (선형분극법을 이용한 보통프틀랜드시멘트 콘크리트의 임계염화물량)

  • Kim, Hong-Sam;Cheong, Hai-Moon;Ahn, Tae-Song
    • Journal of the Korean Ceramic Society
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    • v.44 no.9
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    • pp.524-528
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    • 2007
  • The results of evaluating steel corrosion in concrete containing chloride content of various levels indicated that the more chloride content in concrete leads to the lower potential and higher corrosion current density. However, the open circuit potential of steel varied with time and exposure condition, and the corelation between the open circuit potential and corrosion current density was not obvious. In order to determine the critical threshold content of chloride of steel corrosion in concrete, the concept of average corrosion current density was employed. The range of critical chloride content in portland cement concretes was about $1.56{\sim}1.77%$($Cl^-$, %, wt of cement content) along with water-cement ratio, and higher water-cement ratio resulted in reduction in critical threshold chloride content.

Effects of Sm:Ba:Cu Composition Ratio on the Superconducting Properties of SmBCO Coated Conductor Prepared by using a Composition Gradient Method (SmBCO 초전도 선재 특성에 대한 Sm:Ba:Cu 조성비의 영향)

  • Kim, H.S.;Oh, S.S.;Jang, S.H.;Min, C.H.;Ha, H.S.;Ha, D.W.;Ko, R.K.;Youm, D.J.;Moon, S.H.;Chung, K.C.
    • Progress in Superconductivity
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    • v.13 no.1
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    • pp.7-11
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    • 2011
  • The effects of Sm:Ba:Cu composition ratio in SmBCO coated conductor on their superconducting properties were investigated. The SmBCO coated conductors were fabricated by reactive co-evaporation method using EDDC(Evaporation using Drum in Dual Chamber) system. In this system, we could obtain various samples with different composition ratios in a batch by the technique providing composition gradient at deposition zone. From the specimens prepared by EDDC system, we found that composition ratio is uniform parallel to the drum axis, but gradient along the circumferential direction of the drum. We installed a shield having parallelogram open area between the deposition chamber and the evaporation chamber in EDDC system, and attached a 30 cm long template, which is parallel to drum axis, onto the drum surface. In this configuration, we could obtain SmBCO coated conductors having a gradient composition along the length of template. We measured the composition ratios and surface morphologies with periodic interval by SEM and EDAX, and confirmed the profile of composition ratio. We also measured critical current using non-contact Hall probe critical current measurement system and thereby could plot composition ratio vs. critical current. The maximum critical current was obtained, and the surface morphology with the shape of roof tile was observed at the corresponding composition ratio of Sm:Ba:Cu = 1.01:1.99:4.87. It was also found that composition ratio had an effect on not only critical current but also surface morphology.