• 제목/요약/키워드: engineering critical current density

검색결과 185건 처리시간 0.033초

Fabrication of 6-superconducting layered HTS wire for high engineering critical current density

  • Kim, Gwantae;Ha, Hongsoo;Kim, Hosup;Oh, Sangsoo;Lee, Jaehun;Moon, Seunghyun
    • 한국초전도ㆍ저온공학회논문지
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    • 제23권4호
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    • pp.10-13
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    • 2021
  • Recently, cable conductors composed of numerous coated conductors have been developed to transport huge current for large-scale applications, for example accelerators and fusion reactors. Various cable conductors such as CORC (Conductor on round core), Roebel Cable, and TSTC (Twisted stacked tape cable) have been designed and tested to apply for large-scale applications. But, these cable conductors cannot improve the engineering critical current density (Je) because they are made by simple stacking of coated conductors. In this study, multi-HTS (High temperature superconductor) layers on one substrate (MHOS) wire was fabricated to increase the engineering critical current density by using the exfoliation of superconducting layer from substrate and silver diffusion bonding method. By the repetition of these processes, the 10 m long 6-layer MHOS conductor was successfully fabricated without any intermediate layers like buffer or solder. 6-layer MHOS conductor exhibited a high critical current of 2,460A/12mm-w. and high engineering critical current density of 1,367A/mm2 at liquid nitrogen temperature.

Evaluation of Critical Current Density of FeAs-based Superconductors

  • Otabe, Edmund S.;Kiuchi, Masaru;Matsushita, Teruo;Ni, Baorong;Qi, Yanpeng;Wang, Lei;Gao, Zhaoshun;Wang, Dongliang;Zhang, Xianping;Ma, Yanwei;Nakajima, Yasuyuki;Tamegai, Tsuyoshi
    • 한국초전도ㆍ저온공학회논문지
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    • 제14권2호
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    • pp.1-7
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    • 2012
  • In this review paper, we report the characteristics of the critical current density in FeAs based superconductors which is newly discovered by Hosono group of Tokyo Institute of Technology on 2008. Since the many specimens in present stage are not single crystals, there are two kinds of critical current density observed in the specimens which are so-called local and global critical current densities. Therefore, it is necessary to evaluate both kinds of critical current densities. The history effect in which the global critical current density shows different values in increasing and decreasing magnetic field is also observed when the specimens have the local and the global critical current densities. The wire which critical current is 180 A is successfully developed with using the knowledge of abovementioned characteristics of two kinds of critical current densities and the history effect.

고온초전도마그네트 내부의 스트레인에 의한 임계전류밀도 감소 계산 (Calculation of Critical Current Density Degradation in the HTS Magnet due to Mechanical Strain)

  • 이인규;나완수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1997년도 하계학술대회 논문집 A
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    • pp.260-263
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    • 1997
  • In this paper, we describe the mechanical strain effects on the critical current density of HTS (BSCCO) pancake-type-magnet. Firstly the strain of pancake coil is calculated in terms of coil length, which is also a function of angle, and then the critical current density degradation due to strain is calculated along the coil. We assumed that the critical current density degradation pattern is same with that of $Nb_{3}Sn$. We also modelled the effects of magnetic field on the critical curent degradation, and the results are compared with those with null magnetic field.

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250 m 급 Bi-2223/Ag 고온 초전도선재 제조 (Fabrication of 250 m class Bi-2223/Ag HTS Tapes)

  • 하홍수;오상수;하동우;장현만;김상철;송규정;박찬;권영길;류강식
    • Progress in Superconductivity
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    • 제3권1호
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    • pp.130-133
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    • 2001
  • A multifilamentary Bi-2223 HTS tape for superconducting power applications was studied through the fabrication of 250-meter long tapes by the PIT(powder in tube) process. To fabricate continuous long wire, a drawing machine, a two-drum bull block and a rolled tape winding machine were developed. Especially, 250-meter long tapes were heat treated in the shape of pancake coil to reduce the heat affect zone and to achieve the high critical current. Engineering critical current density was improved through both the enhancements of critical current density by control of thermal process and the increase of filling factor by using thin Ag alloy sheath tubes less than 1.5 mm in thickness. We have made successfully 250-meter long 37 filamentary tapes with high filling factor up to 31 % employing the modified drawing and rolling technique. The critical current of 250-meter long tapes with pancake coil type was measured by transport method at self-field up to 250 gauss of center field. The measured values, based on the transport critical current at self-field, $I_{c}$ -B characteristics and magnetic field analysis, are 34 A of I$_{c}$ and 4.0 $kA/\textrm{cm}^2$ of $J_{e}$ at 250 m, 77 K, and 0 T. We also have achieved the 56 A of I$_{c}$ and 7.0 $0 kA/\textrm{cm}^2$ of$ J_{e}$ in short tapes at 77K, self-field, and 1$mutextrm{V}$/cm.

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Critical Current Degradation Analysis in HTS Pancake Coil due to Self Field Effects

  • Nah, Wan-Soo;Joo, Jin-Ho;Yoo, Jai-Moo
    • Progress in Superconductivity
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    • 제1권1호
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    • pp.68-72
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    • 1999
  • Since the discovery of high Tc superconductors, great efforts have been focused to develop high performance HTS magnets for the ultimate applications to power system devices. Magnet designers, however, have had difficulties in the estimation of the maximum operating current of the designed magnet from the tested short sample data, due to the degradation of the critical current density in the magnet. Similar story applies to the HTS electrical bus bar. It has been found that the critical current of Bi-2223 stacked tapes is much less than the total summation of critical currents of each tape, which is mainly attributed to the self magnetic fields. Furthermore, since the critical current degradation of Bi-2223 tape is greater in the normal magnetic field (to the tape surface) than in the parallel one, detailed magnetic field configurations are required to reduce the self field effects. In this paper, we calculate the self field effects of a stacked conductor, defining self field factors of normal and parallel magnetic fields to the tape surface. Finally, the critical current degradations in the HTS magnet are explained by the introduced self field factors of the stacked conductor.

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$MgB_2$ bulk의 미세구조와 임계전류밀도에 미치는 polyacrylic acid doping 효과 (Effects of Polyacrylic Acid Doping on Microstructure and Critical Current Density of $MgB_2$ Bulk)

  • 이승묵;황수민;이창민;주진호;김찬중
    • Progress in Superconductivity
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    • 제11권2호
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    • pp.87-91
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    • 2010
  • We fabricated the polyacrylic acid (PAA)-doped $MgB_2$ bulks and characterized their lattice parameters, actual C substitutions, microstructures, and critical properties. The boron (B) powder was mixed with PAA using N,N-dimethylformamide as solvent and then the solution was dried out at $200^{\circ}C$ and crushed. The C treated B powder and magnesium powder were mixed and compacted by uniaxial pressing at 500 MPa, followed by sintering at $900^{\circ}C$ for 1 h in high purity Ar atmosphere. We observed that the PAA doping increased the MgO amount but decreased the grain size, a-axis lattice constant, and critical temperature ($T_c$), which is indicative of the C substitution for B sites in $MgB_2$. In addition, the critical current density ($J_c$) at high magnetic field was significantly improved with increasing PAA addition: at 5 K and 6.6 T, the $J_c$ of 7 wt% PAA-doped sample was $6.39\;{\times}\;10^3\;A/cm^2$ which was approximately 6-fold higher than that of the pure sample ($1.04\;{\times}\;10^3\;A/cm^2$). This improvement was probably due to the C substitution and the refinement of grain size by PAA doping, suggesting that PAA is an effective dopant in improving $J_c$(B) performance of $MgB_2$.