• Progress in Superconductivity
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• v.7 no.2
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• pp.167-173
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• 2006

Coated conductors suitable for the fabrication of persistent mode high $T_c$ magnets are suggested and the fabrication method of persistent mode magnets using coated conductor are demonstrated. Persistent current was observed in a small piece of coated conductor. Closed loop of coated conductor with a diameter of around 1 em was successfully prepared and was cooled with a magnetic field of about 500 Gauss in order to induce supercurrent. Coated conductor with a $I_c$ of 100 A/cm-width was used for the preparation of closed loop of coated conductor. Persistent current was confirmed by measuring the magnetic field generated from closed loop of coated conductor by using Gauss meter. Magnetic field of 4.4 Gauss was detected from the supercurrent of closed loop of coated conductor. It shows that superconducting joint of coated conductor is not a prerequisite for the construction of persistent mode magnets. It is thought that this work opens the possibility to use coated conductor for the construction of persistent mode high $T_c$ magnets for MRI, NMR and magnetic separation applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05a
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• pp.38-41
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• 2003

상업용 Ag 판재 위에 cyclic 전위와 일정 전위를 인가하는 전기증착법으로 Tl-1223상 precursor 막을 증착하는 연구를 수행한 다음, 이를 이영역 전기로를 사용하여 열처리함으로써 고온초전도 coated conductors를 제조하는 연구를 수행하였다. 전기증착법으로 비교적 균질하고 치밀한 precursor막을 증착할 수 있었으며, 이 막을 $870^{\circ}C$에서 20분 동안 열처리하여 임계온도가 114 K이고 자속고정능력도 비교적 우수한 50%의 Tl-1223상과 50%의 Tl-1212상으로 구성된 고온초전도 도체를 제조할 수 있었다. 이로부터 아주 값싼 증착법인 전기증착법을 이용하여 후막의 고온초전도 도체를 제조할 수 있음을 증명하였다.

• Progress in Superconductivity and Cryogenics
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• v.24 no.4
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• pp.29-35
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• 2022

We fabricated MHOS (multi-HTS layers on one substrate) high-temperature superconducting (HTS) REBCO conductors using HTS REBCO coated conductor (CC) A-specimen, which induces an artificial magnetic flux pinning effect, and HTS REBCO CC B-specimen, that does not induce this effect. The superconducting magnetic properties of the fabricated MHOS conductors were examined by measuring their magnetic moment m(H) curves using a physical property measurement system (QD PPMS-14). The critical current density (J_c) characteristics of our four-layered MHOS HTS REBCO conductor specimens such as BAAB, BBBB, and AAAA were lower than those of their two-layered and three-layered counterparts. At a temperature T of 30 K the magnetic flux pinning physical indicator δ values (obtained from the relationship J_c ∝ H^-δ) of the three-layer ABA (δ = 0.35) and two-layer AB (δ = 0.43) specimens were found to be significantly lower than those of the four-layer ABBA (δ = 0.51), BAAB (δ = 0.60), AAAA (δ = 0.78) and BBBB (δ = 0.81) structures.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.240-241
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• 2007

In general, high temperature superconducting coated conductors have intermediary buffers layer consisting of seed, diffusion barrier and cap layers. Simplification of the oxide materials buffer architecture in the fabrication of high temperature superconducting coated conductors is required because the deposition of multi-layers buffer architecture leads to a longer manufacturing time and a higher cost process of coated conductors. Thus, single buffer layer deposition seems to be important for practical coated conductor manufacturing process. In this study, a single gradient layered buffer deposition process of YZO for low cost coated conductors has been tried using DC reactive sputtering technique. About several thick YZO gradient single buffer layers deposited by DC co-sputtering process were found to act as a diffusion layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.05a
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• pp.3-3
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• 2009

In order to investigate the possibility of using mixed rare earth $(Nd_{1/3}Eu_{1/3}Gd_{1/3})Ba_2Cu_3O_{7-x}$ (NEG123) as the superconducting layer of the HTS coated conductor, the NEG123 thin film was deposited epitaxialy on LAO(100) single crystal and IBAD_YSZ metal templates by pulsed laser deposition. Systematic studies were carried out to investigate the influences of deposition parameters of PLD on the micro structure, texture and superconducting properties of NEG-123 coated conductor. Deposition at oxygen partial pressure of 600 mTorr was needed to routinely obtain high quality NEG123 films with $J_c$'s (77K) over 2 MA/$cm^2$ and Tc's over 90K (${\Delta}T{\sim}2\;K$). We verified from magnetization study that the NEG123 has an improved in-field Jc as the field increases at temperatures between 10 K and 77 K compared with Gd123. The $J_c$ (77K, self field) and the value of onset $T_c$ of NEG123 thin film on LAO substrate was $4.0MA/cm^2$ and 92K, respectively. This is the first report, to the best of our knowledge, of coated conductors with NEG123 film as the superconducting layer which have Ic and Jc over 40 A/cm-width and 1.6 MA/$cm^2$ at 77K, self field. This study shows the possibility of using NEG123 film as the superconducting layer of the HTS coated conductor which can be used in high magnetic field power electric devices.

• Progress in Superconductivity and Cryogenics
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• v.9 no.1
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• pp.9-13
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• 2007

Coated conductor(CC) is recently in actively progress for the research and development, and its can be used various stabilizer lot the specific requirements for each application. Among various superconducting applications, coated conductor applied to superconducting fault current limiters(SFCLS) bypasses fault current to its stabilizer, where the surge is abruptly reduced ; thus, stainless steel, which has large resistivity can be a suitable stabilizer for SFCLS. Despite high n-value of the YBCO, CC stabilized with stainless steel did not effectively limit the first peak fault current. In the short circuit test results of AMSC's 344S, a half period delay was observed between the fault and the generation of resistance(60Hz). In this paper, we performed short-circuit experiments with stacked and unstacked CC and compared the test results to analyze effective fault current limiting characteristics. we compared time of the generated resistance as the fault current limiting characteristics and made the samples one is the stacked CC and the other is unstacked CC. These samples were used equal numbers of pieces of CC. In addition, comparison and analysis was made for the stacked structure by measuring fault current limiting characteristics with respect to thermal insulation by impregnating with epoxy resin.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.180-181
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• 2006

As a rule, high temperature superconducting coated conductors have multi-layered buffers consisting of seed, diffusion barrier and cap layers. Multi-buffer layer deposition requires longer fabrication time. This is one of main reasons which increases fabrication cost Thus, single buffer layer deposition seems to be important for practical coated conductor process. In this study, a single layered buffer deposition of $CeO_2$ for low cost coated conductors has been tried using thermal evaporation technique 100nm-thick $CeO_2$ layers deposited by thermal evaporation were found to act as a diffusion layer. $0.4{\mu}m$-thick SmBCO superconducting layers were deposited by thermal co-evaporation on the $CeO_2$ buffered Ni-W substrate. Critical current of 118A/$cm^2$ was obtained for the SmBCO coated conductors.

• Progress in Superconductivity and Cryogenics
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• v.20 no.3
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• pp.15-20
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• 2018

No-insulation (NI) pancake magnets are fabricated using Rare earth-Barium-Copper Oxide (REBCO) coated conductor (CC) tapes, which enabled a very compact magnet in the aspects of high critical current density ($J_c$) and high mechanical strength by removing insulation and allowing thinner stabilizer. They have also advantages such as self-quench protection. Therefore, it does not need quench detection and protection that can be very challenging in a high critical temperature ($T_c$) superconducting magnet technology. Recently, it was reported that the NI REBCO CC magnets have some drawbacks of long charging time and high field ramp loss which will be a concern in the operation of cryocooled magnets. These issues are related to the turn-to-turn contact resistivity and can be released by managing it. This is also closely related to the activity of reducing the contact joint resistance in the case of CC joints for long length CC fabrication. Therefore, in this study, the turn-to-turn contact resistance ($R_c$) at the CC contact part of differently stabilized CC tapes was measured. The behaviors of $R_c$ at CC contact parts according to the applied contact pressure were investigated. The range of $R_c$ measured for CC tapes adopted will provide fundamental data for design and fabrication of the CC NI coils.

• Progress in Superconductivity and Cryogenics
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• v.10 no.4
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• pp.13-17
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• 2008

This paper presents experimental and characteristic analysis of hgh-$T_c$ eater-triggered witch using coated conductor (CC) in liquid and gas helium. The high temperature superconducting insert coil which can be installed in a low temperature superconducting (LTS) magnet has been proposed and researched to generate higher magnetic field for MR. Since CC could be an attractive option for HTS insert, it is important to research he characteristics of heater-triggered switch employing CC. We performed the heater test and constructed simulation model using finite element method (FEM.) We performed a protection test and observed normal zone propagation (NZP) signals to evaluate the witch with protection of magnet.

• Progress in Superconductivity and Cryogenics
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• v.8 no.4
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• pp.8-11
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• 2006

High temperature superconducting coated conductor has various buffer structures on Ni-W alloy. We comparatively studied the growth conditions of a multi buffer layer $(CeO_2/YSZ/CeO_2)$ and a single buffer layer$(CeO_2)$ on textured Ni-W alloy tapes. XRD data showed that the qualities of in-plane and out-of-plane textures of the two type buffer structures were good. Also, we investigated the properties of SmBCO superconducting layer that was deposited on the two type buffer structure. The SmBCO superconducting properties on the single and multi buffer structure showed different critical current values and surface morphologies. FWHM of In-plane and out-of-plane textures were $7.4^{\circ},\;5.0^{\circ}$ in the top CeO2 layer of the multi-buffer layers of $CeO_2/YSZ/CeO_2$, and $7.3^{\circ},\;5.1^{\circ}$ in the $CeO_2$ single buffer layer. $1{\mu}m-thick$ SmBCO superconducting layers were deposited on two type buffer layer. $I_c$ of SmBCO deposited on single and multi buffer were 90 A/cm, 150 A/cm and corresponding $J_c$ were $0.9MA/cm^2,\;1.5MA/cm^2$ at 77K in self-field, respectively.