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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Progress in Superconductivity and Cryogenics
Journal Basic Information
Journal DOI :
The Korea Institute of Applied Superconductivity and Cryogenics
Editor in Chief :
Volume & Issues
Volume 11, Issue 4 - Nov 2009
Volume 11, Issue 3 - Sep 2009
Volume 11, Issue 2 - May 2009
Volume 11, Issue 1 - Mar 2009
Selecting the target year
Fabrication of silver stabilizer layer by coating process using nano silver paste on coated conductor
Lee, Jong-Beom ; Kim, Byeong-Joo ; Kim, Hye-Jin ; Yoo, Yong-Su ; Lee, Hee-Gyoun ; Hong, Gye-Won ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 1~4
Mechanical and electrical properties of silver stabilizer layer of coated conductor, which as prepared with nano silver paste as starting materials, have been investigated, Nano silver paste was coated on a YBCO film by dip coating process at a diping speed of 20m/min. Coated film was dried in air and heat treated at
in an oxygen atmosphere. Adhesion strength between YBCO and silver layer was measured by a tape est(ASTM D 3359). Hardness and electrical conductivity of the samples were measured by pencil hardness test (ASTM D 3363) and volume resistance test by LORESTA-GP (MITSHUBISHD, respectively. The sample heat-treated at
showed poor adhesion 1B, but samples heat treated at higher than
showed enhanced adhesion of 5B. The silver layer heat-treated at
showed the high hardness value larger than 9 H, low volume resistance, surface resistance value as well as superior current carrying capacity compared to sputtered silver. SEM observations showed that a dense silver layer was formed with a thickness of about
. Dip coated silver layer prepared by using nano silver paste showed superior electrical and mechanical characteristics.
MgO nanodot formation using the rf-sputtering method
Chung, K.C. ; Yoo, J.M. ; Kim, Y.K. ; Wang, X.L. ; Dou, S.X. ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 5~8
MgO nanodots have been deposited and formed on top of the substrate surface. Mg was sputtered to form the MgO nanodots on the single crystal substrates by rf-sputtering method and followed by heat treatment in the oxygen ambient. The deposition and formation of MgO nanodots have been controlled systematically using the process variables such as substrate temperature, sputtering time, and rf-power. As the substrate temperature increased from the room temperature the density of MgO nanodots decreased. The optimal conditions of MgO nanodots formation using the rf-sputtering was investigated and the maximum density of more than
on single crystal substrates was obtained when the rf-power of 100 watts was applied for 30 seconds at room temperature. The typical size of MgO nanodots was identified to be <160 nm(diameter) and 4-30nm (height) by atomic force microscopy. The modulated surface morphology was examined through surface images and cross-section analysis and discussed for the artificial pinning sites in the superconducting films.
A study on the reduction of ac loss of YBCO coated conductor by a mechanical striation method
Yoo, Yong-Su ; Hong, Gye-Won ; Lee, Hee-Gyoun ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 9~15
High temperature superconductor (HTS) coated conductors has high hysteretic magnetization loss which is an obstacle for the AC applications of coated conductors. We propose a method to reduce the magnetization loss of the coated conductor. It is the mechanical striation method by load variety using office knife. The magnetization loss measured in the mechanical striated YBCO coated conductor without copper layer was compared with the loss generated by perpendicularly exposed external magnetic filed. The reduction in magnetization loss due to the mechanical striation is clearly shown at higher field and was dependent on the striation number. The mechanical striation method was proven to have additional advantages of a low cost and high fabrication process.
A Study on the Insulation Properties of Cryogen for the HTS SMES
Choi, Jae-Hyeong ; Choi, Jin-Wook ; Lee, Hai-Gun ; Song, Jung-Bin ; Kim, Hae-Jong ; Seong, Ki-Chul ; Kim, Sang-Hyun ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 16~19
Recently, for improvement of the magnetic field of high temperature superconductor (HTS) apparatus, many studies investigating on operating in the range of
with liquid helium or the conducting method using cryocooler is actively reviewed. Also, the cooling method using solid nitrogen as cryogen is being suggested. Since the nitrogen has very large specific heat in solid state, it is expected that it can enable long time operation without a continuous supply of cooling energy. However, there is still insufficient data on the characteristics of solid nitrogen such as thermodynamic properties and liquid-solid phase change. Especially, there was almost no study done on the electrical insulation properties of solid nitrogen so far. In this study, solid nitrogen to find the electrical characteristics was made by using cryocooler and cryostat, and investigated the flashover discharge and breakdown. The results of this study will be useful as a basic data for electrical insulation design of the HTS system using solid nitrogen as cryogen.
The Conceptual Design of High-Tc superconducting Magnet for a Superconducting Property Measurement System
Choi, S.J. ; Lee, S.Y. ; Bae, J.H. ; Sohn, M.H. ; Kim, W.S. ; Park, C. ; Lee, J.K. ; Lee, S.J. ; Choi, K. ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 20~24
The superconducting property measurement system is used to acquire electrical and thermal properties on short HTS tape samples and the system is composed of specimen holder for mounting HTS tape and a magnet for applying magnetic fields externally. The magnet consists of two split racetrack windings and is designed to produce maximum 3T of center field. The temperature of specimen holder can be varied in range from 10K to 77K. The field homogeneity is required less than 300 gauss stray field contour within 20cm axially and 3cm radially from origin. We have worked on the conceptual designs of the conduction-cooled magnet for the superconducting characteristic measurement system. The measurement system will be fabricated in near future based on the design parameters presented in this paper.
A study on the current limiting characteristics and magnetic analysis of the non-inductively wound coil
Jang, Jae-Young ; Park, Dong-Keun ; Chang, Ki-Sung ; Na, Jin-Bae ; Kim, Won-Cheol ; Chung, Yood-Do ; Ko, Tae-Kuk ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 25~29
To reduce the power loss in normal state, non-inductively wound high temperature superconducting (HTS) coils are used for fault current limiter (FCL) application. Non-inductively wound coils can be classified into two types: solenoid type and pancake type. These two types have different electrical and thermal and mechanical characteristics due to their winding structure difference. This paper deals with the current limiting characteristics, magnetic field analysis of the two coils. Simulation using finite element method (FEM) was used to analyze the magnetic field distribution and inductance of the coils. Short circuit test using stabilizer-free coated conductor (CC) was also carried out. We can compare the characteristics of the two types of coil by using the data obtained from simulation and short circuit test. We confirmed the feasibility of FCL application by the analysis about the characteristics of non-inductively wound coil using CC.
Charging and Persistent-Current Mode Operating Characteristics of BSCCO Magnet Using High-Tc Superconducting Power Supply
Jo, Hyun-Chul ; Yang, Seong-Eun ; Kim, Young-Jae ; Hwang, Young-Jin ; Yoon, Yong-Soo ; Chung, Yoon-Do ; Ko, Tae-Kuk ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 30~34
This paper deals with charging and persistent-current mode operating characteristics of BSCCO magnet load using high-temperature superconducting (HTS) power supply. The HTS power supply consists of two heater-triggered switches, an iron-core transformer with the primary copper winding and the secondary BSCCO solenoid, and a BSCCO magnet load. The magnet load was fabricated by double pancake winding and its inductance is about 21 mH. A hall sensor was installed at the middle of the magnet load to measure the current in the load. In order to investigate the efficient pumping characteristics, operating tests of heater-triggered switch with respect to dc heater current were carried out, and the electromagnet current was determined by considering saturation characteristics of its iron core. The saturation characteristics of charged current in the magnet load were observed with respect to various pumping periods: 12 s, 14 s, 24 s and 32 s. After charging the magnet load, the persistent current was measured. The operating characteristics of the persistent current mode were mainly determined by joint resistance and magnet load.
A Study on Insulation Characteristics by Thickness of Laminated Polypropylene Paper for an HTS Transmission Cable
Choi, Jin-Wook ; Choi, Jae-Hyeong ; Kim, Hae-Jong ; Cho, Jeon-Wook ; Kim, Sang-Hyun ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 35~38
The high temperature superconducting(HTS) power cable, as a key component of the next generation power transmission system, operates cost-effectively because of much less transmission loss. Currently, a world-wide research has been undertaken actively. In this research, we designed insulation thickness and investigated thickness effect of laminated polypropylene paper(LPP) which is insulation material of HTS cable in case of AC and impulse breakdown.
Theoretical Analysis of Charging Current of Linear Type Magnetic Flux Pump According to the Penetrated Position and Moving Speed of Magnetic Flux
Chung, Yoon-Do ; Bae, Duck-Kweon ; Yoon, Yong-Soo ; Ko, Tae-Kuk ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 39~44
We proposed a linear type magnetic flux pump (LTMFP) as a power supply for superconducting magnet system. In order to explain the operating mechanism of pumping action, the pumping sequence based on penetrated position and moving speed of magnetic flux on the superconducting Nb foil should be understood. In this paper, we induced a theoretical equation for pumping current of LTMFP according to the position of normal spot and corresponding equivalent circuit. In addition, current charging tendencies under the intensity of magnetic flux and frequency were described based on the theoretical pumping equation.
Electrical Insulation Characteristics of HTS Cables according to Bending Strain
Kwang, Dong-Soon ; Kim, Sang-Hyun ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 45~48
Research on the mechanical properties of the dielectric paper and mini-model cable are important for optimum electrical insulation design of HTS cable, because the HTS cable experience of mechanical stress, such as tensile and bending stress. Also, it is operated at cryogenic temperature. Therefore, this paper discusses the experiment results on the AC and lighting impulse breakdown characteristics, partial discharge inception and extinction characteristics, and external shape change of the insulation layer according to bending strain of the mini-model cable.
Numerical Analysis of Moving Type and Static Type Electrodynamic Suspension Simulator with Superconducting Levitation Magnet
Lee, E.R. ; Bae, D.K. ; Chung, Y.D. ; Yoon, Y.S. ; Ko, T.K. ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 49~54
This paper presents the numerical simulation results on the moving type electrodynamic suspension (EDS) simulator and static type EDS simulator using high-Tc superconducting (HTS) levitation magnet. The levitation force of the EDS system is formed by the reaction between the moving magnet and the fixed ground conductor. The possible two ways to simulate the EDS system were simulated in this paper by using finite element method (FEM). The first way was the moving type simulator which consists of the fixed HTS magnet and the moving ground conductor. The second way was the static type simulator which consists of the fixed magnet, the fixed ground conductor and the ac current supply system. To verify the characteristics of high speed EDS system with the moving type simulator heavy, large and fast moving ground conductor is needed. The static type simulator can get the characteristics of the high speed EDS system by applying equivalent ac current to velocity, therefore it does not need large moving part. The static type EDS simulator, which can consist of an HTS magnet, the fixed ground conductor(s), an AC power supply and the measuring devices, also test the effect of the shape of the ground conductor easily. The plate type ground conductor made stronger levitation force than ring type ground conductor. Although the outer diameter 335 mm ring type ground conductor (Ring3) was larger than the outer diameter 235 mm ground conductor (Ring2), the levitation force by Ring2 was stronger than that by Ring3. From the calculation results on this paper, the consideration of the magnetic flux distribution according to the levitation height should be included in the process of the ground conductor design.
Study of the Performance of the Fin-Tube Heat Exchanger of the Miniature Joule-Thomson Refrigerator
Hong, Yong-Ju ; Kim, Hyo-Bong ; Park, Seong-Je ; Choi, Young-Don ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 55~59
Miniature Joule-Thomson refrigerators have been widely used for rapid cooling of infrared detectors, probes of cryosurgery, thermal cameras, missile homing head and guidance system, due to their special features of simple configuration, compact structure and rapid cool-down characteristics. The thermodynamic performance of J-T refrigerator highly depends on the hydraulic and heat transfer characteristics of the recuperative heat exchanger. The typical recuperative heat exchanger of the J-T refrigerator has the double helical tube and fin configuration. In this study, effectiveness-NTU approach was adopted to predict the thermodynamic behaviors of the heat exchanger for the J-T refrigerator. The thermodynamic properties from the REFPROP were used to account the real gas effects of the gas. The results show the effect of the operating conditions on the performance of the heat exchanger and refrigerator for the given heat exchanger. The influences of mass flow rate and the supply pressure on the effectiveness of heat exchanger and the ideal cooling capacity are discussed in details.
Miniature J-T Refrigerator Using Triplet Heat Exchanger
Hwang, G. ; Jeong, S. ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 60~63
Most J-T (Joule-Thomson) refrigerators use a Giaque-Hampson type heat exchanger due to its excellent thermal performance and compactness. The cryoprobe (cryosurgical probe) treating prostate cancer usually has a dimension of 17 gauge (1.6 mm diameter), so it does not have enough space to bear a Giaque-Hampson type heat exchanger. In this paper, the triplet heat exchanger is adopted as the heat exchanger of cryoprobe, and the performance is investigated with an experimental test. The result shows that the triplet heat exchanger can be substituted for Giaque-Hampson type heat exchanger in the application of cryosurgery.
Commissioning results of the KSTAR helium refrigeration system
Cho, K.W. ; Chang, H.S. ; Park, D.S. ; Joo, J.J. ; Moon, K.M. ; Kim, Y.S. ; Bak, J.S. ; Yang, S.H. ; Fauve, E. ;
Progress in Superconductivity and Cryogenics, volume 11, issue 1, 2009, Pages 64~68
To keep the superconducting (SC) magnet coils of KSTAR at proper operating conditions, not only the coils but also other cold components, such as thermal shields (TS), magnet structures, SC bus-lines (BL), and current leads (CL) must be maintained at their respective cryogenic temperatures. A helium refrigeration system (HRS) with an exergetic equivalent cooling power of 9kW at 4.5K without liquid nitrogen
pre-cooling has been manufactured and installed for such purposes. In this proceeding, we will present the commissioning and initial operation results of the KSTAR HRS. Circuits which can simulate the thermal loads and pressure drops corresponding to the cooling channels of each cold component of KSTAR have been integrated into the helium distribution system of the HRS. Using those circuits, the performance and the capability of the HRS, to fulfill the mission of establishing the appropriate operating condition for the KSTAR SC magnet coils, have been successfully demonstrated.