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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 :
Hyung-Seop Shin, Won-Nam Kang
Volume & Issues
Volume 4, Issue 2 - Nov 2002
Volume 4, Issue 1 - May 2002
Selecting the target year
Effects of Pressure on the Breakdown Characteristics of Cryogenic Liquid and Gaseous Nitrogen
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 1~4
Electrical properties of liquid nitrogen (
) and gaseous nitrogen(
) have become of great interest again since the discovery of high temperature superconductors . It is very important from a point of superconducting apparatus protection to elucidate breakdown characteristics in
at atmospheric and pressurized conditions Therefore. this paper studies the effect of pressure on the breakdown characteristics in
. Af high voltage is applied to electrode system with uniform and non-unform field in various gap length. And Breakdown voltages of
are investigated under AC voltage for Pressure ranging from 0 and 0.5 MPa. This research presented basis information of electrical insulation design for liquid nitrogen immersed HTS power apparatus
Deposition condition of NiO deposited on biaxially textured Ni by a MOCVD process
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 5~10
Deposition condition of NiO that is one of Possible buffer layers for YBCO coated conductors was studied. NiO was deposited on textured Ni substrates by a MOCVD (metal-organic chemical vapor deposition) method. The degree of texture, and the surface roughness were analyzed by X-ray Pole figure, atomic force microscope and scanning electron microscope. The (111) and (200) textures were competitively developed , depending on an oxygen partial Pressure(PO2) and deposition temperature (Tp). The (200) textured NiO layer was deposited at Tp=450~47
and PO2= 1.67 Torr Out-of-Plane (
-scan) and in-plane (
-scan) textures of the (200) NiO films were as good as 10.34
respectively The AFM surface roughness of NiO was in the range of 3~4.5 nm at PO2=0.91~3.34 Torr and at Tp=47
, and in the range of 3~13 nm at TP=450~53
and at PO2=1.67 Torr.
Simulation for characterization of high speed probe for measurement of single flux quantum circuits
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 11~15
High speed probe for measurement of sin91e flux quantum circuits is comprised of coaxial cables and microstrip lines in order to carry high speed signals without loss. For the impedance matching between coaxial cable and microstrip line, we have determined the dimension of the microstrip line with 50
impedance by simulation and then have investigated the effect of line width and cross-sectional shape of signal line, dielectric material, thickness of soldering lead at the coaxial-to-microstrip transition Point, and the an91c between dielectric material and end part of the signal line on the characteristics of signal transmission of the microstrip line. From the simulation, we have found that these all parameter's had influenced on the characteristic of signal transmission on the microstrip line and should be reflected in fabricating high speed probe, We have also determined the dimension of coplanar waveguide to fabricate testing sample for performance test of high speed probe
Fabrication of bi-axially textured Ni tapes for YBCO coated conductors by a cold rolling process and heat treatment of Ni powder compacts
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 16~20
Bi-axially textured Ni tapes for YBCO coated conductors were Prepared by cold rolling and heat treatment of Ni Powder compacts. The Ni powder used in this study was 5 urn in particle size and 99.99 % in purity. The process of this study consists of filling of hi powder into a rubber mold, cold-isostatically Pressing and sintering of the powder compacts at 110
for 6h in 96 % Ar - 4 % H
atmosphere. The sintered compacts were cold rolled with a 5 % step reduction ratio into a 100 micron-thick tapes and then heat-treated at 100
for various time periods. The (200) texture of Ni tape was successfully developed through the recrystallization heat treatment of the cold rolled Ni tapes. At 100
, the degree of texture of the heat-treated Ni tapes seems not to be significantly affected by the heat-treatment time. The short heat treatment of S min was sufficient to develop the complete (200) cube texture. The degree of in-Plane and out-of-plane texture of the prepared Ni tapes was 8-10
. The heat treated Ni tapes consisted of equiaxed grains with a size 50-70 microns. and the AFM sol-face roughness was as smooth as 3 nm.
buffer layer for YBCO coated conductors on biaxially textured Ni substrate by MOCVD technique
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 21~26
Textured CeO2 buffer layers for YBCO coated conductors were deposited on biaxially textured Ni substrate by metalorganic chemical vapor deposition (MOCVD). The degree of texture of deposited
films was strong1y dependent on the deposition temperature (Td) and oxygen Partial Pressure(PO2). (
films were well deposited at T=500~52
. PO2=0.90~3.33 Torr. The surface morphology showed that the films consisted of columnar CeO2 films grown from the Ni substrates. The root mean square roughness of CeO
films estimated by atomic force microscopy(AFM) increased as the deposition temperature(Td) increa- sed. The growth rate of the
films deposited at T=52
and PO2=2.30 Torr was 150~200 nm/min that was much faster than that of other Physical deposition methods.
Stability analysis of high-temperature superconductor(Au/YBCO) film using one-dimensional FDM
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 27~30
One dimensional conduction equation is solved by finite difference method, to analyse the stability of Au/YBCO film deposited on a sapphire substrate. Joule heat is included in the case of current sharing state. The analysis shows the quench and recovery of superconductor depending on the amount of thermal disturbance release on the center surface of superconductor. The critical disturbance energies for different filling factor and operating current are calculated.
A 100 HP HTS Motor Design and the Performance Analysis
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 31~37
A 100 〔HP〕 rated synchronous motor with superconducting rotating field winding has been designed based on the formulated equations established from 2 dimensional magnetic field distributions in a cylindrical coordinate The cross-section was drawn based on calculated design results via Fortran program and then modeled with FEM (Finite Element Method) to investigate the machine performances. First of all, the magnetic field distributions are analysed in many ways according to the field directions and the armature currents. Especially after the rotating Held winding is arranged with BSCCO-2223 high-temperature superconducting(HTS) pancake coils, the exerted magnetic field normally on the HTS tape is calculated through FEM. And the machine output power is calculated according to the torque ang1es which lie between the field and the armature main flux lines. Moreover, this Paper includes the eddy-current loss variations of a copper damper located between the field and the armature coils and design considerations of the 100 HP HTS motor utilizing ferro-magnetic material.
Preliminary investigation of a proposed site for SFCL installation in the power systems
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 38~41
We have conducted Preliminary investigation to propose a suitable site for superconducting fault current limiter (SFCL) installation in the KEPCOs 154kV grid This investigation limited the application SFCL to the bus-tie position of the grid in the Seoul area. First, we calculated maximum Potential fault current for all substations. Then, among substations where the fault current exceeds the CB capacity, rye selected two substations where buses are being operated untied. For the selected two. S S/S and M S/S. fault currents at the M S/S were estimated to be 22.5㎄ and 24.3㎄ for two buses untied respectively, but 44.2㎄ if buses were tied. Simulation using a hypothetical SFCL of 5 Ohm impedance showed that it controlled the fault current up to 20. 1㎄ for bus-tie Position, 28.4㎄ and 29.9㎄ for both buses. respectively, each of which are under the capacity of the currently installed 31.5㎄ GIS. For both substations a SFCL with 5 Ohm impedance successfully controls the fault current under the CB capacity, and 10 Ohm SFCL may be recommendable to maximize the SFCL effect.
Conceptual Design of Single Phase 10MVA HTS Transformer
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 42~46
This research is conducted with the object of Piling up the foundation of design technologies for high temperature superconducting (HTS) power transformer which is thought to be as a powerful power transformer of next generation. In this study, not only the theoretical design of high temperature superconducting (HTS) transformer but also the arrangements of superconducting tape and the cooling method have been conducted. Moreover, electromagnetic analyses using finite element method (FEM) were conducted to confirm the efficiency of the designed transformer.
A Study of Magnetic Field Characteristic of Field coil in HTS motor
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 47~51
In this paper, flux distribution and operating current is calculated according to the field coil change in HTS(High Temperature Superconducting) motor. In order to calculate magnetic field characteristic of the field coil. it is computed by changing the outer radius and the inner width of field coil Bio-Savart equation is used as the analysis method for the characteristic analysis of magnet. 2D and 3D FEA(Finite Element Analysis) is used for the magnetic field distribution in HTS motor The operating current is calculated by
linked With the field coil and
curve of superconductor.
The Performance Investigation of 1/4 Wavelength Thermoacoustic Refrigerator with Helium Refrigerant
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 52~57
In this study, a thermoacoustic refrigerator, using a resonant standing acoustic wave. has been built. The refrigerant is helium gas. The description of thermoacoustic refrigerator was Presented. The temperature ratio (cold part temperature over hot part temperature) and the COP (Coefficient of Performance) that normalized by carnot's COP are plotted versus the thermal load applied to the cold end, for- various speaker power.
Numerical Analysis of Performance of Linear Compressor for the Stilting Cryocooler
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 58~62
The purpose of this study is to analyze the charging gas effect on the resonance and performance characteristics of the linear compressor for small scale FPFD Stirling refrigerator. To ensure high performance of FPFD type Stirling refrigerator, the operating frequency of the refrigerator should be around the natural frequency of compressor. The gas spring effect which is induced from Pressure change in cylinder due to motion of pistons has significant effect on the natural frequency of the compressor. The numerical results show the linear compressor has high natural frequency when the charging pressure of working fluid is high and the stroke of compressor, current, input power and efficiency of compressor were shown with different operating conditions.
Study of the performance characteristics of the Stirling type orifice pulse tube refrigerator
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 63~67
In this study, the performance of the Stirling type orifice Pulse tube refrigerator (OPTR) with a linear compressor was investigated by experiment. The dynamic pressures at three points and a temperature at the cold heat exchanger are measured to explore the dependency of the orifice on the performance of the OPTR. The experimental results show that the opening of the orifice has significant effects on the no load temperature and cool down characteristics. The Pressure amplitude in Pulse tube decrease as the opening of the orifice increase, but the mass flow rate through the orifice and the electric input Power to the compressor increase. The results show that the operating frequency and charging Pressure does not affect on the no load temperature. The pressure amplitude in pulse tube decrease as the operating frequency increase or the charging Pressure decreased.
Numerical Analysis on the Transient Cooling Characteristics of an Infrared Detector Cryochamber
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 68~72
This work investigates the transient cooling characteristics of an Infrared (IR) detector cryochamber, which has a critical effect on the cooling load. The current thermal modeling considers the conduction heat transfer through a cold well. the gaseous conduction due to outgassing. and the radiation heat transfer. The transient cooling Performance. i.e. the penetration depth and cooling load, is determined using a finite difference method. It is found that the penetration depth increases as the bore conductivity increases. Gaseous conduction and radiation hardly affect the penetration depth. The transient cooling load increases as the bore conductivity increases. The effects of gaseous conduction and radiation on transient heat transfer are weak at initial stages of cooling. However, their effects become significant as the cooling Process Proceeds.
Thermal Flow Analysis and Design of KSTAR Thermal Shield Panel by Numerical Method
Progress in Superconductivity and Cryogenics, volume 4, issue 2, 2002, Pages 73~77
In order to derive the detailed design of Thermal Shield Cryopanel. which plays a role to make the Tokamak Nuclear Fusion Equipment work at both static and efficient conditions the commercially available software package FLUENT Version 5.3, was utilized. This study investigated the effects of thermal sources and distributions on the temperatures of Lid. Body. Base. and EH-Port Cryopanel by the numerical technique whose grid generations cover the solid and 9as region of the panel. The physical model of the Thermal Shield Cryopanel is that the 10mm diameter of the pipe with 1mm thickness is soldered on the Stainless steel Panel with 4mm thickness. The heat fluxes to the panel are assumed to be by thermal radiation in the vacuum space and by conduction through the supporters. The inlet conditions of Helium gas are 20 atmospheric Pressures and 60K temperature. The panel shapes with cooling Pipes and the operational conditions to keep appropriate temperature distribution of Thermal Shield Cryopanel Have been found and suggested.