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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 8, Issue 4 - Nov 2006
Volume 8, Issue 3 - Sep 2006
Volume 8, Issue 2 - Apr 2006
Volume 8, Issue 1 - Mar 2006
Selecting the target year
tape with metal powder addition
Ko, Jae-Woong ; Yoo, Jai-Moo ; Kim, Young-Kuk ; Chung, Kook-Chae ; Yoo, Sang-Im ; Wang, Xio Lin ; Dou, Shi Xue ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 1~4
tapes with several metal powder addition were fabricated by PIT method with or without heat treatment. The
at 4.2 K and 5 T were obtained for the
tape and 10 vol % of Cu added
tape without heat treatment respectively. The
at 4.2 K and 5 T were obtained for the
tape and 10 vol. % of Al added
tape with heat treatment, respectively. The
curve shows enhancement in
under magnetic field. which suggests enhancement in workability and grain connectivity with several metal powder addition.
Total pressure dependence of YBCO films in MOD method
Yoo, Jai-Moo ; Chung, Kook-Chae ; Ko, Jae-Woong ; Kim, Young-Kuk ; Wang, Xiao Lin ; Dou, Shi Xue ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 5~8
The growth properties of MOD-YBCO films were investigated. To enhance the growth rate of YBCO layer and inhibit the build-up of HF gas during the annealing process in TFA-MOD for YBCO coated conductors the method of low pressure annealing was employed. Total pressure was changed from 700Torr to 1Torr and its effect on growth of YBCO films was compared with atmospheric one. The lower Pressure was effective to control of the pore size in MOD method . Surface morphology of YBCO films processed at low total pres sure was rough and composed of random YBCO (103) grains. But large pores, usually observed at atmospheric process in MOD disappeared and also the number of pores was reduced at low pressure annealing. Also discussed ate the effects of Fluorine-free Y and Cu precursor solution on the development of microstructure. Dense surface me phology and with less and small pores can be provided through controlling Fluorine content.
TEM analysis of IBAD/RABiTS substrates prepared by Tripod polishing
Choi, Soon-Mee ; Chung, Jun-Ki ; Yoo, Sang-Im ; Park, Chan ; Oh, Sang-Soo ; Kim, Cheol-Jin ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 9~14
Sample preparation plays a critical role in microstructure analysis using TEM. Although TEM specimen has been usually prepared by jet-polishing or Ar-ion beam milling technique. these methods could not be applied to YBCO CC which is composed of IBAD or RABiTS substrates, several buffet layers, and YBCO superconducting layer because of big difference in mechanical strengths between the metallic phase and oxide phases. To obtain useful cross-sectional information such as interface between the phases or second phases in YBCO CC, it is prerequisite to secure the large area of thin section in the cross-sectional direction. The superconducting layer or the buffer layers are relatively weak and fragile compared to the metallic substrate such as Ni-5wt%W RABiTS of Hastelloy-based IBAD, and preferential removal of weak ceramic phases during polishing steps makes specimen preparation almost impossible. Tripod polisher and small jig were home-made and employed to sample preparation. The polishing angle was maintained <
throughout the polishing steps using 2 micrometers attached to the tripod plate. TEM specimens with large and thin area could be secured and used for RABiTS/IBAD substrate analyses. In some cases, additional Ar-beam ion milling with low beam current and impinging angle was used for less than 30 sec. to remove debris or polishing media attacked to the specimens.
Fabrication of YBCO films in MOD processing using F-free Y & Cu precursor solution
Kim, Young-Kuk ; Yoo, Jai-Moo ; Ko, Jae-Woong ; Chung, Kook-Chae ; Kim, Young-Jun ; Han, Bong-Soo ; Wang, X.L. ; Dou, S.X. ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 15~18
A new precursor solution wilt low fluorine content was synthesized for MOD processing of coated conductors. In this study, the precursor solution for MOD processing was synthesized using F-free yttrium and copper precursor. It was shown that crack-free and uniform precursor films were formed after calcination in humidified oxygen atmosphere. Less than 2 hours were required to finish the calcination process. The relatively gradual weight loss during the calcination process is attributed to the feasibility of fast calcination profile. The calcined precursor film was converted to a YBCO film without any secondary phases after annealing in wet
atmosphere. Fully converted film shows uniform microstructure and high critical current density.
Fabrication of biaxially textured Ni substrate by line-focused infrared heating
Chung, Jun-Ki ; Kim, Won-Jeong ; Jung, Kyu-Dong ; Bae, Won-Tae ; Kim, Cheol-Jin ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 19~22
Desirable substrates for
coated conductor are highly cube textured Ni or Ni-alloy tapes, which can be produced by cold rolling and recrystallization annealing. We have fabricated hi-axially textured pure Ni tapes for the application of coated conductors. The sintered Ni rod was cold-rolled into the thin tapes of
thickness and the tapes were heat-treated for texture development with line-focused infrared heater. The temperature was maintained at
, using 1kW double ended linear halogen lamp in
atmosphere The biaxially tortured Ni tapes were successfully formed by line-focused infrared heat treatment The texture of the annealed Ni tapes was analysed using the GADDS (general area detector diffraction system). The full width at half maximum values of phi and omega scan for the Ni tapes were less than
and the grain size was
Optimization of process variables in batch-type MOD process
Chung, Kook-Chae ; Yoo, Jai-Moo ; Ko, Jae-Woong ; Kim, Young-Kuk ; Wang, X.L. ; Dou, S.X. ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 23~25
Optimization of process variables, including oxygen and water partial pressure and also an nesting temperature, was performed in batch-type process to fabricate YBCO films on LaAlO3 single crystal. In this work, YBCO oxide powder was used as a starting precursor for metal-organic deposition(MOD)method. The precursor films were fabricated in batch furnace and they were converted to the epitaxial YBCO films at the same furnace with varying the process variables. The oxygen partial pressure was varied from 100ppm to 2000ppm and the water partial pressure from 1.2% to 12.2%. The window for optimal P(O2) was narrow about 700ppm for batch-type process. YBCO films in bathc-thype MOD process were optimized at 740-770oC and P(H2O) of 2.3%-7.3%.
Technical comparison between superconductive RSFQ logic circuits and silicon CMOS digital logics
Cho, W. ; Moon, G. ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 26~28
The development technique of digital logic using CMOS device is close reached several limitations These make technical needs that are ultra high speed superconductive systems based on CMOS silicon digital computing technique. Comparing digital logic based on silicon CMOS, the computing technique based on ultra high speed superconductive systems has many advantages which are ultra low power consumption, ultra high operation speed. etc. It is estimated that features like these increasingly improve the possibility of ultra low power and ultra superconductive systems. In this paper digital logics of current CMOS technique and RSFQ superconductive technique are compared with and analyzed.
Insulation Design for a 154 kV Class HTS Power Cable
Kwag, Dong-Soon ; Cheon, Hyeon-Gweon ; Choi, Jae-Hyeong ; Kim, Hae-Jong ; Cho, Jeon-Wook ; Yun, Mun-Soo ; Kim, Sang-Hyun ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 29~33
A 154 kV class high temperature superconducting (HTS) power cable system is developing in Korea. For insulation design or this cable, the grading method of insulating paper is proposed. The use of graded insulation gives improved bending properties of the cable. Therefore, we discussed the electrical stress distribution and calculation for grading insulation design of a HTS cable. Also. the basic insulation design of 154 kV class HTS power cable was done.
A study on determination of HTS power devices' parameters
Lee, Seung-Ryul ; Kim, Jong-Yul ; Yoon, Jae-Young ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 34~38
There are many parameters that should be considered from the viewpoint of real power system operation and planning in designing HTS power devices. Especially, in the power system with HTS-FCL(fault current limiter) and TR(transformer), there is close correlation between parameters of the HTS power devices. This paper describes some considerations in determining parameters of HTS power devices, which are related to technical and economical aspects. The main parameters in this study are the quench resistance of HTS-FCL and the % impedance of HTS-TR. The results may give basic information for developing the devices.
Development of EMTDC model component for HTS power cable considering critical current, critical temperature and recovery time
Bang, Jong-Hyun ; Kim, Jae-Ho ; Sim, Ki-Deok ; Cho, Jeon-Wook ; Yoon, Jae-Young ; Park, Min-Won ; Yu, In-Keun ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 39~44
Before applying HTS power cable to the real utility. system analysis should be carried out by some simulation tools . Hereby the electrical power system analysis is very important for practical use of HTS devices. Nowadays PSCAD/EMTDC simulation tool is one of the most popular and useful analysis tool for the electrical power system analysis. Unfortunately the model component for HTS power cable is not provided in the PSCAD/EMTDC simulation tool In this paper. the EMTDC model component for HTS power cable has been developed considering critical current, critical temperature and recovery time constant that depend on the sorts of HTS wire. The numerical model of HTS Power cable in PSCAD/EMTDC was designed by using the real experimented data obtained from the real HTS 1G wire test. The utility application analysis of HTS power cable was also performed using the developed model component and the parameters of the real utility network in this study. The author's got good results. The developed model component for HTS power cable could be variously used when the power system includes HTS power cable, especially it will be readily analyzed by PSCAD/EMTDC in order to obtain the data for the level of fault current power flow, and power losses, and so on.
Cryogenic Insulation Technique for HTS Transformer
Kim, Sang-Hyun ; Cheon, Hyeon-Gweon ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 45~48
In the response to the demand for electrical energy , much effort was given to develop and commercialize high temperature superconducting (HTS) power equipments has been made around the world. Especially, HTS transformer is one of the most promising devices . but the cryogenic insulation technology should be established during development Hence many types of dielectric tests should be carried out to understand the dielectric phenomena at cryogenic temperature and to gather various dielectric data. Among the many types dielectric tests . the characteristic of barrier effect were conducted using simulated electrode after analysing the insulating configuration of HTS transformer main winding. The influence of a barrier on the dielectric strength was measured according to the position of the harriet the number of the barrier and thickness or the barrier. It was shown that the effectiveness . namely the ratio of the breakdown voltage in presence of barrier to the voltage without barrier, is highest when the barrier is placed at the needle electrode side. On the contrary, in the case of having the barrier between the electrodes, the harrier was placed between the electrodes the characteristic was even improved slightly.
A fault current analysis and parallel FCL scheme on superconducting new power system
Yoon, Jae-Young ; Lee, Seung-Ryul ; Kim, Jong-Yul ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 49~53
This paper specifies the new power supply paradigm converting 154kV voltage level into 22.9kV class with equivalent capacity using superconducting rower facilities and analyze the fault current characteristics with and without HTS-FCL (High Temperature Superconducting-Fault Current Limiter). Superconducting new power system is the power system to which applies the 22.9kV HTS cable in parallel to HTS transformer and HTS-FCL with low-voltage and mass-capacity characteristics replacing 154kV conventional cable and transformer. The fault current of superconducting new power system will increase greatly because of the mass capacity and low impedance of HTS transformer and cable. This means that the HTS-FCL is necessary to reduce the fault current below the breaking current of circuit breaker. This paper analyze the fault current and suggests the parallel HTS-FCL scheme complementing the inherent problem of HTS-FCL, that is recovery after quenching is impossible within shorter than a few seconds.
A study on the performance characteristics of rotary type Stirling cryocooler
Park, S.J. ; Hong, Y.J. ; Kim, H.B. ; Kim, Y.H. ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 54~58
Stirling cryocooler is relatively compact, reliable, commercially available. and uses helium as a working fluid. Over the past decade and a half, there has been rapid development of Stirling cryocooler, mainly for military and space applications. Stirling cryocoolers have been widely used lot the cooling of infrared sensors and high temperature superconducting filters to the temperature of the liquid nitrogen. The Stirling cryocooler with the rotary compressor is applicable to the cooling device for the compact mobile thermal imaging system, because the cryocoolers have the compact structure and light weight. In this paper, integral Stirling cryocooler is designed, manufactured and fabricated, and performance characteristics are investigated. This cooler delivers approximately 0.6W cooling at 80K for 20W of input power from 24V DC power supply.
Closed-Loop Cooling System for High Field Mangets
Choi, Y.S. ; Kim, D.L. ; Lee, B.S. ; Yang, H.S. ; Painter, T.A. ; Miller, J.R. ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 59~64
A closed-loop cryogenic cooling system for high field magnets is presented. This design is motivated by our recent development of cooling system for 21 tesla Fourier Transform ion Cyclotron Resonance (FT-ICR) superconducting magnets without any replenishment of cryogen. The low temperature superconducting magnets are immersed in a subcooled 1.8 K bath, which is connected hydraulically to the 4.2 K reservoir through a narrow channel. Saturated liquid helium is cooled by Joule-Thomson heat exchanger and flows through the JT valve, isenthalpically dropping its pressure to approximately 1 6 kPa, corresponding saturation temperature of 1.8 K. Helium gas exhausted from pump is now recondensed by two-stage cryocooler located after vapor purify system. The amount of cryogenic Heat loads and required mass flow rate through closed-loop are estimated by a relevant heat transfer analysis, from which dimensions of JT heat exchanger and He II heat exchanger are determined. The detailed design of cryocooler heat exchanger for helium recondensing is performed. The effect of cryogenic loads, especially superfluid heat leak through the gap of weight load relief valve, on the dimensions of cryogenic system is also investigated.
Thermal diffusion experiment of impulsive heat in subcooled liquid nitrogen
Choi, J.H. ; Ha, J.C. ; Byun, J.J. ; Chang, H.M. ; Kim, H.M. ; Ko, T.K. ;
Progress in Superconductivity and Cryogenics, volume 8, issue 1, 2006, Pages 65~70
Transient heat transfer caused by an impulsive heating in subcooled liquid nitrogen is investigated experimentally. This study is part of out ongoing efforts directed to a stable cryogenic cooling system lot superconducting fault current limiters (SFCL). A thin heater attached by epoxy on one surface of a GFRP plate is immersed in liquid-nitrogen bath at temperatures between 77 K and 55 K. A strong heat flux up to
is generated lot 100 ms, and the temperature of the heater sulfate is measured as a function of time. The behavior of bubbles on the heating surface can be explained by comparing the measured temperature history for vertical and two horizontal (up and down) orientations. It is concluded that the subcooling of liquid nitrogen below 70 K is very effective in suppressing bubbles, resulting in better thermal protection and faster recovery from an impulsive heat.