• Progress in Superconductivity and Cryogenics
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• v.17 no.3
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• pp.18-22
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• 2015

This paper deals with high-Tc superconducting (HTS) power charging system with GdBCO magnet, photo-voltaic (PV) controller, and solar panels to charge solar energy. When combining the HTS magnet and the solar energy charging system, additional power source is not required therefore it is possible to obtain high power efficiency. Since there is no resistance in superconducting magnet carrying DC transport current the energy losses caused by joule heating can be reduced. In this paper, the charging characteristics of HTS power charging system was simulated by using PSIM. The charging current of HTS superconducting power charging system is measured and compared with the simulation results. Using the simulation of HTS power charging system, it can be applied to the solar energy applications.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.817-818
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• 2006

A 2.0T class HTS conduction cooled magnet was designed. Designing of magnet shape was performed through two steps. First step is to find a basic cross section for minimize the amount of conductor used and second step to optimize the coil shape to satisfy the magnetic field homogeneity. The magnetic fields was analyzed with FEM and the critical current value of magnet was also expected with the result of field analysis and the Ic to B curve of Bi-2223 HTS tape.

• Progress in Superconductivity and Cryogenics
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• v.11 no.1
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• pp.30-34
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• 2009

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.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2171-2174
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• 2008

The design of thermal radiation shield cooled by a cryocooler is presented. This study is motivated mainly by our recent development of prototype superconducting magnet system for the Cyclotron K120. The superconducting magnet system is composed of the magnet cryostat, transfer line and supply cryostat. In order to minimize thermal radiation load, the superconducting coil form in the magnet cryostat is enclosed by the thermal radiation shield which is thermally connected to the first-stage cold head of a two-stage cryocooler in the supply cryostat. Since the supply cryostat is located far from the magnet cryostat large temperature gradient along the thermal shield is unavoidable. In this paper, the thermal radiation shield is optimized to minimize temperature gradient with taking into account the cryogenic load, system structure and electrical load. The effect of heat source from thermal conduction through mechanical supports on the temperature distribution of thermal radiation shield is also discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.353-353
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• 2009

It is an important task to construct a recycling society with a low damage on the environment in our century. Magnetic separation is expected to be applied for the industrial waste treatment as an important supporting technology. In the magnetic separation of dry condition, the cohesive force between particles is strong compared with that in the wet condition's magnetic separation. The use of high magnetic field by the superconducting magnet enhances the powder's magnetic substance capture ability of the magnetic separation. In this study, the POSCO's coolant sludge of hot rolled steel was used for the superconducting magnetic separation of dry condition. Cryo-cooled NB-Ti superconducting magnet with 100 mm room temperature bore and 600 mm of height was used for magnetic separator.

• Progress in Superconductivity and Cryogenics
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• v.2 no.1
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• pp.24-30
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• 2000

This paper present the characteristics of the internal induced voltage and arc phenomena in liquid helium at the energy transfer from a superconducting magnet to a load resistor. Especially generation mechanism of the oscillated wave from of the coil terminal voltage is analyzed by considering circuit constant of the superconducting magnet, load condition and arc resistance of the mechanical opening switch. The wavefront and peak portion of the voltage are strongly influenced by arc discharge triggered by the switch separation in liquid helium. Abrupt arc extinction leads to voltage oscillation with an enormous peak. It is suggested that the superconducting magnet should be designed to ensure the internal surge when arc is possibly formed by switch opening or coil short circuit between turns or layers. Finally, a suppression method of the oscillating surge is proposed based on the load condition.

• Progress in Superconductivity and Cryogenics
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• v.3 no.1
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• pp.56-63
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• 2001

The thermal stability conditions are investigated for superconducting magnet systems cooled conductively by cryocooler without liquid cryogens. The worst scenario in the systems is that the heat generation in the resistive state exceeds the refrigeration. causing a rise in the temperature of the magnet winding and leading to the burnout. It is shown by an analytical solution that in the continuous resistive state, the temperature may increase indefinitely or a stable steady-state may be reached, depending upon the relative size of the magnet with respect to the refrigeration capacity of the cryocooler. The stability criteria include the temperature-dependent Properties of the magnet materials and the refrigeration characteristics of the cryocooler. A useful graphical scheme is Presented and discussed to demonstrate the physical importance of the results.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.115-118
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• 2000

The superconducting magnet supporting post of the KSTAR system is a flexible structure that absorbs thermal shrink of the superconducting magnet and also a rigid structure that supports the weight of the magnet and dynamic loads. In this work, a structural analyses for the post under the loads were performed. As a result, it turns out that the post would be safe when it is exposed to the loads, such as magnet weight, thermal contraction, and plasma vertical disruption load. And, Buckling and modal analysis results of the post are presented.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.597-599
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• 2000

Fabrication of superconducting magnet system needs high-degree technical know-how, which require not only a lot of investment of man-power and finance but also that of long time. Until now, we have met many technical problems and it have been solved by trial and error. In fact, we have got chance to come into contact with researches into the magnet design for MRI easily but did not contact with the process of fabrication and the techniques. We introduced process of fabrication and techniques for MRI magnet system until before the superconducting magnet combine with cryostat in Korea Electrotechnology Research Institute.

• Progress in Superconductivity and Cryogenics
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• v.10 no.4
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• pp.29-32
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• 2008

The design of a superconducting magnet system producing very high magnetic field is underway at Korea Basic Science Institute (KBSI) to accelerate three kinds of carbon irons (C+2, C+4, C+6) to 120 MeV. A quarter-scaled prototype will be manufactured in order to confirm the feasibility of our design. Magnet Inductances in the system have a great influence on the current ramping rates and contribute to the stored energy, which are usually considered to be unfavorable in magnet operation. The modeling and simulation scheme of a prototype superconducting magnet for the cyclotron K120 is described in this paper. The inductances are calculated by a numerical method with and without iron yokes, respectively. These calculation results will be used as engineering design details such as a current ramping rate and a quench protection design.