• Progress in Superconductivity and Cryogenics
• /
• v.5 no.1
• /
• pp.1-12
• /
• 2003

In this paper we present a brief description and summary results of each of our recent activities in three areas, all devoted to NMR and MRI superconducting magnet technologies: 1) development of a high-field LTS / HTS NMR magnet; 2) development of a novel digital flux injector for slightly resistive NMR magnets; and 3) a proposal fer a low-cost MRI magnet system based on $MgB_2$ composite and an innovative cryogenic design / operation concept.

• Progress in Superconductivity and Cryogenics
• /
• v.19 no.1
• /
• pp.13-16
• /
• 2017

Water issue, especially water pollution, is a serious issue of 21st century. Being an significant technique for securing water resources, superconducting magnetic separation wastewater system was indispensable. A large bore conduction-cooled magnet was custom-tailored for wastewater treatment. The superconducting magnet has been designed, fabricated and tested. The superconducting magnet was composed of NbTi solenoid coils with an effective horizontal warm bore of 400 mm and a maximum central field of 2.56T. The superconducting magnet system was cooled by a two-stage 1.5W 4K GM cryocooler. The NbTi solenoid coils were wound around an aluminum former that is thermally connected to the second stage cold head of the cryocooler through a conductive copper link. The temperature distribution along the conductive link was measured during the cool-down process as well as at steady state. The magnet was cooled down to 4.8K in approximately 65 hours. The test of the magnetic field and quench analysis has been performed to verify the safe operation for the magnet system. Experimental results show that the superconducting magnet reached the designed magnetic performance.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.52 no.11
• /
• pp.572-576
• /
• 2003

For quite a long time various researches and developments of superconducting magnetic energy storage(SMES) device have been done for enhancement of power qualify control of sensitive electric load. This paper describes the design. fabrication and experimental results for the 3MJ SMES magnet made by using the design code of a SMES device that we developed. A computer code was developed to find the parameters of the SMES magnet which has minimum amount of superconductor for the same stored energy, and the 3MJ SMES magnet was designed based upon that. And the 3MJ SMES magnet designed based upon those. In addition, 3MJ SMES magnet was made based on several research results which were ramp up to 1㎄ without quench.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.45 no.1
• /
• pp.24-29
• /
• 1996

Magnetic field theories for the design of highly homogeneous magnet are introduced and a nonlinear optimization method for the design of actively shielded superconducting magnet is presented. The presented design method can optimize both main coil and shielding coil simultaneously by setting constraints on stray field intensity at a specified distance from the magnet center. A 2-Tesla actively shielded superconducting magnet, with 90cm bore diameter, is designed using the presented method. The field homogeneity is 2ppm/30cm DSV and the 5 gauss stray field contour is within 4m axially and 3m radially from the magnet center. (author)., 7 refs., 6 figs., 3 tabs.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 1999.02a
• /
• pp.34-38
• /
• 1999

An acoustic emission(AE) technique has been used to monitor and diagnose quenching phenomenon in racetrack shaped superconducting magnets at cryogenic environment of 4.2K. The ultimate goal is to ensure the safety and reliability of large superconducting magnet systems by being able to identity and locate the sources of quench in superconducting magnets. The characteristics of AE parameters have been analyzed by correlating with quench number, winding tension of superconducting coil and charge rate by transport current. It was found in this study stat there was good correlation between quench current and AE parameters. The source location of quenching in superconducting magnet was also discussed on the correlation between magnet voltage and AE energy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.193-193
• /
• 2010

Magnetic separation is expected to be applied for material refinement as an important supporting technology. In the superconducting magnetic separation, the cohesive force between particles is strong compared with that in the other magnetic separation. The use of high magnetic field by the superconducting magnet enhances the magnetic substance capture ability of the magnetic separation. Industrial raw materials was used for the superconducting magnetic separation. Cry-cooled, NB-Ti superconducting magnet with. 100 mm room temperature bore and 600 mm of height was used for magnetic separator.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.45 no.2
• /
• pp.193-198
• /
• 1996

Low power superconducting persistent current switch(PCS) for the superconducting magnet systems in the persistent mode was developed and its experimental results were analyzed when the system was charged or discharged. The multifilament NbTi wire with Cu matrix was used for the PCS. The constructed NbTi superconducting switch with superconducting magnet system operated successfully. It also operated on-off switching action with good stabilization. The maximum operating current in persistent mode was 60A (at 1T). In persistent current mode, the decay of the persistent current at 60A was observed. Its decay was 3.55% in 60 min. It is possible to make the persistent current switch with the better decaying of persistent current if some problems for joint resistance are solved.

• Progress in Superconductivity
• /
• v.14 no.2
• /
• pp.122-127
• /
• 2012

Current leads are one of the important components for carrying the current to the coil in the superconducting magnet system. Heat leakage through the current lead is the major factor of entire heat load in the cryogenic system because current leads carry the current from room temperature to near 4 K, connecting thermally each other. Therefore, minimization heat load through current lead can reduce the operating temperature of superconducting magnet. The semi-retractable current lead, composed of multi-contact connector and HTS element, is one of good options. Comprehension of Multi-contact connector's structure, contact resistance and heat generation is essential for estimating heat generation in current leads. Multi-contact connector has several louvers inside of socket and the shape, number, size of louvers are different with the size of connector. Therefore contact area, current path and contact resistance are also different. In this study, the contact resistance in multi-contact connector is measured using the electrical power as a function of connector's size and temperature. Also, the unique correlation of electrical contact resistance is derived and heat generation is estimated for superconducting magnet application.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2001.02a
• /
• pp.125-127
• /
• 2001

For the development of a SMES system we fabricated and tested the 1 MJ superconducting magnet The test results show that the magnet is excellent in comparison with previously fabricated magnets outside. The recovery current of the conductor plays an important role in the fabrication of the stable magnets for a SMES system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.4
• /
• pp.753-758
• /
• 2011

Magnetic field and Electric field of High Temperature Superconducting magnet are very important to analysis of superconducting magnet. The maximum perpendicular magnetic field was applied to the outermost pancake windings. The critical current of all the magnet windings is limited by the critical current of the outermost pancake windings. The E-J relation was used to determine the critical current, and an evolution s trategy was adopted for the optimization of gap length between each pancake windins. The results of calculations show that the critical current and the central magnetic field and uniformity increased by 82.6% and 31.6% and 50.8%, respectively, for a magnet consisting of ten pancake windings. This paper did an analysis the cause of increase the critical current and central magnetic field and uniformity in no gap and optimal gap model.