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Your search keyword '"Bak, J. S."' showing total 3 results
Start Over Author "Bak, J. S." Topic low temperature engineering
3 results on '"Bak, J. S."'

1. Analysis of the Thermal Loads on the KSTAR Cryogenic System.

Author

Kirn, Y. S., Oh, Y. K., Kirn, W. C., Park, Y. M., Lee, Y. J., Jin, S. B., Sa, J. W., Choi, C. H., Cho, K. W., Bak, J. S., and Lee, G. S.

Subjects
LOW temperature engineering, PHYSICAL sciences, MAGNETICS, RADIATION, PHYSICS
Abstract

A large-scale helium refrigeration system is one of the key components for the KSTAR (Korea Superconducting Tokamak Advanced Research) device. In the design of the refrigeration system, an estimation of the thermal loads on the cold mass is an important issue according to the operation scenario. The cold mass of the KSTAR device is about 250 tons including 30 superconducting (SC) coils and the magnet structure. In addition to the static thermal loads, pulsed thermal loads to the refrigeration system have been considered in the operation stage. The main pulsed thermal loads on magnet system are AC losses in the SC coils and eddy current losses in the magnet structure that depend on the magnetic field variation rate. The nuclear radiation loss due to plasma pulse operation is also considered. The designed cooling capacity of the refrigeration system is estimated to be about 9 kW at 4.5 K isothermal. In this paper, calculation of the various kinds of thermal loads on KSTAR cryogenic system and design of the large-scale helium refrigeration system are presented. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2004
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2. Hydraulics of KSTAR Central Solenoid Model Coil 2nd Campaign.

Author

Soo Hwan Park, Han, W. S., Moon, K. M., Park, W. W., Kim, J. S., Yonekawa, Hirofumi, Yong Chu, Hyun Jung Lee, Cho, K. W., Park, K. R., Kim, W. C., Yaung-Soo Kim, Oh, Y. K., and Bak, J. S.

Subjects
SUPERCONDUCTING magnets, SOLENOIDS, HYDRAULICS, HELIUM, TOROIDAL magnetic circuits, LOW temperature engineering, FRICTION
Abstract

KSTAR (Korea Superconducting Tokamak Advanced Research) superconducting magnet consists of a CICC (Cable-In-Conduit Conductor) and is cooled down less than 5 K using supercritical helium. The length of CICC is 610 m for TF coil and maximum about 2,500 m for PF coil respectively, especially the cooling channel is about maximum 300 m in PF coil because of continuous winding scheme. There are many cooling channels in KSTAR coils especially 84 channels in TF magnet system and 100 channels in PF magnet system. Flow imbalance affects cool down of magnet and leads to a difficulty of flow control. The pressure drop between CICC terminals has a close relationship with CICC hydraulic characteristic, helium refrigerator's performance and efficiency. The friction factor which is a representative parameter can be obtained under cryogenic operation condition. We attempt to find out the friction factor of KSTAR CS and PF CICC according to the test result of KSTAR CSMC (Central Solenoid Model Coil) 2nd campaign and compare the results with previous tests. The hydraulic characteristics of KSTAR superconducting magnet system like mass flow distribution, friction factor in conductor, pressure drop and etc during CSMC test and initial commissioning of KSTAR are presented. We can confirm the KSTAR CICC's unique hydraulic behavior in states of cool down and current charging period. Also, we expect that measured data will help to operate KSTAR and be a reference for thermo-hydraulic simulation. [ABSTRACT FROM AUTHOR]

Published
2009
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3. Construction and Commissioning of the KSTAR Helium Distribution System.

Author

Lee, Y. J., Park, Y. M., Kim, Y. S., Jang, H. S., Kwag, S. W., Chang, Y. B., Park, H. T., Woo, I. S., Song, N. H., Bang, E. N., Ha, T. H., Baek, S., Kim, M. K., Kim, W. C., Oh, Y. K., and Bak, J. S.

Subjects
SUPERVISORY control systems, SUPERCONDUCTING magnets, LOW temperature engineering, HELIUM, VALVES, DETECTORS
Abstract

The KSTAR components requiring cryogenic helium coolant for superconducting magnet operations are connected to the helium refrigeration system (HRS) through the helium distribution system (HDS), the final helium distribution station. Twenty eight cryogenic valves including 4 quench protecting valves, many sensors such as temperature sensors, pressure transmitters, and flowmeters are mounted on the system. The HDS has to control the 4.5 K supercritical helium (600 g/s) for 30 superconducting coils and their superconducting bus-lines, 55 K helium (270 g/s) pressurized to 18 bars for the thermal shields and the gravity supports, and a maximum 17.5 g/s of liquid helium for 18 current leads, provided from the HRS which has a 4.5 K equivalent cooling power of 9kW. The helium distribution system consists of a helium distribution box (DB), 5 helium transfer lines, a PLC based helium control system (HCS), etc. The helium control system is connected to the KSTAR supervisory control & interlock system. The detailed status regarding the construction, commissioning during first cool-down, and the instrumentation & control (I&C) system are included in this paper. [ABSTRACT FROM AUTHOR]

Published
2009
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