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S.H. Park,
Y. Chu,
H. Yonekawa,
Y.O. Kim,
K.P. Kim,
I.S. Woo,
W.S. Han,
J.S. Hong, K.R. Park,
H.K. Na,
M. Kwon
[show abstract]
[hide abstract]
ABSTRACT: The Korea Superconducting Tokamak Advanced Research (KSTAR) adopted superconducting coils which consist of rectangular cable-in-conduit conductors (CICC) without a central hole for supercritical helium. Most of all, the KSTAR has a unique superconducting magnet system with Nb<sub>3</sub>Sn and NbTi such as ITER. We expect that the test results of KSTAR experiments can also provide useful information for ITER and the other fusion devices. Up to now, the KSTAR superconducting magnet system is showing a larger flexibility and reliability in operation. For example, the TF magnet system has achieved the current charging of 36.2 kA and PF magnet system has been also charged up to ±4 kA without difficulties during the last two times KSTAR campaigns. The significant thermo-hydraulic characteristics such as helium flow distribution, pressure drop between the inlet and outlet of coil, the friction factor and the temperature variation according to the current charging operations are introduced in this paper.
IEEE Transactions on Appiled Superconductivity 07/2011; · 1.04 Impact Factor
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ABSTRACT: During the operation of the Korea Superconducting Tokamak Advanced Research (KSTAR), there exist various disturbances that cause the conductors to become unstable. The KSTAR Toroidal Magnet (TF) system was designed to secure the sufficient stability against them. The stability analysis showed that the energy margin of the TF Cable-In-Conduit (CIC) conductor was sufficiently high so that the expected disturbances could not cause the conductor to quench. During the 2nd KSTAR campaign in 2009, the cryogenic stability of the TF magnet system was analysed by energizing it up to 36 kA that is a bit higher than the designed current of 35.2 kA. The temperature increase measured at helium outlets was less than 0.1 K, which was well consistent with the analysis. Even in the reference plasma scenario, it was expected from the analysis that there still exists the sufficient temperature margin more than 4 K. The quench analysis was carried out to validate the design of the present TF CIC conductor from the magnet protection's point of view. In this paper, the cryogenic stability of the TF magnet system was estimated and the quench detection parameters were derived for protecting possible damages from quenches.
IEEE Transactions on Appiled Superconductivity 07/2011; · 1.04 Impact Factor
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[show abstract]
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ABSTRACT: There are limits to a single biometric observation such as variation in an individual biometric feature due to the condition of a sensor, the health condition of a human, illumination variation and so on. To overcome such limitations, the authors propose a new multimodal biometric approach integrating finger vein recognition and finger geometry recognition at the score level. The method presents three advantages compared to previous works: (i) the proposed multimodal biometric system can be constructed as a tiny device, which uses a finger vein and finger geometry features acquired from a single finger; (ii) the proposed finger geometry recognition, based on Fourier descriptors, is robust to the translation and rotation of a finger; and (iii) the authors obtained better recognition accuracy using the score-level fusion method based on a support vector machine than by other score-level fusion methods such as the MAX, MIN and SUM rules. The results showed that the equal error rate of the proposed method decreased by as much as 1.089 and 1.627% compared with finger vein recognition and finger geometry recognition methods, respectively.
IET Computer Vision 10/2010; · 0.64 Impact Factor
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ABSTRACT: To detect quenches in the Poloidal Field (PF) magnet system is more difficult than the Toroidal Field (TF) magnet system due to excessively high inductive voltages generated by PF pulse-currents and plasma currents. According to reference scenarios being considered so far, the maximum voltage across the PF coils is inductively generated up to about 3.5 kV during the start of plasma (SoP) stage in a very short time period. The voltage measured by compensation of the inductive voltage should be below a certain level which is called as the quench voltage threshold. However, the compensated voltage might be higher than the threshold even with the well-designed compensation schemes. Accordingly, the quench voltage threshold and the quench protection delay time should be properly determined for the quench detection not to take a false action which could cause the fast energy discharge. From the quench simulation using the calculation of hot spot temperature and the resistive voltage growth as a function of time, the proper values of the quench detection parameters of the PF magnet system were derived for the maximum hot temperature rise to be limited within 150 K.
IEEE Transactions on Appiled Superconductivity 07/2010; · 1.04 Impact Factor
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[show abstract]
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ABSTRACT: The AC loss in a large superconducting magnet coil shows a tendency to be changed after assembly. For the ac loss measurement of the Korea Superconducting Tokamak Advanced Research (KSTAR) superconducting coils after assembly, several current scenarios, trapezoidal pulses and a DC offset sinusoidal pulses, were applied to the PF1 Upper (U) and Lower (L) coils during the commissioning. The measurement was done once before and once after the plasma discharge experiments. All coil data were obtained by the tokamak monitoring system and helium distribution system which were designed to measure temperature, pressure, and mass-flow at both inlets and outlets of the coils. The PF1 coils of the cable-in-conduit conductor type were made of Nb<sub>3</sub>Sn superconducting strands, whose winding scheme is 20 layers with each layer having 9 turns. Each has 10 cooling channels for the heat removal by the supercritical helium at 4.5 K. For the trapezoidal pulse tests, the current was increased up to 4 kA with several different ramp rates and a 2 kA DC offset and 0.5 kA sine waves with different frequencies from 0.1 Hz to 0.3 Hz were applied to the coil. According to the analyses, the AC loss was slightly decreased for the same condition after 700 plasma shots. It was believe that such a result was due to reduced inter-strand resistances which changed the transverse resistance between the inter-strands. The coupling time constant was estimated to be 32 ms in the trapezoidal tests and 13.6 ms for the DC offset sinusoidal pulses. The former is larger than the latter because of the effect of the jacket eddy current loss due to Incoloy 908 which is a ferromagnetic material. Considering the jacket eddy current losses, the coupling time constant was recalculated and the value estimated to be about 13 ms for all current wave forms during first commissioning.
IEEE Transactions on Appiled Superconductivity 07/2010; · 1.04 Impact Factor
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ABSTRACT: In general, the vein pattern in a finger vein image is not distinctive owing to light scattering through the skin layer, which makes detection of the finger vein region difficult. To solve this problem, a new finger vein image restoration method is proposed. Experimental results show that the equal error rate of finger vein recognition with the proposed restoration method is 0.76% and that without it is 1.35%.
Electronics Letters 11/2009; · 0.96 Impact Factor
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Yong Chu,
H. Yonekawa,
Y.O. Kim, K.R. Park,
Hyun Jung Lee,
M.K. Park,
Y.M. Park,
S.J. Lee,
T.H. Ha,
Y.K. Oh,
J.S. Bak
[show abstract]
[hide abstract]
ABSTRACT: To protect the KSTAR (Korea Superconducting Tokamak Advanced Research) superconducting coils against a quench, the quench detection system based on voltage measurement was fabricated. It used a detect/dump scheme which detects the presence of non-recovering normal zones and activates a dump circuit that transfers most of the stored energy into a dump resistor. Even though it is desirable to discharge the coil energy as fast as possible after quench detection, a time delay between the quench detection and the complete dump circuit actuation will be necessary in order that the quench voltage is to be distinguished from various noises. The quench threshold voltage and the delay time should be set before operation for quench voltage detection so that the maximum hot-spot temperature could be limited to 150 K. This paper describes the hardware techniques to prevent the malfunction of the quench detection due to voltage noises arising from the KSTAR operating scenarios. During the first operation of the KSTAR machine, the inductive voltages and other voltage noises were measured and effectively compensated below voltage thresholds. A quench did not occur and the quench detection system was well operated without any false activation.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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K.R. Park,
Yong Chu,
H. Yonekawa,
E.N. Baang,
Y.O. Kim,
Hyun Jung Lee,
Y.M. Park,
Y.J. Lee,
H.S. Chang,
D.K. Lee,
J.H. Choi,
S.H. Park,
S.H. Hahn,
K.H. Kim,
I.S. Hwang,
M.K. Park,
K.W. Cho,
Y.S. Kim,
Y.K. Oh,
J.S. Bak
[show abstract]
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ABSTRACT: To achieve the first plasma of the Korea superconducting tokamak advanced research (KSTAR), the KSTAR superconducting coils were tested in advance. As they should operate in excessively low temperature of 4.5 K and high magnetic field environment of 7.5 T, it is crucial to monitor the cryogenic and the structural behaviors of KSTAR device during the commissioning period including a cool-down. The temperatures of the KSTAR toroidal field (TF) coil and the poloidal field (PF) coils were measured during the entire operating period. The mechanical stresses on the TF and PF structures were continuously monitored to check if they go beyond the limiting value calculated through the simulation. The alignment of the KSTAR device was checked by using displacement sensors. The TF coils were successfully supplied with 15 kA DC current for 8 hours, and the maximum 5 kA/s current variation of the PF coils were tested. For the main experiment, the interlock test of the quench detection system for the KSTAR coils was carried out at reduced currents of 1 kA. From these results the quench protection circuit, and the current-flow of the KSTAR superconducting coils proved to be well performed for the first plasma operation.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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Soo Hwan Park,
W.S. Han,
K.M. Moon,
W.W. Park,
J.S. Kim,
H. Yonekawa,
Yong Chu,
Hyun Jung Lee,
K.W. Cho, K.R. Park,
W.C. Kim,
Yaung-Soo Kim,
Y.K. Oh,
J.S. Bak
[show abstract]
[hide abstract]
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.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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H. Yonekawa,
Y.O. Kim,
Hyun Jung Lee,
S.W. Yoon,
S.H. Hahn,
K.S. Lee,
D.K. Lee,
Soo Hwan Park,
Yong Chu,
E.N. Bang, K.R. Park,
Y.K. Oh,
J.S. Bak,
J.A. Leuer
[show abstract]
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ABSTRACT: An in situ measurement of the magnetic field generated by the assembled superconducting magnet coils was held by using precision Hall sensors during the commissioning of the Korea Superconducting Tokamak Advanced Research (KSTAR) device. This was done in order to investigate the magnetic influence of Incoloy 908, which is the jacket material for the cable-in-conduit conductors (CICCs) of the Nb<sub>3</sub>Sn coils. After the PF coils were discharged from 1 kA the vertical remanent field at the plasma center was more than 10 G, while the TF coils were not energized. The vertical magnetic field generated by the PF coils had a discrepancy of up to 50 G between measurement and the calculation assuming no magnetic influence of Incoloy 908. Thus, non-negligible ferromagnetism was identified and attributed to Incoloy 908. In contrast, most of the hysteresis observed in the magnetic measurements was eliminated when the Incoloy 908 of the TF windings was saturated by the TF coil charging.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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Y.M. Park,
Y.J. Lee,
Yaung-Soo Kim,
I.S. Woo,
S.W. Kwag,
Y.B. Chang,
N.H. Song,
H.T. Park,
C.S. Kim,
K.S. Lee,
E.N. Bang,
Y. Chu,
H. Yonekawa, K.R. Park,
H.L. Yang,
T.H. Ha,
J.S. Bak
[show abstract]
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ABSTRACT: The function of the current feeder system (CFS) is for conducting large currents from the power supplies to the KSTAR superconducting (SC) magnets. The CFS consists of SC bus-lines, joints, and current leads. The bus-line conductor is a circular cable-in-conduit conductor (CICC), which consists of a 4.5 mm thick stainless steel 316L seamless pipe containing 324 strands of chrome coated NbTi superconductor and 243 strands of OFHC. The ends of the CICC are assembled with specially designed lap joints. The joining resistance is controlled to less than 2.5 nano-ohm to minimize Joule heating. The outer surfaces of the CICC were electrically insulated up to 15 kV with jackets made of Kapton film and prepreged E-glass tape. Helically wrapped conducting fiber was used to measure the voltages of bus-line quenches. Two pairs of prototype brass leads for poloidal field (PF) and toroidal field (TF) coils have been fabricated and tested up to the currents of 26 kA for the PF leads and 35 kA for the TF leads. The test results satisfied all the requirements so that all 18 leads were manufactured and assembled on site. This paper will describe the detailed manufacturing progress and commissioning results of the KSTAR CFS.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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Yaung-Soo Kim,
Y.M. Park,
Y.J. Lee,
S.W. Kwag,
Y.B. Chang,
N.H. Song,
I.S. Woo,
H.T. Park,
K.W. Cho,
H.S. Chang, [......],
S. Baek,
J.S. Hong,
T.H. Ha,
Y.J. Kim,
I.S. Hwang,
H.L. Yang,
Y.K. Oh,
J.S. Bak,
M. Kwon,
G.S. Lee
[show abstract]
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ABSTRACT: The cryogenic system for the KSTAR superconducting (SC) magnets has been commissioned. It consists of a cold box, distribution boxes (DB) and cryogenic transfer lines. The cold box and DB #1 provide 600 g/s of supercritical helium to cool the SC magnets, their SC bus-lines, and the magnet support structures. It also provides 17.5 g/s of liquid helium to the current leads and supplies cold helium flow to the thermal shields. The main duties of the DB #2 are the relative distribution of the cryogenic helium among the cooling channels of each KSTAR cold component and the emergency release of over-pressurized helium during abnormal events such as quenches of the SC magnets. After individual commissioning, the system was integrated and cooled down with the KSTAR device. In this paper, the construction and commissioning results of the KSTAR cryogenic system will be introduced. In addition, we will present the cool-down results of the KSTAR device.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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ABSTRACT: Cryptographic systems have been widely used in many information security applications. One main challenge that these systems have faced has been how to protect private keys from attackers. Recently, biometric cryptosystems have been introduced as a reliable way of concealing private keys by using biometric data. A fuzzy vault refers to a biometric cryptosystem that can be used to effectively protect private keys and to release them only when legitimate users enter their biometric data. In biometric systems, a critical problem is storing biometric templates in a database. However, fuzzy vault systems do not need to directly store these templates since they are combined with private keys by using cryptography. Previous fuzzy vault systems were designed by using fingerprint, face, and so on. However, there has been no attempt to implement a fuzzy vault system that used an iris. In biometric applications, it is widely known that an iris can discriminate between persons better than other biometric modalities. In this paper, we propose a reliable fuzzy vault system based on local iris features. We extracted multiple iris features from multiple local regions in a given iris image, and the exact values of the unordered set were then produced using the clustering method. To align the iris templates with the new input iris data, a shift-matching technique was applied. Experimental results showed that 128-bit private keys were securely and robustly generated by using any given iris data without requiring prealignment.
IEEE Transactions on Systems Man and Cybernetics Part B (Cybernetics) 11/2008; · 3.08 Impact Factor
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Kim Keeman,
H K Park, K R Park,
B S Lim,
S I Lee,
M K Kim,
Y Chu,
W H Chung,
S H Baek,
J Y Choi, [......],
I S Woo,
W S Han,
D K Lee,
Y K Oh,
K W Cho,
J S Park,
G S Lee,
H J Lee,
T K Ko,
S J Lee
[show abstract]
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ABSTRACT: The mission of Korea Superconducting Tokamak Advanced Research (KSTAR) project is to develop an advanced steady-state superconducting tokamak for establishing a scientific and technological basis for an attractive fusion reactor. Because one of the KSTAR mission is to achieve a steady-state operation, the use of superconducting coils is an obvious choice for the magnet system. The KSTAR superconducting magnet system consists of 16 Toroidal Field (TF) coils and 14 Poloidal Field (PF) coils. Internally-cooled Cable-In-Conduit Conductors (CICC) are put into use in both the TF and PF coil systems. The TF coil system provides a field of 3.5 T at the plasma center and the PF coil system is able to provide a flux swing of 17 V-sec. The major achievement in KSTAR magnet-system development includes the development of CICC, the development of a full-size TF model coil, the development of a coil system for background magnetic-field generation, the construction of a large-scale superconducting magnet and CICC test facility. TF and PF coils are in the stage of fabrication to pave the way for the scheduled completion of KSTAR by the end of 2006.
Plasma Science and Technology 10/2006; 6(5):2445. · 0.41 Impact Factor
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S. Lee,
Y. Chu,
W.H. Chung,
S.J. Lee,
S.M. Choi,
S.H. Park,
H. Yonekawa,
S.H. Baek,
J.S. Kim,
K.W. Cho, K.R. Park,
B.S. Lim,
Y.K. Oh,
K. Kim,
J.S. Bak,
G.S. Lee
[show abstract]
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ABSTRACT: The KSTAR Central Solenoid Model Coils (CSMC), which are in the form of split coils with same dimension, have been tested. The CSMC were successfully charged up to 20 kA and down to zero with different ramp rates. Various pulse waveforms were applied to the CSMC to analyse the AC-loss characteristics of the coils. The measurement method was a gas-flow calorimetry. In this work, two types of waveforms, the DC-biased sinusoidal wave (I<sub>dc</sub>=2, 4 kA; DeltaI<sub>ac</sub>=1 kA; f=0.08~0.67 Hz) and a single triangular pulse (I<sub>max</sub>=6~10 kA; dI/dt=0.5~2 kA/s), are selected and analysed. From the measured data at the one outlet where helium channel 3 and 4 are merged, the AC loss parameters, related with the hysteresis loss and the coupling loss, are calculated. The B-field strength differs depending on the position within the cooling channels. The spatial field variation and the ramp rate were 0.048~1.9 T and 8.1~ 71 mT/s for the DC-biased sinusoidal waves, while 0.29~ 4.3 T and 0.024~ 0.86 T/s for the triangular pulses. The measured AC losses are compared with estimated values and the behavior agrees well. The coupling time constant (ntau) varies with the field strength. In case of the triangular pulses, ntau increases by increasing the field amplitude and the maximum value of ntau is 41 ms with I<sub>max</sub>=10 kA
IEEE Transactions on Appiled Superconductivity 07/2006; · 1.04 Impact Factor
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S Lee,
Y Chu,
W H Chung,
S J Lee,
S M Choi,
S H Park,
H Yonekawa,
S H Baek,
J S Kim,
K W Cho, K R Park,
B S Lim,
Y K Oh,
K Kim,
J S Bak,
G S Lee
[show abstract]
[hide abstract]
ABSTRACT: The KSTAR Central Solenoid Model Coils (CSMC), which are in the form of split coils with same dimension, have been tested. The CSMC were successfully charged up to 20 kA and down to zero with different ramp rates. Various pulse waveforms were applied to the CSMC to analyse the AC-loss characteristics of the coils. The measurement method was a gas-flow calorimetry. In this work, two types of waveforms, the DC-biased sinusoidal wave (= 2, 4 kA; = 1 kA; = 0 08 0 67 Hz) and a single triangular pulse (= 6 10 kA; = 0 5 2 kA s), are selected and analysed. From the measured data at the one outlet where helium channel 3 and 4 are merged, the AC loss parameters, related with the hysteresis loss and the coupling loss, are calculated. The B-field strength differs depending on the position within the cooling channels. The spatial field variation and the ramp rate were 0.048 1.9 T and 8.1 71 mT/s for the DC-biased sinusoidal waves, while 0.29 4.3 T and 0.024 0.86 T/s for the triangular pulses. The measured AC losses are compared with estimated values and the behavior agrees well. The coupling time constant () varies with the field strength. In case of the triangular pulses, increases by increasing the field amplitude and the maximum value of is 41 ms with = 10 kA.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY. 01/2006; 16.
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Keeman Kim,
H.K. Park, K.R. Park,
B.S. Lim,
S.I. Lee,
M.K. Kim,
Y. Chu,
W.H. Chung,
S.H. Baek,
J.Y. Choi, [......],
Y.J. Song,
I.S. Woo,
W.S. Han,
D.K. Lee,
D.W. Song,
J.S. Park,
G.S. Lee,
H.J. Lee,
T.K. Ko,
S.J. Lee
[show abstract]
[hide abstract]
ABSTRACT: The Mission of Korea Superconducting Tokamak Advanced Research (KSTAR) Project is to develop a steady-state-capable advanced superconducting tokamak for establishing a scientific and technological basis for an attractive fusion reactor. Because the KSTAR mission includes the achievement of a steady-state-capable operation, the use of superconducting coils is an obvious choice for the magnet system. The KSTAR superconducting magnet system consists of 16 TF (Toroidal Field) and 14 PF (Poloidal Field) coils. Both of the TF and PF coil system use internally-cooled Cable-In-Conduit Conductors (CICC) The TF coil system provides a field of 3.5 T at a plasma center and the PF coil system is able to provide a flux swing of 17 V-sec. The major achievement in KSTAR magnet system development includes the development of CICC, the development of a full size TF model coil, the development of a background magnetic field generation coil system, the construction of a large scale superconducting magnet and CICC test facility. TF and PF coils are in the stage of the fabrication for the KSTAR completion in the year 2005.
Plasma Science, 2003. ICOPS 2003. IEEE Conference Record - Abstracts. The 30th International Conference on; 07/2003
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ABSTRACT: The KSTAR is a superconducting tokamak under construction at the National Fusion Research Center (NFRC) in Daejeon, Korea. The project, of which mission aims at a steady-state operation and advanced tokamak physics, is under peak phase in the fabrication and assembly works. The fabrication of the major structures such as vacuum vessel and port, cryostat, thermal shields, and gravity support has been already completed. The manufacture and testing of the 30 superconducting magnets are actively being progressed. Sixteen toroidal field coils, four large poloidal field coils, and four central solenoid coils are completed until April 18, 2006. Cool-down and current charging tests of a real-sized prototype TF coil and a pair of CS model coil have been carried out to verify the operational feasibility of the KSTAR coils. The assembly of the device has begun from the beginning of 2004. Now, the cryostat base, gravity support, vacuum vessel body, vacuum vessel thermal shields, and all of the 16 toroidal field magnets are completed in the assembly on the tokamak pit. Assembly finish is scheduled for August 2007. This paper will present detail progress of the manufacturing and assembly of the KSTAR tokamak.
Cryogenics.
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ABSTRACT: The KSTAR is a superconducting tokamak under construction at the National Fusion Research Center (NFRC) in Daejeon, Korea. The project mission aims at a steady-state operation and advanced tokamak physics. At present, the project is in the peak of fabrication and assembly phase. The fabrication of the major tokamak structures such as vacuum vessel, cryostat, port system, thermal shields, and gravity support, has been completed. The manufacture and testing of the 30 superconducting magnets are rigorously progressing. As of September 2005, 16 toroidal field (TF) coils and four large poloidal field coils have been completed. To verify the operational feasibility of the KSTAR coils, cool-down and current charging tests of a real sized prototype TF coil and a pair of central solenoid (CS) model coil have been carried out. The assembly of the device has begun in the beginning of 2004. Now, the vacuum vessel body, thermal shields and 11 toroidal field magnets were assembled on the tokamak position. Assembly finish is scheduled for August 2007. This paper describes the manufacture and assembly progress of the KSTAR tokamak.
Fusion Engineering and Design.
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Y M Park,
Y J Lee,
S W Kwag,
Y B Chang,
C S Kim,
K S Lee,
N H Song,
E N Bang,
H L Yang,
Y S Kim, K R Park,
B S Lim,
C H Choi,
Y K Oh,
J S Bak
[show abstract]
[hide abstract]
ABSTRACT: There has been remarkable development progress on the KSTAR superconducting (SC) magnet and the interface systems including a cryogenic interface system and a current feeder system (CFS) which are required for SC magnet operation. All SC coils required for the KSTAR have been completed in fabrication and are under assembly on site. For the toroidal field (TF) coils, 18 coils have been fabricated, including 16 coils for installation, a prototype coil (TF00) for the performance test and a spare coil (TF17). Three pairs of poloidal field (PF) coils and 4 pairs of central solenoid (CS) coils have also been fabricated. As the cryogenic interface, a helium refrigeration system (HRS) with a cooling capacity of 9 kW at 4.5 K is under fabrication by Samsung Corporation and Air Liquide in France. The installation and commissioning of HRS itself will be completed by the middle of 2007. The CFS, consists of SC buslines, joints, and current leads. SC buslines made of NbTi cable-in-conduit conductor are under assembly with joint connections and surface insulation. Two pairs of prototype leads for PF and TF coils have been fabricated and tested up to the current levels of 26 kA for PF leads and 35 kA for TF leads. Those values are two times higher than optimum design values. Two current lead boxes and vacuum pumping system have been fabricated and 9 pairs of leads with a helium flow control system for the first plasma experiments will be fabricated and assembled by February, 2007.
