Development and experimental evaluation of a prototype of the TF secondary quench detection system for KSTAR
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A prototype of the Toroidal Field (TF) Secondary Quench Detection system (SQD) was developed and implemented with the Korea Superconducting Tokamak Advanced Research (KSTAR) device to carry out the design verification of the SQD. The SQD can detect a quench based on the change of absolute pressures and mass flow rates of helium in the cooling lines of the TF coils. If the primary quench detection system of the TF coils cannot detect quench or the fast discharge of the TF coils cannot be carried out as planned, SQD should work to prevent the TF coils and the peripheral structures from severe damages. In addition, SQD should operate in the reliable and stable condition against disturbances caused by Poloidal Field (PF) coil discharge, plasma perturbation, and any faults of subsystems of the KSTAR device. The 2 out of 3 (2003) voting configuration was applied to SQD to enhance reliability and stability of quench detection. The prototype SQD consists of absolute and differential pressure transducers, signal interfaces, logic solvers, and interlock systems. All the transducers were selected from metallic types with no electronic circuit in order to reduce the failure rates caused by strong electromagnetic field and radiation around the Tokamak. The transducers were installed in manifolds of the helium inlet lines of the KSTAR TF coils. Their signals were amplified and compared to the reference voltage for quench decision in the signal interface unit. The quench signal generated by the signal interface unit was transmitted to the 2003 voting modules of the logic solvers. The design requirements of SQD were verified through testing the prototype SQD in the 2014 KSTAR campaign.Keywords:
KSTAR
Interlock
SIGNAL (programming language)
Recent commissioning of two major fully superconducting (SC)-shaped tokamaks, Experimental Advanced Superconducting Tokamak (EAST) and Korean Superconducting Tokamak Advanced Research (KSTAR), represents a significant advance in magnetic fusion research. The key to commissioning success in these complex and unique tokamaks was as follows: 1) use of a robust, flexible plasma control system (PCS) based on the validated DIII-D design; 2) use of the TokSys design and modeling environment, which is tightly coupled with the DIII-D PCS architecture for first-plasma scenario development and plasma diagnosis; and 3) collaborations with experienced internationally recognized teams of tokamak operations and control experts. We provide an overview of the generic modeling environment and plasma control tools developed and validated within the DIII-D experimental program and applied through an international collaborative program to successfully address the unique constraints associated with the startup of these next-generation tokamaks. The unique characteristics of each tokamak and the machine constraints that must be included in device modeling and simulation, such as SC coil current slew rate limits and the presence of nonlinear magnetic materials, are discussed, along with commissioning and initial operational results. Lessons learned from the startup experience in these devices are summarized, with special emphasis on ramifications for International Thermonuclear Experimental Reactor (ITER).
KSTAR
Thermonuclear Fusion
DIII-D
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KSTAR
Interlock
Overheating (electricity)
Heating system
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KSTAR
Interlock
Shut down
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KSTAR
Position (finance)
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The KSTAR (Korea Superconducting Tokamak Advanced Research) device is under construction using superconducting (SC) coils for long pulse operation. The KSTAR superconducting magnet system consists of 16 D-shaped toroidal field (TF) coils, 3 pairs of poloidal field (PF) coils, and 4 pairs of central solenoid (CS) coils. Two kinds of SC coils have been fabricated and tested in the coil test facility in the Korea Basic Science Institute (KBSI). One of the coils was a prototype TF coil, TF00 coil, which has been fabricated in the same size as the real coils using Nb3Sn SC cable-in-conduit conductor (CICC). The other was a pair of CS model coils, which were fabricated as a part of a background field system to test the superconductor in a pulsed field environment. The major objectives of the SC coil tests were (i) to verify the coil design and fabrication process in the KSTAR coil development, (ii) to measure the coil performances during cool-down, current excitation, and discharge scenarios, and (iii) to achieve the operational experience of the SC coil test facility and the SC magnet system in the KSTAR device. The prototype TF coil was cooled down to the operating temperature of 4.5 K in 10 days. The coil was charged in steps and this was followed by slow or fast discharges. The transient hydraulic parameters were measured according to the different scenarios. The results of the coil test showed that no noticeable defects of the coil were found, such as helium leaks at cryogenic temperature, and helium circulation through the coil was sufficient to keep the coil at the operating temperature. The CS model coil was also cooled down in 9 days and basic current excitation and discharge tests of the coil have been done. To assess the ac performance of the coil, current charging experiments of the coil will be continued until the end of 2004. In this paper, the experimental results of the prototype TF coil and the CS model coil are described as well as the general coil test facility.
KSTAR
Solenoid
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A prototype toroidal field (TF) coil, TF00 coil, of the Korea Superconducting Tokamak Advanced Research (KSTAR) project has been assembled and tested at the coil test facility in Korea Basic Science Institute (KBSI). The TF00 coil is a real‐sized TF coil made of Nb3Sn superconducting cable‐in‐conduit conductor (CICC). The coil test was conducted by several campaigns according to the objectives. The first campaign, which was carried out by Jan. 2003, has objectives of cooling the coil into operating temperature and finding any defect in the coil such as cold leaks. From the results of the first campaign experiment, any defect in the coil was not found. The second campaign, which was carried out by Aug. 2003, has objectives to get the operating characteristics according to the current ramp up and discharge operations. In this paper, the coil test results are introduced as well as the details of the coil test system setup.
KSTAR
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Korea Superconducting Tokamak Advanced Research (KSTAR) has three interlock systems. The Supervisory Interlock System (SIS) protects against damage to machines from abnormal events. The Fast Interlock System (FIS) prevents the destruction of the internal vacuum components from the uncontrolled plasma and heating beams. The Personal Safety Interlock (PSI) keeps humans from harmful environments and conditions. This paper presents the evolution of the KSTAR SIS and FIS operations since 2009. The SIS was implemented for KSTAR in 2007 and optimized the critical conditions and actuator actions to improve and avoid issues. The significant changes in the KSTAR interlocks are removing and changing the inappropriate interlock conditions and adding the required conditions to improve efficiency and fit the advanced experimental environments. The first implemented FIS independent of the Central Control System (CCS) in 2009 continues to upgrade its hardware and software to enable the interlocks and actions with high time resolution until 2017. The machine protection logic in the FIS evaluated and developed to reduce operational failures. This paper analyses the modified conditions for interlocks, the actions to protect machines, and their effects.
KSTAR
Interlock
Upgrade
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Edge plasma characteristics of a high-recycling divertor operation regime of the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak are presented. The results were obtained by numerical simulation using a two-dimensional (2-D) two-fluid edge plasma transport code coupled with a 2-D Monte Carlo recycling neutral transport code. The simulations successfully display the two major characteristics of a scrapeoff layer in a high-recycling regime: a parallel temperature gradient and parallel pressure conservation. The results of the simulation can be utilized to provide guidelines for future operation of the KSTAR tokamak regarding the relation between upstream plasma properties and divertor operation regimes.
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Introduction ELMs (Egde Localized Modes) in the tokamak have strong effects on its divertor conditions with a rapid increase in heat flux, and the pedestal parameters related to ELMs can work as constraints which impact the tokamak edge conditions to determine global confinements [1]. Therefore, a comprehensive understanding of the relations among ELM phenomena, pedestal parameters, and divertor heat conditions is essential for advanced tokamak operations like H-mode discharges. In this paper, the effects of ELMs on divertor heat flux and edge pedestal parameters are found by an integrated core-edge transport simulation for the KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak [2]. Numerical model and simulation results Predictive numerical simulations of ELMy H-mode discharges are carried out for the KSTAR tokamak using an integrated plasma transport code, which has been recently developed in the authors’ laboratory for a simultaneous treatment of core, edge pedestal, and scrape-off layer (SOL) regions of the tokamak [3]. In this integrated modelling, ELMs are supposed to be triggered by ballooning and peeling modes as expressed by the following equations [4, 5]:
KSTAR
Pedestal
Edge-localized mode
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In this paper, we present the results of a study of the preionization effects for the Korean Superconducting Tokamak Advanced Research (KSTAR) tokamak (R/sub 0/=1.8 m, a=0.5 m, /spl kappa/=2, /spl delta/=0.8, B/sub T/=3.5 T, I/sub p/=2 MA, T/sub pulse/=300 s) that is under construction by the Korea Basic Science Institute (KBSI). The preionization will be given by the Electron Cyclotron Heating (ECH) System with an 84-GHz 500-kW gyrotron tube being made by Communications and Power Industries. The ECH preionization effects are investigated by a 0-dimensional code (TECHP0D) that includes the operational scenarios of KSTAR tokamak. The code is now improved and advanced with carbon, oxygen, and iron impurity effects, and with the self and mutual inductances of seven pairs of superconducting poloidal coils for the KSTAR tokamak.
KSTAR
Gyrotron
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