A5064835589- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Laser-induced spectroscopy and plasma
- Laser-Plasma Interactions and Diagnostics
- Advanced Electrical Measurement Techniques
- Radio Frequency Integrated Circuit Design
- Acoustic Wave Resonator Technologies
- Optical Systems and Laser Technology
- Gyrotron and Vacuum Electronics Research
- Image and Signal Denoising Methods
- Machine Fault Diagnosis Techniques
- Soil Moisture and Remote Sensing
- Advanced Data Storage Technologies
- Nuclear reactor physics and engineering
- Astronomical Observations and Instrumentation
- Advanced Computational Techniques and Applications
- Photocathodes and Microchannel Plates
- Robotics and Automated Systems
- Geophysical Methods and Applications
- Semiconductor Lasers and Optical Devices
- Adaptive optics and wavefront sensing
Korea Institute of Fusion Energy
2013-2025
Korea Basic Science Institute
2001-2006
École Polytechnique Fédérale de Lausanne
2003
Korea Advanced Institute of Science and Technology
1996-2002
Los Alamos National Laboratory
2002
The 94 GHz single-channel interferometer at the versatile experiment spherical torus has been upgraded into a multi-channel heterodyne for electron density profile measurements. Five Gaussian beam chords generated by pair of Powell lenses and collimating are vertically spaced 75 mm intervals from midplane to lower part main chamber. beams passing through plasma received detector array consisting half-wave rotator modules an integrated lens antenna mixer. local oscillator is expanded another...
The extensive design effort for KSTAR has been focused on two major aspects of the project mission - steady-state-operation capability and advanced tokamak physics. steady state aspect is reflected in choice superconducting magnets, provision actively cooled in-vessel components, long pulse current drive heating systems. incorporated features associated with flexible plasma shaping, double null divertor passive stabilizers, internal control coils a comprehensive set diagnostics. Substantial...
Abstract KSTAR Doppler reflectometer is designed based on frequency steering phased array antenna (FSPAA) operating in X-mode over the full V-band (50-75 GHz). In FSPAA system, microwave radiation angle varies as a function of frequency, allowing rapid changes without mechanical movement. This very attractive advantage fusion reactor environments where concept maintenance-free important. However, has limitations broadside direction due to open-stopband problem. this paper, various types...
Abstract Interferometers based on phase measurement technique have been widely used to measure the plasma line integrated density (LID) in magnetic fusion devices. Phase jump is an inherent drawback of techniques. Once a occurs, errors should be compensated for by referring complementary diagnostics. In multi-chord interferometer profiles, can using relationship between adjacent receivers. To utilize receivers, microwaves emitted from single transmitter are spatially distributed all The...
Frequency modulation reflectometer has been developed to measure the plasma density profile of Korea Superconducting Tokamak Advanced Research tokamak. Three reflectometers are operating in extraordinary polarization mode frequency range Q band (33.6–54 GHz), V (48–72 and W (72–108 GHz) up 7 × 1019 m−3 when toroidal magnetic field is 2 T on axis. The antenna installed inside vacuum vessel. A new window by using 50 μm thick mica film 0.1 mm gold gasket. filter bank low pass filter, notch...
The plasma current position is measured based on the multipole moment method in Korea Superconducting Tokamak Advanced Research (KSTAR) device [G. S. Lee et al., Nucl. Fusion 41, 1515 (2001)]. Since a limited number of magnetic probes and flux loops were installed for first campaign, an iteration used to interpolate field area absent probes. A numerical technique developed which automatically compensates linear drift integrator. cross checked with charge coupled images. In KSTAR, displaced...
In noninductively driven discharges, 0.9 MW second harmonic (X2) off-axis co-electron cyclotron current drive deposition is combined with 0.45 X2 central heating to create an electron internal transport barrier (eITB) in steady plasma conditions resulting a 1.6-fold increase of the confinement time (τEe) over ITER-98L-mode scaling. The eITB associated reversed shear profile enhanced by large bootstrap fraction (up 80%) and sustained for up 10 redistribution times. A linear dependence...
The Tokamak à Configuration Variable (TCV) tokamak (R = 0.88 m, a < 0.25 B 1.54 T) programme is based on flexible plasma shaping and heating for studies of confinement, transport, control power exhaust. Recent advances in fully sustained off-axis electron cyclotron current drive (ECCD) scenarios have allowed the creation plasmas with high bootstrap fraction, steady-state reversed central shear an internal transport barrier. High elongation plasmas, κ 2.5, are produced at low normalized using...
The development of an integrator for magnetic diagnostics becomes more important as the pulse length fusion devices gets longer and longer, especially present-day superconducting devices. A small offset in signal can cause a significant drift output long experiments. lock-in amplifying digital has been developed Wendelstein 7-X (W7-X). It succeeds suppressing to low value but requires about 100 ms data processing. To shorten processing time, Field Programmable Gate Array (FPGA) built...
A Doppler reflectometer has been designed to measure the poloidal propagation velocity on Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. It operating frequency range of V-band (50-75 GHz) and monostatic antenna configuration with extraordinary mode (X-mode). The single sideband modulation an intermediate 50 MHz is used for heterodyne measurement 200 in-phase quadrature (I/Q) phase detector. corrugated conical horn approximate Gaussian beam it installed together oversized...
A frequency modulation reflectometer has been developed to measure the density profile of KSTAR tokamak. It two channels operating in X-mode range Q band (33-50 GHz) and V (50-75 GHz). The full is swept 20 μs. mixer output directly digitized at sampling rate 100 MSamples∕s. new phase detection algorithm analyze both amplitude modulated signal. benchmarked for a synthesized modulation-frequency This applied data analysis reflectometer.
The first phase of the HANBIT project that started in 1996, is ending this year. goal to establish a decent experimental facility based on mirror device and set up framework for operating machine as National Joint Users’ Facility. A five-year plan has been being undertaken improve performance HANBIT, refurbished from old TARA machine, by adding diagnostics heating capacity. As achieved, second planned, which basic confinement physics will be pursued well plasma applications training people....
The first plasma with target values of the current and pulse duration was finally achieved on June 13, 2008 in Korea Superconducting Tokamak Advanced Research (KSTAR). diagnostic systems played an important role achieving successful operation for KSTAR tokamak. employed including magnetic diagnostics, millimeter-wave interferometer, inspection illuminator, Hα, visible spectrometer, filterscope, electron cyclotron emission (ECE) radiometer have provided main parameters, which are essential...
Frequency modulated continuous wave (FMCW) reflectometer has been widely used to measure the plasma density profile by launching linear frequency microwave into and measuring group delay of reflected at cutoff density. For a certain range, just passes through reflects back from vacuum inner wall. By analyzing phase information passing-through microwave, line integrated (LID) can be obtained. An FMCW operating in this particular regime is called sweep interferometer (FSI). If much higher than...
Classifying and monitoring the L-, H-mode, plasma-free state are essential for stable operational control of tokamaks. Edge reflectometry measures plasma density profiles, but large volume data complexity in reconstruction pose significant challenges. There is a need efficient methods to analyze complex reflectometer real-time, which can be addressed using advanced computational techniques. Here, we show that machine learning (ML) techniques classify discharge states raw signal from an edge...
Scalogram is widely used to measure instantaneous frequencies of non-stationary signals. However, the basic property scalogram observed only for stationary sinusoidal functions. A signal analytically derived in this paper. Based on property, a new frequency measurement algorithm proposed. In addition, filter that can separate two similar signals developed based wavelet transform.
Abstract We explore the inboard-limited internal transport barrier (ITB) as an alternative advanced operation scenario for KSTAR. This paper presents in detail progress of ITB experiment at In earlier study, formed both ion and electron thermal channels, early neutral-beam injection (NBI) power over 4 to 5 MW under a limited L-mode was crucial access. present we access experimentally with about 3 NBI by using upper single null (USN), which is unfavorable H-mode condition higher L–H...
HANBIT is a magnetic mirror confinement device. Recently, after finishing the first campaign for basic system development, it started second high-temperature plasma physics study in configuration. Here, we introduce briefly device and report initial experiment results on RF-plasma heating simple It appears that discharge characteristics of are quite different from those other devices, an explanation presented to clarify difference.
A phase comparator provides two outputs proportional to the cosine and sine of input difference. new algorithm is devised which calculates from without a jump limit 2π. Instead calculating absolute at given time, it relative differences between subsequent measurements accumulates them get phase. The can be avoided if sampling time selected fast enough that variation does not exceed 2π during period.
Frequency modulated continuous wave reflectometers have been used to measure the plasma density profiles of KSTAR tokamak. Three are operating in an extraordinary polarization mode frequency range Q band (33-50 GHz), V (50-75 and W (75-110 GHz). Each full is linearly swept 20 μs. The accuracy profile measurement dependent on how precisely calibrated. Two new techniques developed situ calibrate instantaneous during sweep time First intermediate (IF) receiver analyzed based wavelet transform...
Abstract The structure of the toroidal rotation profile with mixed heating by neutral beam injection (NBI) and electron cyclotron resonance (ECH) has been investigated in KSTAR L-mode plasmas. ECH varying layer positions was used for a mix control. experimental results show that causes counter-current increment both off-axis on-axis heating. For plasmas, produces larger than ECH. Analysis ion heat momentum transport plasmas shows temperature gradient is main reason degradation confinement...
A piezoelectric valve, which has a flow rate of about 463 mbar l/s, been installed to fuel the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. The valve is in situ calibrated by analyzing pressure rise curve while fueling vessel at constant rate. calibration method and results are presented. In addition rate, other vacuum system parameters, such as pumping speed volume, were experimentally obtained. Based on these measurements, KSTAR simulator was developed calculate drive...