A5071294365- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Plasma Diagnostics and Applications
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Quantum chaos and dynamical systems
- Particle accelerators and beam dynamics
- Fluid Dynamics and Turbulent Flows
- Nuclear Physics and Applications
- Nuclear reactor physics and engineering
- Gyrotron and Vacuum Electronics Research
- Atomic and Subatomic Physics Research
- Seismic Waves and Analysis
- Scientific Measurement and Uncertainty Evaluation
- Magnetic Bearings and Levitation Dynamics
- Electromagnetic Simulation and Numerical Methods
- Characterization and Applications of Magnetic Nanoparticles
- Wind and Air Flow Studies
- Atmospheric and Environmental Gas Dynamics
- Combustion and flame dynamics
- Brake Systems and Friction Analysis
- Surface and Thin Film Phenomena
- Particle Dynamics in Fluid Flows
Ulsan National Institute of Science and Technology
2014-2022
Princeton University
1989-2022
Pohang University of Science and Technology
2008-2022
Princeton Plasma Physics Laboratory
1989-2022
Korea Institute of Fusion Energy
2016-2022
The effect of static $n=1$ resonant magnetic perturbation (RMP) on the spatial structure and temporal dynamics edge-localized modes (ELMs) edge turbulence in tokamak plasma has been investigated. Two-dimensional images measured by a millimeter-wave camera KSTAR revealed that coherent filamentary (i.e., ELMs) are still present region when usual large scale collapse confinement, i.e., ELM crash, is completely suppressed RMP. Cross-correlation analyses 2D show (1) RMP enhances turbulent...
Abstract Magnetic islands (MIs), resulting from a magnetic field reconnection, are ubiquitous structures in magnetized plasmas. In tokamak plasmas, recent researches suggested that the interaction between an MI and ambient turbulence can be important for nonlinear evolution, but lack of detailed experimental observations analyses has prevented further understanding. Here, we provide comprehensive such as spreading into enhancement at reconnection site, elucidating intricate effects plasma on...
The accuracy in estimation of two important tearing mode stability parameters (Δ' and wc) is improved by employing two-dimensional (2D) ECE imaging data which help one to overcome the resolution limit conventional one-dimensional data. experimentally measured 2D images are directly compared with synthetic ones from a Te model estimate an excellent agreement achieved. results imply that observed classically stable but has non-negligible bootstrap current drive.
We present experimental observations suggesting that the non-diffusive avalanche-like events are a prevalent and universal process of electron turbulent heat transport in tokamak core plasmas. They observed low confinement mode weak internal barrier plasmas absence magnetohydrodynamic instabilities. In addition, temperature profile corrugation, which indicates existence $E \times B$ shear flow layers, is clearly demonstrated as well their dynamical interaction with events. The measured width...
We discuss the recent history and latest developments of electron cyclotron emission imaging diagnostic technique, wherein temperature is measured in magnetically confined plasmas with two-dimensional spatial resolution. The key enabling technologies for this technique are large-aperture optical systems linear detector arrays sensitive to millimeter-wavelength radiation. present status progress on existing instruments as well new under development future experiments. also data analysis...
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We present that a statistical method known as the Complexity-Entropy analysis is useful to characterize state of plasma turbulence and flux in resonant magnetic perturbation (RMP) edge localized mode (ELM) control experiment. The RMP ELM suppression phase with stochastic pedestal top temperature fluctuation can be distinguished from natural free chaotic fluctuation. It discussed near originated narrow layer field penetration top. forced island emit drift wave comparable sizes (relatively...
Propagation of the various errors in a new asymmetric Abel-inversion method [Hyeon K. Park, Plasma Phys. Controlled Fusion 31, 2035 (1989)] is investigated. In order to provide meaningful error analysis inversion process, both effects geometrical factors and measuremental are studied. The dominant source uncertainty determination local electron density due spline fitting interferometric measurements with uneven spacings. propagation these highly spatially localized heavily damped this...
Abstract The evolutions of toroidally coupled radially-distant and radially-adjacent tearing modes are visualized in 2D detail on the Korea superconducting tokamak for advanced research. in-phase out-board mid-plane become destabilized or compete with each other depending their spatial separation. When two far apart, both increasingly destabilized. On hand, when they close to other, one becomes stabilized while In such cases, an additional mode is often formed outer rational flux surface...
Abstract Gradual or abrupt transitions from a coherent mode to quasi-coherent (QCM, type of trapped electron turbulence) are observed in the core region low-density plasmas Korea Superconducting Tokamak Advanced Research. The is initiated vicinity q = 1 surface by off-axis cyclotron resonant heating (ECH), and gradually abruptly evolves into QCM as collisionality slowly rapidly increased through density control. When further increases above critical level, changed broadband turbulence, which...
A low-power 60 GHz gyrotron collective Thomson scattering diagnostic has been operating on TFTR to test the feasibility of detecting alpha particles when perpendicular magnetic field. An enhanced scattered signal is predicted result from interaction energetic ions with plasma resonances in lower hybrid frequency range. Millimeter-wave power levels at were approximately 200 W for typical pulse lengths 50 ms. Deuterium and possible fusion product ion cyclotron frequencies their harmonics...
This overview discusses the status of fusion energy development in Republic Korea. Korea studies through research and 2 ways: one by performing Superconducting Tokamak Advanced Research (KSTAR) for a domestic approach other participating international collaboration project ITER. had remarkable progresses not only KSTAR but also ITER 2016. In KSTAR, world record more than 70 seconds high-performance plasma (H-mode) operation superconducting tokamak has been achieved. For project, toroidal...
The dynamics of multiple closed flux tubes in the core a sawtoothing tokamak plasma are studied using nonlinear simulations. This is motivated by recent observations long-lived hot spots electron cyclotron emission (ECE) images KSTAR plasmas with heating (ECH) (Yun et al 2012 Phys. Rev. Lett. 109 145003). Using an empirical source term reduced set MHD equations, it shown that helicity h = 1 easily produced and survive for observed time intervals only if safety factor close to unity (|q − 1|...
Although the total radiated power in Tokamak Fusion Test Reactor is often as high 70% of heating power, most radiation concentrated near surface plasma, and interior loss almost negligible. Fractional declines during neutral beam heating. Under interesting plasma conditions, profiles are dominated by asymmetrical peaks, which indicate locally intense edge radiation. As high-density limit approached, under a bright band (a “marfe”) appears on inner side column. Marfe location affected...
A 60 GHz gyrotron collective Thomson scattering alpha particle diagnostic has been implemented for the D-T period on Tokamak Fusion Test Reactor (TFTR). Gyrotron power of 0.1–1 kW in pulses up to 1 s can be launched X mode. Efficient corrugated waveguides are used with antennas and vacuum windows TFTR Microwave Scattering system. multichannel synchronous detector receiver system spectrum analyzer acquire scattered signals. 200 megasample/s digitizer resolve fine structure frequency spectrum....
Long-pulse plasma operation at high normalized beta, βN, above the n = 1 ideal MHD no-wall stability limit in KSTAR is presently limited by tearing instabilities rather than resistive wall modes. H-mode during recent device campaign produced discharges having strong m/n 2/1 βN lower beta limit. The unstable mode consequently reduced confinement and toroidal rotation significantly. experiment confirmed that an extended duration of electron cyclotron heating (ECH) initial phase discharge plays...
A new microwave imaging reflectometry (MIR) system for KSTAR is being developed based on the experience gained via TEXTOR proof-of-principle [H. Park et al., Rev. Sci. Instrum. 74, 4239 (2003)] which aimed to measure poloidal image of electron density fluctuations essential transport studies. The will adopt a multi-frequency probe beam source in range 90 ∼ 100 GHz (X-mode case), enable measurement 2-D (radial and poloidal) multiple cut-off layers, simultaneously. optical MIR be combined with...
The role of electromagnetic (EM) waves in magnetic fusion plasma—ranging from radio frequency (RF) to microwaves—has been extremely important, and understanding EM wave propagation related technology this field has significantly advanced plasma research. Auxiliary heating current drive systems, aided by various forms high-power RF microwave sources, have contributed achieving the required steady-state operation plasmas with high temperatures (i.e., up approximately 10 keV; 1 eV = 10000 K)...
Advances in heterodyne receiver array technology coupled with a simplified optical design have resulted significantly expanded plasma coverage and enhanced sensitivity, while simultaneously reducing the local oscillator power levels required to pump imaging mixer arrays. Details of next generation concept its application on DIII-D tokamak are discussed. Additionally, details technologies applied redesigned TEXTOR ECE system provided.
An Electron Cyclotron Emission Imaging (ECEI) diagnostic system for the WEST tokamak has been developed under UNIST-WEST collaboration. This is designed to overcome accessibility and thermomechanical constraints long pulse operation. The first O-mode channel will be installed in trimester of 2019 probe low field side (LFS) plasma. Two large metallic reflective mirrors are inside duct which being used maintenance access. They suspended on a rail facilitate mirror manipulation. ex-vessel...