A5054246631- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Fusion materials and technologies
- Gyrotron and Vacuum Electronics Research
- Flow Measurement and Analysis
- Dust and Plasma Wave Phenomena
- High-pressure geophysics and materials
- Laser Material Processing Techniques
- Thermography and Photoacoustic Techniques
- Occupational Health and Safety Research
- Semiconductor Lasers and Optical Devices
- Quantum chaos and dynamical systems
- Aerodynamics and Acoustics in Jet Flows
- Electromagnetic Simulation and Numerical Methods
- Machine Learning in Materials Science
- Ranque-Hilsch vortex tube
- Lightning and Electromagnetic Phenomena
- Solid State Laser Technologies
- Magnetic Bearings and Levitation Dynamics
- Wind and Air Flow Studies
- Electromagnetic Launch and Propulsion Technology
Korea Institute of Fusion Energy
2016-2024
China Academy of Engineering Physics
2000-2024
Psychoanalytic Institute of Northern California
2022
Seoul National University
2016-2022
Wuhan University of Technology
2021
Beijing Institute of Technology
2020
China Academy of Space Technology
2020
Guangzhou Vocational College of Science and Technology
2020
Yonsei University
2016
Auburn University
2013
Abstract The self-organization is one of the most interesting phenomena in non-equilibrium complex system, generating ordered structures different sizes and durations. In tokamak plasmas, various self-organized have been reported, two them, coexisting near-marginal (interaction dominant) regime, are avalanches E × B staircase. Avalanches mean ballistic flux propagation event through successive interactions as it propagates, staircase means a globally pattern zonal flow layers. Various models...
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...
Nonlinear bounce-averaged kinetic theory [B. H. Fong and T. S. Hahm, Phys. Plasmas 6, 188 (1999)] is used for magnetically trapped electron dynamics the purpose of achieving efficient gyrokinetic simulations Trapped Electron Mode (TEM) Ion Temperature Gradient mode with electrons (ITG-TEM) in shaped tokamak plasmas. The equations are explicitly extended to plasma equilibria from previous ones concentric circular plasmas, implemented a global nonlinear code, Gyro-Kinetic Plasma Simulation...
The effects of plasma elongation on trapped electron mode (TEM) driven turbulence and transport are investigated with detailed analyses fluctuation, zonal flow pressure. For the study, global nonlinear TEM simulations different elongations () performed by employing a bounce-averaged gyrokinetic code gKPSP. From simulations, -scalings heat conductivity (), ion particle diffusivity found as , respectively. Higher is to enhance flows their shearing rate at short radial scales, which in turn...
Abstract The first principle nonlinear gyrokinetic numerical simulation successfully reproduces the experimental observations of non-diffusive large scale avalanching events in a KSTAR MHD-quiescent L-mode plasma. Power law scaling electron temperature fluctuation δT e and Hurst exponent factor H from experiment are good agreement. In addition, verifies that global pattern mean zonal flow is corrugated with staircase-like structure responsible for creased profile , which also observed...
We extend the bounce-averaged kinetic (BK) electron model to be applicable in general tokamak magnetic geometries and implement it on global δf particle-in-cell gyrokinetic code gKPSP. perform a benchmark study of updated BK against flux-tube codes, CGYRO GENE. From comparisons among simulations based local parameters KSTAR L-mode plasma, we confirm reasonable agreement linear results from different codes. In nonlinear gKPSP simulation with narrow plasma gradient region whose width...
The linear physics of lower hybrid waves (LHWs) and their nonlinear interaction with particles through Landau damping are studied the gyrokinetic electron fully kinetic ion (GeFi) particle simulation model in electrostatic limit. Unlike most other wave modes, LHWs can resonantly interact both electrons ions, former being highly magnetized latter nearly unmagnetized around frequency. Direct interactions and/or ions investigated for cases various k∥/k,Ti/Te, amplitudes. In (ELD), dispersion...
In this work, the time-dependent solution for Lotka–Volterra predator–prey model is derived with help of Lambert W function. This allows an exact analytical expression period associated limit cycle oscillations and also response time between predator prey population. These results are applied to interaction zonal density corrugations turbulent particle flux in gyrokinetic simulations collisionless trapped-electron mode turbulence. turbulence simulations, shown increase when approaching...
Abstract The E × B flow staircase-like pattern observed in the first principle gyrokinetic numerical experiments of tokamak fusion plasmas forms due to a nonlinear time delay. Simulations demonstrate finite delay between staircase occurrence particle transport and that density profile. This novel finding shows instability can arise from perturbations then influence background turbulence. plays roles not only shearing but also as saturation mechanism instability. Experimental measurements...
Plasma elongation effects on turbulence and zonal flow are explicitly investigated for the first time with global bounce-averaged gyrokinetic simulations a collisionless trapped electron mode (CTEM). As most efficient steady state simulation scheme this problem, provides deeper insights into nonlinear physics separated from linear in investigation. Based studies limited range of parameters, our results show that shorter radial scale flows which prominent CTEM more enhanced higher leading to...
This work presents a nonlinear gyrokinetic analysis, which addresses one of the perennial conundrums in ohmically heated fusion plasmas. The widely observed linear ohmic confinement (LOC) to saturated (SOC) transition energy time with increasing density is successfully reproduced from simulations for first time. Suppression trapped electron turbulence by collisional detrapping due found be responsible transition. microturbulence modes ion temperature gradient coincide, but not necessary...
A previous gauge-invariant gyrokinetic equation based on an approximate canonical Hamiltonian coordinate system is extended to exact with the time scale well separated. By using this formalism a new orbit-averaged equation, which valid for both trapped and passing particles, established.
Acoustically-excited bubble dynamics is the foundation of pipeline detection based on acoustic technology. Due to existence multiple bubbles in flow, Bjerknes forces among arbitrary under excitation may enforce bubble-bubble interaction and then change features dynamics. Based traditional free bubble’s Rayleigh-Plesset (R-P) model, this paper tries establish model consideration second force distribution axial direction. Meanwhile, influence finite wave speed compressible fluid considered....
The first principle gyrokinetic simulations of trapped electron turbulence in tokamak fusion plasmas demonstrate the energy transfers from most linearly unstable modes at high [Formula: see text] to intermediate via parametric decay process a short period linear-nonlinear transition phase. Dominant nonlinear wave-wave interactions occur near mode rational surface text]. In fully turbulence, inverse cascade occurs between cutoff wave number and with power law scaling text], while are...
The bounce-kinetic model based on the modern nonlinear theory [Fong and Hahm, Phys. Plasmas 6, 188 (1999)] has been developed used for simulations previously. This work reports an extension of including more accurate treatment barely trapped particles its implementation in Gyro-Kinetic Plasma Simulation Program gyrokinetic code [Kwon et al., Comp. Commun. 215, 81 (2017)]. leads to collisionless electron mode at low magnetic shear.
The first-principle gyrokinetic numerical experiments investigating the isotopic dependence of energy confinement achieve a quantitative agreement with experimental empirical scalings, particularly in Ohmic and L-mode tokamak plasmas. Mitigation turbulence radial electric field intensity <a:math...
Collisionless trapped-electron mode (CTEM) turbulence is an important contributor to heat and particle transport in fusion devices. The ion-temperature gradient (ITG)/trapped-electron (TEM) fluid models are rarely treated analytically, due the large number of channels involved, e.g., ion/electron transport. CTEM model [Anderson et al., Plasma Phys. Controlled Fusion 48, 651 (2006)] provides a simplified model, regime where density drive (∇n) negligible compared electron temperature (∇Te)....
Abstract Thermal lens technology has attracted much attention because of its high sensitivity, low detection limit and being suitable for the analyses minute samples. been widely used in many fields, such as chemistry, physics, environmental monitoring, electronics, material science life science. In this paper, laser thermal measurement is studied based on Newton’s ring interferometry, especially case low-power laser. The application method small samples also discussed. It helpful to study...
We demonstrate a wavelength tunable continuous wave single-frequency Cr:ZnSe laser based on self-seeded ring cavity configuration in this paper. The system is anti-coated crystal which has length of 6 mm and low signal transmission 15% (at 1908nm). Unidirectional operation obtained by using retro-reflecting device can retro reflect self-seed back into the cavity. output coupler also optimized to get unidirectional operation. With three different birefringent filters inserting cavity, with...
The physical consideration, design, and characteristics of a compact microwave plasma cathode are expounded in this paper. impedance matching is calculated to improve the transmission efficiency. influence magnetic field on discharge property extracted electron beam current investigated. off-resonance mode (a non-ECR mode) put forward, which bigger than 875 G chamber. dependence extraction voltage, input power, operation pressure described. 2.45-GHz power transmitted via coaxial line....