71 citations · 314 across the 23 of their papers we have counts for
25 papers
Study of low-frequency core-edge coupling in a tokamak: III. Core-localized MHD continuum pulsations \& distant forced reconnection
Andreas Bierwage, Panith Adulsiriswad, Gyungjin Choi +2
Slow magnetoacoustic pulsations (SMAPs) are found in MHD simulations of a tokamak plasma whose safety factor near the center is flat and slightly above unity (). S…
Study of Low-Frequency Core-Edge Coupling in a Tokamak: I. Experimental Observation in KSTAR
Wonjun Lee, Andreas Bierwage, Seungmin Bong +6
Double-peaked fishbone events across multiple KSTAR discharges are investigated. The normalized beta and the edge safety factor under which the f…
Study of Low-Frequency Core-Edge Coupling in a Tokamak: II. Spatial Channeling & Focusing In Antenna-Driven MHD
Andreas Bierwage, Wonjun Lee, Young-chul Ghim +7
Motivated by evidence for core-edge coupling in the form of double-peaked fishbone-like low-frequency modes () in KSTAR, which exhibit synchronized Alfvénic…
Bright Spot Characterization of Low dI/dt X-pinch Plasmas using Soft X-ray Spectroscopy with Bennett Relation
YeongHwan Choi, Muhyeop Cha, Hakmin Lee +8
This study investigates the characteristics of X-pinch plasmas driven under low current rise rate () conditions using soft x-ray spectroscopy combined with the Bennett relat…
Construction and analysis of guiding center distributions for tokamak plasmas with ambient radial electric field
Andreas Bierwage, Philipp Lauber, Noriyoshi Nakajima +8
The contribution of a time-independent toroidally-symmetric radial electric field is implemented in VisualStart [Comp. Phys. Comm. 275 (2022) 108305; arXiv:2111.08224], a cod…
Will shifted and truncated Maxwellian EVDF near the wall exhibit different electron currents?
Yegeon Lim, Young-chul Ghim
Experiments to explore the predicted consequences on the I-V characteristics of a Langmuir probe based on the fluid approach for electrons and the electron Bohm criterion are condu…
Enhancing Disruption Prediction through Bayesian Neural Network in KSTAR
Jinsu Kim, Jeongwon Lee, Jaemin Seo +3
Disruption in tokamak plasmas, stemming from various instabilities, poses a critical challenge, resulting in detrimental effects on the associated devices. Consequently, the proact…
Bayesian modelling of multiple plasma diagnostics at Wendelstein 7-X
Sehyun Kwak, J. Svensson, S. Bozhenkov +7
Consistent inference of the electron density and temperature has been carried out with multiple heterogeneous plasma diagnostic data sets at Wendelstein 7-X. The predictive models…
Deep neural network Grad-Shafranov solver constrained with measured magnetic signals
Semin Joung, Jaewook Kim, Sehyun Kwak +7
A neural network solving Grad-Shafranov equation constrained with measured magnetic signals to reconstruct magnetic equilibria in real time is developed. Database created to optimi…
Evolution of magnetic Kubo number of stochastic magnetic fields during the edge pedestal collapse simulation
Jaewook Kim, Wonjun Lee, Hogun Jhang +3
Using a statistical correlation analysis, we compute evolution of the magnetic Kubo number during an edge pedestal collapse in nonlinear reduced magnetohydrodynamic simulations. Th…
Estimation of reliable range of electron temperature measurements with sets of given optical bandpass filters for KSTAR Thomson scattering system based on synthetic Thomson data
Keon-hee Kim, Tae-suk Oh, Kyeo-reh Park +2
One factor determining the reliability of measurements of electron temperature using a Thomson scattering (TS) system is transmittance of the optical bandpass filters in polychroma…
Experimental determination of the correlation properties of plasma turbulence using 2D BES systems
M. F. J. Fox, A. R. Field, F. van Wyk +3
A procedure is presented to map from the spatial correlation parameters of a turbulent density field (the radial and binormal correlation lengths and wavenumbers, and the fluctuati…
Bayesian electron density inference from JET lithium beam emission spectra using Gaussian processes
Sehyun Kwak, J. Svensson, M. Brix +1
A Bayesian model to infer edge electron density profiles is developed for the JET lithium beam emission spectroscopy system, measuring Li I line radiation using 26 channels with ~1…
Reliability of the two-point measurement of the spatial correlation length from Gaussian-shaped fluctuating signals in fusion-grade plasmas
Jaewook Kim, Y. U. Nam, M. Lampert +1
A statistical method for the estimation of spatial correlation lengths of Gaussian-shaped fluctuating signals with two measurement points is examined to quantitatively evaluate its…
Collisionality scaling of the electron heat flux in ETG turbulence
G J Colyer, A A Schekochihin, F I Parra +4
In electrostatic simulations of MAST plasma at electron-gyroradius scales, using the local flux-tube gyrokinetic code GS2 with adiabatic ions, we find that the long-time saturated…
Bayesian modelling of the emission spectrum of the JET Li-BES system
Sehyun Kwak, J. Svensson, M. Brix +2
A Bayesian model of the emission spectrum of the JET lithium beam has been developed to infer the intensity of the Li I (2p-2s) line radiation and associated uncertainties. The det…
Conditions for generating synthetic data to investigate characteristics of fluctuating quantities
Jaewook Kim, M. F. J. Fox, A. R. Field +2
Synthetic data describing coherent random fluctuations have widely been used to validate numerical sim- ulations against experimental observations or to examine the reliability of…
Quantifying noise sources in the KSTAR 2014 Thomson Scattering system from the measured variation on electron temperature
Tae-suk Oh, K. H. Kim, J. H. Lee +6
With the Thomson scattering (TS) system in KSTAR, temporal evolution of electron temperature () is estimated using a weighted look-up table method with fast sampling ( o…
Comparison of BES measurements of ion-scale turbulence with direct, gyrokinetic simulations of MAST L-mode plasmas
A R Field, D Dunai, Y-c Ghim +7
Observations of ion-scale (k_y*rho_i <= 1) density turbulence of relative amplitude dn_e/n_e <= 0.2% are available on the Mega Amp Spherical Tokamak (MAST) using a 2D (8 radial x 4…
Characteristics of Plasma Turbulence in the Mega Amp Spherical Tokamak
Young-chul Ghim
Turbulence is a major factor limiting the achievement of better tokamak performance as it enhances the transport of particles, momentum and heat which hinders the foremost objectiv…
Local dependence of ion temperature gradient on magnetic configuration, rotational shear and turbulent heat flux in MAST
Y. -c. Ghim, A. R. Field, A. A. Schekochihin +3
Experimental data from the Mega Amp Spherical Tokamak (MAST) is used to show that the inverse gradient scale length of the ion temperature R/LTi (normalized to the major radius R)…
Experimental Signatures of Critically Balanced Turbulence in MAST
Y. -c. Ghim, A. A. Schekochihin, A. R. Field +8
Beam Emission Spectroscopy (BES) measurements of ion-scale density fluctuations in the MAST tokamak are used to show that the turbulence correlation time, the drift time associated…
Experimental verification of Boltzmann equilibrium for negative ions in weakly collisional electronegative plasmas
Y. -C. Ghim, N. Hershkowitz
Weakly collisional Ar-O2 electronegative plasmas are investigated in a dc multidipole chamber. An electronegative core and an electropositive halo are observed. The density ratio o…
Calculation of spatial response of 2D BES diagnostic on MAST
Y. -c. Ghim, A. R. Field, S. Zoletnik +1
The Beam Emission Spectroscopy (BES) turbulence diagnostic on MAST is to be upgraded in June 2010 from a 1D trial system to a 2D imaging system (8 radial \times 4 poloidal channels…