I. Holod
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View article: Understanding Large-Scale Plasma Simulation Challenges for Fusion Energy on Supercomputers
Understanding Large-Scale Plasma Simulation Challenges for Fusion Energy on Supercomputers Open
Understanding plasma instabilities is essential for achieving sustainable fusion energy, with large-scale plasma simulations playing a crucial role in both the design and development of next-generation fusion energy devices and the modelli…
View article: Non-linear MHD modelling of transients in tokamaks: a review of recent advances with the JOREK code
Non-linear MHD modelling of transients in tokamaks: a review of recent advances with the JOREK code Open
Transient magneto-hydrodynamic (MHD) events like edge localized modes (ELMs) or disruptions are a concern for magnetic confinement fusion power plants. Research with the MHD code JOREK towards understanding control of such instabilities is…
View article: Nonlinear MHD modeling of soft β limits in W7-AS
Nonlinear MHD modeling of soft β limits in W7-AS Open
An important question for the outlook of stellarator reactors is their robustness against pressure driven modes, and the underlying mechanism behind experimentally observed soft β limits. Towards building a robust answer to these questions…
View article: Nonlinear MHD modeling of soft $β$ limits in W7-AS
Nonlinear MHD modeling of soft $β$ limits in W7-AS Open
An important question for the outlook of stellarator reactors is their robustness against pressure driven modes, and the underlying mechanism behind experimentally observed soft $β$ limits. Towards building a robust answer to these questio…
View article: Towards Robust Solvers for Nuclear Fusion Simulations Using JOREK: A Numerical Analysis Perspective
Towards Robust Solvers for Nuclear Fusion Simulations Using JOREK: A Numerical Analysis Perspective Open
One of the most well-established codes for modeling non-linear Magnetohydrodynamics (MHD) for tokamak reactors is JOREK, which solves these equations with a Bézier surface based finite element method. This code produces a highly sparse but…
View article: First Experiments and Radiographs on the MegaJOuLe Neutron Imaging Radiography (MJOLNIR) Dense Plasma Focus
First Experiments and Radiographs on the MegaJOuLe Neutron Imaging Radiography (MJOLNIR) Dense Plasma Focus Open
We report a dense plasma focus (DPF) is a relatively compact coaxial plasma gun, which completes its discharge as a Z-pinch. These devices are designed to operate at a variety of scales to produce short (<100 ns) pulses of ions, X-rays, an…
View article: Global gyrokinetic particle simulations of microturbulence in W7-X and LHD stellarators
Global gyrokinetic particle simulations of microturbulence in W7-X and LHD stellarators Open
Global gyrokinetic particle simulations of electrostatic ion temperature gradient (ITG) instability show that the most unstable eigenmode is localized to some magnetic fieldlines or discrete locations on the poloidal plane in the Wendelste…
View article: Effect of polarity on beam and plasma target formation in a dense plasma focus
Effect of polarity on beam and plasma target formation in a dense plasma focus Open
Dense plasma focus (DPF) devices are conventionally operated with a polarity such that the inner electrode (IE) is the anode. It has been found that interchanging the polarity of the electrodes (i.e., IE as the cathode) can cause an order …
View article: Effects of RMP-induced changes of radial electric fields on microturbulence in DIII-D pedestal top
Effects of RMP-induced changes of radial electric fields on microturbulence in DIII-D pedestal top Open
Gyrokinetic simulations of DIII-D tokamak with axisymmetric equilibrium show that the reduction in the radial electric field shear at the top of the pedestal during edge localized mode (ELM) suppression with the n = 2 resonant magnetic per…
View article: Extending the validation of multi-mode model for anomalous transport to high beta poloidal tokamak scenario in DIII-D
Extending the validation of multi-mode model for anomalous transport to high beta poloidal tokamak scenario in DIII-D Open
The Multi-Mode Model (MMM7.1) for anomalous transport is tested in predictive modeling of temperature profiles of a high beta poloidal DIII-D discharge. This new H-mode plasma regime, with high beta poloidal and high bootstrap currents, ha…
View article: Drift-wave stability in the field-reversed configuration
Drift-wave stability in the field-reversed configuration Open
Gyrokinetic simulations of C-2-like field-reversed configuration (FRC) find that electrostatic drift-waves are locally stable in the core. The stabilization mechanisms include finite Larmor radius effects, magnetic well (negative grad-B), …
View article: Global linear gyrokinetic simulation of energetic particle-driven instabilities in the LHD stellarator
Global linear gyrokinetic simulation of energetic particle-driven instabilities in the LHD stellarator Open
Energetic particles are inherent to toroidal fusion systems and can drive instabilities in the Alfvén frequency range, leading to decreased heating efficiency, high heat fluxes on plasma-facing components, and decreased ignition margin. Th…
View article: Final Technical Report for DOE theory grant DE-SC0010416 Gyrokinetic Particle Simulation of Plasma Edge Pedestal
Final Technical Report for DOE theory grant DE-SC0010416 Gyrokinetic Particle Simulation of Plasma Edge Pedestal Open
The problem of stability and transport of pressure driven modes in DIII-D tokamak pedestal region has been studied vigorously using gyrokinetic simulations
View article: Linear simulation of ion temperature gradient driven instabilities in W7-X and LHD stellarators using GTC
Linear simulation of ion temperature gradient driven instabilities in W7-X and LHD stellarators using GTC Open
The global gyrokinetic toroidal code (GTC) has been recently upgraded to do simulations in non-axisymmetric equilibrium configuration, such as stellarators. Linear simulation of ion temperature gradient (ITG) driven instabilities has been …
View article: Suppressed ion-scale turbulence in a hot high-β plasma
Suppressed ion-scale turbulence in a hot high-β plasma Open
An economic magnetic fusion reactor favours a high ratio of plasma kinetic pressure to magnetic pressure in a well-confined, hot plasma with low thermal losses across the confining magnetic field. Field-reversed configuration (FRC) plasmas…
View article: Microturbulence in DIII-D tokamak pedestal. III. Effects of collisions
Microturbulence in DIII-D tokamak pedestal. III. Effects of collisions Open
Gyrokinetic simulations of the H-mode pedestal in DIII-D discharge 145701 find that the kinetic ballooning mode (KBM) is the most unstable mode for low toroidal numbers (n ≤ 25) and that the trapped electron mode (TEM) dominates over the K…
View article: Microturbulence in DIII-D tokamak pedestal. IV. Electrostatic turbulent transport
Microturbulence in DIII-D tokamak pedestal. IV. Electrostatic turbulent transport Open
Gyrokinetic simulations of electrostatic microturbulence in the edge plasmas of DIII-D shot 131997 find that the geodesic acoustic mode (GAM) is generated after nonlinear saturation both at the pedestal top and in the peak gradient region,…
View article: Effect of resonant magnetic perturbations on microturbulence in DIII-D pedestal
Effect of resonant magnetic perturbations on microturbulence in DIII-D pedestal Open
Vacuum resonant magnetic perturbations (RMP) applied to otherwise axisymmetric tokamak plasmas produce in general a combination of non-resonant effects that preserve closed flux surfaces (kink response) and resonant effects that introduce …
View article: Gyrokinetic particle simulation of fast-electron driven beta-induced Aflvén eigenmode
Gyrokinetic particle simulation of fast-electron driven beta-induced Aflvén eigenmode Open
The fast-electron driven beta-induced Alfvén eigenmode (e-BAE) in toroidal plasmas is investigated for the first time using global gyrokinetic particle simulations, where the fast electron is described by the drift kinetic equation. The si…
View article: Gyrokinetic particle simulation of a field reversed configuration
Gyrokinetic particle simulation of a field reversed configuration Open
Gyrokinetic particle simulation of the field-reversed configuration (FRC) has been developed using the gyrokinetic toroidal code (GTC). The magnetohydrodynamic equilibrium is mapped from cylindrical coordinates to Boozer coordinates for th…
View article: Microturbulence in DIII-D tokamak pedestal. II. Electromagnetic instabilities
Microturbulence in DIII-D tokamak pedestal. II. Electromagnetic instabilities Open
Here, gyrokinetic simulations have been used to identify electromagnetic microinstabilities in the H-mode pedestal region of DIII-D shot 131 997 using global gyrokinetic code GTC. It was found that dominant instability at the top of the pe…
View article: Gyrokinetic particle simulation of microturbulence for general magnetic geometry and experimental profiles
Gyrokinetic particle simulation of microturbulence for general magnetic geometry and experimental profiles Open
Developments in gyrokinetic particle simulation enable the gyrokinetic toroidal code (GTC) to simulate turbulent transport in tokamaks with realistic equilibrium profiles and plasma geometry, which is a critical step in the code–experiment…
View article: Properties of toroidal Alfvén eigenmode in DIII-D plasma
Properties of toroidal Alfvén eigenmode in DIII-D plasma Open
Linear properties of the toroidal Alfvén eigenmode (TAE) excited by energetic particles (EP) in a DIII-D tokamak experiment have been studied in global gyrokinetic particle simulations treating self-consistently kinetic effects of EP, ther…