A5011353475- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Fusion materials and technologies
- Solar and Space Plasma Dynamics
- Particle accelerators and beam dynamics
- Silicon Carbide Semiconductor Technologies
- Dust and Plasma Wave Phenomena
- GaN-based semiconductor devices and materials
- Semiconductor materials and devices
- Laser-induced spectroscopy and plasma
- Advanced Data Storage Technologies
- Advanced Thermoelectric Materials and Devices
- Particle physics theoretical and experimental studies
- Tropical and Extratropical Cyclones Research
- High-pressure geophysics and materials
- Plasma Diagnostics and Applications
- Structural Analysis of Composite Materials
- Fluid Dynamics and Turbulent Flows
- Nuclear reactor physics and engineering
- Particle Accelerators and Free-Electron Lasers
- High-Energy Particle Collisions Research
- Particle Detector Development and Performance
General Atomics (United States)
2023-2025
University of Wisconsin–Madison
2017-2025
Max Planck Institute for Plasma Physics
2024
Los Alamos National Laboratory
2014
Colorado State University
2012
Abstract The most efficient and promising operational regime for the International Thermonuclear Experimental Reactor tokamak is high-confinement mode. In this regime, however, periodic relaxations of plasma edge can occur. These edge-localized modes pose a threat to integrity fusion device. Here we reveal strong impact energetic ions on spatio-temporal structure in tokamaks using nonlinear hybrid kinetic–magnetohydrodynamic simulations. A resonant interaction between fast at electromagnetic...
In a series of high performance diverted discharges on DIII-D, we demonstrate that strong negative triangularity (NT) shaping robustly suppresses all edge-localized mode (ELM) activity over wide range plasma conditions: ⟨n⟩=0.1-1.5×10^{20} m^{-3}, P_{aux}=0-15 MW, and |B_{t}|=1-2.2 T, corresponding to P_{loss}/P_{LH08}∼8. The full dataset is consistent with the theoretical prediction magnetic shear in NT edge inhibits access ELMing H-mode regimes; experimental pressure profiles are found be...
Abstract Strongly-shaped diverted negative triangularity (NT) plasmas in the DIII-D tokamak demonstrate simultaneous access to high normalized density, current, pressure, and confinement. NT are shown exist across an expansive parameter space compatible with fusion power production, revealing surprisingly good core stability properties that compare favorably conventional positive DIII-D. Non-dimensionalizing key parameters, expanded operating spaces featuring edge safety factors below 3,...
Abstract Negative triangularity (NT) is a potentially transformative configuration for tokamak-based fusion energy with its high-performance core, edge localized mode (ELM)-free edge, and low-field-side divertors that could readily scale to an integrated reactor solution. Previous NT work on the TCV DIII-D tokamaks motivated installation of graphite-tile armor lower outer wall DIII-D. A dedicated multiple-week experimental campaign was conducted qualify scenario future reactors. During...
Abstract Tokamak plasmas with strong negative triangularity (NT) shaping typically exhibit fundamentally different edge behavior than conventional L-mode or H-mode plasmas. On DIII-D, every plasma sufficiently ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mrow><mml:mi>δ</mml:mi><mml:mo><</mml:mo><mml:msub><mml:mi>δ</mml:mi><mml:mrow><mml:mi>crit</mml:mi></mml:mrow></mml:msub><mml:mo>≃</mml:mo><mml:mo>−</mml:mo><mml:mn>0.12</mml:mn></mml:mrow></mml:math>...
Abstract Negative Triangularity (NT) plasmas have demonstrated robustly ELM-free high-performance operation and provide a unique testbed to study how plasma shaping affects turbulent transport. The Beam Emission Spectroscopy (BES) diagnostic provides localized 2D measurements of low-k ($k_{\theta} \rho_s < 1$) density fluctuations. In sweep upper triangularity at fixed power, H-mode access is suppressed an NT-edge observed. turbulence amplitude ($\tilde{n}/n$) shown decrease by $\sim50\%$...
Abstract Experiments on ASDEX Upgrade (AUG) in 2021 and 2022 have addressed a number of critical issues for ITER EU DEMO. A major objective the AUG programme is to shed light underlying physics confinement, stability, plasma exhaust order allow reliable extrapolation results obtained present day machines these reactor-grade devices. Concerning pedestal physics, mitigation edge localised modes (ELMs) using resonant magnetic perturbations (RMPs) was found be consistent with reduction linear...
The Alfvén instability nonlinearly excited the energetic-particle-driven geodesic acoustic mode on ASDEX-Upgrade tokamak, as demonstrated experimentally. mechanism of excitation and nonlinear evolution is not yet fully understood. In present work, a first-principles simulation using MEGA code investigated properties in both linear growth saturated phases. Here we show that successfully reproduced coexistence these two modes, agreed with experimental results well. Conclusive evidence showed...
Abstract Throughout the 2023 DIII-D negative triangularity (NT) campaign, unexpected magnetic fluctuations indicative of an edge localized instability were observed in majority strongly shaped ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.55</mml:mn> <mml:mtext>⩽</mml:mtext> <mml:mi>δ</mml:mi> <mml:mn>0.45</mml:mn> </mml:mrow> </mml:math> ) discharges. Moreover, these same found to be absent weaker NT plasma shapes....
Abstract On the basis of several recent breakthroughs in fusion research, many activities have been launched around world to develop power plants on fastest possible time scale. In this context, high-fidelity simulations plasma behavior large supercomputers provide one main pathways accelerating progress by guiding crucial design decisions. When it comes determining energy confinement a magnetic device, which is key quantity interest, gyrokinetic turbulence are considered approach choice –...
Abstract The ASDEX Upgrade (AUG) programme, jointly run with the EUROfusion MST1 task force, continues to significantly enhance physics base of ITER and DEMO. Here, full tungsten wall is a key asset for extrapolating future devices. high overall heating power, flexible mix comprehensive diagnostic set allows studies ranging from mimicking scrape-off-layer divertor conditions DEMO at density fully non-inductive operation ( q 95 = 5.5, ) low density. Higher installed electron cyclotron...
Abstract An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling AUG discharges was established which able to reproduce experimental H-mode plasma profiles based on engineering parameters only. In center, theoretical predictions current redistribution by a dynamo effect were confirmed experimentally. For core transport, stabilizing fast ion distributions turbulent transport shown be important explain isotope and...
Field-line localized ballooning modes have been observed at the edge of high confinement mode plasmas in ASDEX Upgrade with rotating 3D perturbations induced by an externally applied $n=2$ error field and during a moderate level mitigation. The are to lines which experience one two zero crossings radial flux surface displacement rotation period. localization agrees very well largest growth rates from infinite-$n$ ideal stability calculations using realistic magnetohydrodynamic equilibrium....
Abstract In tokamaks, a leading platform for fusion energy, periodic filamentary plasma eruptions known as edge-localized modes occur in plasmas with high-energy confinement and steep pressure profiles at the edge. These could damage tokamak wall but can be suppressed using small three-dimensional magnetic perturbations. Here we demonstrate that these perturbations change topology just inside gradient region of We identify signatures island, their observation is linked to suppression modes....
Abstract The first achievement of highly radiating plasmas in negative triangularity is shown with an operational space featuring high core radiation at Greenwald fraction obtained the injection reactor-relevant seeded gases. These (NT) shape diverted discharges reach values normalized plasma pressure (BN > 2) no ELMs and a simultaneous reduction divertor heat flux. We demonstrate that as long impurity level kept low to avoid excessive fuel dilution accumulation, integration NT...
The impact of three-dimensional (3D) tokamak geometry from external magnetic perturbations on edge instabilities has been examined in high confinement mode plasmas with localised modes (ELMs) ASDEX Upgrade. 3D probed using rigidly rotating MP fields. measured distortions the plasma boundary are compared to single-fluid ideal magnetohydrodynamic (MHD) equilibria VMEC and MARS-F applying resistive MHD, whereas uses only MHD. Both codes accurately reproduce radial displacements density...
Recent experimental observations have found toroidally localized MHD instabilities in the plasma edge during operation with applied magnetic perturbations on ASDEX Upgrade H-mode low collisionality (ν ≈ 0.4).Large displacements are induced by a stable kink response to 3D perturbations.This results changes of geometric quantities, which turn leads localization edge.Infinite-n ideal ballooning theory is shown predict existence these instabilities, as well observed toroidal...
Strongly-shaped diverted negative triangularity (NT) plasmas in the DIII-D tokamak demonstrate simultaneous access to high normalized current, pressure, density, and confinement. NT are shown exist across an expansive parameter space compatible with fusion power production, revealing surprisingly good core stability properties that compare favorably conventional positive DIII-D. Non-dimensionalizing operating space, edge safety factors below 3, betas above Greenwald density fractions 1,...
Abstract Measurements of the turbulent density wavenumber spectrum, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>δ</mml:mi> <mml:msub> <mml:mover> <mml:mi>n</mml:mi> <mml:mo stretchy="false">ˆ</mml:mo> </mml:mover> <mml:mi>e</mml:mi> </mml:msub> stretchy="false">(</mml:mo> <mml:mi>k</mml:mi> <mml:mo>⊥</mml:mo> stretchy="false">)</mml:mo> </mml:math> , using Doppler Back-Scattering (DBS) diagnostic are reported from DIII-D H-mode plasmas with electron...
Abstract Experiments on the DIII-D tokamak demonstrate that edge localized mode (ELM) stability can be manipulated using electron cyclotron current drive (ECCD) in conjunction with resonant magnetic perturbations (RMPs). The injection of counter-plasma-current ECCD reduces RMP amplitude required to suppress ELMs and bifurcates pedestal into a high-confinement regime 7 kPA pressure. This is first time such high confinement has been accessed through bifurcation from ballooning branch predicted...
Tokamak plasmas with strong negative triangularity (NT) shaping typically exhibit fundamentally different edge behavior than conventional L-mode or H-mode plasmas. Over the entire DIII-D database, sufficiently are found to be inherently free of localized modes (ELMs), even at injected powers well above predicted L-H power threshold. A critical triangularly ($\delta_\mathrm{crit}\simeq-0.15$), consistent ELM-free operation is identified, beyond which access second stability region for...
The first achievement of highly radiating plasmas in negative triangularity is shown with an operational space featuring high core radiation at Greenwald fraction obtained the injection reactor-relevant seeded gases. These (NT) shape diverted discharges reach values normalized plasma pressure (BetaN > 2) no ELMs. We demonstrate that as long impurity level kept low to avoid excessive fuel dilution and accumulation, integration NT configuration not only achievable but it can lead confinement...