A5081614415- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Advanced Data Storage Technologies
- Nuclear Materials and Properties
- Neural Networks and Applications
- Fluid Dynamics and Turbulent Flows
- Non-Destructive Testing Techniques
- Atomic and Subatomic Physics Research
- Atomic and Molecular Physics
- Graphene research and applications
- 3D Surveying and Cultural Heritage
- Scientific Computing and Data Management
- Laser-induced spectroscopy and plasma
- 3D Shape Modeling and Analysis
- Welding Techniques and Residual Stresses
- Business Process Modeling and Analysis
- Distributed and Parallel Computing Systems
General Atomics (United States)
2016-2025
University of Illinois Urbana-Champaign
2023
University of California, Los Angeles
2017-2019
Lawrence Livermore National Laboratory
2017-2019
The University of Texas at Austin
2019
Massachusetts Institute of Technology
2019
Fusion Academy
2019
Fusion (United States)
2016-2019
University of Wisconsin–Madison
2019
Williams (United States)
2017
One modeling framework for integrated tasks (OMFIT) is a comprehensive which has been developed to enable physics codes interact in complicated workflows, and support scientists at all stages of the cycle. The OMFIT development follows unique bottom-up approach, where design capabilities organically evolve progressive integration components that are required accomplish goals increasing complexity. provides workflow easily generating full kinetic equilibrium reconstructions constrained by...
Abstract The objectives of NSTX-U research are to reinforce the advantages STs while addressing challenges. To extend confinement physics low- A , high beta plasmas lower collisionality levels, understanding transport mechanisms that set performance and pedestal profiles is being advanced through gyrokinetic simulations, reduced model development, comparison NSTX experiment, as well improved simulation RF heating. develop stable non-inductive scenarios needed for steady-state operation,...
Fusion whole device modeling simulations require comprehensive models that are simultaneously physically accurate, fast, robust, and predictive. In this paper we describe the development of two neural-network (NN) based as a means to perform snon-linear multivariate regression theory-based for core turbulent transport fluxes, pedestal structure. Specifically, find NN-based approach can be used consistently reproduce results TGLF EPED1 over broad range plasma regimes, with computational...
Recent EAST/DIII-D joint experiments on the high poloidal beta tokamak regime in DIII-D have demonstrated fully noninductive operation with an internal transport barrier (ITB) at large minor radius, normalized fusion performance increased by ≥30% relative to earlier work (Politzer et al 2005 Nucl. Fusion 45 417). The advancement was enabled improved understanding of 'relaxation oscillations', previously attributed repetitive ITB collapses, and fast ion behavior this regime. It found that...
DIII-D research is being accelerated by leveraging high performance computing (HPC) and data resources available through the National Energy Research Scientific Computing Center (NERSC) Superfacility initiative. As part of this initiative, a high-resolution, fully automated, whole discharge kinetic equilibrium reconstruction workflow was developed that runs at NERSC for most shots in under 20 min. This has eliminated long-standing barrier opened door to more sophisticated analyses, including...
A series of carefully designed experiments on DIII-D have taken advantage a broad set turbulence and profile diagnostics to rigorously test gyrokinetic simulations. In this paper the goals, tools performed in these validation studies are reviewed specific examples presented. It is found that predictions transport fluctuation levels mid-core region (0.4 < ρ 0.75) better agreement with experiment than those outer (ρ ⩾ where edge coupling effects may become increasingly important multiscale...
Robust validation of predictive turbulent transport models requires quantitative comparisons to experimental measurements at multiple levels, over a range physically relevant conditions. Toward this end, series carefully designed experiments has been performed on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] obtain comprehensive multifield, multipoint, multiwavenumber fluctuation and their scalings with key dimensionless parameters. The results two representative studies are...
Accurate prediction of fusion performance in present and future tokamaks requires taking into account the strong interplay between core transport, pedestal structure, current profile, plasma equilibrium. An integrated modeling workflow capable calculating steady-state self-consistent solution to this strongly coupled problem has been developed. The leverages state-of-the-art components for collisional turbulent equilibrium stability. Testing against a DIII-D discharge shows that is robustly...
TRANSP simulations are being used in the OMFIT workflow manager to enable a machine-independent means of experimental analysis, postdictive validation, and predictive time-dependent on DIII-D, NSTX, JET, C-MOD tokamaks. The procedures for preparing input data from plasma profile diagnostics equilibrium reconstruction, as well processing heating current drive sources assumptions about neutral recycling, vary across machines, but streamlined by using common manager. Settings simulation...
Plasmas with a negative triangularity shape have been created on the DIII-D tokamak that, despite maintaining standard L-mode edge radial profiles, reach volume averaged pressure levels typical of H-mode scenarios. Within auxiliary power available for these experiments, plasmas exhibit near-zero degradation while sustaining βN = 2.7 and H98,y2 1.2 several energy confinement times. Detailed comparison matched discharges at positive indicates that Trapped Electron Modes are weakened...
Abstract An integrated modeling workflow capable of finding the steady-state plasma solution with self-consistent core transport, pedestal structure, current profile, and equilibrium physics has been developed tested against a DIII-D discharge. Key features achieved core-pedestal coupled are its ability to account for transport impurities in self-consistently, as well use machine learning accelerated models structure turbulent physics. Notably, is implemented within One Modeling Framework...
Diverted discharges at negative triangularity on the DIII-D tokamak sustain normalized confinement and pressure levels typical of standard H-mode scenarios (H98y2 ≃ 1, βN 3) without developing an edge pedestal, despite auxiliary power far exceeding L → H threshold expected from conventional scaling laws. The degradation is substantially weaker than ITER-89P scaling, resulting in a factor that improves with increasing power. absence pedestal beneficial several ways, such as eliminating need...
Abstract Recent progress in the application of machine learning (ML)/artificial intelligence (AI) algorithms to improve Equilibrium Fitting (EFIT) code equilibrium reconstruction for fusion data analysis applications is presented. A device-independent portable core solver capable computing or reconstructing different tokamaks has been created facilitate adaptation ML/AI algorithms. large EFIT database comprising DIII-D magnetic, motional Stark effect, and kinetic generated developments...
Joint experiment/theory/modelling research has led to increased confidence in predictions of the pedestal height ITER. This work was performed as part a US Department Energy Research Target FY11 identify physics processes that control H-mode structure. The study included experiments on C-Mod, DIII-D and NSTX well interpretation experimental data with theory-based modelling codes. provides ability models for peeling–ballooning stability, bootstrap current, width scaling make correct...
One Modeling Framework for Integrated Tasks (OMFIT) has been used to develop a consistent tool interfacing with, mapping, visualizing, and fitting tokamak profile measurements. OMFIT is integrate the many diverse diagnostics on multiple devices into regular data structure, consistently applying spatial temporal treatments each channel of data. Tokamak are fundamentally time dependent treated so from start, with front-loaded logic-based manipulations such as filtering based identification...
Impurity transport in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] is investigated stationary high confinement (H-mode) regimes without edge localized modes (ELMs). In plasmas maintained by resonant magnetic perturbation (RMP), ELM-suppression, and QH-mode, time of fluorine (Z = 9) equivalent to that ELMing discharges with 40 Hz ELMs. For selected impurity injection, particle compared energy range τp/τe≈2−3. QH-mode operation, shown be smaller for intense, coherent magnetic,...
Experiments have been executed in the DIII-D tokamak to extend suppression of Edge Localized Modes (ELMs) with Resonant Magnetic Perturbations (RMPs) ITER-relevant levels beam torque. The results support hypothesis for RMP ELM based on transition from an ideal screened response a tearing at resonant surface that prevents expansion pedestal unstable width [Snyder et al., Nucl. Fusion 51, 103016 (2011) and Wade 55, 023002 (2015)]. In ITER baseline plasmas I/aB = 1.4 ν* ∼ 0.15, ELMs are readily...
Electron profile stiffness was studied in DIII-D L-mode discharges by systematically varying the heat flux a narrow region with electron cyclotron heating and measuring local change produced ∇Te. found to slowly increase toroidal rotation velocity. A critical inverse temperature gradient scale length 1/LC ∼ 3 m−1 identified at ρ=0.6 be independent of rotation. Both pulse diffusivity power balance diffusivity, latter determined integrating measured dependence on –∇Te, were fit reasonably well...
A critical gradient threshold has been observed for the first time in a systematic, controlled experiment locally measured turbulent quantity core of confined high-temperature plasma. In an DIII-D tokamak where L(T(e))(-1) = |∇T(e)|/T(e) and toroidal rotation were varied, long wavelength (k(θ)ρ(s) ≲ 0.4) electron temperature fluctuations exhibit L(T(e))(-1): below, they change little; above, steadily increase. The increase δT(e)/T(e) is concurrent with increased heat flux transport...
For the first time, DIII-D experiments have achieved stationary quiescent H-mode (QH-mode) operation for many energy confinement times at simultaneous ITER-relevant values of beta, confinement, and safety factor, in an ITER-like shape. QH-mode provides excellent even very low plasma rotation, while operating without edge localized modes (ELMs) with strong impurity transport via benign harmonic oscillation (EHO). By tailoring shape to improve stability, space has also been extended densities...
The geodesic acoustic mode (GAM), a coherent form of the zonal flow, plays critical role in turbulence regulation and cross-magnetic-field transport. In DIII-D tokamak, unique information on multi-field characteristics radial structure eigenmode GAMs has been measured. Two simultaneous distinct, radially overlapping (i.e., constant frequency vs. radius) have observed poloidal E×B flow L-mode plasmas. As plasma transitions from an to Ohmic regime, one these becomes continuum GAM (frequency...
The first systematic investigation of core electron thermal transport and the role local ion temperature gradient/trapped mode/electron gradient (ITG/TEM/ETG)-scale turbulence is performed in high temperature, low collisionality H-mode plasmas DIII-D tokamak. Wavenumber spectra L-mode density are measured by Doppler backscattering. wavenumber directly contrasted for time with nonlinear gyrokinetic simulation results. Core ITG/TEM-scale substantially reduced/suppressed E × B shear promptly...
Energy transport analyses of the DIII-D high- EAST-demonstration discharges have been performed using TGYRO package with TGLF turbulent and NEO neoclassical models under OMFIT integrated modeling framework. Ion energy is shown to be dominated by ion temperature profiles predicted agree closely experimental measured for these discharges. largely insensitive reductions in flow shear stabilization. The Shafranov shift play a role suppression below level. Electron under-predicted significant...
Accurate plasma state reconstruction will be crucial for the success of ITER and future fusion plants, but harsh conditions a burning make diagnostic operation more challenging than in current machines. Integrated data analysis (IDA) based on Bayesian inference allows improved information gain by combining many diagnostics into single step using sophisticated forward models. It also provides framework to seamlessly combine predictive modeling data, which can invaluable data-poor environment....