A5034362339- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Nuclear reactor physics and engineering
- Solar and Space Plasma Dynamics
- Physics of Superconductivity and Magnetism
- Semiconductor materials and devices
- Black Holes and Theoretical Physics
- Electrostatic Discharge in Electronics
- Advancements in Semiconductor Devices and Circuit Design
- Electromagnetic Launch and Propulsion Technology
- Advanced Data Storage Technologies
- Fluid Dynamics and Turbulent Flows
- Dust and Plasma Wave Phenomena
- Noncommutative and Quantum Gravity Theories
- Atomic and Subatomic Physics Research
- Diamond and Carbon-based Materials Research
- Gas Dynamics and Kinetic Theory
- Particle physics theoretical and experimental studies
- Cosmology and Gravitation Theories
- Atmospheric and Environmental Gas Dynamics
General Atomics (United States)
2015-2024
Oak Ridge National Laboratory
2016-2024
Fusion Academy
2019-2024
Fusion (United States)
2019-2024
University of California, Los Angeles
1998-2022
Princeton Plasma Physics Laboratory
2011-2022
University of Wisconsin–Madison
2011-2022
Chinese Academy of Sciences
2017-2021
Oak Ridge Associated Universities
2021
University of California, San Diego
2016-2021
A physically comprehensive and theoretically based transport model tuned to three-dimensional (3-D) ballooning mode gyrokinetic instabilities gyrofluid nonlinear turbulence simulations is formulated with global local magnetic shear stabilization E×B rotational stabilization. Taking no fit coefficients from experiment, the tested against a large profile database good agreement. This capable of describing enhanced core confinement barriers in negative central discharges on The used make...
A new theory-based transport model with comprehensive physics (trapping, general toroidal geometry, fully electromagnetic, electron-ion collisions, impurity ions) has been developed. The core of the is trapped-gyro-Landau-fluid (TGLF) equations, which provide a fast and accurate approximation to linear eigenmodes for gyrokinetic drift-wave instabilities (trapped ion electron modes, temperature gradient kinetic ballooning modes). TGLF more accurate, an extended range validity, compared its...
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,...
Abstract Progress in physics understanding and theoretical model development of plasma transport confinement (TC) the ITPA TC Topical Group since publication ITER Physics Basis (IPB) document (Doyle et al 2007 Nucl. Fusion 47 S18) was summarized focusing on contributions to burning prediction control. This paper provides a general streamlined overview advances that were mainly led by joint experiments activities for last 15 years (see JEX/JA table appendix). starts with scientific strategy...
A new system of gyro-Landau fluid (GLF) equations for tokamak plasmas is presented. The include both trapped particles, which can average the Landau resonance, and passing particles do have a resonance. trap GLF (TGLF) model unrestricted in fraction or perpendicular wave number electrostatic perturbation. linearly unstable eigenmodes TGLF low-frequency ion modes all way up to high-frequency electron temperature gradient driftwaves. Extensive benchmarking linear with large database...
The first transport code simulations using the newly developed trapped gyro-Landau-fluid (TGLF) theory-based model are presented. TGLF has comprehensive physics to approximate turbulent due drift-ballooning modes in tokamaks. is a next generation that improves accuracy of particle response and finite Larmor radius effects compared its predecessor, GLF23. solves for linear eigenmodes ion electron modes, temperature gradient electromagnetic kinetic ballooning either shifted circle or shaped...
The trapped gyro-Landau fluid (TGLF) transport model computes the quasilinear particle and energy driftwave fluxes in tokamaks with shaped geometry, finite aspect ratio collisions. TGLF have been successfully verified against a large database of collisionless nonlinear gyrokinetic simulations using GYRO code. Using new collision TGLF, we find remarkable agreement between 64 electron–ion In validating DIII-D JET H-mode hybrid discharges temperature density profiles are excellent measured...
New transport experiments on JET indicate that ion stiffness mitigation in the core of a rotating plasma, as described by Mantica et al. [Phys. Rev. Lett. 102, 175002 (2009)] results from combined effect high rotational shear and low magnetic shear. The observations have important implications for understanding improved confinement advanced tokamak scenarios. Simulations using quasilinear fluid gyrofluid models show features mitigation, while nonlinear gyrokinetic simulations do not....
The 2D spectrum of the saturated electric potential from gyrokinetic turbulence simulations that include both ion and electron scales (multi-scale) in axisymmetric tokamak geometry is analyzed. paradigm when zonal (axisymmetic) ExB flow shearing rate competes with linear growth shown to not apply scale turbulence. Instead, it mixing by velocity turbulent distribution function growth. A model this mechanism be able capture suppression electron-scale ion-scale threshold for increase reduced....
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...
This work characterizes the core transport physics of SPARC early-campaign plasmas using PORTALS-CGYRO framework. Empirical modeling with L-mode confinement indicates an ample window breakeven (Q > 1) without need H-mode operation. Extensive multi-channel (electron energy, ion and electron particle) flux-matched conditions nonlinear CGYRO code for turbulent coupled to macroscopic plasma evolution PORTALS reveals that maximum fusion performance be attained will highly dependent on...
A bifurcation in the particle and energy confinement properties of a tokamak plasma, with similar to experimentally observed L-mode H-mode transition, is shown follow from simple model for transport. The basic assumptions are that edge turbulence suppressed by sheared E×B flow, radial ion pressure gradient approximately balanced electric field. thermal diffusivities assumed be given nonlinear functions field shear, which related density gradients. steady-state profiles found have large...
A new sustained high-performance regime, combining discrete edge and core transport barriers, has been discovered in the DIII-D tokamak. Edge localized modes (ELMs) are replaced by a steady oscillation that increases particle transport, thereby allowing control with no ELM-induced pulsed divertor heat load. The barrier resembles those usually seen low (L) mode edge, without degradation often associated ELMs. barriers separated narrow region of high zero crossing E x B shearing rate.
The capability to inject deuterium pellets from the magnetic high field side (HFS) has been added DIII-D tokamak [J. L. Luxon and G. Davis, Fusion Technol. 8, 441 (1985)]. It is observed that injected HFS lead deeper mass deposition than identical outside midplane, in spite of a factor 4 lower pellet speed. have used generate peaked density profile plasmas [peaking (ne(0)/〈ne〉) excess 3] develop internal transport barriers when centrally heated with neutral beam injection. are formed...
Fusion power has been increased by a factor of 3 in DIII-D tailoring the pressure profile to avoid kink instability $H$-mode plasmas. The resulting plasmas are found have neoclassical ion confinement. This reduction transport losses beam-heated with negative central shear is correlated dramatic density fluctuations. Improved magnetohydrodynamic stability achieved controlling plasma width. In deuterium highest gain $Q$ (the ratio fusion input power), was 0.0015, corresponding an equivalent...
A sheared slab magnetic field model B=B0[ẑ+(x/Ls)ŷ], with inhomogeneous flows in the ŷ and ẑ directions, is used to perform a fully kinetic stability analysis of ion temperature gradient (ITG) dissipative trapped electron (DTE) modes. The concomitant quasilinear stress components that couple local perpendicular (y component) parallel (z momentum transport are also calculated anomalous viscous stresses obtained. breakdown ITG-induced generally observed at moderate values flow. Even absence...
For the first time, profiles (0.3<ρ<0.9) of electron temperature and density fluctuations in a tokamak have been measured simultaneously results compared to nonlinear gyrokinetic simulations. Electron neutral beam-heated, sawtooth-free low confinement mode (L-mode) plasmas DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] are found be similar frequency normalized amplitude, with amplitude increasing radius. The radial profile two fluctuation fields allows for new rigorous...
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...
The shear in the mean field velocity Doppler shift is shown to suppress amplitude of electric potential fluctuations by inducing a peak radial wave number spectrum. An analytic model process shows that fluctuation spectrum shifts direction where linearly destabilizing but nonlinear mixing causes recentering about shifted at reduced A for 2D used quasilinear calculation transport accurately reproduce suppression energy and particle Reynolds stress due shear.
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...
A new paradigm of zonal flow mixing as the mechanism by which E B fluctuations impact saturation gyrokinetic turbulence has recently been deduced from nonlinear 2D spectrum electric potential in simulations. These state art simulations span physical scales both ion and electron turbulence. It was found that rate, rather than shearing competes with linear growth at scales. model for developed applied to quasilinear trapped gyro-Landau fluid transport (TGLF). The first validation tests 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...
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...