A5067290528- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Solar and Space Plasma Dynamics
- Electromagnetic Launch and Propulsion Technology
- Nuclear Physics and Applications
- Fluid Dynamics Simulations and Interactions
- Earthquake Detection and Analysis
- Laser-induced spectroscopy and plasma
- Nuclear and radioactivity studies
- Dust and Plasma Wave Phenomena
- Distributed and Parallel Computing Systems
- Microwave Engineering and Waveguides
- Particle Detector Development and Performance
- Graphite, nuclear technology, radiation studies
- Bluetooth and Wireless Communication Technologies
- Astrophysical Phenomena and Observations
- Neural Networks and Applications
- Geophysics and Sensor Technology
- Seismology and Earthquake Studies
General Atomics (United States)
2018-2025
Massachusetts Institute of Technology
2024
Oak Ridge Associated Universities
2017-2023
Institute of Plasma Physics
2021
Chinese Academy of Sciences
2021
University of California, San Diego
2021
Oak Ridge National Laboratory
2017
University of California, Irvine
2014-2015
Peking University
2014
Sichuan University
2014
Abstract The tokamak approach, utilizing a toroidal magnetic field configuration to confine hot plasma, is one of the most promising designs for developing reactors that can exploit nuclear fusion generate electrical energy 1,2 . To reach goal an economical reactor, reactor 3–10 simultaneously require reaching plasma line-averaged density above empirical limit—the so-called Greenwald 11 —and attaining confinement quality better than standard high-confinement mode 12,13 However, such...
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 Divertor detachment offers a promising solution to the challenge of plasma-wall interactions for steady-state operation fusion reactors. Here, we demonstrate excellent compatibility actively controlled full divertor with high-performance ( β N ~ 3, H 98 1.5) core plasma, using high-β p (poloidal beta, > 2) scenario characterized by sustained internal transport barrier (ITB) and modest edge (ETB) in DIII-D tokamak. The high- high-confinement facilitates which, turn, promotes...
Abstract A theoretical model is presented that for the first time matches experimental measurements of pedestal width-height Diallo scaling in low-aspect-ratio high- β tokamak NSTX. Combining linear gyrokinetics with self-consistent equilibrium variation, kinetic-ballooning, rather than ideal-ballooning plasma instability, shown to limit achievable confinement spherical pedestals. Simulations are used find novel Gyrokinetic Critical Pedestal constraint, which determines steepest pressure...
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...
Abstract Physics-based simulations project a compact net electric fusion pilot plant with nuclear testing mission is possible at modest scale based on the advanced tokamak concept, and identify key parameters for its optimization. These utilize new integrated 1.5D core-edge approach whole device modeling to predict performance by self-consistently applying transport, pedestal current drive models converge fully non-inductive stationary solutions, predicting profiles energy confinement given...
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...
Recent experiments on EAST have achieved the first long pulse H-mode (61 s) with zero loop voltage and an ITER-like tungsten divertor, demonstrated access to broad plasma current profiles by increasing density in fully-noninductive lower hybrid current-driven discharges. These discharges reach wall thermal particle balance, exhibit stationary good confinement (H98y2 ~ 1.1) low core electron transport, are only possible optimal active cooling of armors. In separate experiments, was...
Systematic experimental and modeling investigations on DIII-D show attractive transport properties of fully non-inductive high βp plasmas. Experiments that the large-radius internal barrier (ITB), a key feature providing excellent confinement in regime, is maintained when scenario extended from q95 ∼ 12 to 7 rapid near-zero toroidal rotation. The robustness versus rotation was predicted by gyrofluid showing dominant neoclassical ion energy even without E × B shear effect. physics mechanism...
Experiments at DIII-D and EAST have demonstrated simultaneous high confinement, divertor detachment, active control of detachment level, all which are required for ITER. Comparing via Te Jsat, it appears that is the most straightforward sensor to use accessing onset, while Jsat offers more precise degree detachment. Based on these results, using nitrogen seeding has so far shown best ability follow a target value with low disruptivity little no degradation performance when an Internal...
Abstract Nonlinear 3D MHD simulations of shattered-pellet injection (SPI) in JET show prototypical SPI-driven disruptions using the M3D-C1 and NIMROD extended-MHD codes. Initially, radiation-driven thermal quenches are accelerated by activity as pellet crosses rational surfaces, leading to a radiation spike, global stochasticization magnetic field, complete quench. Eventually, current quenches, preceded spike seen Ohmic heating becomes equal radiative cooling. The results qualitatively...
Experimental and modeling investigations on the DIII-D EAST tokamaks show attractive transport stability properties of fully noninductive, high poloidal-beta (βP) plasmas, their suitability for steady-state operating scenarios in ITER CFETR. A key feature high-βP regime is large-radius (ρ > 0.6) internal barrier (ITB), often observed all channels (ne, Te, Ti, rotation), responsible both excellent energy confinement quality properties. Experiments have shown that, with a ITB, very βN βP...
Experiments have demonstrated improved energy confinement due to the spontaneous formation of an internal transport barrier in high bootstrap fraction discharges. Gyrokinetic analysis, and quasilinear predictive modeling, demonstrates that observed is caused by suppression turbulence primarily from large Shafranov shift. It shown shift can produce a bifurcation regions positive magnetic shear or continuous reduction for weak negative shear. Operation at safety factor lowers pressure gradient...
Global gyrokinetic particle simulation of resistive tearing modes has been developed and verified in the toroidal code (GTC). GTC linear simulations fluid limit kink-tearing cylindrical geometry agree well with magnetohydrodynamic eigenvalue initial value codes. Ion kinetic effects are found to reduce radial width modes. find that toroidicity reduces growth rates.
The gyrokinetic toroidal code (GTC) capability has been extended for simulating internal kink instability with kinetic effects in geometry. global simulation domain covers the magnetic axis, which is necessary current-driven instabilities. GTC fluid limit of modes cylindrical geometry verified by benchmarking a magnetohydrodynamic eigenvalue code. Gyrokinetic simulations find that ion significantly reduce growth rate even when banana orbit width much smaller than radial perturbed current...
To prepare for steady-state operation of future fusion reactors (e.g. the International Thermonuclear Experimental Reactor and China Fusion Engineering Test (CFETR)), experiments on DIII-D have extended high poloidal beta (βP) scenario to reactor-relevant edge safety factor q95 ∼ 6.0, while maintaining a large-radius internal transport barrier (ITB) using negative magnetic shear. Excellent energy confinement quality (H98y2 > 1.5) is sustained at normalized (βN 3.5). This high-performance ITB...
Recent high-poloidal-beta (high-βP) experiments on DIII-D and EAST have made coordinated breakthroughs for high confinement quality at density near the Greenwald limit. Density gradient amplification of turbulence suppression βP can explain both these achievements. Experiments achieved fraction (fGr = line-averaged density/Greenwald density) above 1 simultaneously with normalized energy (H98y2) around 1.5, as required in fusion reactor designs but never before verified tokamak divertor...
Abstract Theoretical studies have suggested that nonlinear effects can lead to “radio frequency condensation”, which coalesces RF power deposition and driven current near the center of a magnetic island. It is predicted an initially broad profile coalesce in islands when they reach sufficient width, providing automatic stabilization. Experimental validation theory has thus far been lacking. This paper proposes experiments on DIII-D for testing refining effects.
Abstract This study presents analysis of gyrokinetic simulations on the National Spherical Torus
Experiment (NSTX) to investigate effects electromagnetic fields plasma turbulence and
transport. The simulations, performed with varying levels fidelity using CGYRO
code, include electrostatic (ES), single-field (EM1), and two-field electromagnetic
(EM2) models. A detailed comparison across simulation database reveals that electromagnetic
effects increase...
A verification benchmark has been carried out between the M3D-C1 and NIMROD extended-magnetohydrodynamic codes for simulations of impurity-induced disruption mitigation. Disruptions are a significant concern future tokamaks high-fidelity required in order to ensure success mitigation techniques (e.g. shattered-pellet injection) large-scale fusion reactors. Both magnetohydrodynamic (MHD) have coupled Killer Pellet RADiation code impurity dynamics. The show excellent agreement four...
On DIII-D, the high scenario has an internal transport barrier (ITB), , and very normalized confinement . Recently, plasmas starting with these conditions have been dynamically driven to where we find ITB performance persist for five energy times. These are projected meet ITER steady-state goal of Q = 5. The is maintained at lower a strong reverse shear, consistent predictions that negative central shear can threshold ITB. There two observed states in scenario: H-mode state edge pedestal,...
Abstract Self-consistent modeling using the stability, transport, equilibrium, and pedestal (STEP) workflow in OMFIT integrated framework (predicting with EPED, core profiles TGYRO, current profile ONETWO, EFIT for equilibrium) suggests ITER future devices such as China Fusion Engineering Test Reactor (CFETR) Zhuang et al (2019 Nucl. 59 112010) will benefit from high-density operation (Greenwald limit fraction <?CDATA $f_\mathrm{gw} \approx$?> <mml:math...
Bayesian statistics offers a powerful technique for plasma physicists to infer knowledge from the heterogeneous data types encountered. To explain this power, simple example, Gaussian Process Regression, and application of inverse problems are explained. The likelihood is key distribution because it contains model, or theoretic predictions, desired quantities. By using prior knowledge, inferred quantities interest based on given can be inferred. Because not single prediction, uncertainty...
Abstract Understanding the physics of low-confinement (L-), improved-confinement (I-), and high-confinement (H-) modes is critical for fusion reactors. The finding herein reports observations two types turbulence coexisting near L-mode edge, one magnetohydrodynamic (MHD)-like another micro-tearing mode (MTM)-like, linked to H-mode I-mode confinement in DIII-D tokamak. Ion-scale magnetic density measured using a Faraday-effect radial-interferometer-polarimeter beam-emission-spectroscopy...
Abstract Kinetic equilibrium reconstructions make use of profile information such as particle density and temperature measurements in addition to magnetics data compute a self-consistent equilibrium. They are used multitude physics-based modeling. This work develops multi-layer perceptron (MLP) neural network (NN) model surrogate for kinetic Equilibrium Fitting (EFITs) trains on the 2019 DIII-D discharge campaign database reconstructions. We investigate impact including various diagnostic...