A5080537882- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Solar and Space Plasma Dynamics
- Plasma Diagnostics and Applications
- Nuclear reactor physics and engineering
- Advanced Data Storage Technologies
- Inertial Sensor and Navigation
- Fluid Dynamics and Turbulent Flows
- Geophysics and Sensor Technology
- Dust and Plasma Wave Phenomena
- Astronomical Observations and Instrumentation
- High-pressure geophysics and materials
- Electromagnetic Launch and Propulsion Technology
- Wind and Air Flow Studies
- Particle Accelerators and Free-Electron Lasers
- Fluid Dynamics Simulations and Interactions
- Physics of Superconductivity and Magnetism
- Laser-Matter Interactions and Applications
- Atomic and Subatomic Physics Research
- Computer Graphics and Visualization Techniques
- Earthquake Detection and Analysis
Princeton Plasma Physics Laboratory
2015-2024
Princeton University
2012-2024
Culham Centre for Fusion Energy
2021
Culham Science Centre
2021
Plasma Technology (United States)
2021
Fusion Academy
2021
Fusion (United States)
2021
ITER
2021
Sandia National Laboratories California
2018
Korea Advanced Institute of Science and Technology
2000-2017
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,...
Global electrostatic ITG turbulence physics, together with background dynamics, has been simulated in a realistic tokamak core geometry using XGC1, full-function 5D gyrokinetic particle code. An adiabatic electron model used. Some verification exercises of XGC1 have presented. The simulation volume extends from the magnetic axis to pedestal top inside separatrix. Central heating is applied, and number, momentum energy conserving linearized Monte Carlo Coulomb collision In turbulent region,...
The fundamental properties of steep neoclassical plasma pedestals in a quiescent tokamak have been investigated with new guiding center particle code XGC: an X-point included Guiding Center code. It is shown that the width steepest similar to experimentally observed edge pedestal width, and must be accompanied by self-consistent negative radial electric field well. also can form naturally at diverted as source from neutral penetration (and heat flux core plasma) balanced sharply increasing...
A systematic, constructive and self-consistent procedure to quantify nonlocal, nondiffusive action at a distance in plasma turbulence is exposed applied turbulent heat fluxes computed from the state-of-the-art full-$f$, flux-driven gyrokinetic GYSELA XGC1 codes. striking commonality found: transport below dynamically selected mesoscale has structure of L\'evy distribution, strongly nondiffusive, scale-free, avalanche mediated; larger scales, we report observation self-organized flow which...
The XGC1 edge gyrokinetic code is used for a high fidelity prediction the width of heat-flux to divertor plates in attached plasma condition. simulation results are validated against empirical scaling $\lambda_q \propto B_P^{-\gamma}$ obtained from present tokamak devices, where $\lambda_q$ mapped outboard midplane and $\gamma_q=1.19$ as defined by T. Eich et al. [Nucl. Fusion 53 (2013) 093031], $B_P$ magnitude poloidal magnetic field at separatrix surface. This predicts \leq 1mm$ when...
An overview of the physics intrinsic torque is presented, with special emphasis on phenomenology toroidal rotation in tokamaks, its theoretical understanding, and variety momentum transport bifurcation dynamics.Ohmic reversals ECH-driven counter are discussed some detail.Symmetry breaking by LSN vs. USN asymmetry related to origin at separatrix.
A fast edge turbulence suppression event has been simulated in the electrostatic version of gyrokinetic particle-in-cell code XGC1 a realistic diverted tokamak geometry under neutral particle recycling. The results show that sequence turbulent Reynolds stress followed by neoclassical ion orbit-loss driven together conspire to form sustaining radial electric field shear and quench transport just inside last closed magnetic flux surface. main action is located thin layer around ψN≃0.96–0.98,...
Spontaneous rotation sources in a quiescent tokamak edge plasma are studied without an external momentum source, such as, beam injected or wall-born neutrals. Discussions based upon example neoclassical solutions from gyrokinetic particle code. The main study is performed DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] with the ion Grad-B drift directed toward single-null divertor. Comparison reversed case also shown. It found that there robust spontaneous co-current toroidal source far...
It is found from a heat-flux-driven full-f gyrokinetic particle simulation that there ion temperature gradient (ITG) turbulence across an entire L-mode-like edge density pedestal in diverted tokamak plasma which the mild without structure, hence normalized parameter ηi=(d log Ti/dr)/(d n/dr) varies strongly high (>4 at top/shoulder) to low (<2 slope) values. Variation of and ηi same scale as correlation length, compressing slope region. The resulting thermal flux on order...
SUMMARY Exploding dataset sizes from extreme‐scale scientific simulations necessitates efficient data management and reduction schemes to mitigate I/O costs. With the discrepancy between bandwidth computational power, scientists are forced capture infrequently, thereby making collection an inherently lossy process. Although compression can be effective solution, random nature of real‐valued datasets renders lossless routines ineffective. These techniques also impose significant overhead...
Transport barrier formation and its relation to sheared flows in fluids plasmas are of fundamental interest various natural laboratory observations critical importance achieving an economical energy production a magnetic fusion device. Here we report the first observation edge transport event gyrokinetic simulation carried out realistic tokamak geometry. The results show that turbulent Reynolds stress driven ExB act concert with neoclassical orbit loss quench form just inside last closed...
Multimachine empirical scaling predicts an extremely narrow heat exhaust layer in future high magnetic field tokamaks, producing power densities that require mitigation. In the experiments presented, width of this is nearly doubled using actuators to increase turbulent transport plasma edge. This achieved low collisionality, confinement edge pedestals with their gradients limited by instead large-scale, coherent instabilities. The flux profile and divertor leg diffusive spreading both double...
Flux-driven global gyrokinetic codes are now mature enough to make predictions in terms of turbulence and transport tokamak plasmas. Some the recent breakthroughs three such codes, namely GYSELA, ORB5 XGC1, reported compared wherever appropriate. In all turbulent appears be mediated by avalanche-like events, for a broad range ρ * = i / values, ratio gyro-radius over minor radius. Still, radial correlation length scales with , leading gyro-Bohm scaling effective coefficient below ≈ 1/300. The...
Efficient handling of large volumes data is a necessity for exascale scientific applications and database systems. To address the growing imbalance between amount available storage being produced by high speed (FLOPS) processors on system, must be compressed to reduce total placed file General-purpose loss less compression frameworks, such as zlib bzlib2, are commonly used datasets requiring compression. Quite often, however, many sets compress poorly, referred hard-to-compress datasets, due...
The National Spherical Torus Experiment (NSTX) has undergone a major upgrade, and the NSTX Upgrade (NSTX-U) Project was completed in summer of 2015.NSTX-U first plasma subsequently achieved, diagnostic control systems have been commissioned, H-mode accessed, magnetic error fields identified mitigated, physics research campaign carried out.During ten run weeks operation, NSTX-U surpassed record pulse-durations toroidal (TF), high-performance ~1 MA plasmas comparable to best sustained near...
The application of a bundling technique to model the diverse charge states tungsten impurity species in total-f gyrokinetic simulations is demonstrated. method strategically groups ions similar charge, optimizing computational efficiency. initial radial configuration these bundles and their respective charges are derived from coronal approximation quasi-neutrality plasma. A low-density JET H-mode like plasma simulated using neoclassical version XGC across entire volume, spanning magnetic...
A new nonambipolar neoclassical transport (X-transport) mechanism has been identified which can be an irreducible baseline source of a strong radial electric field and edge pedestal formation immediately inside the separatrix in diverted tokamak. Due to vanishingly small poloidal magnetic vicinity divertor X-point, there exists ion velocity space hole at thermal energy level. This becomes nonambipolar, collisional, convective plasma ions, as ions scatter into out loss X-point. The widths Er...
Efficient analytics of scientific data from extreme-scale simulations is quickly becoming a top-notch priority. The increasing simulation output sizes demand for paradigm shift in how conducted. In this paper, we argue that query-driven over compressed---rather than original, full-size---data promising strategy order to meet storage-and-I/O-bound application challenges. As proof-of-principle, propose parallel query processing engine, called ISABELA-QA designed and optimized knowledge priors...
The simplified δf mixed-variable/pullback electromagnetic simulation algorithm implemented in XGC for core plasma simulations by Cole et al. [Phys. Plasmas 28, 034501 (2021)] has been generalized to a total-f that can include, the first time, boundary diverted magnetic geometry with neutral particle recycling, turbulence, and neoclassical physics. implementation is based on pioneering work Kleiber Mischenko [Kleiber al., Phys. 23, 032501 (2016); Mishchenko Comput. Commun. 238, 194 (2019)]....
The mission of the National Spherical Torus Experiment (NSTX) is demonstration physics basis required to extrapolate next steps for spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based (ST-CTF), and support ITER. Key issues are transport, steady state high β operation. To better understand electron new high- k scattering diagnostic was used extensively investigate gyro-scale fluctuations with varying temperature gradient scale length. Results from n = 3...
Treatment of binary Coulomb collisions when the full gyrokinetic distribution function is evolved discussed here. A spectrum different collision operators presented, differing through both physics that can be addressed and numerics they are based on. Eulerian-like (semi-Lagrangian) particle in cell (PIC) (Monte-Carlo) schemes successfully cross-compared, a detailed confrontation to neoclassical theory shown.
Multi-species kinetic neoclassical transport through the QH-mode pedestal and scrape-off layer on DIII-D is calculated using XGC0, a 5D full-f particle-in-cell drift-kinetic solver with self-consistent neutral recycling sheath potentials. Quantitative agreement between flux-driven simulation experimental electron density, impurity orthogonal measurements of temperature flow profiles achieved by adding random-walk particle diffusion to guiding-center drift motion. The radial electric field...
Understanding the multi-scale neoclassical and turbulence physics in edge region (pedestal + scrape-off layer (SOL)) is required order to reliably predict performance future fusion devices. We explore turbulent characteristics from a XGC1 gyrokinetic simulation DIII-D like tokamak geometry, here excluding neutrals collisions. For an H-mode type plasma with steep pedestal, it found that electron density fluctuations increase towards separatrix, stay high well into SOL, reaching maximum value...