A5008654555- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Nuclear Materials and Properties
- Particle accelerators and beam dynamics
- Laser-induced spectroscopy and plasma
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Nuclear reactor physics and engineering
- Metal and Thin Film Mechanics
- Semiconductor materials and devices
- Atomic and Subatomic Physics Research
- Atomic and Molecular Physics
- Silicon and Solar Cell Technologies
- Silicon Carbide Semiconductor Technologies
- Magnetic Field Sensors Techniques
- Advanced Sensor Technologies Research
- Diamond and Carbon-based Materials Research
- Advancements in Semiconductor Devices and Circuit Design
- GaN-based semiconductor devices and materials
- Spacecraft and Cryogenic Technologies
- Advanced Materials Characterization Techniques
Oak Ridge National Laboratory
2015-2024
National Technical Information Service
2021
Office of Scientific and Technical Information
2021
Oak Ridge Associated Universities
2008-2018
Lawrence Livermore National Laboratory
2014-2018
Sandia National Laboratories California
2018
University of California, San Diego
2008-2018
Knoxville College
2018
University of Tennessee at Knoxville
2016-2018
General Atomics (United States)
2009-2018
In this paper the manipulation of power deposition on divertor targets at DIII-D by application resonant magnetic perturbations (RMPs) for suppression large type-I edge localized modes (ELMs) is analysed. We discuss modification ELM characteristics RMP applied. It shown that width pattern in ELMy H-mode depends linearly deposited energy, whereas phase discharge those patterns are controlled externally induced perturbation. was also found heat transport due to small, plasma pedestal electron...
High repetition rate injection of deuterium pellets from the low-field side (LFS) DIII-D tokamak is shown to trigger high-frequency edge-localized modes (ELMs) at up $12\ifmmode\times\else\texttimes\fi{}$ low natural ELM frequency in $H$-mode plasmas designed match ITER baseline configuration shape, normalized beta, and input power just above threshold. The pellet size, velocity, location were chosen limit penetration outer 10% plasma. resulting perturbations plasma density energy...
A study of three-dimensional (3D) perturbed magnetic field structures and transport for edge localized mode control experiments with resonant perturbations at DIII-D is presented. We focus on ITER-Similar Shape plasmas ITER relevant electron pedestal collisionalities . This performed in comparison results from TEXTOR-Dynamic Ergodic Divertor circular limiter plasmas. For both the structure analyzed vacuum paradigm—superimposing external RMP unperturbed equilibrium. TEXTOR L-mode this...
A comprehensive set of L–H transition experiments has been performed on DIII-D to determine the requirements for access H-mode plasmas in ITER's first (non-nuclear) operational phase with H and He second (activated) D plasmas. The power threshold, P TH , was evaluated different configurations auxiliary heating methods main ion species. Helium have significantly higher than deuterium at low densities all schemes, but similar as high except H-neutral beam injection-heated discharges, which are...
Abstract Recent experiments on DIII-D have increased confidence in the ability to suppress edge-localized modes (ELMs) using edge-resonant magnetic perturbations (RMPs) ITER, including an improved physics basis for edge response RMPs as well expansion of RMP ELM suppression more ITER-like conditions. Complete has been achieved utilizing n = 3 ITER baseline scenario. In addition, expanded include plasmas with helium concentrations near 25% and use 2 RMPs. Analysis kinetic profile suggests...
Abstract ST40 is a compact, high-field ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>B</mml:mi> <mml:mi mathvariant="normal">T</mml:mi> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mtext>⩽</mml:mtext> <mml:mn>2.1</mml:mn> <mml:mstyle scriptlevel="0"/> <mml:mtext>T</mml:mtext> </mml:math> ) spherical tokamak (ST) with mission to expand the physics and technology basis for ST route commercial fusion. The research programme covers...
We report on a recent set of experiments performed in NSTX to explore the effects non-axisymmetric magnetic perturbations stability edge-localized modes (ELMs). The application these 3D fields was found have strong effect ELM stability, including destabilization ELMs H-modes otherwise free large ELMs. Exploiting perturbations, been controllably introduced into lithium-enhanced ELM-free H-modes, causing reduction impurity accumulation while maintaining high confinement. Although show...
The application of nonaxisymmetric magnetic fields is shown to destabilize edge-localized modes (ELMs) during otherwise ELM-free periods discharges in the National Spherical Torus Experiment (NSTX). Profile analysis shows applied increased temperature and pressure gradients, decreasing edge stability. This robust effect was exploited for a new form ELM control: triggering ELMs at will high performance H mode plasmas enabled by lithium conditioning, yielding time-averaged energy confinement...
Linear, two-fluid, resistive modelling of the plasma response to applied non-axisymmetric fields shows significant displacement edge temperature and density profiles. The calculated displacements, often 2 cm or more in H-mode pedestals with parameters appropriate DIII-D, are due helical distortions resulting from stable modes being driven finite amplitude by fields. In many cases, these displacements greater magnitude, different phase, than separatrix manifolds predicted vacuum modelling....
It is important to develop a predictive capability for the tungsten source rate near strike points during H-mode operation in ITER and beyond. deuterium plasma exposures were performed on W-coated graphite molybdenum substrates DIII-D divertor using DiMES. The W-I 400.9 nm spectral line was monitored by fast filtered diagnostics cross calibrated via high-resolution spectrometer resolve inter-ELM W erosion. effective ionization/photon (S/XB) unique method developed based surface analysis....
Abstract Using a recently installed impurity powder dropper (IPD), boron (<150 μ m) was injected into lower single null (LSN) L-mode discharges in WEST. IPDs possibly enable real-time wall conditioning of the plasma-facing components and may help to facilitate H-mode access full-tungsten environment The this experiment featured I p = 0.5 MA, B T 3.7 T, q 95 4.3, t pulse 12–30 s, n e,0 ∼ 4 × 10 19 m −2 , P LHCD 4.5 MW. Estimates deuterium particle fluxes, derived from combination visible...
Abstract High-Z plasma facing components redeposit within the sheath through a combination of two distinct mechanisms: prompt (or geometric-driven) and local sheath-driven) redeposition. Experimental efforts are needed to determine leading-order parameters influencing prompt-vs-local trade-off, which sets fraction material entering scrape-off layer. In preparation for such experiments, isolated PYEAD-RustBCA-GITR coupled net erosion code using Sobol’ sensitivity analysis. Then, experiments...
Good alignment of the magnetic field line pitch angle with mode structure an external resonant perturbation (RMP) is shown to induce modulation pedestal electron pressure p(e) in high confinement rotation plasmas at DIII-D tokamak a shape similar ITER, next step experiment. This caused by edge safety factor q95 enhancement thermal transport, while contrast, RMP induced particle pump out does not show significant resonance. The measured reduction correlates increase modeled stochastic layer...
The engineering limits of plasma-facing components (PFCs) constrain the allowable operational space tokamaks. Poorly managed heat fluxes that push PFCs beyond their not only degrade core plasma performance via elevated impurities, but can also result in PFC failure due to thermal stresses or melting. Simple axisymmetric assumptions fail capture complex interaction between three-dimensional (3-D) geometry and two-dimensional 3-D plasmas. This results fusion systems must either operate with...
Modification of the two existing DIII-D neutral beamlines is planned to allow vertical steering provide off-axis beam current drive (NBCD) peaked as far half plasma minor radius. New calculations for a downward-steered indicate strong with good localization so long toroidal magnetic field, B T , and current, I p point in same direction. This due alignment injection (NBI) local pitch field lines. model has been tested experimentally on by injecting equatorially mounted NBs into reduced size...
Bulk ion toroidal velocity profiles, V||D+, peaking at 40–60 km/s are observed with Mach probes in a narrow edge region of DIII-D discharges without external momentum input. This intrinsic rotation can be well reproduced by first principle, collisionless kinetic loss model thermal that predicts the existence loss-cone distribution space resulting co-Ip directed velocity. We consider two models, one which includes turbulence-enhanced transport, as Pfirsch-Schluter (P-S) fluid mechanism....
Abstract A set of experiments are planned to exploit the high SOL collisionality enabled by a tightly baffled slot divertor geometry suppress tungsten leakage in DIII-D. toroidal row graphite tiles from Small Angle Slot (SAS) is being coated with 10–15 μ m tungsten. New spectroscopic viewing chords in-vacuo optics will measure W gross erosion source surface spatial and temporal resolution. In parallel, bottom SAS changed flat ‘V’ shape. SOLPS-ITER/DIVIMP simulations conducted drifts using...
The spatial and temporal evolution of the total pedestal pressure profile has been measured during between successive edge localized modes (ELMs) type-I ELMing H-mode discharges in DIII-D. Measurements are used to test a model that predicts kinetic ballooning (KBMs) provide strong constraint on gradient obtained an inter-ELM cycle cause width scale as square root poloidal beta. Discharges two different parameter regimes examined for evidence reaches limit prior onset ELM. Both show rapid...
The injection of small deuterium pellets at high repetition rates up to 12× the natural edge localized mode (ELM) frequency has been used trigger high-frequency ELMs in otherwise low ELM H-mode discharges DIII-D tokamak [J. L. Luxon and G. Davis, Fusion Technol. 8, 441 (1985)]. resulting pellet-triggered result lower energy particle fluxes divertor than ELMs. plasma global confinement density are not strongly affected by pellet perturbations. core impurity is reduced with application...
In this paper, results of a direct comparison TEXTOR and DIII-D experiments with resonant magnetic perturbation (RMP) fields are presented. This resistive L-mode plasmas at highly conductive H-mode is useful to identify generic physics mechanisms during application RMP strong field line pitch angle alignment in the plasma edge.A reduction pedestal electron pressure pe increasing extension vacuum modelled stochastic layer recovery decreasing width found caused by q95 edge (0.8 < ΨN < 0.95)...
During the first operational phase (referred to as OP1.1) of new Wendelstein 7-X (W7-X) stellarator, five poloidal graphite limiters were mounted on inboard side vacuum vessel, one in each toroidal modules which form W7-X vessel. Each limiter consisted nine specially shaped tiles, designed conform last closed field line geometry bean-shaped section standard OP1.1 magnetic configuration (Sunn Pedersen et al 2015 Nucl. Fusion 55 126001). We observed with multiple infrared and visible camera...