A5049120697- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Particle accelerators and beam dynamics
- Nuclear reactor physics and engineering
- Semiconductor materials and devices
- Nuclear Materials and Properties
- Laser-induced spectroscopy and plasma
- Solar and Space Plasma Dynamics
- Physics of Superconductivity and Magnetism
- Advanced Data Storage Technologies
- Thin-Film Transistor Technologies
- Electrostatic Discharge in Electronics
- Nuclear Physics and Applications
- Advancements in Semiconductor Devices and Circuit Design
- Atomic and Molecular Physics
- Dust and Plasma Wave Phenomena
- Silicon and Solar Cell Technologies
- Semiconductor Quantum Structures and Devices
- Silicon Carbide Semiconductor Technologies
- GaN-based semiconductor devices and materials
- Metallurgical Processes and Thermodynamics
General Atomics (United States)
2015-2024
Cork University Hospital
2023
Lawrence Livermore National Laboratory
1995-2018
Duke University
2015
University of California, Los Angeles
2009-2011
University of Wisconsin–Madison
1985-2011
Massachusetts Institute of Technology
2011
Princeton Plasma Physics Laboratory
2011
University of California, San Diego
2001-2010
University of York
2009
Progress, since the ITER Physics Basis publication (ITER Editors et al 1999 Nucl. Fusion 39 2137–2664), in understanding processes that will determine properties of plasma edge and its interaction with material elements is described. Experimental areas where significant progress has taken place are energy transport scrape-off layer (SOL) particular anomalous scaling, particle SOL plays a major role diverted plasmas main-chamber elements, localized mode (ELM) deposition on mechanism for ELM...
The 'Progress in the ITER Physics Basis' (PIPB) document is an update of 'ITER (IPB), which was published 1999 [1]. IPB provided methodologies for projecting performance burning plasmas, developed largely through coordinated experimental, modelling and theoretical activities carried out on today's large tokamaks (ITER R&D). In IPB, projections (1998 Design) were also presented. pointed some outstanding issues. These issues have been addressed by Participant Teams (the European Union, Japan,...
A model based on magnetohydrodynamic (MHD) stability of the tokamak plasma edge region is presented, which describes characteristics localized modes (ELMs) and pedestal. The emphasizes dual role played by large bootstrap currents driven sharp pressure gradients in pedestal region. Pedestal reduce magnetic shear, stabilizing high toroidal mode number (n) ballooning modes, while at same time providing drive for intermediate to low n peeling modes. result that coupled peeling–ballooning...
A multi-machine database for the H-mode scrape-off layer power fall-off length, λq in JET, DIII-D, ASDEX Upgrade, C-Mod, NSTX and MAST has been assembled under auspices of International Tokamak Physics Activity. Regression inside finds that most important scaling parameter is poloidal magnetic field (or equivalently plasma current), with decreasing linearly increasing Bpol. For conventional aspect ratio tokamaks, regression , yielding λq,ITER ≅ 1 mm baseline inductive burning scenario at Ip...
Analysis of Type I ELMs from ongoing experiments shows that ELM energy losses are correlated with the density and temperature pedestal plasma before crash. The loss normalized to is found correlate across collisionality (ν*ped), decreasing increasing ν*ped. Other parameters affect size, such as edge magnetic shear, etc, which influence volume affected by ELMs. particle influenced this weakly dependent on other parameters. In JET DIII-D, under some conditions, can be observed (`minimum'...
We develop and test a model, EPED1.6, for the H-mode pedestal height width based upon two fundamental calculable constraints: (1) onset of non-local peeling–ballooning modes at low to intermediate mode number, (2) nearly local kinetic ballooning high number. Calculation these constraints allows unique, predictive determination both width. The present version model is first principles, in that no parameters are fit observations, includes important non-ideal effects. Extensive successful...
Large Type-I edge localized modes (ELMs) are completely eliminated with small n = 3 resonant magnetic perturbations (RMP) in low average triangularity, , plasmas and ITER similar shaped (ISS) plasmas, relevant collisionalities . Significant differences the RMP requirements properties of ELM suppressed found when comparing two triangularities. In ISS current required to suppress ELMs is approximately 25% higher than triangularity plasmas. It also that width q95 window for suppression smaller...
The pressure at the top of edge transport barrier (or “pedestal height”) strongly impacts tokamak fusion performance. Predicting pedestal height in future devices such as ITER [ITER Physics Basis Editors, Nucl. Fusion 39, 2137 (1999)] remains an important challenge. While uncertainties remain, magnetohydrodynamic stability calculations intermediate wavelength (the “peeling-ballooning” model), accounting for diamagnetic stabilization, have been largely successful determining observed maximum...
Edge-localized-modes (ELMs) are a ubiquitous feature of H-mode in tokamaks. When gradients the transport barrier grow to exceed MHD stability limit ELM instability grows explosively, rapidly transporting energy and particles onto open field lines material surfaces. Though ELMs provide additional particle impurity through barrier, enabling steady operation, resulting heat flux transients plasma facing surfaces project large amplitude future low collisionality burning Measurements deposition...
Intermittent plasma objects (IPOs) featuring higher pressure than the surrounding plasma, and responsible for ∼50% of E×BT radial transport, are observed in scrape off layer (SOL) edge DIII-D tokamak [J. Watkins et al., Rev. Sci. Instrum. 63, 4728 (1992)]. Conditional averaging reveals that IPOs, produced at a rate ∼3×103 s−1, positively charged also polarized, poloidal electric fields up to 4000 V/m. The IPOs move poloidally speeds 5000 m/s radially with E×BT/B2 velocities ∼2600 near last...
Intermittent plasma objects (IPOs), featuring higher pressure than the surrounding plasma, are responsible for ∼50% of E×BT radial transport in scrape off layer (SOL) Doublet III D (DIII-D) tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] L- and H-mode discharges. Conditional averaging reveals that IPOs positively charged feature internal poloidal electric fields up to 4000 V/m. The move radially with E×BT/B2 velocities ∼2600 m/s near last closed flux surface (LCFS), ∼330 wall. slow down...
Understanding the physics of edge pedestal and localized modes (ELMs) is great importance for ITER optimization tokamak concept. The peeling–ballooning model has quantitatively explained many observations, including ELM onset constraints, in standard H-mode regime. ELITE code been developed to efficiently evaluate stability comparison with observation predictions future devices. We briefly review recent progress model, experimental validation height predictions, nonlinear 3D simulations...
Metallic mirrors will be used in ITER for optical diagnostics working different spectral ranges. Their properties change with time due to erosion, deposition, and particle implantation. First tests of molybdenum were performed the DIII-D divertor under deposition-dominated conditions. Two sets recessed 2cm below floor private flux region exposed a series identical, lower-single-null, ELMing (featuring edge localized modes) H-mode discharges detached plasma conditions both legs. The first set...
We review and test the peeling–ballooning model for edge localized modes (ELMs) pedestal constraints, a based upon theoretical analysis of magnetohydrodynamic (MHD) instabilities that can limit height drive ELMs. A highly efficient MHD stability code, ELITE, is used to calculate quantitative constraints on pedestal, including height. Because impact collisionality bootstrap current, these are dependent density temperature separately, rather than simply pressure. ELITE calculations directly...
The pressure at the top of edge transport barrier (or ‘pedestal height’) strongly impacts fusion performance, while large localized modes (ELMs), driven by free energy in pedestal region, can constrain material lifetimes. Accurately predicting height and ELM behavior ITER is an essential element prediction optimization performance. Investigation intermediate wavelength MHD ‘peeling–ballooning’ modes) has led to improved understanding important constraints on mechanism for ELMs. combination...
Recent research in scrape-off layer (SOL) and divertor physics is reviewed; new existing data from a variety of experiments have been used to make cross-experiment comparisons with implications for further ITER. Studies the region near separatrix addressed relationship profiles turbulence as well scaling parallel power flow. Enhanced low-field side radial transport implicated driving flows inboard side. The medium-n nature edge localized modes (ELMs) has elucidated measurements determined...
The EPED model predicts the H-mode pedestal height and width based upon two fundamental calculable constraints: (1) onset of non-local peeling-ballooning modes at low to intermediate mode number, (2) nearly local kinetic ballooning high number. We present detailed tests in discharges with edge localized (ELMs), employing new resolution measurements, finding good quantitative agreement across a range parameters. is then applied for first time quiescent (QH), similar level between predicted...
Observations of divertor plasma detachment in tokamaks are reviewed. Plasma is characterized terms transport and dissipation power, momentum particle flux along the open field lines from midplane to divertor. Asymmetries onset other characteristics between inboard outboard plasmas found be primarily driven by drifts. The effect plate geometry magnetic configuration on summarized. Control has progressed with a development number diagnostics characterize detached state real-time. Finally...
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...
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...
Recent DIII-D [J. L. Luxon et al., Nucl. Fusion 43, 1813 (2003)] experiments show a correlation between the extent of overlap magnetic islands induced in edge plasma by perturbation coils and complete suppression Type-I localized modes (ELMs) plasmas with ITER-like electron pedestal collisionality νe*∼0.1, flux surface shape low safety factor (q95≈3.6). With fixed amplitude n=3 resonant (RMP), ELM is obtained only finite window (q95) consistent maximizing component applied helical field....
A coordinated effort to measure divertor heat flux characteristics in fully attached, similarly shaped H-mode plasmas on C-Mod, DIII-D, and NSTX was carried out 2010 order construct a predictive scaling relation applicable next step devices including ITER, FNSF, DEMO. Few published laws are available those that have been were obtained under widely varying conditions geometries, leading conflicting predictions for this critically important quantity. This study designed overcome these...
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 Since the publication of review Progress in ITER Physics Basis (PIPB) 2007, significant progress has been made understanding processes at plasma-material interface. This review, part ITPA Nuclear Fusion Special Issue On Path to Burning Plasma Operation , presents these developments, focusing on key areas such as physics plasma exhaust, interactions, and properties plasma-facing materials their evolution under exposure. The coordinated efforts Topical Group Scrape-Off Layer Divertor...