A5063763929- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Semiconductor materials and devices
- Electrostatic Discharge in Electronics
- Laser-induced spectroscopy and plasma
- Nuclear Physics and Applications
- Advanced Data Storage Technologies
- Nuclear reactor physics and engineering
- Gyrotron and Vacuum Electronics Research
- Silicon Carbide Semiconductor Technologies
- Diamond and Carbon-based Materials Research
- Solar and Space Plasma Dynamics
- GaN-based semiconductor devices and materials
- Advancements in Semiconductor Devices and Circuit Design
- Laser Design and Applications
- Metal and Thin Film Mechanics
- Thin-Film Transistor Technologies
- Physics of Superconductivity and Magnetism
- Atomic and Molecular Physics
- Energetic Materials and Combustion
Oak Ridge National Laboratory
2008-2019
General Atomics (United States)
1978-2015
University of California, Los Angeles
2004-2012
Lawrence Livermore National Laboratory
2007
DIII-D National Fusion Facility
2001-2003
Fusion (United States)
1994-2003
Princeton Plasma Physics Laboratory
1986-1999
Osaka University
1997
Princeton University
1984-1996
Joint European Torus
1993-1994
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...
Significant progress has been made in the area of advanced modes operation that are candidates for achieving steady state conditions a fusion reactor. The corresponding parameters, domain operation, scenarios and integration issues discussed this chapter. A review presently developed scenarios, including discussions on operational space, is given. heating current drive recent years, especially off-axis drive, which essential achievement required profile. actuators necessary to produce...
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 transport effects induced by resistive ballooning modes are estimated from a theory, and found to be mainly thermal electron conduction losses. An expression for diffusivity ${\ensuremath{\chi}}_{e}$ is derived. theoretical predictions agree well with experimental values of obtained power balance the ISX-$B$ plasmas at high poloidal beta.
Results are reported of electron-cyclotron-heating experiments in which 80 kW microwave power from a 35-GHz gyrotron is injected into tokamak with large single-pass absorption. For 10-ms pulses, incident the high-field side torus, central electron temperature increases 850 to 1250 eV, agreement empirical transport-code calculations. first time it demonstrated that scales linearly power.
Peak fusion power production of 6.2\ifmmode\pm\else\textpm\fi{}0.4 MW has been achieved in TFTR plasmas heated by deuterium and tritium neutral beams at a total 29.5 MW. These have an inferred central alpha particle density 1.2\ifmmode\times\else\texttimes\fi{}${10}^{17}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$ without the appearance either disruptive magnetohydrodynamics events or detectable changes Alfv\'en wave activity. The measured loss rate energetic particles agreed with...
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...
Discharges which can satisfy the high gain goals of burning plasma experiments have been demonstrated in DIII-D tokamak under stationary conditions at relatively low current (q95>4). A figure merit for fusion (βNH89/q952) has maintained values corresponding to Q = 10 operation a >6 s or 36τE and 2τR. The key element is relaxation profile state with qmin>1. In absence sawteeth fishbones, stable achieved up estimated no-wall β limit. Feedback control energy content particle inventory allow...
Integrated simulations are performed to establish a physics basis, in conjunction with present tokamak experiments, for the operating modes International Thermonuclear Experimental Reactor (ITER). Simulations of hybrid mode done using both fixed and free-boundary 1.5D transport evolution codes including CRONOS, ONETWO, TSC/TRANSP, TOPICS ASTRA. The is simulated GLF23 CDBM05 energy models. injected powers limited negative ion neutral beam, cyclotron electron heating systems. Several plasma...
A potential new standard in stationary tokamak performance is emerging from experiments on DIII-D. These have demonstrated the ability to operate near free boundary, n = 1 stability limit with good confinement quality under conditions. The normalized fusion at or above that projected for Qfus 10 operation International Thermonuclear Experimental Reactor (ITER) design over a wide operating range both edge safety factor (2.8–4.7) and plasma density (35–70% of Greenwald density). Projections...
Recent calculations have shown that when external momentum sources and plasma rotation are included in the neoclassical theory, standard results for impurity transport can be strongly altered. Under appropriate conditions, inward convection is reduced by co-injection enhanced counter-injection. In order to examine theoretical predictions, several observations of been made ISX-B tokamak during neutral-beam injection comparison with seen Ohmic heating alone. Both intrinsic contaminants...
Confinement studies on the Impurity Study Experiment (ISX-B) in beam-heated plasmas contaminated with small quantities of low-Z impurities are reported. Experimental results correlation particle and energy confinement presented. A linear relationship plasma density is observed. As increased further, this effect saturates becomes independent electron density. The experiments have been extended to higher beam power, resulting an expansion ISX-B operating space. Impurities other than neon...
The Tomamak Fusion Test reactor has performed initial high-power experiments with the plasma fueled nominally equal densities of deuterium and tritium. Compared to pure plasmas, energy stored in electron ions increased by \ensuremath{\sim}20%. These increases indicate improvements confinement associated use tritium possibly heating electrons \ensuremath{\alpha} particles created D-T fusion reactions.
Discharges exhibiting the highest plasma energy and fusion reactivity yet realized in DIII-D tokamak [Plasma Physics Controlled Nuclear Fusion Research, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159] have been produced by combining benefits of a hollow or weakly sheared central current profile [Phys. Plasmas 3, 1983 (1996)] with high confinement (H mode) edge. In these discharges, low-power neutral beam injection heats electrons during initial ramp, “freezes in”...
High-speed pellet fuelling experiments have been performed on the ISX-B device in a new regime characterized by large global density rise both Ohmically and neutral-beam heated discharges. Hydrogen pellets of 1 mm diameter were injected plasma midplane at velocities exceeding km·s−1. In low-temperature Ohmic discharges, penetrate beyond magnetic axis, such cases sharp decrease ablation is observed as passes centre. This behaviour can be accounted for an model that includes dynamic cooling...
Neutral-beam injection of up to 2.5 MW into plasmas in the ISX-B tokamak (R0 = 0.93 m, a 0.27 BT 0.9–1.5 T, Ip 70–210 kA, e 2.5–10×1013 cm−3) has created with volume-averaged beta ∼ 2.5%, peak values 9%, and root-mean-square 3.5%. Energy confinement time is observed decrease by about factor two as beam power goes from 0 MW; caused predominantly electron falling below predictions 'Alcator scaling' 3–4 at high power. An empirical relationship form fits our measurements over wide range plasma...
Several spectral lines produced by charge transfer of neutral-beam hydrogen atoms with completely ionized oxygen have been detected in the impurity studies experiment $B$ ($\mathrm{I}\mathrm{S}\mathrm{X}\ensuremath{-}B$) tokamak, and used to compute absolute concentrations ${\mathrm{O}}^{8+}$. charge-exchange recombination is found a minor effect on total radiative losses, but enhanced transport during injection appears raise radiation from interior discharges factors 3 5. This result may...
Cross-field diffusion of energetic ions by microturbulence is measured during neutral-beam injection into the DIII-D tokamak. Fast-ion D(alpha), neutron, and motional Stark effect measurements diagnose fast-ion distribution function. As expected for transport plasma turbulence, anomalies relative to classical prediction are greatest in high temperature plasmas, at low energy, larger minor radius. Theoretical estimates comparable experimental levels.
Recent progress on ITER steady-state (SS) scenario modelling by the ITPA-IOS group is reviewed. Code-to-code benchmarks as IOS group's common activities for two SS scenarios (weak shear and internal transport barrier scenario) are discussed in terms of transport, kinetic profiles, heating current drive (CD) sources using various codes. Weak magnetic integrate plasma core edge combining a theory-based model (GLF23) with scaled experimental boundary profiles. The profiles (at normalized radius...
Abstract Neutral beam injection into reversed-magnetic shear DIII-D plasmas produces a variety of Alfvénic activity including toroidicity-induced Alfvén eigenmodes (TAEs) and reversed (RSAEs). With measured equilibrium profiles as inputs, the ideal MHD code NOVA is used to calculate these plasmas. The postprocessor NOVA-K then perturbatively actual stability modes, finite orbit width Larmor radius effects, reasonable agreement with spectrum observed modes found. Using experimentally mode...
Since its inception in 2002, the International Tokamak Physics Activity topical group on Integrated Operational Scenarios (IOS) has coordinated experimental and modelling activity development of advanced inductive scenarios for applications ITER tokamak. The physics basis prospects have been significantly during that time, especially with respect to results. principal findings this research are as follows. Inductive capable higher normalized pressure (βN ⩾ 2.4) than baseline scenario = 1.8)...
Abstract The potential of the hybrid scenario (first developed as an advanced inductive for high fluence) a regime high-beta, steady-state plasmas is demonstrated on DIII-D tokamak. These experiments show that beneficial characteristics hybrids, namely safety factor ⩾1 with low central magnetic shear, stability limits and excellent confinement, are maintained when strong current drive (electron cyclotron neutral beam) applied to increase calculated non-inductive fraction ≈100% (≈50%...
The amplitude and frequency of modes driven in the edge region tokamak high mode (H-mode) discharges [type I edge-localized (ELMs)] are shown to depend on discharge shape. measured pressure gradient threshold for instability its scaling with shape compared predictions from ideal magnetohydrodynamic theory low toroidal number (n) instabilities by current density good agreement is found. Reductions observed shapes either squareness or triangularity where stability predicted be reduced most...