A5008292006- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Solar and Space Plasma Dynamics
- Semiconductor materials and devices
- Nuclear Physics and Applications
- Nuclear physics research studies
- Nuclear reactor physics and engineering
- Laser-induced spectroscopy and plasma
- Physics of Superconductivity and Magnetism
- Nuclear Materials and Properties
- Advanced Chemical Physics Studies
- Thin-Film Transistor Technologies
- Atomic and Molecular Physics
- Silicon and Solar Cell Technologies
- Fluid Dynamics and Turbulent Flows
- Advanced Data Storage Technologies
- Silicon Carbide Semiconductor Technologies
- Advancements in Semiconductor Devices and Circuit Design
- Diamond and Carbon-based Materials Research
- Electrostatic Discharge in Electronics
University of California, San Diego
2013-2022
General Atomics (United States)
1995-2018
Oak Ridge Associated Universities
2017-2018
Max Planck Institute for Plasma Physics - Greifswald
2018
Princeton University
2018
Oak Ridge National Laboratory
2018
University of California, Los Angeles
1990-2017
William & Mary
2017
Williams (United States)
2017
Princeton Plasma Physics Laboratory
2017
Fruits from 107 genotypes of Vaccinium L., Rubus and Ribes were analyzed for total anthocyanins (ACY), phenolics (TPH), antioxidant capacities as determined by oxygen radical absorbing capacity (ORAC) ferric reducing power (FRAP). Fruit size was highly correlated (r = 0.84) with ACY within corymbosum but not to across eight other species, or 27 blackberry hybrids. Certain fruits pigmented flesh lower in ACY, TPH, ORAC, FRAP compared those values berries nonpigmented flesh. ORAC ranged 19 131...
A stochastic magnetic boundary, produced by an applied edge resonant perturbation, is used to suppress most large edge-localized modes (ELMs) in high confinement ($H$-mode) plasmas. The resulting $H$ mode displays rapid, small oscillations with a bursty character modulated coherent 130 Hz envelope. transport barrier and core are unaffected the despite threefold drop toroidal rotation. These results demonstrate that boundaries compatible may be attractive for ELM control next-step fusion tokamaks.
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...
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...
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...
Toroidicity induced Alfven eigenmodes (TAE) are observed in the DIII-D tokamak when energetic beam ions ( approximately 75 keV) used to destabilize mode. Measurements of neutron emission indicate that up 70% injected power is lost during strong TAE activity. poloidal distribution fast ion losses suggest greatest near vessel midplane. Fast discharges with combined fishbones and bursts 1.5 2 times greater than fishbone without TAB The scaling MHD mode amplitude exhibits no threshold amplitude,...
Large sub-millisecond heat pulses due to Type-I edge localized modes (ELMs) have been eliminated reproducibly in DIII-D for periods approaching nine energy confinement times (τE) with small dc currents driven a simple magnetic perturbation coil. The current required eliminate all but few isolated ELM impulses during coil pulse is less than 0.4% of plasma current. Based on field line modelling, the fields resonate flux surfaces across most pedestal region (0.9 ⩽ ψN 1.0) when q95 = 3.7 ± 0.2,...
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....
Density pumpout and edge-localized mode (ELM) suppression by applied $n=2$ magnetic fields in low-collisionality DIII-D plasmas are shown to be correlated with the magnitude of plasma response driven on high-field side (HFS) axis but not low-field (LFS) midplane. These distinct responses a direct measurement multimodal response, each structure preferentially excited different spectrum detected LFS or HFS. Ideal resistive magneto-hydrodynamic (MHD) calculations find that is primarily...
Proton energy spectra from ($d,p$) reactions induced by 12-MeV deuterons on targets of ${\mathrm{Mo}}^{92}$, ${\mathrm{Mo}}^{94}$, ${\mathrm{Mo}}^{98}$, and ${\mathrm{Nb}}^{93}$ were measured with 7-9-keV resolution. Angular distributions proton groups in the used to determine $l$ values transitions yielding respective groups. In Mo isotopes, all expected strength is found for leading ${s}_{\frac{1}{2}}$, ${d}_{\frac{3}{2}}$, ${d}_{\frac{5}{2}}$ states. contrast situation isotonic Zr where...
DIII-D experiments on rapid shutdown runaway electron (RE) beams have improved the understanding of processes involved in RE beam control and dissipation. Improvements feedback enabled stable confinement out to volt-second limit ohmic coil, as well enabling a ramp down zero current. Spectroscopic studies shown that neutrals tend be excluded from centre. Measurements energy distribution function indicate broad with mean order several MeV peak energies 30–40 MeV. The appears more skewed...
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...
Abstract Shattered pellet injection (SPI) is one of the prime candidates for ITER disruption mitigation system because its deeper penetration and larger particle flux than massive gas (MGI) (Taylor et al 1999 Phys. Plasmas 6 1872) using deuterium (Commaux 2010 Nucl. Fusion 50 112001, Combs IEEE Trans. Plasma Sci . 38 400, Baylor 2009 49 085013). The will likely use mostly high Z species such as neon more effective thermal pumping constraints on maximum amount or helium that could be...
DIII-D experiments at low density (n_{e}∼10^{19} m^{-3}) have directly measured whistler waves in the 100-200 MHz range excited by multi-MeV runaway electrons. Whistler activity is correlated with intensity (hard x-ray emission level), occurs novel discrete frequency bands, and exhibits nonlinear limit-cycle-like behavior. The frequencies scale magnetic field strength electron as expected from dispersion relation. modes are stabilized increasing field, which consistent wave-particle...
Edge conditions in DIII-D are being quantified order to provide insight into the physics of H mode regime. Several studies show that electron temperature is not key parameter controls L-H transition. Gradients edge and pressure much more promising candidates for elements such parameters. They systematically increase during L phases discharges which make a transition mode, these increases typically larger than underlying quantities. The quality confinement strongly correlated with height...
Cross-field fluctuation-driven transport is studied in edge and scrape-off layer (SOL) plasmas the DIII-D tokamak using a fast reciprocating Langmuir probe array allowing local measurements of particle heat fluxes. Two different non-diffusive mechanisms that can contribute strongly to cross-field SOL high-density discharges are identified compared. The first these involves intermittent events observed at plasma separatrix SOL. Intermittence has qualitatively similar character L-mode ELM-free...
A new sustained high-performance regime, combining discrete edge and core transport barriers, has been discovered in the DIII-D tokamak. Edge localized modes (ELMs) are replaced by a steady oscillation that increases particle transport, thereby allowing control with no ELM-induced pulsed divertor heat load. The barrier resembles those usually seen low (L) mode edge, without degradation often associated ELMs. barriers separated narrow region of high zero crossing E x B shearing rate.
Large Type-I edge-localized mode (ELM) heat pulses may limit the life of divertor targets in a burning plasma. Recent experiments show that pitch-resonant nonaxisymmetric magnetic perturbations plasma edge 0.0005 or less main field offer useful solution, but there is little room presently designed ITER for even small perturbation coils. We present proposed coil requirements ELM suppression, derived primarily from DIII-D suppression experiments. by calculated examples large arrays coils (e.g....
Far Scrape-Off Layer (SOL) and near-wall plasma parameters in DIII-D depend strongly on the discharge confinement regime. In L-mode discharges cross-field transport increases with average density flattens far SOL profiles, thus increasing contact low field side (LFS) main chamber wall. H-mode between edge localized modes (ELMs) plasma–wall is weaker than L-mode. During ELM fluxes of particles heat to LFS wall increase transiently above values. Depending conditions, ELMs are responsible for...
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 low amplitude (δbr∕BT=1 part in 5000) edge resonant magnetic field perturbation with toroidal mode number n=3 and poloidal numbers between 8 15 has been used to suppress most large type I localized modes (ELMs) without degrading core plasma confinement. ELMs have suppressed for periods of up 8.6 energy confinement times when the safety factor q95 is 3.5 4. The are replaced by packets events (possibly II ELMs) small amplitude, narrow radial extent, a higher level density fluctuations,...
Neutral beam injection into reversed magnetic shear DIII-D and ASDEX Upgrade plasmas produces a variety of Alfvénic activity including toroidicity-induced Alfvén eigenmodes (RSAEs). These modes are studied during the discharge current ramp phase when incomplete penetration results in high central safety factor increased drive due to multiple higher order resonances. Scans injected 80 keV neutral power on showed transition from classical AE dominated fast ion transport and, as previously...