A5057537941- High-Temperature Coating Behaviors
- Fusion materials and technologies
- Magnetic confinement fusion research
- Laser-induced spectroscopy and plasma
- Advanced materials and composites
- Nuclear Materials and Properties
- Advanced ceramic materials synthesis
- Catalytic Processes in Materials Science
- Metal and Thin Film Mechanics
- Laser-Plasma Interactions and Diagnostics
- Atomic and Molecular Physics
- Nuclear materials and radiation effects
- Plasma Diagnostics and Applications
- Atomic and Subatomic Physics Research
- Material Properties and Applications
- Superconducting Materials and Applications
- Advanced MRI Techniques and Applications
- Particle accelerators and beam dynamics
- Probabilistic and Robust Engineering Design
- Reservoir Engineering and Simulation Methods
- Hydrocarbon exploration and reservoir analysis
- Ion-surface interactions and analysis
- Diamond and Carbon-based Materials Research
- Fatigue and fracture mechanics
- Advanced Materials Characterization Techniques
Oak Ridge National Laboratory
2022-2024
University of Nevada, Reno
2024
Auburn University
2017-2023
GE Global Research (United States)
1997-2023
Pi (United Kingdom)
2023
Oak Ridge Institute for Science and Education
2022
Oak Ridge Associated Universities
2022
Lawrence Livermore National Laboratory
1983-2021
General Atomics (United States)
2021
Baker Hughes (United States)
2020
Thermal barrier coatings (TBCs) are increasingly susceptible to degradation by molten calcium–magnesium alumino silicate (CMAS) deposits in advanced engines that operate at higher temperatures and environments laden with siliceous debris. This paper investigates the thermochemical aspects of phenomena using a model CMAS composition ZrO 2 –7.6%YO 1.5 (7YSZ) grown vapor deposition on alumina substrates. The changes microstructure chemistry characterized after isothermal treatments 4 h...
A study was carried out on volunteer Eskimo families at Barrow, Alaska. The total population consisted of 508 subjects with complete information including a clinical examination as well refractions and without cycloplegics. Correlations between refractive errors parents children siblings are determined 41 family units comprising 197 subjects. correlations were not significantly different from zero, whereas the high significant. These results interpreted to suggest that there is no major...
The temperature capability of yttria‐stabilized zirconia thermal barrier coatings (TBCs) is ultimately tied to the rate evolution “nontransformable” t ′ phase into a depleted tetragonal form predisposed monoclinic transformation on cooling. phase, however, has been shown decompose in small fraction time necessary phase. Instead, modulated microstructure consisting coherent array Y‐rich and Y‐lean lamellar phases develops early process, with mechanistic features suggestive spinodal...
Phase evolution accompanying the isothermal aging of free‐standing air‐plasma sprayed ( APS ) 7–8 wt% yttria‐stabilized zirconia (8 YSZ thermal barrier coatings TBC s) is described. Aging was carried out at temperatures ranging from 982°C to 1482°C in air. The high‐temperature kinetics phase metastable t′ into a mixture transformable Y‐rich (cubic) and Y‐lean (tetragonal) phases are documented through ambient temperature X‐ray diffraction XRD characterization. A Hollomon–Jaffe parameter...
The correlation between microstructural and phase evolution in aged, yttria‐partially‐stabilized zirconia, air plasma‐sprayed coatings is discussed. Freestanding with the dense, vertically cracked structure were isothermally aged at 1482°C (2700°F) air. Characterization of resulting microstructures was conducted using transmission electron microscopy, then compared a parallel analysis via synchrotron X ‐ray diffraction ( XRD ) described Part I. Additional context provided by related studies...
A systematic study of factors affecting the delamination energy release rate and mode mix a thermal barrier coating attached to substrate is presented accounting for influence gradients combined with rapid hot surface cooling. Transient induce stress through substrate, which produce overall bending if not very thick it constrained. Due their influences on stresses, thickness constraint are important aspects mechanics coating-substrate systems, must be considered when laboratory tests...
A machine learning approach has been implemented to measure the electron temperature directly from emission spectra of a tokamak plasma. This utilized neural network (NN) trained on dataset 1865 time slices operation DIII-D using extreme ultraviolet / vacuum (EUV/VUV) spectroscopy matched with high-accuracy divertor Thomson scattering measurements temperature, $T_e$. NN is shown be particularly good at predicting $T_e$ low temperatures ($T_e < 10$ eV) where demonstrated mean average error...
Failure mechanisms were determined for electron‐beam physical‐vapor‐deposited thermal barrier coating (TBC) systems from the degradation of mechanical properties and microstructural changes in a furnace cycle test. Bond strength TBCs resulted initiation growth interfacial delamination defects between yttria‐stabilized zirconia topcoat thermally grown alumina (TGO). It is proposed that started concave depressions bondcoat surface created by grit‐blast‐cleaning process defect was driven...
The properties of emitting ions in a plasma provides both potential for diagnostics and key information required modeling. Generalized collisional radiative theory powerful tool the modeling low moderately dense plasmas. A new Python program is presented that solves ionization balance equations application to fusion, laboratory, astrophysical It produces generalized coefficients can be easily imported into existing codes spectral diagnostics. An overview code presented, along with selected...
This paper describes the results from multidisciplinary characterization/scattering techniques used for quantitative characterization of industrial thermal barrier coating (TBC) systems in advanced gas turbines. While past requirements TBCs primarily addressed function insulation/life extension metallic components, new demands necessitate a requirement spallation resistance/strain tolerance, i.e., prime reliance, on part TBC. In an extensive effort to incorporate these TBCs,...
The ATA is an induction accelerator designed to produce 70 ns pulses of electrons at currents 10 kA and energies in excess 50 MeV. capable operating average rate 5 Hz or 1 kHz for ten pulses. parameters were chosen primarily provide the experimental basis advancing understanding electron beam propagation physics. 85 m has been under construction past four years adopted mainly improved version ETA technology satisfy required parameters. Initial operation facility energy conversion system from...
Transformational plasticity associated with the monoclinic‐to‐cubic phase transition at 730°C in Bi 2 O 3 was observed and characterized. This phenomenon is explained terms of Greenwood Johnson's model internal stress‐induced deformation, proceeding, this instance, by a time‐dependent, grain‐size‐sensitive creep mechanism, probably grain‐boundary sliding. Criteria are proposed for choosing other prospective transformationally plastic ceramics; they met WO 6 , which also exhibits extensive...
Abstract Fundamental mechanisms governing the erosion and prompt re-deposition of tungsten impurities in tokamak divertors are identified analyzed to inform lifetime plasma-facing components ITER other future devices. Various experiments conducted at DIII-D benchmark predictive models presented, leveraging DiMES removable sample exposure probe capability Metal Rings Campaign, which toroidally symmetric rows tungsten-coated tiles were installed divertor. In divertors, width electric sheath is...
Abstract Experimental data, together with interpretive modeling tools, are examined to study trends in the tungsten (W) source all-W environment of WEST tokamak, both from divertor and main chamber. In particular, a poloidal limiter protecting an ion cyclotron resonance heating (ICRH) antenna is used as proxy for chamber sourcing. The key carried out by stepping up lower hybrid current drive (LHCD) power, only auxiliary power source. Limiter W sources exhibit qualitatively similar...
Neutral tungsten is the primary candidate as a wall material in divertor region of International Thermonuclear Experimental Reactor (ITER). The efficient operation ITER depends heavily on precise atomic physics calculations for determination reliable erosion diagnostics, helping to characterize influx impurities into core plasma. following paper presents detailed structure neutral using multiconfigurational Dirac-Fock method, drawing comparisons with experimental measurements where...
A cycloplegic and non-cycloplegic refraction was obtained on 946 eyes of 213 male subjects 291 female Eskimos between 6 88 years old. When the results are compared with those white by Bannon, good agreement is found two studies in case hypermetropic but relatively poor for myopic subjects. Bannon approximately 38% his cases showing less myopia under cycloplegia whereas present study 75% cycloplegia. The Barrow population shows an exceptionally high proportion myopes age group 11 26 60% being...
Abstract Long-lived metastable states in neutral tungsten are shown to potentially impact measurements of erosion from plasma facing components. Time-dependent collisional radiative modeling is used analyze the role these emission and ionization. The large number non-quasistatic atomic can take on order milliseconds reach equilibrium, depending conditions, causing be affected by populations. Previous using 400.88 nm line could effects. Therefore, a scheme for measuring relative fractions...