A5067336625- Magnetic confinement fusion research
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Superconducting Materials and Applications
- Nuclear Materials and Properties
- Nuclear reactor physics and engineering
- Nuclear Physics and Applications
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Cold Fusion and Nuclear Reactions
- Semiconductor materials and devices
- Fusion and Plasma Physics Studies
- Spacecraft and Cryogenic Technologies
- Laser-induced spectroscopy and plasma
- Ion-surface interactions and analysis
- Metal and Thin Film Mechanics
- Atmospheric aerosols and clouds
- Biofield Effects and Biophysics
- Atmospheric and Environmental Gas Dynamics
- Advanced Materials Characterization Techniques
- Ionosphere and magnetosphere dynamics
- Integrated Circuits and Semiconductor Failure Analysis
- Silicon and Solar Cell Technologies
- Muon and positron interactions and applications
- Magneto-Optical Properties and Applications
University of Tennessee at Knoxville
2016-2024
Victoria University
2024
Knoxville College
2017-2023
Royal Netherlands Meteorological Institute
2020-2022
Max Planck Institute for Plasma Physics
2019
Max Planck Society
2019
Oak Ridge National Laboratory
2016-2018
Sandia National Laboratories California
2013-2018
University of California, San Diego
2018
Oak Ridge Associated Universities
2018
Abstract. The Hybrid End-To-End Aerosol Classification (HETEAC) model for the Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) mission is introduced. serves as common baseline development, evaluation, implementation of EarthCARE algorithms. It guarantees consistency different aerosol products from multi-instrument platform facilitates conformity broad-band optical properties needed radiative-closure assessments. While hybrid approach ensures that theoretical description...
Linear plasma generators are cost effective facilities to simulate divertor conditions of present and future fusion reactors. They used address important R&D gaps in the science material interactions towards viable facing components for Next generation have be able access expected on targets ITER devices. The steady-state linear device MPEX will this regime with electron temperatures 1–10 eV densities . resulting heat fluxes about 10 MW is designed deliver those a novel Radio Frequency...
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...
Plasma-facing materials in the divertor of a magnetic fusion reactor have to tolerate steady state plasma heat fluxes range 10 MW/m2 for ∼107 s, addition neutron fluences, which can damage plasma-facing high displacements per atom (dpa) ∼50 dpa. Materials solutions needed components are yet be developed and tested. The material exposure experiment (MPEX) is newly proposed linear device designed deliver necessary flux target testing, including capability expose priori neutron-damaged samples...
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...
Proto-MPEX is a linear plasma device being used to study novel RF source concept for the planned Material Plasma Exposure eXperiment (MPEX), which will address plasma-materials interaction (PMI) nuclear fusion reactors. Plasmas are produced using large diameter helicon operating at frequency of 13.56 MHz power levels up 120 kW. In recent experiments has deuterium plasmas with densities ~6 × 1019 m–3 measured location 2 m downstream from antenna and 0.4 target. Previous production on have...
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...
Mixed-material DIVIMP–WallDYN modeling, now incorporating ExB drifts, is presented that simultaneously reproduces tungsten (W) erosion and deposition patterns observed during the DIII-D metal rings campaign, in which a toroidally symmetric set of W-coated tiles were installed carbon (C) divertor. Since most reactor plasma facing component (PFC) designs call for mixed-material environments, including ITER's W/Be environment, divertor targets will quickly evolve into reconstituted surfaces...
Experimental evidence is presented of near-scrape off layer (SOL) tungsten accumulation near the crown lower single-null L-mode discharges in DIII-D Metal Rings Campaign, based on a peripheral-SOL collector probe (CP) array and OEDGE modelling. Such has been long-theorized due to parallel force balance SOL dominated by ion temperature gradient [1,2] but direct experimental lacking. Impurity at this location undesirable since it largely sets boundary condition for impurity levels confined...
Abstract. The Hybrid End-To-End Aerosol Classification (HETEAC) model for the Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) mission is introduced. serves as common baseline development, evaluation, implementation of EarthCARE algorithms. It guarantees consistency different aerosol products from multi-instrument platform facilitates conform specification broad-band optical properties needed radiative closure assessments. While hybrid approach ensures that theoretical description...
Abstract A novel impurity transport model that approximates SOL turbulence as a fluctuating poloidal electric field is shown to be an acceptable replacement for the traditional approach of assigning arbitrary radial diffusion coefficient ions. The implemented in DIVIMP code and applied L-Mode tungsten divertor experiment on DIII-D. represented between ±1000 V m −1 based previous measurements. resulting intermittent v r = E θ × B T causes ions both into core well far-SOL. Simultaneous...
In this work, we examine how deuterium becomes trapped in plasma-exposed tungsten and forms near-surface platelet-shaped precipitates. How these bubbles nucleate grow, as well the amount of within, is crucial for interpreting experimental database. Here, use a combined experimental/theoretical approach to provide further insight into underlying physics. With Tritium Plasma Experiment, exposed series ITER-grade samples high flux D plasmas (up 1.5 × 1022 m−2 s−1) at temperatures ranging...
The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) at Oak Ridge National Laboratory (ORNL) is a precursor linear plasma device to the (MPEX), which will study material interactions (PMIs) for future fusion reactors. This paper discuss initial steps performed towards completing power balance on Proto-MPEX quantify where energy lost from plasma, including relevant diagnostic package implemented. Machine operating parameters that improve Proto-MPEX’s performance may be identified,...
Abstract A major challenge facing the design and operation of next-step high-power steady-state fusion devices is to develop a viable divertor solution with order-of-magnitude increases in power handling capability relative present experience, while having acceptable target plate erosion being compatible maintaining good core plasma confinement. new initiative has been launched on DIII-D scientific basis for design, installation, an advanced evaluate boundary solutions applicable next step...
Exposure of tungsten to low energy (<100 eV) helium plasmas at temperatures between 900–1900 K in both laboratory experiments and tokamaks has been shown cause severe nanoscale modification the near surface resulting growth tendrils. Tendril formation can lead non-sputtered erosion dust formation. Here we report on characterization a compact electron cyclotron resonance (ECR) He plasma source with an ion flux ∼2.5 × 1019 ions m−2 s−1, average fluence 3 1024 m−2, morphology changes seen...
Lithium coatings in the Tokamak eXperiment (LTX) led to flat temperature profiles. The profiles were observed along with a hot, low density edge, implying broad, collisionless scrape-off layer (SOL). Additionally, vacuo X-ray photoelectron spectroscopy (XPS) measurements established that lithium evaporatively deposited onto high-Z plasma facing components (PFCs) became oxidized while retaining ability achieve good performance long after was applied PFCs. Longstanding theory predicted...
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...
This paper overviews the work that has been done to date towards development of a compact, reliable means detect Highly Enriched Uranium (HEU) and other fissile materials utilizing pulsed Inertial Electrostatic Confinement (IEC) D-D fusion device. To date, UW IEC device achieved 115 kV pulses in excess 2 ampere, with neutron rates 1.8x109 n/s during 0.5 ms pulse at 10 Hz. MCNP modeling indicates detection samples U-235 as small grams is achievable current production rates, initial...
Triplet sets of replaceable graphite rod collector probes (CPs), each with collection surfaces on opposing faces and oriented normal to the magnetic field, were inserted at outboard mid-plane DIII-D study divertor tungsten (W) transport in Scrape-Off Layer (SOL). Each CP collects particles along field lines different parallel sampling lengths (determined by diameters SOL transport) giving radial profiles from main wall inward R-Rsep ∼ 6 cm. The CPs deployed a first-of-a-kind experiment using...
Abstract It is estimated that pilot plants and reactors may experience rates of net erosion deposition solid plasma facing component (PFC) material 10 3 –10 5 kg yr −1 . Even if the (wear) problem can be solved, redeposition so much has potential for major interference with operation, including disruptions due to so-called ‘unidentified flying objects (UFOs)’ unsafe dust levels. The implications appear no less serious than contact divertor target: a explosion or UFO-disruption could as...