A5077927230- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Fusion materials and technologies
- Ion-surface interactions and analysis
- High-pressure geophysics and materials
- Metal and Thin Film Mechanics
- Nuclear Physics and Applications
- Laser-Matter Interactions and Applications
- Magnetic confinement fusion research
- Nuclear Materials and Properties
- Laser Design and Applications
- Advanced Surface Polishing Techniques
- Diamond and Carbon-based Materials Research
- Energetic Materials and Combustion
- Nanofabrication and Lithography Techniques
- Plasma Applications and Diagnostics
- Surface Modification and Superhydrophobicity
- Advanced materials and composites
- Additive Manufacturing and 3D Printing Technologies
- Atomic and Molecular Physics
- Plasma Diagnostics and Applications
- Polymer Surface Interaction Studies
- Microwave-Assisted Synthesis and Applications
- Advanced Optical Sensing Technologies
- Pulsed Power Technology Applications
General Atomics (United States)
2011-2024
University of Georgia
2024
Lawrence Livermore National Laboratory
2011-2021
Curtin University Sarawak
2021
Schafer Corporation (United States)
2005
Compound parabolic concentrator (CPC) targets are utilized at the National Ignition Facility Advanced Radiographic Capability (NIF-ARC) laser to enhance acceleration of electrons and production high energy photons, for durations 10 ps energies up 2.4 kJ. A large enhancement mean electron (>2 ×) photon brightness (>10×) is found with CPC compared flat targets. Using multiple diagnostic techniques different spatial locations scaling by gold activation data, spectra characterized...
Free-standing polymer thin films are typically fabricated using a sacrificial underlayer (between the film and its deposition substrate) or overlayer (on top of to assist peeling) in order facilitate removal from substrate. We show direct delamination extraordinarily (as as 8 nm) poly(vinyl formal) (PVF), polystyrene, poly(methyl methacrylate). Large (up 13 cm diameter) PVF could be captured on wire supports produce free-standing films. By modifying substrate lower interfacial energy...
The implosion efficiency in inertial confinement fusion depends on the degree of stagnated fuel compression, density uniformity, sphericity, and minimum residual kinetic energy achieved. Compton scattering-mediated 50--200 keV x-ray radiographs indirect-drive cryogenic implosions at National Ignition Facility capture dynamic evolution as it goes through peak revealing low-mode 3D nonuniformities thicker with lower than simulated. By differencing two taken different times during same...
The first indirect drive implosion experiments using Beryllium (Be) capsules at the National Ignition Facility confirm superior ablation properties and elucidate possible Be-ablator issues such as hohlraum filling by ablator material. Since 1990s, Be has been preferred Inertial Confinement Fusion (ICF) because of its higher mass rate compared to that carbon-based ablators. This enables ICF target designs with velocities lower radiation temperatures improved hydrodynamic stability through...
Picosecond-scale laser–matter interactions using compound parabolic concentrators have demonstrated strongly relativistic ponderomotive effects with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mo>∼</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>10</mml:mn> </mml:mrow> <mml:mo>×</mml:mo> </mml:math> increase in x-ray source brightness, positron production and multi-MeV proton acceleration versus flat targets, a marginally intensity laser.
Abstract The circular economy has been promoted as a solution to plastic pollution, but cities and communities bear the brunt of pollution. Circularity Assessment Protocol (CAP) is systems method collaborative open data collection for use decision‐ policy‐making. CAP utilized in 51 14 countries illustrated here Metro Manila. Results include identifying manufacturing parent companies bring table; documenting most (77%) products are single‐use multi‐layer film packaging; small, growing formal...
AbstractAbstractVarious morphologies have been observed in sputter-deposited Be ablator capsules, including nodular growth, cone growth and twisted grain growth. By devising an agitation method that includes both bouncing rolling the spherical mandrels during deposition, by reducing coating rate, consistent columnar structure has now obtained up to 170 mm. Low mode deformation of shells is on thin CH mandrels, but suppressed if stiffer are used. Ablator density measured weighing x-ray...
Relativistic electron temperatures were measured from kilojoule, subrelativistic laser-plasma interactions. Experiments show an order of magnitude higher than expected a ponderomotive scaling, where up to 2.2 MeV generated using intensity 1×10^{18}W/cm^{2}. Two-dimensional particle-in-cell simulations suggest that electrons gain superponderomotive energies by stochastic acceleration as they sample large area rapidly changing laser phase. We demonstrate such high are possible intensities...
In ablator shell fabrication, trace elements and impurities are introduced in the deposition pyrolysis process, which must be controlled below a critical level. However, it is opacity, not individual elements, matters an Inertial Confinement Fusion (ICF) implosion. Radiography measures allowing accurate determination of total impurity effect lump sum. Furthermore, by using sputter target element information, we can determine radial profile oxygen to ±0.4 at. %. Oxygen very difficult measure...
Achieving a high conversion efficiency into relativistic electrons is central to short-pulse laser application and fundamentally relies on creating interaction regions with intensities $\ensuremath{\gg}{10}^{18}\phantom{\rule{0.28em}{0ex}}\mathrm{W}/{\mathrm{cm}}^{2}$. Small focal length optics are typically employed achieve this goal; however, solution impractical for large kJ-class systems that constrained by facility geometry, debris concerns, component costs. We fielded target-mounted...
When used with 1.06-mm beryllium (Be) capsules on the National Ignition Facility, gold hohlraums inner diameter of 5.75 mm and helium gas fill density 1.6 mg/cm3 exhibit significant drive degradation due to laser energy backscatter (of order 14%–17%) “missing” X-ray (about 32% during main pulse). Also, hard simulate cross-beam transfer (CBET) must be control implosion symmetry. Larger, 6.72-mm densities ≤0.6 generally offer improved efficiency, reduced hot-electron preheat, better symmetry...
Abstract Proton radiography using short-pulse laser drivers is an important tool in high-energy density (HED) science for dynamically diagnosing key characteristics plasma interactions. Here we detail the first demonstration of target-normal sheath acceleration (TNSA)-based proton NIF-ARC system aided by use compound parabolic concentrators (CPCs). The multi-kJ energies available at allows a high-brightness source and thus enabling wide range applications HED science. In this demonstration,...
The National Ignition Facility point design uses a five-layer capsule to modify the X-ray absorption in order achieve optimized shock timing. A stepwise copper dopant defines layer structure; however, as-deposited Cu distribution is significantly altered during CH mandrel removal by pyrolysis. changes are significant: (a) diffuses on average several microns, distance more than an of magnitude larger predicted from bulk diffusion data, and (b) distribution, as result diffusion, highly...
The National Direct-Drive Inertial Confinement Fusion Program consists of the 100 Gbar Campaign on 30 kJ, 351 nm, 60-beam OMEGA Laser System and megajoule direct-drive (MJDD) 1.8 MJ, 192-beam Ignition Facility (NIF). main goals are to demonstrate understand physics for hot-spot conditions formation relevant ignition at MJ scale, while MJDD seeks laser plasma interactions, energy coupling, imprint ignition-scale coronal plasmas. An overview multiyear, systematic effort that is underway...
This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films. Typically, films are prepared using either sacrificial layers, which may damage film or affect its mechanical properties, they made on freshly cleaved mica, substrate that is difficult to scale. Further, size typically limited few square millimeters. In this method, we modify surface with polyelectrolyte alters strength adhesion between deposition substrate. The can be shown remain...
The NIF point design uses a five-layer capsule to modify the X-ray absorption in order achieve optimized shock timing. A stepped copper dopant defines layer structure. production of involves pyrolysis remove inner plastic mandrel. Copper atoms diffuse radially and azimuthally throughout during pyrolysis. This diffusion significantly diminishes performance implosion. Thermal coated oxide barrier layers employed between mitigate mandrel removal process. do not through this fabrication method...
Graded copper-doped Be shells have been fabricated by sputter coating on spherical mandrels. While such coatings consistent microstructure and acceptable void content size, we found that they suffer from sufficient interconnected porosity leading to relatively rapid gas leakage. In this paper, present an extensive study of D2 leakage out made coating. The appears follow molecular flow dynamics as determined examining the temperature dependence flow. Furthermore, time suggests channels are...
The point design of beryllium capsules includes three Cu-doped layers in a 160-μm-thick shell to achieve the desired X-ray absorption profile. were deposited on glow discharge polymer mandrels using magnetron sputtering process. Cu diffusion during pyrolysis remove after coating has caused nonuniform distribution along azimuthal direction due inhomogeneous diffusion. This nonuniformity could lead Rayleigh-Taylor instability capsule implosion. One methods solve this issue is incorporate oxide...
The choice of the mandrel material has a significant bearing on properties sputter-coated beryllium shell needed for NIF targets. Here, we present our work screening four materials, their impact Be and issues related to subsequent removal. Beryllium shells sputter deposited hollow glow discharge polymer or GDP spheres met most target specifications. However, they had greater opacity due partial oxidation during burnout step. Poly (α-methyl styrene), silicon nickel beads were explored as...
Ablative targets for the National Ignition Campaign (NIC) have been fabricated by sputter coating spherical mandrels made of glow discharge polymer (GDP) with graded copper doped beryllium (Be) layers. The inner mandrel must be completely removed to meet specific ignition design requirements. process removing requires elevated temperature in presence oxygen. However, elevating air also oxidizes Be and can cause blistering on surface shell. This paper will discuss a refined technique, which...
AbstractSputter coating of beryllium on spherical mandrels has been used at Lawrence Livermore National Laboratory and General Atomics to produce graded, copper doped shells. While these coatings have consistent microstructure acceptable void content, different coaters produced results with respect argon implantation. Each individual system met the requirements for implantation, but deviation from one another run exceeded variability as specified by Ignition Facility target design...
We use X-ray phase contrast imaging to characterize the inner surface roughness of deuterium-tritium (D-T) ice layers in capsules for future ignition experiments. It is therefore important quantify how well data correlate with actual roughness. benchmarked accuracy our system using surrogates fabricated characterized high precision standard techniques. Cylindrical azimuthally uniform sinusoidal perturbations 100-μm period and 1-μm amplitude demonstrated 0.02-μm limited by resolution imager...