A5012810689- Laser-induced spectroscopy and plasma
- Laser-Plasma Interactions and Diagnostics
- Laser Material Processing Techniques
- High-pressure geophysics and materials
- Atomic and Molecular Physics
- Laser Design and Applications
- Advanced Surface Polishing Techniques
- Laser-Matter Interactions and Applications
- Nuclear Physics and Applications
- Advanced X-ray Imaging Techniques
- Ocular and Laser Science Research
- Ion-surface interactions and analysis
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Integrated Circuits and Semiconductor Failure Analysis
- Photonic and Optical Devices
- Scientific Measurement and Uncertainty Evaluation
- Magnetic confinement fusion research
- Semiconductor Lasers and Optical Devices
- Diamond and Carbon-based Materials Research
- Mass Spectrometry Techniques and Applications
- Silicone and Siloxane Chemistry
- Advanced Sensor Technologies Research
- Engineering and Material Science Research
- Dust and Plasma Wave Phenomena
General Atomics (United States)
2009-2024
University of California, San Diego
2014
Lawrence Livermore National Laboratory
2011
Illinois Institute of Technology
2009
Los Alamos National Laboratory
2001
University of British Columbia
1992-1998
Several nanosecond 0.53-μm laser pulses separated by several tens of nanoseconds have been shown to significantly enhance (three ten times) material removal rates while minimizing redeposition and heat-affected zones. Economic, high-quality, high-aspect ratio holes (>10:1) in metals are produced as a result. A phenomenological model whereby the second pulse interacts with ejecta first close proximity surface is consistent observations. Incident wavelengths 1.05 0.35 μm also benefit...
Femtosecond laser heating of a solid offers the possibility producing plasmas with near-solid densities. Many reflectivity measurements have been made on such to probe their electrical conductivity. In particular, experiment Milchberg, Freeman, and Davey has interpreted as showing significant discrepancy between theoretical measured conductivities. Here we present an alternative interpretation based careful analysis hydrodynamic expansion nonlocal interaction incident field. We find...
A recent study on the optical emission from a shock front in flight silicon has revealed significant deviations of shock-produced state thermodynamic equilibrium. The findings also yielded an estimate rate energy equilibration between electrons and ions plasma above solid densities, providing important insight into transport properties strongly coupled plasma. Highlights this have been reported earlier. Here, we present detailed account theoretical calculation, experimental measurement,...
Absolute-intensity measurements of luminous emissions from shocked silicon show significant disagreement with predictions that assume thermal equilibrium between electrons and ions is reached immediately behind the shock front. Taking into account both electron-ion equilibration electron conduction, we have estimated an coupling coefficient ${10}^{16}$ W/${\mathrm{m}}^{3}$ -K This finding will also important ramifications in pyrometric determinations temperatures.
We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution of stagnated plasma cores (hot spots) spherically shock compressed spheres shell implosion targets. By utilizing circular tungsten tantalum apertures with diameters ranging from 20 2 mm, combination image plate gated detectors as well magnifications 4 64, we demonstrated high-resolution hot spot plasmas at energies above 5 keV. Here give an overview experimental...
Abstract The current capsule target design for the first ignition experiments at NIF Facility beginning in 2009 will be a copper-doped beryllium capsule, roughly 2 mm diameter with 160-µm walls. have 75-µm layer of solid deuterium-tritium on inside surface, and powered by X-rays generated from gold/uranium cocktail hohlraum. specifications are extremely rigorous, particularly respect to interfaces, which must very smooth inhibit Rayleigh-Taylor instability growth. This paper outlines design,...
Foam targets have gained considerable importance over the last decade in laser–matter interaction. They find widespread applications such as inertial confinement fusion and secondary sources for particles radiation. At same time, advent of high repetition-rate laser systems, be they short-pulse tens femtosecond regime or kilo-Joule nanosecond regime, calls equally repetition rate targetry systems. A well-established system is tape target. In this article, we present successful marriage a...
Complex and precise research targets are required for the inertial confinement fusion (ICF) experiments conducted at National Ignition Facility. During Campaign (NIC) target development team embarked on completed a science technology campaign to provide capability produce rate needed by NIC. An engineering design precision, manufacturing, fielding was developed. This new processes, tooling, equipment metrologize assemble components. In addition, of processing also required.Since NIC had...
An approach for using intense femtosecond lasers to produce an equivalent idealized slab plasma of uniform electron density and temperature is described demonstrated through numerical simulations. With a laser as probe, such allows the direct measurement ac conductivity in strongly coupled regime. It also serves initial value problem study hot expanded states matter.
Most of the previous studies on nanosecond (ns) laser-induced plasma typically use relatively short ns laser pulses (pulse duration less than ∼30 to 50 ns). In this paper, long with 200 have been used, and produced during metal ablation in air at atmospheric pressure has studied through time-resolved observation using an intensified charge-coupled device camera. Due much longer pulse duration, radiation intensity distribution front propagation different physical features from those by...
An important component of the U.S. effort to achieve thermonuclear ignition in 2010 on National Ignition Facility is development high quality 2 mm diameter spherical capsules function as ablator and contain cryogenic DT fuel. Three capsule designs have been developed, detailed fabrication specifications for each design established placed under change control. A research program with activities coordinated mainly between Lawrence Livermore, General Atomics Los Alamos underway demonstrate...
AbstractThe National Ignition Facility (NIF) tuning and ignition capsules will be gas filled through a laser precision drilled hole with fill tube attached. To field these targets, several physics assembly requirements must met. These drive the morphology of final capsule (CFTA). Unexpectedly, they have also driven need for tube-transition subassembly, which is significant in extra time required fabrication. We implemented engineering solutions that allow successful fabrication, testing,...
Simultaneous temporally and spatially resolved measurements of the phase change reflectivity S- P-polarized femtosecond laser probes are obtained from hot expanded states produced by heating a solid aluminum target. The combined set data provides an integral test equation-of-state models in regime up to 10 Mbar densities 0.01–1 times solid. results suggest that target stoichiometry at few Å level should be considered analysis such experiments.
The formation and propagation of heat fronts produced by an intense femtosecond-laser pulse are examined in numerical simulations which treat self-consistently laser absorption, thermal conduction, hydrodynamics. results revealed that the initial front is dictated absorption as evanescent wave. effect conduction becomes important temperature solid increases. also suggest such may be used to probe electrical conductivities hot, dense plasmas.
This paper studies the double-pulse effect in high-intensity (≥∼GW/cm2) nanosecond (ns) laser ablation, which refers to significant material removal rate enhancement for ablation by two ns pulses (often separated a delay time of ∼10 100 ns). The early-stage interaction second pulse with plasma plume created first is very important understanding physical mechanism double effect. However, properties early stage (during or within 20 30 after completion pulse) are difficult measure...
We have successfully fabricated 2 mm beryllium targets pressurized with a gas mixture of ~20 atm deuterium and ~0.1 argon. These been used for indirect drive Inertial Confinement Fusion (ICF) experiments on the Z-pinch machine at Sandia National Laboratories leading to record neutron yields ~3.5 × 1011 [J.E. Bailey, et al., "Be Capsule Implosions Driven by Dynamic Hohlraum X-rays," Bull. Am. Phys. Soc. 51, 107 (2006)]. This paper will discuss process fabricating such from intact shells (Be...
AbstractExperiments on the Omega laser at Laboratory for Laser Energetics require tantalum oxide (Ta2O5) aerogel thin films with a thickness ranging from 70 to 150 μm and densities of 250 500 mg/cm3. Experiments have been done in disk geometry diameters ~2 3 mm annular slots machined into it without slots. These experiments place demanding specifications targets terms thickness, dimensionality, mass density variation. Future radiation National Ignition Facility will larger ~7 diameter 200...
We report on results from experiments using laser-cut X shaped foils (or foil X-pinches) driven by the 250 kA, 150 ns rise-time GenASIS Linear Transformer Driver. Optical probing of X-pinches shows considerable dynamic and qualitative similarity with more traditional wire X-pinches. Results demonstrate excellent quality X-ray emission flux, timing, source size. The offer advantages such as improved, reproducible cross-point symmetry, opportunity for rep-rated operation, which is not possible...
X-ray penumbral imaging has been successfully fielded on a variety of inertial confinement fusion (ICF) capsule implosion experiments the National Ignition Facility (NIF). We have demonstrated sub-5 μm resolution stagnated plasma cores (hot spots) at x-ray energies from 6 to 30 keV. These measurements are crucial for improving our understanding hot deuterium-tritium fuel assembly, which can be affected by various mechanisms, including complex 3-D perturbations caused support tent, fill tube...
Using numerical simulations we elucidate a novel phenomenon of electron thermal conduction in two-temperature, dense plasma produced by femtosecond lasers. We also illustrate that the phase shift and amplitude an optical probe reflected from rear surface laser-heated thin foil offers new means testing theoretical models conductivities electron-ion equilibration rates dense, strongly coupled plasma.
Quantitative data analyses of laser-cut Cu foil X-pinch experiments on the 150 ns quarter-period, ∼250 kA GenASIS driver are presented. Three different designs tested to determine effects initial structure pinch outcome. Foil also presented alongside results from wire X-pinches with comparable mass. The X-ray flux and temporal profile emission differed significantly that X-pinches, all confined a ∼3 period as opposed delayed, long-lasting electron beam common in X-pinches. Spectroscopic show...
A variety of shaped fill holes is needed in beryllium capsules for inertial confinement fusion experiments to allow pyrolysis the plastic (CH) mandrels, deuterium (D2) or deuterium-tritium gas fill, and tube attachments. The required include through-holes ranging diameters from ~5 30 μm counterbores ~13 17 with depths <37 μm. These are laser drilled using a double-pulse nanosecond format. Hole diameter depth can be controlled by altering pulse format, energy, beam delivery optics....
AbstractAbstractWe have successfully fabricated 2 mm beryllium targets pressurized with a gas mixture of ~20 atm deuterium and ~0.1 argon. These been used for indirect drive Inertial Confinement Fusion (ICF) experiments on the Z-pinch machine at Sandia National Laboratories leading to record neutron yields ~3.5 × 1011 [J.E. Bailey, et al., "Be Capsule Implosions Driven by Dynamic Hohlraum X-rays," Bull. Am. Phys. Soc. 51, 107 (2006)]. This paper will discuss process fabricating such from...