A5091508536- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Atomic and Molecular Physics
- Laser-Matter Interactions and Applications
- Laser Design and Applications
- High-pressure geophysics and materials
- Advanced X-ray Imaging Techniques
- Combustion and Detonation Processes
- Magnetic confinement fusion research
- Nuclear Physics and Applications
- Solid State Laser Technologies
- Diamond and Carbon-based Materials Research
- Laser Material Processing Techniques
- Crystallization and Solubility Studies
- Energetic Materials and Combustion
- X-ray Diffraction in Crystallography
- Computational Fluid Dynamics and Aerodynamics
- X-ray Spectroscopy and Fluorescence Analysis
- Cold Fusion and Nuclear Reactions
- Ionosphere and magnetosphere dynamics
- Gas Dynamics and Kinetic Theory
- Nuclear reactor physics and engineering
- Crystallography and Radiation Phenomena
- Advanced X-ray and CT Imaging
- Astrophysical Phenomena and Observations
Lawrence Livermore National Laboratory
2013-2025
Los Alamos National Laboratory
1996-2018
Massachusetts Institute of Technology
1989-2017
Fusion Academy
2012-2017
Fusion (United States)
2012-2017
General Atomics (United States)
2012-2017
University of Rochester
2012-2017
Energetics (United States)
2012-2017
SLAC National Accelerator Laboratory
2017
Plasma Technology (United States)
2016
We report observations of amplified spontaneous emission at soft x-ray wavelengths. An optical laser ionized thin foils selenium to produce a population inversion the $2{p}^{5}3p$ and $2{p}^{5}3s$ levels neonlike ion. Using three time-resolved, spectroscopic measurements we demonstrated gain-length products up 6.5 gain coefficients 5.5\ifmmode\pm\else\textpm\fi{}1.0 ${\mathrm{cm}}^{\ensuremath{-}1}$ for $J=2 \mathrm{to} 1$ lines 206.3 209.6 \AA{}. also observed considerable amplification...
We describe a design for producing soft x-ray laser via $3p\ensuremath{-}3s$ transitions in Ne-like selenium (wavelength of about 200 \AA{}). A 0.53-\ensuremath{\mu} m laser, focused 1.2\ifmmode\times\else\texttimes\fi{}0.02-cm spot to \ensuremath{\sim} 5\ifmmode\times\else\texttimes\fi{}${10}^{13}$ W/${\mathrm{cm}}^{2}$, heats and burns through thin foil Se. Besides ionizing the Se state, explodes foil, creating region uniform electron density. This allows propagation x rays down 1-cm-long...
A high-temperature plasma is created when an intense laser pulse focused onto the surface of a solid. An ultrafast x-ray radiation emitted from such length less than picosecond. high-speed streak camera detector was used to determine duration these pulses, and computer simulations plasmas agree with experimental results. Scaling laws predict that brighter more efficient sources will be obtained by use pulses. These can for time-resolved scattering studies development lasers.
The National Ignition Facility (NIF) at Lawrence Livermore Laboratory includes a precision laser system now capable of delivering 1.8 MJ 500 TW 0.35-μm light to target. NIF has been operational since March 2009. A variety experiments have completed in support NIF's mission areas: national security, fundamental science, and inertial fusion energy. capabilities infrastructure are place its missions with nearly 60 X-ray, optical, nuclear diagnostic systems. primary goal the Campaign (NIC) on...
As fusion experiments at the National Ignition Facility (NIF) approach and exceed breakeven, energy from burning capsule is predicted to couple gold walls reheat hohlraum. On December 5, 2022, experiment N221204 exceeded target historically achieving 3.15 MJ of 2.05 laser drive; for first time, igniting reheated hohlraum beyond peak laser-driven radiation temperature 313 eV a 350 eV, in less than half nanosecond. This reheating effect has now been unambiguously observed by two independent...
Several targets are described that in simulations give yields of 1–30 MJ when indirectly driven by 0.9–2 0.35 μm laser light. The article describes the targets, modeling was used to design them, and done set specifications for system proposed National Ignition Facility. Capsules with beryllium or polystyrene ablators enclosed gold hohlraums. All designs utilize a cryogenic fuel layer; it is very difficult achieve ignition at this scale noncryogenic capsule. It necessary use multiple bands...
Gold disks have been irradiated with 1.06 μm laser light at intensities between 7 × 1013 and 3 1015 W/cm2, pulse lengths 200 1000 psec. Due to the high Z long pulse, inverse bremsstrahlung becomes an important absorption mechanism competes strongly resonance stimulated scattering. In addition measured absorptions, data on temporal, spatial, angular, spectral characteristics of x-ray emission are presented. Temporally spectrally resolved back-reflected light, polarization-dependent...
Double shell capsules are predicted to ignite and burn at relatively low temperature (∼3 keV) via volume ignition a potential low-convergence path substantial α-heating possibly the National Ignition Facility. shells consist of dense, high-Z pusher, which first shock heats then performs work due changes in pressure (PdV work) on deuterium-tritium gas, bringing entire fuel high thermonuclear conditions near implosion stagnation. The pusher is accelerated subsequent compression an intervening...
This paper, extended from a Letter [Chen et al., Phys. Rev. E 110, L013201 (2024)] published in 2024, presents detailed results set of experiments studying the x-ray drive produced laser-heated ignition-scale hohlraums at National Ignition Facility. The reveal that deficiencies non-local thermodynamic equilibrium atomics physics calculations gold emissivity lead to overestimation “M-band” radiation and are responsible for discrepancies predictions vs measurements these hohlraums. These were...
We have demonstrated efficient coupling of 0.35 $\ensuremath{\mu}\mathrm{m}$ laser light for radiation production in inertial confinement fusion (ICF) cavity targets. Temperatures 270 eV are measured cavities used implosions and 300 smaller cavities, significantly extending the temperature range attained laboratory to those required high-gain indirect drive ICF. High-contrast, shaped pulses implosion experiments also been first time. Low levels scattered fast electrons observed, indicating...
An accurate simple model for the hydrodynamics of laser heated exploding foils is presented. Particular emphasis given to applications in design soft x-ray lasers. The predicts conditions foil plasma (e.g., temperature, density, and scale length), experimental parameters optical intensity, pulse duration, target thickness, composition). based on an isothermal, homogeneous expansion similarity solution ideal hydrodynamic equations. Both analytical numerical solutions equations are studied....
The choice of an optimal wavelength for soft x-ray holography is discussed, based on a description scattering by biological structures within aqueous environment. We conclude that wavelengths slightly longer than the 43.7-A carbon K-edge provide good trade off between minimizing necessary source power and dose absorbed sample maximizing penetrability x-rays through wet samples. This differs from previous notion water window (between 23.2 A 43.7 A) would be best holography. problem motion...
Details of schemes for two tabletop size x-ray lasers that require a high-intensity short-pulse driving laser are discussed. The first is based on rapid recombination following optical-field ionization. Analytical and numerical calculations the output properties presented. Propagation in confocal geometry discussed solution lasing Li-like N at 247 Å described. Since calculated gain coefficient depends strongly electron temperature, methods calculating heating field ionization Recent...
Disk targets of Be, CH, Ti, and Au have been irradiated with 0.53-\ensuremath{\mu}m laser light in 3-30-J, 600-ps pulses, at intensities from 3\ifmmode\times\else\texttimes\fi{}${10}^{13}$ to \ensuremath{\sim}4\ifmmode\times\else\texttimes\fi{}${10}^{15}$ W/${\mathrm{cm}}^{2}$. The measured absorptions, hard-x-ray fluxes, sub-keV emission properties are compared hydrocode simulations. results show strong collisional absorption, some Brillouin scattering, little suprathermal electron...
A series of 40 experiments on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] to study energy balance and implosion symmetry in reduced- full-scale ignition hohlraums was shot at energies up 1.3 MJ. This paper reports findings analysis ensemble experimental data obtained that has produced an improved model for simulating hohlraums. Last year first observation a NIF hohlraum transfer between cones beams as function wavelength shift those reported [P....
Recent experiments conducted at the National Ignition Facility achieved two main goals: providing radiation drive and symmetry suitable for subsequent ignition experiments. Of many diagnostics fielded, one provided a time-resolved wavelength spectrum of light reflected from target by stimulated Raman scatter (SRS). SRS occurs when incident reflects off self-generated electron plasma waves. Analyses indicate that synthetic spectra better match those an atomic physics model with greater...
Achieving inertial confinement fusion ignition requires a symmetric, high velocity implosion. Experiments show that we can reach 95 ± 5% of the required by using 420 TW, 1.6 MJ laser pulse. In addition, experiments with depleted uranium hohlraum an increase in capsule performance which suggests additional 18 5 μm/ns hohlraums over gold hohlraums. Combining these two would give 99 velocity. have ability to tune symmetry crossbeam transfer. We control second Legendre mode (P2) changing...
For several years, we have been calculating the radiation drive in laser-heated gold hohlraums using flux-limited heat transport with a limiter of 0.15, tabulated values local thermodynamic equilibrium opacity, and an approximate model for not (NLTE) emissivity (DCA_2010). This has successful predicting vacuum hohlraums, but gas-filled used to capsule implosions, consistently predicts too much bang times earlier than measured. In this work, introduce new that brings calculated time into...
Analyses of high foot implosions show that performance is limited by the radiation drive environment, i.e., hohlraum. Reported here are significant improvements in which result an enhancement implosion performance. Using a longer, larger case-to-capsule ratio hohlraum at lower gas fill density improves symmetry control implosion. Moreover, for first time, these hohlraums produce reduced levels hot electrons, generated laser-plasma interactions, comparable to near-vacuum hohlraums, and well...
Advances in hohlraums for inertial confinement fusion at the National Ignition Facility (NIF) were made this past year hohlraum efficiency, dynamic shape control, and hot electron x-ray preheat control. Recent experiments are exploring behavior over a large landscape of parameters by changing shape, gas-fill, laser pulse. Radiation hydrodynamic modeling, which uses measured backscatter, shows that gas-filled utilize between 60% 75% power to match bang-time, whereas near-vacuum 98%....
Diffusive x-ray-driven heat waves are found in a variety of astrophysical and laboratory settings, e.g., the heating hohlraum used for inertial confinement fusion, hence intrinsic interest. However, accurate analytic diffusion wave (also called Marshak wave) solutions difficult to obtain due strong nonlinearity radiation equation. The typical approach is solve near front, by ansatz apply solution globally. This works fairly well “steepness” but energy not conserved it does lead consistent...
Radiation transport through high-opacity materials can be described using the Rosseland mean opacity of medium, which is dominated by low-opacity regions in frequency-dependent opacity. By mixing gold and gadolinium, we fill one material with another material, resulting a $1.5\ifmmode\times\else\texttimes\fi{}$ higher than either constituents. For given laser energy, this raise temperature heated hohlraums, or for desired temperature, require less energy.