A5018537551- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Laser-Matter Interactions and Applications
- High-pressure geophysics and materials
- Nuclear Physics and Applications
- Laser Design and Applications
- Atomic and Molecular Physics
- Magnetic confinement fusion research
- Combustion and Detonation Processes
- Energetic Materials and Combustion
- Astro and Planetary Science
- Ionosphere and magnetosphere dynamics
- Diamond and Carbon-based Materials Research
- Advanced Fiber Laser Technologies
- Solar and Space Plasma Dynamics
- Ion-surface interactions and analysis
- Gamma-ray bursts and supernovae
- Atomic and Subatomic Physics Research
- Plasma Diagnostics and Applications
- Nuclear reactor physics and engineering
- Particle Accelerators and Free-Electron Lasers
- Gas Dynamics and Kinetic Theory
- Laser Material Processing Techniques
- Cold Fusion and Nuclear Reactions
- Particle accelerators and beam dynamics
Los Alamos National Laboratory
2014-2024
Lawrence Livermore National Laboratory
2007-2023
University of Rochester
2008-2017
Energetics (United States)
2008-2017
General Atomics (United States)
2010-2017
University of Nevada, Reno
2017
Computational Sciences (United States)
2017
Prism Computational Sciences (United States)
2017
Applied Energetics (United States)
2002-2015
Fusion Academy
2002-2014
A signal of $106\ifmmode\pm\else\textpm\fi{}14$ positrons above background has been observed in collisions a low-emittance 46.6 GeV electron beam with terawatt pulses from Nd:glass laser at 527 nm wavelength an experiment the Final Focus Test Beam SLAC. The are interpreted as arising two-step process which photons backscattered to energies by followed collision between high-energy photon and several produce electron-positron pair. These results first laboratory evidence for inelastic...
Studies of multiphoton ionization noble gases have been carried out using 1-\ensuremath{\mu}m, 1-ps laser pulses with intensities up to the mid- ${10}^{16}$ W/${\mathrm{cm}}^{2}$. To our knowledge, this work represents first study production highly ionized noble-gas ions done exclusively in tunneling regime. It is found regime that at a given intensity depends on both potential and charge state species. The onset occurs when sum Coulomb electric potentials causes electron be unbound.
Point design targets have been specified for the initial ignition campaign on National Ignition Facility [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 443, 2841 (2004)]. The contain D-T fusion fuel in an ablator of either CH with Ge doping, or Be Cu. These shells are imploded a U Au hohlraum peak radiation temperature set between 270 300 eV. Considerations determining point include laser-plasma interactions, hydrodynamic instabilities, laser operations, target fabrication....
Nonlinear Compton scattering has been observed in the collision of a low-emittance 46.6-GeV electron beam with terawatt pulses from Nd:glass laser at 1054 and 527 nm wavelengths an experiment Final Focus Test Beam SLAC. Peak intensities ${10}^{18}\phantom{\rule{0ex}{0ex}}\mathrm{W}/{\mathrm{cm}}^{2}$ have achieved, corresponding to value 0.6 for parameter $\ensuremath{\eta}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}e{E}_{\mathrm{rms}}/m{\ensuremath{\omega}}_{0}c$. Results are...
Laser ionization of noble gases was studied with a 1.053-μm, 1-psec Nd:glass laser. A systematic scan intensities from mid-1013 W/cm2 to mid-1016 performed, resulting in the production charge states as high Xe12+. Ionization occurs exclusively tunneling regime. We compare experimental ion rates those predicted by several different theories. Agreement between ion-production curves and theoretical predictions is good for two models: (1) an elaboration Keldysh model, developed Ammosov et al. [...
We report on measurements of quantum electrodynamic processes in an intense electromagnetic wave, where nonlinear effects (both multiphoton and vacuum polarization) are prominent. Nonlinear Compton scattering electron-positron pair production have been observed collisions 46.6 GeV 49.1 electrons the Final Focus Test Beam at SLAC with terawatt pulses 1053 nm 527 wavelengths from a Nd:glass laser. Peak laser intensities...
We measure up to 2x10;{10} positrons per steradian ejected out the back of approximately mm thick gold targets when illuminated with short ( 1 ps) ultraintense 1x10;{20} W/cm;{2}) laser pulses. Positrons are produced predominately by Bethe-Heitler process and have an effective temperature 2-4 MeV, distribution peaking at 4-7 MeV. The angular is anisotropic. Modeling based on measurements indicate positron density be 10;{16} positrons/cm;{3}, highest ever created in laboratory.
High-resolution spectrometry of charged particles from inertial-confinement-fusion (ICF) experiments has become an important method studying plasma conditions in laser-compressed capsules. In at the 60-beam OMEGA laser facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)], utilizing capsules with D2, D3He, DT, or DTH fuel a shell plastic, glass, D2 ice, we now routinely make spectral measurements primary fusion products (p, D, T, He3, α), secondary (p), “knock-on” T) elastically...
We demonstrate a laser beam-smoothing technique known as polarization smoothing. A birefringent optical wedge splits the individual beams into two orthogonally polarized that, when coupled with distributed phase plate, produce speckle patterns shifted respect to one another. This instantaneously reduces on-target nonuniformity by factor of √. measured this reduction optically and its effect is demonstrated in laser-driven targets.
We have observed longitudinal acceleration of free electrons by photon scattering in the low-energy Thomson regime. This is first observation transition between and Compton regimes electron due to higher-order interactions.
Enhancement of the ion temperature and fusion yield has been observed in magnetized laser-driven inertial confinement implosions on OMEGA Laser Facility. A spherical CH target with a 10 atm D2 gas fill was imploded polar-drive configuration. magnetic field 80 kG embedded subsequently trapped compressed by imploding conductive plasma. As result hot-spot magnetization, electron radial heat losses were suppressed neutron enhanced 15% 30%, respectively.
The 60-beam Omega laser system at the University of Rochester's Laboratory for Laser Energetics (LLE) has been a workhorse on frontier fusion and high-energy-density physics more than decade. LLE scientists are currently extending performance this unique, direct-drive by adding high-energy petawatt capabilities.
OMEGA, a 60-beam, 351 nm, Nd:glass laser with an on-target energy capability of more than 40 kJ, is flexible facility that can be used for both direct- and indirect-drive targets designed to ultimately achieve irradiation uniformity 1% on direct-drive capsules shaped pulses (dynamic range ≳400:1). The OMEGA program the next five years includes plasma physics experiments investigate laser–matter interaction at temperatures, densities, scale lengths approaching those 1.8 MJ National Ignition...
Detailed angle and energy resolved measurements of positrons ejected from the back a gold target that was irradiated with an intense picosecond duration laser pulse reveal are in collimated relativistic jet. The laser-positron conversion efficiency is ∼2×10{-4}. jets have ∼20 degree angular divergence distributions quasimonoenergetic 4 to 20 MeV beam temperature ∼1 MeV. sheath electric field on surface shown determine positron energy. distribution controlled by varying field, through...
A distinctive way of quantitatively imaging inertial fusion implosions has resulted in the characterization two different types electromagnetic configurations and measurement temporal evolution capsule size areal density. Radiography with a pulsed, monoenergetic, isotropic proton source reveals field structures through deflection trajectories, densities are quantified energy lost by protons while traversing plasma. The consist (i) many radial filaments complex striations bifurcations,...
Excessive increase in the shell entropy and degradation from spherical symmetry inertial confinement fusion implosions limit compression could impede ignition. The is controlled by accurately timing shock waves launched into at an early stage of implosion. seeding Rayleigh-Taylor instability, main source asymmetry growth, also set times during transit across shell. In this paper we model perturbation growth directly driven targets measured on OMEGA laser system [T. R. Boehly et al., Opt....
The temperature of laser-driven shock waves is interest to inertial confinement fusion and high-energy-density physics. We report on a streaked optical pyrometer that measures the self-emission shocks simultaneously with velocity interferometer system for any reflector (VISAR). Together these diagnostics are used obtain temporally spatially resolved temperatures approximately megabar driven by OMEGA laser. provide brief description diagnostic how it VISAR. Key spectral calibration results...
We present the first x-ray scattering measurements of state compression and heating in laser irradiated solid beryllium. The scattered spectra at two different angles show Compton plasmon features indicating a dense Fermi-degenerate plasma with Fermi energy above 30 eV temperatures range 10--15 eV. These indicate by factor 3 agreement Hugoniot data detailed radiation-hydrodynamic modeling.
Reaching ignition in direct-drive (DD) inertial confinement fusion implosions requires achieving central pressures excess of 100 Gbar. The OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] is used to study the physics that are hydrodynamically equivalent designs on National Ignition Facility (NIF) [J. A. Paisner Laser Focus World 30, 75 (1994)]. It shown highest hot-spot (up 40 Gbar) achieved target with a fuel adiabat α ≃ 4, an implosion velocity 3.8 × 107 cm/s, and...
The compression $(\ensuremath{\eta})$ of liquid deuterium between 45 and 220 GPa under laser-driven shock loading has been measured using impedance matching to an aluminum (Al) standard. An Al impedance-match model derived from a best fit absolute Hugoniot data used quantify minimize the systematic errors caused by uncertainties in high-pressure equation state. In below 100 results show that $\ensuremath{\eta}\ensuremath{\simeq}4.2$, agreement with previous magnetically driven flyer...
Capsule performance optimization campaigns will be conducted at the National Ignition Facility [G. H. Miller, E. I. Moses, and C. R. Wuest, Nucl. Fusion 44, 228 (2004)] to substantially increase probability of ignition. The experimentally correct for residual uncertainties in implosion hohlraum physics used our radiation-hydrodynamic computational models using a variety ignition capsule surrogates before proceeding cryogenic-layered implosions experiments. quantitative goals technique...
Mixing of plastic ablator material, doped with Cu and Ge dopants, deep into the hot spot ignition-scale inertial confinement fusion implosions by hydrodynamic instabilities is diagnosed x-ray spectroscopy on National Ignition Facility. The amount hot-spot mix mass determined from absolute brightness emergent K-shell emission. dopants placed at different radial locations in show ablation-front instability primarily responsible for mix. Low neutron yields between 34(-13,+50) ng 4000(-2970,+17...
Direct-drive-implosion experiments on the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] have showed discrepancies between simulations of scattered (non-absorbed) light levels and measured ones that indicate presence a mechanism reduces coupling efficiency by 10%–20%. This appears to be due crossed-beam energy transfer (CBET) involves electromagnetic-seeded, low-gain stimulated Brillouin scattering. CBET scatters from central portion incoming beam outgoing light, reducing...