A5002671988- Laser-induced spectroscopy and plasma
- Laser-Plasma Interactions and Diagnostics
- Laser-Matter Interactions and Applications
- Atomic and Molecular Physics
- High-pressure geophysics and materials
- Plasma Diagnostics and Applications
- Laser Design and Applications
- Nuclear Physics and Applications
- Ion-surface interactions and analysis
- Combustion and Detonation Processes
- Magnetic confinement fusion research
- Mass Spectrometry Techniques and Applications
- Energetic Materials and Combustion
- Pulsed Power Technology Applications
- Electron and X-Ray Spectroscopy Techniques
- Cold Fusion and Nuclear Reactions
- Fusion materials and technologies
- Particle accelerators and beam dynamics
- Spectroscopy and Laser Applications
- Advanced X-ray Imaging Techniques
- Laser Material Processing Techniques
- Graphite, nuclear technology, radiation studies
- Nuclear and radioactivity studies
- Analytical chemistry methods development
- Radiation Detection and Scintillator Technologies
University of Rochester
2016-2025
Energetics (United States)
2016-2025
Applied Energetics (United States)
2019-2024
Lawrence Livermore National Laboratory
2008-2019
University of Alberta
2019
General Atomics (United States)
2011
Fusion Academy
2010
Massachusetts Institute of Technology
2008
A novel method by C. Zhou and R. Betti [Bull. Am. Phys. Soc. 50, 140 (2005)] to assemble ignite thermonuclear fuel is presented. Massive cryogenic shells are first imploded direct laser light with a low implosion velocity on adiabat leading assemblies large areal densities. The assembled ignited from central hot spot heated the collision of spherically convergent ignitor shock return shock. resulting assembly features hot-spot pressure greater than surrounding dense pressure. Such...
Along with laser-indirect (X-ray)-drive and magnetic-drive target concepts, laser direct drive is a viable approach to achieving ignition gain inertial confinement fusion. In the United States, national program has been established demonstrate understand physics of drive. The utilizes Omega Laser Facility conduct implosion coupling at nominally 30-kJ scale laser–plasma interaction MJ National Ignition Facility. This article will discuss motivation challenges for broad-based presently...
Planar laser-plasma interaction (LPI) experiments at the National Ignition Facility (NIF) have allowed access for first time to regimes of electron density scale length (∼500 700 μm), temperature (∼3 5 keV), and laser intensity (6 16×10^{14} W/cm^{2}) that are relevant direct-drive inertial confinement fusion ignition. Unlike in shorter-scale-length plasmas on OMEGA, scattered-light data NIF show near-quarter-critical LPI physics is dominated by stimulated Raman scattering (SRS) rather than...
Fast Ignition Inertial Confinement Fusion is a variant of inertial fusion in which DT fuel first compressed to high density and then ignited by relativistic electron beam generated fast (< 20 ps) ultra-intense laser pulse, usually brought the dense plasma via inclusion re-entrant cone. The transport this from cone apex into critical part scheme, as it can strongly influence overall energetics. Here we review progress theory numerical simulation context Ignition. Important aspects basic...
This Letter presents the first experimental demonstration of capability to launch shocks several-hundred Mbar in spherical targets—a milestone for shock ignition [R. Betti et al., Phys. Rev. Lett. 98, 155001 (2007)]. Using temporal delay between launching strong at outer surface target and time when converges center, shock-launching pressure can be inferred using radiation-hydrodynamic simulations. Peak ablation pressures exceeding 300 are absorbed laser intensities ∼3×1015 W/cm2. The...
Current theoretical predictions of the stopping range fast electrons in dense cores fast-ignition fusion targets differ by about a factor 2. Inconsistencies previous derivations are discussed and correct values power, scattering coefficients, ranges obtained. Such more-accurate results can be used studies ignition conditions particles-in-cell Monte Carlo simulations collisional electron transport plasma targets. Convenient approximate relations for angular moments hot-electron distribution...
Fast ignition is a two-step inertial confinement fusion concept where megaelectron volt electrons ignite the compressed core of an imploded fuel capsule driven by relatively low-implosion velocity. Initial surrogate cone-in-shell, fast-ignitor experiments using highly shaped driver pulse to assemble dense in front cone tip were performed on OMEGA/OMEGA EP Laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997); L. J. Waxer Photonics News 16, 30 (2005)]. With optimal timing, OMEGA produced...
Shock ignition is a two-step inertial confinement fusion concept where strong shock wave launched at the end of laser pulse to ignite compressed core low-velocity implosion. Initial shock-ignition technique experiments were performed OMEGA Laser Facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using 40-μm-thick, 0.9-mm-diam, warm surrogate plastic shells filled with deuterium gas. The showed significant improvement in performance low-adiabat, implosions compared conventional...
Measurements of the hot-electron generation by two-plasmon-decay instability are made in plasmas relevant to direct-drive inertial confinement fusion. Density-scale lengths $400\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ at ${n}_{\mathrm{cr}}/4$ planar CH targets allowed be driven saturation for vacuum intensities above $\ensuremath{\sim}3.5\ifmmode\times\else\texttimes\fi{}{10}^{14}\text{ }\mathrm{W}\text{ }{\mathrm{cm}}^{\ensuremath{-}2}$. In saturated regime, $\ensuremath{\sim}1%$ laser...
Time-resolved K(α) spectroscopy has been used to infer the hot-electron equilibration dynamics in high-intensity laser interactions with picosecond pulses and thin-foil solid targets. The measured K(α)-emission pulse width increases from ~3 6 ps for intensities ~10(18) 10(19) W/cm(2). Collisional energy-transfer model calculations suggest that hot electrons mean energies ~0.8 2 MeV are contained inside target. inferred broadly consistent ponderomotive scaling over relevant intensity range.
The energy in hot electrons produced by the two plasmon decay instability, planar targets, is measured to be same when driven one or laser beams and significantly reduced with four for a constant overlapped intensity on OMEGA EP. This caused multiple sharing common electron-plasma wave. A model, consistent experimental results, predicts that can only drive resonant wave region of numbers bisecting beams. In this region, gain proportional beam intensity.
To support direct-drive inertial confinement fusion experiments at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] in its indirect-drive beam configuration, polar-direct-drive (PDD) concept [S. Skupsky et al., Phys. Plasmas 11, 2763 has been proposed. PDD geometry requires direct-drive–specific smoothing, phase plates, repointing NIF beams toward equator to ensure symmetric target irradiation. First study energetics preheat...
Recent experiments on the Laboratory for Laser Energetics' OMEGA laser have been carried out to produce strong shocks in solid spherical targets with direct illumination. The are launched at pressures of several hundred Mbars and reach Gbar upon convergence. results relevant validation shock-ignition scheme development an experimental platform study material properties pressures. investigate strength ablation pressure hot-electron production incident intensities ∼2 6 × 1015 W/cm2 demonstrate...
Raman side scatter, whereby scattered light is resonant while propagating perpendicularly to a density gradient in plasma, was identified experimentally planar-target experiments at the National Ignition Facility intensities orders of magnitudes below threshold for absolute instability. We have derived new theoretical description convective scatter threshold, validated by numerical simulations. show that inertial confinement fusion full ignition scale, i.e., with mm-scale spot sizes and...
Stimulated Raman scattering (SRS) has been explored comprehensively in planar-geometry experiments at the National Ignition Facility conditions relevant to corona of inertial confinement fusion ignition-scale direct-drive targets. These measured electron temperatures 4 5 keV simulated density scale lengths Ln 400 700 μm, and laser intensities quarter-critical up 1.5 × 1015 W/cm2 have determined SRS thresholds scaling behavior for various beam geometries. Several mechanisms, including...
Considerable progress has been made in deuterium-tritium-layered implosion experiments on the OMEGA Laser System, bringing prospects for thermonuclear ignition direct-drive configurations with megajoule-class lasers closer to reality. Doing so required navigating balance between improved 1D performance and multidimensional stability. Using statistical modeling based over 350 cryogenic implosions identify various degradation mechanisms, combined simulations experimental techniques such as...
The fraction of laser energy converted into hot electrons by the two-plasmon-decay instability is found to have different overlapped intensity thresholds for various configurations on Omega Laser Facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997); J. H. Kelly Phys. IV 75 (2006)]. A factor-of-2 difference in threshold observed between two- and four-beam configurations. increases a factor 2 4- 18-beam 3 60-beam This explained linear common-wave model where multiple beams drive common...
Laser–plasma interaction instabilities can be detrimental for direct-drive inertial confinement fusion by generating high-energy electrons that preheat the target. An experimental platform has been developed and fielded on National Ignition Facility to investigate hot-electron production from laser–plasma at ignition-relevant conditions. The radiation-hydrodynamic code DRACO used design planar-target experiments generate plasma conditions comparable ignition designs: IL ∼ 1015 W/cm2, Te...
Recent spherical-target laser–plasma interaction experiments, performed on the OMEGA EP laser, have been analyzed for stimulated Raman scattering (SRS). This has motivated by results obtained National Ignition Facility (NIF) that demonstrated importance of SRS, and in particular SRS side scatter, directly driven inertial confinement fusion (ICF) conditions [Rosenberg et al. Phys. Rev. Lett. 120, 055001 (2018); Michel E 99, 033203 (2019)]. The analysis, based a generalized ray tracing...
Thin-foil targets were irradiated with high-power (1 ≤ P(L) 210 TW), 10-ps pulses focused to intensities of I>10(18) W/cm(2) and studied K-photon spectroscopy. Comparing the energy emitted in K photons target-heating calculations shows a laser-energy-coupling efficiency hot electrons η(L-e) = 20 ± 10%. Time-resolved x-ray emission measurements suggest that laser is coupled over entire duration incident drive. Comparison data previous at similar independent laser-pulse from 1 τ(p) 10 ps.