D. N. Fittinghoff
A5028353918- Laser-Plasma Interactions and Diagnostics
- Nuclear Physics and Applications
- Laser-Matter Interactions and Applications
- High-pressure geophysics and materials
- Laser-induced spectroscopy and plasma
- Advanced Fiber Laser Technologies
- Radiation Detection and Scintillator Technologies
- Spectroscopy Techniques in Biomedical and Chemical Research
- Nuclear reactor physics and engineering
- Advanced Fluorescence Microscopy Techniques
- Cold Fusion and Nuclear Reactions
- Laser Design and Applications
- Advanced X-ray Imaging Techniques
- Atomic and Subatomic Physics Research
- Ion-surface interactions and analysis
- Laser Material Processing Techniques
- Combustion and Detonation Processes
- Magnetic confinement fusion research
- Optical Coherence Tomography Applications
- Spectroscopy and Quantum Chemical Studies
- Particle Accelerators and Free-Electron Lasers
- Energetic Materials and Combustion
- Particle accelerators and beam dynamics
- Gyrotron and Vacuum Electronics Research
- Mass Spectrometry Techniques and Applications
Lawrence Livermore National Laboratory
2015-2024
Lawrence Livermore National Security
2024
Los Alamos National Laboratory
2011-2023
University of Rochester
2012-2020
Energetics (United States)
2012-2020
General Atomics (United States)
2012-2020
Sandia National Laboratories
2012-2018
University of New Mexico
2018
Massachusetts Institute of Technology
2012-2018
Diamond Materials (Germany)
2018
We summarize the problem of measuring an ultrashort laser pulse and describe in detail a technique that completely characterizes time: frequency-resolved optical gating. Emphasis is placed on choice experimental beam geometry implementation iterative phase-retrieval algorithm together yield accurate measurement time-dependent intensity phase over wide range circumstances. compare several commonly used geometries, displaying sample traces for each showing where appropriate, we give detailed...
We have measured the ion yields for helium ionized by 120 fs, 614 nm laser pulses intensities near ${10}^{16}$ W/${\mathrm{cm}}^{2}$. found that these ultrashort ${\mathrm{He}}^{+2}$ data exhibit a feature which saturates in parallel with ${\mathrm{He}}^{+}$ signal indicating ionization may proceed nonsequentially. propose new mechanism, can exist only tunneling regime, such nonsequential ionization.
Abstract Obtaining a burning plasma is critical step towards self-sustaining fusion energy 1 . A one in which the reactions themselves are primary source of heating plasma, necessary to sustain and propagate burn, enabling high gain. After decades research, here we achieve burning-plasma state laboratory. These experiments were conducted at US National Ignition Facility, laser facility delivering up 1.9 megajoules pulses with peak powers 500 terawatts. We use lasers generate X-rays radiation...
A series of cryogenic, layered deuterium-tritium (DT) implosions have produced, for the first time, fusion energy output twice peak kinetic imploding shell. These experiments at National Ignition Facility utilized high density carbon ablators with a three-shock laser pulse (1.5 MJ in 7.5 ns) to irradiate low gas-filled ($0.3\text{ }\text{ }\mathrm{mg}/\mathrm{cc}$ helium) bare depleted uranium hohlraums, resulting hohlraum radiative temperature $\ensuremath{\sim}290\text{ }\mathrm{eV}$. The...
Abstract In a burning plasma state 1–7 , alpha particles from deuterium–tritium fusion reactions redeposit their energy and are the dominant source of heating. This has recently been achieved at US National Ignition Facility 8 using indirect-drive inertial-confinement fusion. Our experiments use laser-generated radiation-filled cavity (a hohlraum) to spherically implode capsules containing deuterium tritium fuel in central hot spot where occur. We have developed more efficient hohlraums...
An inertial fusion implosion on the National Ignition Facility, conducted August 8, 2021 (N210808), recently produced more than a megajoule of yield and passed Lawson's criterion for ignition [Phys. Rev. Lett. 129, 075001 (2022)]. We describe experimental improvements that enabled N210808 present first measurements from an igniting plasma in laboratory. metrics like product hot-spot energy pressure squared, absence self-heating, increased by ∼35%, leading to record values enhancement...
We present the design of first igniting fusion plasma in laboratory by Lawson's criterion that produced 1.37 MJ energy, Hybrid-E experiment N210808 (August 8, 2021) [Phys. Rev. Lett. 129, 075001 (2022)10.1103/PhysRevLett.129.075001]. This uses indirect drive inertial confinement approach to heat and compress a central "hot spot" deuterium-tritium (DT) fuel using surrounding dense DT piston. Ignition occurs when heating from absorption α particles created process overcomes loss mechanisms...
An indirect-drive inertial fusion experiment on the National Ignition Facility was driven using 2.05 MJ of laser light at a wavelength 351 nm and produced 3.1±0.16 total yield, producing target gain G=1.5±0.1 exceeding unity for first time in laboratory [Phys. Rev. E 109, 025204 (2024)10.1103/PhysRevE.109.025204]. Herein we describe experimental evidence increased drive capsule additional energy control over known degradation mechanisms, which are critical to achieving high performance....
We show that frequency-resolved optical gating combined with spectral interferometry yields an extremely sensitive and general method for temporal characterization of nearly arbitrarily weak ultrashort pulses even when the reference is not transform limited. experimentally demonstrate measurement full time-dependent intensity phase a train average energy 42 zeptojoules (42 x 10(-21) J), or less than one photon per pulse.
The “High-Foot” platform manipulates the laser pulse-shape coming from National Ignition Facility to create an indirect drive 3-shock implosion that is significantly more robust against instability growth involving ablator and also modestly reduces convergence ratio. This strategy gives up on theoretical high-gain in inertial confinement fusion order obtain better control of bring experimental performance in-line with calculated performance, yet keeps absolute capsule relatively high. In...
A neutron imaging diagnostic has recently been commissioned at the National Ignition Facility (NIF). This new system is an important tool for inertial fusion studies NIF measuring size and shape of burning DT plasma during ignition stage Inertial Confinement Fusion (ICF) implosions. The technique utilizes a pinhole aperture, placed between source detector. detection measures two dimensional distribution neutrons passing through pinhole. designed to collect images times. long flight path this...
High Density Carbon (HDC) is a leading candidate as an ablator material for Inertial Confinement Fusion (ICF) capsules in x-ray (indirect) drive implosions. HDC has higher density (3.5 g/cc) than plastic (CH, 1 g/cc), which results thinner with larger inner radius given capsule scale. This leads to absorption and shorter laser pulses compared equivalent CH designs. paper will describe series of experiments carried out examine the feasibility using both gas filled hohlraums lower density,...
Recent experiments on the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] demonstrate that utilizing a near-vacuum hohlraum (low pressure gas-filled) is viable option for high convergence cryogenic deuterium-tritium (DT) layered capsule implosions. This made possible by using dense ablator (high-density carbon), which shortens drive duration needed to achieve convergence: measured 40% higher efficiency than typical gas-filled hohlraums, requires less laser...
We report on the most recent and successful effort at controlling trajectory symmetry of a high density carbon implosion National Ignition Facility. use low gasfill (0.3 mg/cc He) bare depleted uranium hohlraum with around 1 MJ laser energy to drive 3-shock-ignition relevant implosion. assess performance we demonstrate control convergence 1, 3–5, 12, 27 better than ±5 μm using succession experimental platforms. The was maintained peak fuel velocity 380 km/s. Overall, measurements are...
We report on the first layered deuterium-tritium (DT) capsule implosions indirectly driven by a "high-foot" laser pulse that were fielded in depleted uranium hohlraums at National Ignition Facility. Recently, high-foot have demonstrated improved resistance to ablation-front Rayleigh-Taylor instability induced mixing of ablator material into DT hot spot [Hurricane et al., Nature (London) 506, 343 (2014)]. Uranium provide higher albedo and thus an increased drive equivalent additional 25 TW...
The Bigfoot approach is to intentionally trade off high convergence, and therefore areal-density, in favor of implosion velocity good coupling between the laser, hohlraum, shell, hotspot. This results a short laser pulse that improves hohlraum symmetry predictability, while reduced compression reduces hydrodynamic instability growth. thus far include demonstrated low-mode control at two different geometries (5.75 mm 5.4 diameters) target scales (5.4 6.0 spanning 300–405 TW power 0.8–1.6 MJ...
The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring two-dimensional size and shape of neutrons produced in burning deuterium-tritium plasma during ignition stage inertial confinement fusion (ICF) implosions NIF. Since source small (∼100 μm) are deeply penetrating (>3 cm) all materials, apertures used to achieve desired 10-μm resolution 20-cm long, single-sided tapers gold. These apertures, which have triangular cross...
To reach the pressures and densities required for ignition, it may be necessary to develop an approach design that makes easier simulations guide experiments. Here, we report on a new short-pulse inertial confinement fusion platform is specifically designed more predictable. The has demonstrated $99%+0.5%$ laser coupling into hohlraum, high implosion velocity ($411\text{ }\text{ }\mathrm{km}/\mathrm{s}$), hotspot pressure ($220+60\text{ }\mathrm{Gbar}$), cold fuel areal density compression...
The impact to fusion energy production due the radiative loss from a localized mix in inertial confinement implosions using high density carbon capsule targets has been quantified. and local cooling of reacting plasma conditions was quantified neutron x-ray images reconstruct hot spot during thermonuclear burn. Such features arise ablator material that is injected into Rayleigh-Taylor growth surface perturbations, particularly tube used fill with deuterium tritium fuel. Observations,...
Abstract Indirect Drive Inertial Confinement Fusion Experiments on the National Ignition Facility (NIF) have achieved a burning plasma state with neutron yields exceeding 170 kJ, roughly 3 times prior record and necessary stage for igniting plasmas. The results are despite multiple sources of degradations that lead to high variability in performance. Results shown here, first time, include an empirical correction factor mode-2 asymmetry regime addition previously determined corrections...
We use the algorithmic method of generalized projections (GP's) to retrieve intensity and phase an ultrashort laser pulse from experimental trace in frequency-resolved optical gating (FROG). Using simulations, we show that GP's improves significantly convergence properties algorithm over basic FROG algorithm. In measurements, GP-based achieves lower errors than previous algorithms. The also permits inclusion arbitrary material response function problem.
We report on the polarization dependence of ionization helium and neon by 120-fs pulses at 614 nm. For linearly polarized data for ${\mathrm{He}}^{2+}$ ${\mathrm{Ne}}^{2+}$ show enhancements over sequential tunneling. circularly no distinct enhancements. Dynamic resonances, which produce similar in multiphoton regime, do not explain tunneling regime. Two direct-ionization models are considered: a shake-off model, semiclassical model rescattering an electron ion core. The exhibited yield...
We introduce a transient-grating beam geometry for frequency-resolved optical-gating measurements of ultrashort laser pulses and show that it offers significant advantages over currently used geometries. Background free phase matched long interaction length, is the most sensitive third-order pulse-measurement geometry. In addition, greater than ∼300 fs in length ∼1 µJ energy, nonlinear medium can be removed nonlinearity air to measure pulse.
The first inertial confinement fusion implosion experiments with equimolar deuterium-tritium thermonuclear fuel have been performed on the National Ignition Facility. These use 0.17 mg of potential for ignition and significant yield conditions. has fielded as a cryogenic layer inside spherical plastic capsule that is mounted in center cylindrical gold hohlraum. Heating hohlraum 192 laser beams total energy 1.6 MJ produces soft x-ray field 300 eV temperature. ablation pressure produced by...