A. R. Christopherson
A5082064003- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- High-pressure geophysics and materials
- Cold Fusion and Nuclear Reactions
- Magnetic confinement fusion research
- Nuclear Physics and Applications
- Laser-Matter Interactions and Applications
- Fusion materials and technologies
- Laser Design and Applications
- Ion-surface interactions and analysis
- Atomic and Molecular Physics
- Pulsed Power Technology Applications
- Plasma Diagnostics and Applications
- Planetary Science and Exploration
- Astro and Planetary Science
- Fusion and Plasma Physics Studies
- Spacecraft and Cryogenic Technologies
- Gas Dynamics and Kinetic Theory
- Combustion and Detonation Processes
- Engineering and Material Science Research
- Plasma Applications and Diagnostics
- Radioactive Decay and Measurement Techniques
- Tribology and Lubrication Engineering
- Nuclear Issues and Defense
- Laser Material Processing Techniques
Lawrence Livermore National Laboratory
2022-2024
Xcel Energy (United States)
2024
University of Rochester
2014-2022
Energetics (United States)
2014-2022
Applied Energetics (United States)
2018-2021
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...
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...
Fusion “scientific breakeven” (i.e., unity target gain <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msub><a:mrow><a:mi>G</a:mi></a:mrow><a:mrow><a:mtext>target</a:mtext></a:mrow></a:msub></a:mrow></a:math>, total fusion energy out <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mo>></c:mo></c:math> laser input) has been achieved for the first time (here, <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"...
Alpha particles would need to provide 50 kJ of heating achieve a burning plasma regime - where more energy is released by the fusion reactions than absorbed fuel at National Ignition Facility.
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...
The theory of ignition for inertial confinement fusion capsules [R. Betti et al., Phys. Plasmas 17, 058102 (2010)] is used to assess the performance requirements cryogenic implosion experiments on Omega Laser Facility. hydrodynamic similarity developed in both one and two dimensions tested using multimode simulations with hydrocode DRACO [P. B. Radha 12, 032702 (2005)] hydro-equivalent implosions (implosions same velocity, adiabat, laser intensity). scale direct-drive OMEGA National Ignition...
One-dimensional metrics can be considered an upper bound on the performance that achieved given implosion with imploding mass Mimp and a adiabat α, driven to velocity V by specified ablation pressure Pa for single shell capsules low-opacity ablators. The quantitative value of ignition metric depends definition ignition. We review choices have been made various authors before settling based yield amplification 30 where is ratio from includes alpha particle neutron deposition relative obtained...
It is shown that inertial confinement fusion targets designed with low implosion velocities can be shock-ignited using laser-plasma interaction generated hot electrons (hot-$e$'s) to obtain high energy gains. These designs are robust multimode asymmetries and predicted ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules hot-$e$'s which produced only at a large laser facility like the National Ignition Facility, laser-to-hot-$e$ conversion...
The study of Rayleigh–Taylor instability in the deceleration phase inertial confinement fusion implosions is carried out using three-dimensional (3-D) radiation-hydrodynamic Eulerian parallel code DEC3D. We show that yield-over-clean a strong function residual kinetic energy (RKE) for low modes. Our analytical models indicate behavior larger hot-spot volumes observed modes and consequential pressure degradation can be explained terms increasing RKE. These results are derived simple adiabatic...
It is shown that direct-drive implosions on the OMEGA laser have achieved core conditions would lead to significant alpha heating at incident energies available National Ignition Facility (NIF) scale. The extrapolation of experimental results from NIF energy assumes only implosion hydrodynamic efficiency unchanged higher energies. This approach independent uncertainties in physical mechanism degrade OMEGA, and relies solely a volumetric scaling experimentally observed conditions. estimated...
Laser-direct drive (LDD), along with laser indirect (X-ray) (LID) and magnetic pulsed power, is one of the three viable inertial confinement fusion approaches to achieving ignition gain in laboratory. The LDD programme primarily being executed at both Omega Laser Facility Laboratory for Energetics National Ignition (NIF) Lawrence Livermore Laboratory. research includes cryogenic implosions, fundamental physics including material properties, hydrodynamics laser–plasma interaction physics. on...
Hot electrons generated by laser-plasma instabilities degrade the performance of laser-fusion implosions preheating DT fuel and reducing core compression. The hot-electron energy deposition in has been directly measured for first time comparing hard x-ray signals between DT-layered mass-equivalent ablator-only implosions. electron profile is inferred through dedicated experiments using Cu-doped payloads varying thickness. preheat accurately explains areal-density degradation observed many...
In order to understand how close current layered implosions in indirect-drive inertial confinement fusion are ignition, it is necessary measure the level of alpha heating present. To this end, pairs experiments were performed that consisted a low-yield tritium-hydrogen-deuterium (THD) implosion and high-yield deuterium-tritium (DT) validate experimentally simulation-based methods determining yield amplification. The THD capsules designed reduce simultaneously DT neutron (alpha heating)...
A comprehensive model is developed to study alpha-heating in inertially confined plasmas. It describes the time evolution of a central low-density hot spot by compressible shell, heated fusion alphas, and cooled radiation thermal losses. The includes deceleration, stagnation, burn phases inertial confinement implosions, valid for sub-ignited targets with ≤10× amplification yield from alpha-heating. results radiation-hydrodynamic simulations are used derive realistic initial conditions...
Three-dimensional (3-D) implosion asymmetries lead to significant variations in ion-temperature measurements inertial confinement fusion experiments. We present an analytical method generalize the physical properties of velocity variance Brysk model. This analysis provides a consistent explanation for 3-D effects inferred various single modes and multimodes modeled by deceleration-phase hydrocode DEC3D neutron transport code IRIS3D. The effect hot-spot flow asymmetry on is shown be uniquely...
Separating ignition of the central hot spot from propagating burn in surrounding dense fuel is crucial to conclusively assess achievement inertial confinement fusion (ICF). We show that transition onset occurs when alpha heating within has amplified yield by 15× 25× with respect compression-only case without energy deposition. This amplification corresponds a value fractional f_{α}≈1.4 (f_{α}=0.5 energy/hot energy). The parameter f_{α} can be inferred ICF experiments measuring neutron yield,...
A detailed analytic model is presented here to investigate the physics of burn propagation in inertially confined plasmas. The onset ignition and occurs when alpha heating hot spot causes rapid ablation shell mass into spot. This allows large energy gains be achieved since most fuel located shell. Here, we first present a comprehensive review previous models that have been used describe hot-spot evolution ignition; then show proper description propagating wave requires includes conservation...
Target preheat by superthermal electrons from laser-plasma instabilities is a major obstacle to achieving thermonuclear ignition via direct-drive inertial confinement fusion at the National Ignition Facility (NIF). Polar-direct-drive surrogate plastic implosion experiments were performed on NIF quantify levels an ignition-relevant scale and develop mitigation strategies. The used infer hot-electron temperature, energy fraction, divergence, directly measure spatial deposition profile inside...
Cryogenic deuterium–tritium ice target implosions on OMEGA with new small-spot (SG5-650) distributed phase plates (DPPs) achieved an (11±4)% increase in energy coupling compared to larger-spot SG5-850 DPPs by decreasing the ratio of laser spot diameter from 0.93 0.75. The SG5-650 provide a focus size 674 μm, which is defined as that encircles 95% measured beam 834 μm for SG5-850, are standard cryogenic OMEGA. hydrodynamic efficiency, kinetic imploding shell energy, increased 4.5% 5.0% based...
Evolution of the hot spot plasma conditions was measured using high-resolution x-ray spectroscopy at National Ignition Facility. The capsules were filled with DD gas trace levels Kr and had either a high-density-carbon (HDC) ablator or tungsten (W)-doped HDC ablator. Time-resolved measurement Heβ spectra, absolutely calibrated by simultaneous time-integrated measurement, allows inference electron density temperature through observing Stark broadening relative intensities dielectronic...
Experiments were performed with CH, Be, C, and SiO2 ablators interacting high-intensity UV laser radiation (5 × 1015 W/cm2, λ = 351 nm) to determine the optimum material for hot-electron production strong-shock generation. Significantly more hot electrons are produced in CH (up ∼13% instantaneous conversion efficiency), while amount is a factor of ∼2 3 lower other ablators. A larger fraction correlated higher effective ablation pressure. The efficiency attributed stronger damping...
This paper describes a technique for identifying trends in performance degradation inertial confinement fusion implosion experiments. It is based on reconstruction of the core with combination low- and mid-mode asymmetries. was applied to an ensemble hydro-equivalent deuterium–tritium implosions OMEGA which achieved inferred hot-spot pressures ≈56 ± 7 Gbar [Regan et al., Phys. Rev. Lett. 117, 025001 (2016)]. All experimental observables pertaining could be reconstructed simultaneously same...
A recent experiment conducted on the National Ignition Facility (NIF) described in study by Abu-Shawareb et al. [Phys. Rev. Lett. 129, 075001 (2022)] achieved a fusion yield output of 1.3 MJ from ∼ 220 kJ x-ray energy absorbed capsule, demonstrating remarkable progress field laser driven inertial confinement fusion. In A. R. Christopherson [“Effects charged particle heating hydrodynamics inertially confined plasmas,” Ph.D. thesis (2020)], plasma conditions needed to claim onset ignition and...
In this paper, we present a theoretical framework for interpreting the hot-spot electron temperature (Te) inferred from hard (10- to 20-keV) x-ray continuum emission inertial confinement fusion implosions on OMEGA. We first show that Te represents emission-weighted, harmonic mean of distribution, both spatially and temporally. A scheme is then provided selecting photon energy which weighting approximates neutron weighting. Simulations are used quantify predicted relationship between Te,...