A5100334156- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- High-pressure geophysics and materials
- Atomic and Molecular Physics
- Laser-Matter Interactions and Applications
- Magnetic confinement fusion research
- Laser Design and Applications
- Nuclear Physics and Applications
- Ionosphere and magnetosphere dynamics
- Planetary Science and Exploration
- Advanced X-ray Imaging Techniques
- Dust and Plasma Wave Phenomena
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- Particle Accelerators and Free-Electron Lasers
- X-ray Spectroscopy and Fluorescence Analysis
- Ion-surface interactions and analysis
- Plasma Diagnostics and Applications
- Earthquake Detection and Analysis
- Solar and Space Plasma Dynamics
- Muon and positron interactions and applications
- Particle Detector Development and Performance
- Cosmology and Gravitation Theories
- Mass Spectrometry Techniques and Applications
Lawrence Livermore National Laboratory
2016-2025
Nanchang University
2013-2024
General Atomics (United States)
2009-2024
Hexi University
2023
University of Science and Technology of China
2019-2023
Institute of Plasma Physics
2023
Chinese Academy of Sciences
2023
Colorado State University
2021
Energetics (United States)
2016-2021
University of Rochester
2016-2021
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...
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.
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...
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...
We report new experimental results obtained on three different laser facilities that show directed laser-driven relativistic electron-positron jets with up to 30 times larger yields than previously and a quadratic (∼E_{L}^{2}) dependence of the positron yield energy. This favorable scaling stems from combination higher energy electrons due increased intensity recirculation MeV in mm-thick target. Based this scaling, first principles simulations predict possibility using such jets, produced...
The study of relativistic electron–positron pair plasmas is both fundamental physics interest and important to understand the processes that shape magnetic field dynamics, particle acceleration, radiation emission in high-energy astrophysical environments. Although it highly desirable laboratory, their generation control constitutes a critical challenge. Significant experimental theoretical progress has been made over recent years explore use intense lasers produce dense plasma laboratory...
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...
Abstract Relativistic electron-positron plasmas are ubiquitous in extreme astrophysical environments such as black-hole and neutron-star magnetospheres, where accretion-powered jets pulsar winds expected to be enriched with pairs. Their role the dynamics of is many cases believed fundamental, but their behavior differs significantly from typical electron-ion due matter-antimatter symmetry charged components. So far, our experimental inability produce large yields positrons quasi-neutral...
The viability of fast-ignition (FI) inertial confinement fusion hinges on the efficient transfer laser energy to compressed fuel via multi-MeV electrons. Preformed plasma due prepulse strongly influences ultraintense interactions and hot electron generation in hollow cone an FI target. We induced a consequent preplasma copper targets measured deposition zone main pulse by imaging emitted K_{alpha} radiation. Simulation radiation hydrodynamics particle cell modeling interaction agree well...
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...
Compound parabolic concentrator (CPC) targets are utilized at the National Ignition Facility Advanced Radiographic Capability (NIF-ARC) laser to enhance acceleration of electrons and production high energy photons, for durations 10 ps energies up 2.4 kJ. A large enhancement mean electron (>2 ×) photon brightness (>10×) is found with CPC compared flat targets. Using multiple diagnostic techniques different spatial locations scaling by gold activation data, spectra characterized...
The hyperfine splitting of the $1s$ ground state hydrogenlike Tl has been measured for two stable isotopes using emission spectroscopy in SuperEBIT electron-beam ion trap, giving $3858.22\ifmmode\pm\else\textpm\fi{}0.30 \AA{}$ ${}^{203}{\mathrm{Tl}}^{80+}$ and $3821.84\ifmmode\pm\else\textpm\fi{}0.34 ${}^{205}{\mathrm{Tl}}^{80+}$ with a wavelength difference $\ensuremath{\Delta}\ensuremath{\lambda}=36.38\ifmmode\pm\else\textpm\fi{}0.35 \AA{}.$ This is consistent estimates based on anomaly...
The Bremsstrahlung and K-shell emission from 1×1×1 mm3 planar targets irradiated by a short-pulse 3×1018–8×1019 W/cm2 laser were measured. was measured using filter stack spectrometer with spectral discrimination up to 500 keV. single photon counting charge coupled device. From Monte Carlo modeling of the target emission, conversion efficiencies into 1–3 MeV electrons 3%–12%, representing 20%–40% total efficiencies, inferred for intensities 8×1019 W/cm2. Comparisons scaling laws synthetic...
An ultraintense short pulse lasers incident on solid targets can generate relativistic electrons that then accelerate energetic protons and ions. These fast ions effectively heat the target, beyond region of direct laser interaction, are important to realizing ignition concept. To study these produced from laser-target interactions, we have developed a range spectrometers cover large energy (from less than 0.1 MeV above 100 MeV). They physically compact, high performance, low cost. We will...
The Advanced Radiographic Capability (ARC) laser system at the National Ignition Facility (NIF) is designed to ultimately provide eight beamlets with a pulse duration adjustable from 1 30 ps, and energies up 1.5 kJ per beamlet. Currently, four have been commissioned. In first set of 6 commissioning target experiments, individual were fired onto gold foil targets energy beamlet 20–30 ps length. x-ray distribution measured, yielding conversion efficiencies 4–9 × 10−4 for x-rays greater than 70...
New short-pulse kilojoule, Petawatt-class lasers, which have recently come online and are coupled to large-scale, many-beam long-pulse facilities, undoubtedly serve as very exciting tools capture transformational science opportunities in high energy density physics. These lasers also happen reside a unique laser regime: high-energy (kilojoule), relatively long (multi-picosecond) pulse-lengths, large (10s of micron) focal spots, where their use driving energetic particle beams is largely...
We measured the absolute response of image plate (Fuji BAS SR2040) for electrons at energies between 100keV and 4MeV using an electron spectrometer. The source was produced from a short pulse laser irradiated on solid density targets. This paper presents calibration results photon stimulated luminescence per this energy range. Monte Carlo radiation transport code MCNPX are also presented three representative incident angles onto plates corresponding depositions these angles. These provide...
This paper presents experimental scalings of the electrons and positrons produced by intense laser-target interactions at relativistic laser intensities (1018–1020 W cm−2). The data were acquired from three short-pulse facilities with energies ranging 80 to 1500 J. We found a non-linear (≈EL2) scaling positron yield [Chen et al., Phys. Rev. Lett. 114, 215001 (2015)] linear electron energy. These are explained theoretical numerical analyses. Positron acceleration target sheath field is...
Collimation of positrons produced by laser-solid interactions has been observed using an externally applied axial magnetic field. The collimation leads to a narrow divergence positron beam, with equivalent full width at half maximum beam angle 4° vs the un-collimated about 20°. A fraction laser-produced relativistic electrons energies close those is collimated, so charge imbalance ratio (ne−/ne+) in co-propagating collimated electron-positron jet reduced from ∼100 (no collimation) ∼2.5 (with...
An x-ray source generated by an electron beam produced using a Self-Modulated Laser Wakefield Accelerator (SM-LWFA) is explored for use in high energy density science facilities. By colliding the beam, with maximum of 380 MeV, total charge >10 nC and divergence 64 × 100 mrad, from SM-LWFA driven 1 ps 120 J laser, into high-Z foil, x/gamma-ray was generated. A broadband bremsstrahlung spectrum temperatures ranging 0.8 to 2 MeV measured almost orders magnitude flux increase when compared other...