A5065578195- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Laser-Matter Interactions and Applications
- High-pressure geophysics and materials
- Laser Design and Applications
- Atomic and Molecular Physics
- Magnetic confinement fusion research
- Nuclear Physics and Applications
- Particle Accelerators and Free-Electron Lasers
- Gamma-ray bursts and supernovae
- Advanced X-ray Imaging Techniques
- Plasma Diagnostics and Applications
- Particle accelerators and beam dynamics
- Astro and Planetary Science
- Radiation Therapy and Dosimetry
- Ionosphere and magnetosphere dynamics
- Diamond and Carbon-based Materials Research
- Geophysics and Sensor Technology
- Cold Fusion and Nuclear Reactions
- Geomagnetism and Paleomagnetism Studies
- Planetary Science and Exploration
- Laser Material Processing Techniques
- Astrophysics and Cosmic Phenomena
- Radiation Detection and Scintillator Technologies
- Radiation Effects and Dosimetry
University of Michigan
2016-2025
Optical Sciences (United States)
2012-2024
Michigan United
2013-2023
Lawrence Livermore National Laboratory
2013-2021
Columbia University
2009-2021
Lancaster University
2017-2021
Cockcroft Institute
2018-2021
Applied Mathematics (United States)
2021
University of California, San Francisco
2021
University of Rochester
2021
The direct laser acceleration (DLA) of electrons in underdense plasmas can provide hundreds nC accelerated to near-GeV energies using currently available lasers. Here we demonstrate the key role electron transverse displacement and use it analytically predict expected maximum energies. energy scaling is shown be agreement with full-scale quasi-3D particle-in-cell simulations a pulse propagating through preformed guiding channel directly used for optimizing DLA near-future facilities....
We present measurements of a magnetic reconnection in plasma created by two laser beams (1 ns pulse duration, $1\ifmmode\times\else\texttimes\fi{}{10}^{15}\text{ }\text{ }\mathrm{W}\text{ }{\mathrm{cm}}^{\ensuremath{-}2}$) focused close proximity on planar solid target. Simultaneous optical probing and proton grid deflectometry reveal high velocity, collimated outflowing jets 0.7---1.3 MG fields at the focal spot edges. Thomson scattering from layer are consistent with electron temperatures...
The first evidence of x-ray harmonic radiation extending to 3.3 \AA{}, 3.8 keV (order $n>3200$) from petawatt class laser-solid interactions is presented, exhibiting relativistic limit efficiency scaling ($\ensuremath{\eta}\ensuremath{\sim}{n}^{\ensuremath{-}2.5}--{n}^{\ensuremath{-}3}$) at multi-keV energies. This holds up a maximum order, ${n}_{\mathrm{RO}}\ensuremath{\sim}{8}^{1/2}{\ensuremath{\gamma}}^{3}$, where $\ensuremath{\gamma}$ the Lorentz factor, above which an intensity...
The dynamics of plasma electrons in the focus a petawatt laser beam are studied via measurements their x-ray synchrotron radiation. With increasing intensity, forward directed x rays extending to 50 keV is observed. measured well described asymptotic limit oscillating channel. critical energy spectrum found scale as Maxwellian temperature simultaneously electron spectra. At low intensity transverse oscillations negligible predominantly accelerated axially by generated wakefield. high...
A beam of multi-MeV helium ions has been observed from the interaction a short-pulse high-intensity laser pulse with underdense plasma. The ion was found to have maximum energy for He2+ (40(+3)(-8)) MeV and directional along propagation path, highest being collimated cone less than 10 degrees. 2D particle-in-cell simulations show that are accelerated by sheath electric field is produced at back gas target. This generated transfer hot electron beam, which exits target generating large...
We examine a regime in which linearly polarized laser pulse with relativistic intensity irradiates sub-critical plasma for much longer than the characteristic electron response time. A steady-state channel is formed this case quasi-static transverse and longitudinal electric fields. These relatively weak fields significantly alter dynamics. The field reduces dephasing between wave, leading to an enhancement of energy gain from pulse. ultimately limited by superluminosity wave fronts induced...
Probing of electromagnetic fields in high-energy-density experiments is key to understanding questions fusion processes such as how the are compressed, diffuse through plasma, and can seed instabilities. Many kinetic studied, including collisionless shocks, filamentary instabilities, jets, magnetic reconnection, turbulence, all depend on field structure. In this review, an overview experimental techniques underpinning theoretical principles modeling proton-based imaging presented, followed...
Experiments were performed to investigate the propagation of a high intensity (I approximately 10(21) W cm(-2)) laser in foam targets with densities ranging from 0.9n(c) 30n(c). Proton acceleration was used diagnose interaction. An improvement proton beam energy and efficiency is observed for lowest density (n(e)=0.9n(c)), compared higher foams. Simulations show that penetrates deeper into target due its relativistic results greater collimation ensuing hot electrons. This rear surface...
The propagation of ultra intense laser pulses through matter is connected with the generation strong moving magnetic fields in channel as well formation a thin ion filament along axis channel. Upon exiting plasma field displaces electrons at back target, generating quasistatic electric that accelerates and collimates ions from filament. Two-dimensional Particle-in-Cell simulations show 1 PW pulse tightly focused on near-critical density target able to accelerate protons up an energy 1.3 GeV....
Coherent x-ray beams with a subfemtosecond (<10(-15) s) pulse duration will enable measurements of fundamental atomic processes in completely new regime. High-order harmonic generation (HOHG) using short (<100 fs) infrared lasers focused to intensities surpassing 10(18) W cm(-2) onto solid density plasma is promising means generating such pulses. Critical the relativistic oscillating mirror mechanism steepness gradient at reflection point, characterized by scale length, which can strongly...
Short pulse laser interactions at intensities of 2×10(21) W cm(-2) with ultrahigh contrast (10(-15)) on submicrometer silicon nitride foils were studied experimentally by using linear and circular polarizations normal incidence. It was observed that, as the target decreases in thickness, electron heating begins to occur for polarization leading sheath acceleration contaminant ions, while thicker targets no or is observed. For polarization, all showed exponential energy spreads similar...
Laser-wakefield accelerators (LWFAs) are high acceleration-gradient plasma-based particle capable of producing ultra-relativistic electron beams. Within the strong focusing fields wakefield, accelerated electrons undergo betatron oscillations, emitting a bright pulse X-rays with micrometer-scale source size that may be used for imaging applications. Non-destructive X-ray phase contrast and tomography heterogeneous materials can provide insight into their processing, structure, performance....
The emission characteristics of intense laser driven protons are controlled using ultrastrong (of the order 10(9) V/m) electrostatic fields varying on a few ps time scale. field structures achieved by exploiting high potential target (reaching multi-MV during interaction). Suitably shaped targets result in reduction proton beam divergence, and hence an increase flux while preserving quality. peak focusing power its temporal variation shown to depend characteristics, allowing for collimation...
Laser-driven magnetic reconnection is investigated using proton deflectometry. Two laser beams of nanosecond duration were focused in close proximity on a solid target to intensities I∼1×1015 W cm−2. Through the well known ∇ne×∇Te mechanism, azimuthal fields are generated around each focal spot. During expansion two plasmas, oppositely oriented field lines brought together resulting region between spots. The spatial scales and plasma parameters consistent with proceeding due Hall mechanism....
Experiments were performed using the Omega EP laser, which provided pulses containing 1kJ of energy in 9ps and was used to investigate high-power, relativistic intensity laser interactions with near-critical density plasmas, created from foam targets densities 3–100 mg/cm3. The effect changing plasma on both light transmitted through proton beam accelerated interaction investigated. Two-dimensional particle-in-cell simulations enabled dynamics propagation be studied detail. polarization...
Experiments were performed using the Omega EP laser, operating at 740 J of energy in 8 ps (90 TW), which provides extreme conditions relevant to fast ignition studies. A carbon and hydrogen plasma plume was used as underdense target interaction laser pulse propagating channeling through imaged proton radiography. The early time expansion, channel evolution, filamentation, self-correction measured on a single shot via this method. wall modulation observed attributed surface waves. After...
Experiments were performed on the Omega EP laser facility to study pulse propagation, channeling phenomena and electron acceleration from high-intensity, high-power interactions with underdense plasma. A CH plasma plume was used as target interaction of through imaged using proton radiography. High-energy spectra measured for different experimental parameters. Structures observed along channel walls are interpreted having developed surface waves, which likely serve an injection mechanism...
Superponderomotive-energy electrons are observed experimentally from the interaction of an intense laser pulse with a relativistically transparent target. For target, kinetic modeling shows that generation energetic is dominated by energy transfer within main, classically overdense, plasma volume. The produces narrowing, funnel-like channel inside volume generates field structure responsible for electron heating. combines slowly evolving azimuthal magnetic field, generated strong...
We describe here efforts to create and study magnetized electron–positron pair plasmas, the existence of which in astrophysical environments is well-established. Laboratory incarnations such systems are becoming ever more possible due novel approaches techniques plasma, beam laser physics. Traditional plasmas studied date, both nature laboratory, exhibit a host different wave types, many generically unstable evolve into turbulence or violent instabilities. This complexity instability these...
Abstract Experimental measurements using the OMEGA EP laser facility demonstrated direct acceleration (DLA) of electron beams to (505 ± 75) MeV with (140 30) nC charge from a low-density plasma target 400 J, picosecond duration pulse. Similar trends energy density are also observed in self-consistent two-dimensional particle-in-cell simulations. The intensity pulse is sufficiently large that electrons rapidly expelled along propagation axis form channel. dominant mechanism confirmed be DLA...
Direct Laser Acceleration (DLA) of electrons during a high-energy, picosecond laser interaction with an underdense plasma has been demonstrated to be substantially enhanced by controlling the focusing geometry. Experiments using OMEGA EP facility measured accelerated maximum energies exceeding 120 times ponderomotive energy under certain focusing, pulse energy, and density conditions. Two-dimensional particle-in-cell simulations show that conditions alter field evolution, channel fields...
Measurements of the bidirectional plasma jets that form at surface a solid target during laser-generated driven magnetic reconnection are presented. Resistivity enhancement least 25× classical Spitzer value is required when applying Sweet–Parker model to reconcile experimentally observed time scale. Analytic calculations show fast model, which includes priori effects microturbulent resistivity enhancement, better reproduces experimental observations.
Laser-driven d(d, n)-3He beam-target fusion neutron production from bulk deuterated plastic (CD) targets is compared with a pitcher-catcher target scheme using an identical laser and detector arrangement. For intensities in the range of (1–3) × 1019 W cm−2, it was found that produced high yield (5 104 neutrons per steradian) beamed preferentially propagation direction. Numerical modeling shows importance considering temperature adjusted stopping powers to correctly model production. The CD...
Experiments where a laser-generated proton beam is used to probe the megagauss strength self-generated magnetic fields from nanosecond laser interaction with an aluminum target are presented. At intensities of 10(15) W cm(-2) and under conditions significant fast electron production strong heat fluxes, mean-free-path long compared temperature gradient scale length hence nonlocal transport important for dynamics field in plasma. The hot flux transports away focal region through Nernst effect...
Experiments at the HERCULES laser facility have produced directional neutron beams with energies up to 16.8(±0.3) MeV using d12(d,n)23He,Li73(p,n)47Be,andLi37(d,n)48Be reactions. Efficient Li12(d,n)48Be reactions required selective acceleration of deuterons through introduction a deuterated plastic or cryogenically frozen D2O layer on surface thin film target. The measured yield was ≤1.0 (±0.5)×107 neutrons/sr flux 6.2(±3.7) times higher in forward direction than 90°. This demonstrates that...