A5032083305- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astrophysics and Cosmic Phenomena
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Fluid Dynamics and Turbulent Flows
- Geomagnetism and Paleomagnetism Studies
- Magnetic confinement fusion research
- High-pressure geophysics and materials
- Plasma Diagnostics and Applications
- Particle Dynamics in Fluid Flows
- Astrophysics and Star Formation Studies
- Atomic and Molecular Physics
- Laser Design and Applications
- Planetary Science and Exploration
- Plasma and Flow Control in Aerodynamics
- Gas Dynamics and Kinetic Theory
- Particle Accelerators and Free-Electron Lasers
- Advanced Optical Sensing Technologies
- Computational Fluid Dynamics and Aerodynamics
- Laser-Matter Interactions and Applications
- Combustion and flame dynamics
- Seismic Waves and Analysis
University of Oxford
2013-2022
Rutherford Appleton Laboratory
2017
Queen's University Belfast
2017
University of Chicago
2017
University of York
2017
Lawrence Livermore National Laboratory
2011-2013
University of Nevada, Reno
2013
University of Michigan–Ann Arbor
2013
Osaka University
2013
University of Rochester
2013
Laser wakefield acceleration of electrons holds great promise for producing ultracompact stages GeV scale, high-quality electron beams applications such as x-ray free lasers and high-energy colliders. Ultrahigh intensity laser pulses can be self-guided by relativistic plasma waves (the wake) over tens vacuum diffraction lengths, to give >1 energy in centimeter-scale low density plasmas using ionization-induced injection inject charge into the wake even at densities. By restricting a distinct...
Abstract Magnetic fields are ubiquitous in the Universe. The energy density of these is typically comparable to fluid motions plasma which they embedded, making magnetic essential players dynamics luminous matter. standard theoretical model for origin strong through amplification tiny seed via turbulent dynamo level consistent with current observations. However, experimental demonstration mechanism has remained elusive, since it requires conditions that extremely hard re-create terrestrial...
A series of Omega experiments have produced and characterized high velocity counter-streaming plasma flows relevant for the creation collisionless shocks. Single double CH2 foils been irradiated with a laser intensity ∼ 1016 W/cm2. The ablated was 4 mm from foil surface using Thomson scattering. peak flow 2000 km/s, an electron temperature 110 eV, ion 30 density 1018 cm−3 were measured in single configuration. Significant increases temperatures seen geometry. conditions used to calculate...
Significance Magnetic fields exist throughout the universe. Their energy density is comparable to of fluid motions plasma in which they are embedded, making magnetic essential players dynamics luminous matter The origin and amplification these their observed strengths far from being understood. standard model for galactic intergalactic through seed via turbulent processes level consistent with current observations. For this process be effective, needs reach a strongly nonlinear phase....
Astrophysical collisionless shocks are common in the universe, occurring supernova remnants, gamma ray bursts, and protostellar jets. They appear colliding plasma flows when mean free path for ion-ion collisions is much larger than system size. It believed that such could be mediated via electromagnetic Weibel instability astrophysical environments without pre-existing magnetic fields. Here, we present laboratory experiments using high-power lasers investigate dynamics of high-Mach-number...
A study of the transition from collisional to collisionless plasma flows has been carried out at National Ignition Facility using high Mach number (M>4) counterstreaming plasmas. In these experiments, CD-CD and CD-CH planar foils separated by 6–10 mm are irradiated with laser energies 250 kJ per foil, generating ∼1000 km/s flows. Varying foil separation distance scales ion density average bulk velocity and, therefore, ion-ion Coulomb mean free path, interaction region midplane. The...
Understanding magnetic-field generation and amplification in turbulent plasma is essential to account for observations of magnetic fields the universe. A theoretical framework attributing origin sustainment these so-called fluctuation dynamo was recently validated by experiments on laser facilities low-magnetic-Prandtl-number plasmas ([Formula: see text]). However, same proposes that should operate differently when [Formula: text], regime relevant many astrophysical environments such as...
In conventional gases and plasmas, it is known that heat fluxes are proportional to temperature gradients, with collisions between particles mediating energy flow from hotter colder regions the coefficient of thermal conduction given by Spitzer's theory. However, this theory breaks down in magnetized, turbulent, weakly collisional although modifications difficult predict first principles due complex, multiscale nature problem. Understanding transport important astrophysical plasmas such as...
Collisionless shocks are often observed in fast-moving astrophysical plasmas, formed by non-classical viscosity that is believed to originate from collective electromagnetic fields driven kinetic plasma instabilities. However, the development of small-scale processes into large-scale structures, such as a collisionless shock, not well understood. It also unknown what extent contain macroscopic with long coherence length. For these reasons, it valuable explore shock formation, including...
The properties of supersonic, compressible plasma turbulence determine the behavior many terrestrial and astrophysical systems. In interstellar medium molecular clouds, plays a vital role in star formation evolution our galaxy. Observations density velocity power spectra Orion B Perseus clouds show large deviations from those predicted for incompressible turbulence. Hydrodynamic simulations attribute this to high Mach number (ISM), although exact details dependence are not well understood....
The universe is permeated by magnetic fields, with strengths ranging from a femtogauss in the voids between filaments of galaxy clusters to several teragauss black holes and neutron stars. standard model behind cosmological fields nonlinear amplification seed via turbulent dynamo values observed. We have conceived experiments that aim demonstrate study mechanism laboratory. Here we describe design these through simulation campaigns using FLASH, highly capable radiation magnetohydrodynamics...
We are performing scaled astrophysics experiments on Omega and NIF. Laser driven counter-streaming interpenetrating supersonic plasma flows can be studied to understand astrophysical electromagnetic phenomena in a controlled laboratory setting. In our experiments, the flow state is measured using Thomson scattering diagnostics, demonstrating indeed super-sonic collisionless regime. observe surprising additional electron ion heating from drag force double that attributed electrostatic...
The interaction between a molecular cloud and an external agent (e.g., supernova remnant, plasma jet, radiation, or another cloud) is common phenomenon throughout the Universe can significantly change star formation rate within galaxy. This process leads to fragmentation of its subsequent compression can, eventually, initiate gravitational collapse stable cloud. It is, however, difficult study such systems in detail using conventional techniques (numerical simulations astronomical...
We report the measurements of electrostatic field structures associated with an shock formed in laser-produced counter-streaming plasmas proton imaging. The thickness structure is estimated from images different kinetic energies 4.7 MeV to 10.7 MeV. width transition region characterized by electron scale length plasma, suggesting that due a collisionless shock.
Studies of a blast wave produced from carbon rods and plastic spheres in an argon background gas have been conducted using the Vulcan laser at Rutherford Appleton Laboratory. A 1500 J was focused onto these targets, rear-side observations emission front were recorded fast-framing camera. The is asymmetrical shape tends to more symmetrical as it progresses due production second shock later time, which pushes out wave. Plastic produce faster waves, breakthrough visible before stalls. results...
Uniform density and temperature Xe plasmas have been produced over >4 mm scale-lengths using x-rays generated in a cylindrical Pb cavity. The cavity is 750 μm depth diameter, heated by 300 J, 2 ns square, 1054 nm laser pulse focused to spot size of 200 at the entrance. plasma characterized simultaneous imaging Thomson scattering measurements from both electron ion features. feature measurement determines spatial profile, these parameters as constraints analysis allows an accurate...
Identifying the sources of highest energy cosmic rays requires understanding how they are deflected by stochastic, spatially intermittent intergalactic magnetic field. Here we report measurements energetic charged-particle propagation through a laser-produced magnetized plasma with these properties. We characterize diffusive transport particles experimentally. The results show that is and that, for regime interest highest-energy rays, diffusion coefficient unaffected spatial intermittency