A5059920712- Laser-Plasma Interactions and Diagnostics
- High-pressure geophysics and materials
- Laser-induced spectroscopy and plasma
- Advanced X-ray Imaging Techniques
- Diamond and Carbon-based Materials Research
- Laser-Matter Interactions and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Laser Design and Applications
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
- Atomic and Molecular Physics
- Ion-surface interactions and analysis
- Advanced Optical Sensing Technologies
- Gamma-ray bursts and supernovae
- Particle Detector Development and Performance
- Radiation Therapy and Dosimetry
- Optical Systems and Laser Technology
- Plasma Diagnostics and Applications
- Planetary Science and Exploration
- Advanced X-ray and CT Imaging
- Astrophysical Phenomena and Observations
- Particle accelerators and beam dynamics
- Gyrotron and Vacuum Electronics Research
- Tardigrade Biology and Ecology
- High-Energy Particle Collisions Research
Imperial College London
2019-2025
Czech Academy of Sciences, Institute of Physics
2024
Queen's University Belfast
2012-2023
University of Michigan
2023
University of Nebraska–Lincoln
2021-2022
John Adams Institute for Accelerator Science
2021
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....
Single-shot absorption measurements have been performed using the multi-keV X-rays generated by a laser wakefield accelerator. A 200 TW was used to drive accelerator in mode which produced broadband electron beams with maximum energy above 1 GeV and broad divergence of $\approx15$ miliradians FWHM. Betatron oscillations these electrons $1.2\pm0.2\times10^6$ photons/eV 5 keV region, signal-to-noise ratio approximately 300:1. This sufficient allow high-resolution XANES at K-edge titanium...
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<title>Abstract</title> Understanding dense fuel hydrodynamics is critical for predicting burning plasma behavior in laser-driven inertial confinement fusion. Traditional diagnostic sources face many limitations brightness, spatio-temporal resolution, and their ability to capture kinetic effects electromagnetic fields influencing interaction dynamics. We present a dual-probe, multi-messenger laser wakefield accelerator system, combining ultrafast X-rays relativistic electron beams at 1~Hz,...
We have designed a new filter pack array to measure angular variations in x-ray spectra during single shot. The was composed of repeating identical columns aluminum and copper filters varying thicknesses. These were located at different positions the spectrum each corresponding angle. This utilized an experiment energy evolution betatron x rays laser wakefield accelerator by curving with transverse density gradient, streaking across front charge-coupled device (CCD) camera. After subtracting...
We describe a laser-plasma platform for photon-photon collision experiments to measure fundamental quantum electrodynamic processes such as the linear Breit-Wheeler process with real photons. The has been developed using Gemini laser facility at Rutherford Appleton Laboratory. A wakefield accelerator and bremsstrahlung convertor are used generate collimated beam of photons energies hundreds MeV, that collide keV x-ray generated by heated plasma target. To detect pairs collisions, magnetic...
Abstract Ultrafast high-brightness X-ray pulses have proven invaluable for a broad range of research. Such are typically generated via synchrotron emission from relativistic electron bunches using large-scale facilities. Recently, significantly more compact sources based on laser-wakefield accelerated (LWFA) beams been demonstrated. In particular, laser-driven sources, where the radiation is by transverse oscillations electrons within plasma accelerator structure (so-called betatron...
We report on an experimental observation of the streaking betatron x rays in a curved laser wakefield accelerator. The was realized by launching pulse into plasma with transverse density gradient. By controlling and gradient, we steering driver, electron beam, simultaneously. Moreover, observed energy-angle correlation streaked utilized it diagnosing acceleration process single-shot mode. Our work could also find applications advanced control beam particle propagation. More importantly,...
Abstract Laser-driven compact particle accelerators can provide ultrashort pulses of broadband X-rays, well suited for undertaking X-ray absorption spectroscopy measurements on a femtosecond timescale. Here the Extended Absorption Fine Structure (EXAFS) features K-edge copper sample have been observed over 250 eV window in single shot using laser wakefield accelerator, providing information both electronic and ionic structure simultaneously. This capability will allow investigation ultrafast...
The collisional (or free-free) absorption of soft x rays in warm dense aluminium remains an unsolved problem. Competing descriptions the process exist, two which we compare to our experimental data here. One these is based on a weak scattering model, another uses corrected classical approach. These models show distinctly different behaviors with temperature. Here describe evidence for 26-eV photons solid density (${T}_{e}\ensuremath{\approx}1$ eV). Radiative x-ray heating from...
We present measurements of the complex ion structure warm dense carbon close to melting line at pressures around 100 GPa. High-pressure samples were created by laser-driven shock compression graphite and probed intense laser-generated x-ray sources with photon energies 4.75 keV 4.95 keV. High-efficiency crystal spectrometers allow for spectrally resolving scattered radiation. Comparing ratio elastically inelastically radiation, we find evidence a bonded liquid that is predicted ab-initio...
Fast-electron generation and dynamics, including electron refluxing, is at the core of understanding high-intensity laser-plasma interactions. This field itself strong relevance to fast ignition fusion development new short-pulse, intense, x-ray, γ-ray, particle sources. In this paper, we describe experiments that explicitly link fast-electron refluxing anisotropy in hard-x-ray emission. We find x-ray emission be strongly correlated suppression refluxing. contrast some previous work, peak...
Using the LCLS facility at SLAC National Accelerator Laboratory, we have observed X-ray scattering from iron compressed with laser driven shocks to Earth-core like pressures above 400GPa. The data shows shots where melting is incomplete and observe hexagonal close packed (hcp) crystal structure shock densities up 14.0 gcm-3 but no evidence of a double-hexagonal (dhcp) crystal. observation crystalline these densities, heating expected be in excess equilibrium melt temperature, may indicate...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation M. Makita, G. Nersisyan, K. McKeever, T. Dzelzainis, S. White, B. Kettle, Dromey, D. Doria, Zepf, C. L. Lewis, A. P. Robinson, Hansen, Riley; Fast electron propagation in Ti foils irradiated with sub-picosecond laser pulses at Iλ2>1018 Wcm−2μm2. Phys. Plasmas 1 February 2014; 21 (2): 023113....
The rapid progress that plasma wakefield accelerators are experiencing is now posing the question as to whether they could be included in design of next generation high-energy electron-positron colliders. However, typical structure accelerating wakefields presents challenging complications for positron acceleration. Despite seminal proof-of-principle experiments and theoretical proposals, experimental research plasma-based acceleration positrons currently limited by scarcity beams suitable...
M-L band x-rays (3-3
We present data on emission of $K$-shell radiation from Ti foils irradiated with subpicosecond pulses second harmonic (527 nm) the TARANIS laser system at intensities up to ${10}^{18}\phantom{\rule{0.28em}{0ex}}\text{W}\phantom{\rule{0.16em}{0ex}}{\text{cm}}^{\ensuremath{-}2}$. The are used demonstrate that a resonance absorption type mechanism is responsible for light and estimate fast electron temperatures 30--60 keV in broad agreement expectation models steep density gradient. Data taken...
X-ray absorption spectroscopy (XAS) can provide a wealth of information regarding the structure and state sample. Techniques such as XANES (X-ray Absorption Near Edge Structure) EXAFS (Extended Fine simultaneous measurement temperature both electronic ionic distributions. Making these measurements using single ultrashort probe pulse provides powerful tool for investigating, example, laboratory-based high energy-density samples. These states are notoriously difficult to due their extreme...
Abstract Laser wakefield accelerators commonly produce on-axis, low-divergence, high-energy electron beams. However, a high charge, annular shaped beam can be trapped outside the bubble and accelerated to energies. Here we present parametric study on production of low-energy-spread, ultra-relativistic ring beams in two-stage gas cell. Ring-shaped with energies higher than 750 MeV are observed simultaneously axis, continuously injected electrons. Often multiple different produced studies...
We report on experimental measurements of energy transfer efficiencies in a GeV-class laser wakefield accelerator. Both the from to plasma and accelerated electron beam was diagnosed by simultaneous measurement deceleration photons acceleration electrons as function length. The extraction efficiency, which we define ratio gained lost self-guided mode, maximized at $19\ifmmode\pm\else\textpm\fi{}3%$ tuning density additional information provided octave-spanning spectrum allows for independent...
We describe laboratory experiments to generate x-ray photoionized plasmas of relevance accretion-powered sources such as neutron star binaries and quasars, with significant improvements over previous work. A key quantity is referenced, namely the photoionization parameter, defined ξ=4πF/ne where F flux ne electron density. This normally meaningful in an astrophysical steady-state context, but also commonly used literature a figure merit for that are, necessity, time-dependent. demonstrate...