A5055115572- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Laser-Matter Interactions and Applications
- High-pressure geophysics and materials
- Laser Design and Applications
- Advanced X-ray Imaging Techniques
- Atomic and Molecular Physics
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
- Particle accelerators and beam dynamics
- Magnetic confinement fusion research
- Radiation Therapy and Dosimetry
- Pulsed Power Technology Applications
- Ion-surface interactions and analysis
- Laser Material Processing Techniques
- Gamma-ray bursts and supernovae
- Advanced Fiber Laser Technologies
- Advanced X-ray and CT Imaging
- Planetary Science and Exploration
- Solid State Laser Technologies
- Diamond and Carbon-based Materials Research
- Solar and Space Plasma Dynamics
- Particle Detector Development and Performance
- Advanced Optical Sensing Technologies
- Crystallography and Radiation Phenomena
Imperial College London
2016-2025
John Adams Institute for Accelerator Science
2014-2025
Isaac Newton Institute for Mathematical Sciences
2014-2025
Rutherford Appleton Laboratory
1993-2018
Ministry of Education of the People's Republic of China
2018
Peking University
2018
Shanxi University
2018
University of Maryland, College Park
2010-2018
Shanghai Institute of Optics and Fine Mechanics
2018
Cockcroft Institute
2018
Plasmas are an attractive medium for the next generation of particle accelerators because they can support electric fields greater than several hundred gigavolts per meter. These accelerating generated by relativistic plasma waves-space-charge oscillations-that be excited when a high-intensity laser propagates through plasma. Large currents background electrons then trapped and subsequently accelerated these waves. In forced wake field regime, where pulse length is order wavelength, we show...
The dynamics of energetic particles in strong electromagnetic fields can be heavily influenced by the energy loss arising from emission radiation during acceleration, known as reaction. When interacting with a high-energy electron beam, today's lasers are sufficiently intense to explore transition between classical and quantum reaction regimes. We present evidence collision an ultrarelativistic beam generated laser-wakefield acceleration (ϵ>500 MeV) laser pulse (a0>10). measure postcollision...
Abstract Electron–positron pair plasmas represent a unique state of matter, whereby there exists an intrinsic and complete symmetry between negatively charged (matter) positively (antimatter) particles. These play fundamental role in the dynamics ultra-massive astrophysical objects are believed to be associated with emission ultra-bright gamma-ray bursts. Despite extensive theoretical modelling, our knowledge this matter is still speculative, owing extreme difficulty recreating neutral...
Substantial energy loss in an electron beam passing through a high-intensity laser provides clear evidence of the radiation reaction, shedding light on how electrons interact with extreme electromagnetic fields.
We report on the generation of a narrow divergence (${\ensuremath{\theta}}_{\ensuremath{\gamma}}<2.5\text{ }\text{ }\mathrm{mrad}$), multi-MeV (${E}_{\mathrm{max}}\ensuremath{\approx}18\text{ }\mathrm{MeV}$) and ultrahigh peak brilliance ($>1.8\ifmmode\times\else\texttimes\fi{}{10}^{20}\text{ }\mathrm{photons}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }{\mathrm{mm}}^{\ensuremath{-}2}\text{ }{\mathrm{mrad}}^{\ensuremath{-}2}$ 0.1% BW) $\ensuremath{\gamma}$-ray beam from scattering an...
The application of high intensity laser-produced gamma rays is discussed with regard to picosecond resolution deep-penetration radiography. spectrum and angular distribution these measured using an array thermoluminescent detectors for both underdense (gas) target overdense (solid) target. It found that the use in a laser plasma accelerator configuration produces much more intense directional source. peak dose also increased significantly. Radiography demonstrated experiments source size estimated.
The acceleration of electrons to approximately 0.8 GeV has been observed in a self-injecting laser wakefield accelerator driven at plasma density 5.5x10(18) cm(-3) by 10 J, 55 fs, 800 nm pulse the blowout regime. is found be self-guided for 1 cm (>10zR), measurement single filament containing >30% initial energy this distance. Three-dimensional particle cell simulations show that intensity within guided amplified beyond its focused value normalized vector potential a0>6, thus driving highly...
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...
We report on the acceleration of impurity-free quasimononenergetic proton beams from an initially gaseous hydrogen target driven by intense infrared (λ=10 μm) laser. The front surface was observed optical probing to be forward radiation pressure A beam ∼MeV energy simultaneously recorded with narrow spread (σ∼4%), low normalized emittance (∼8 nm), and negligible background. scaling ratio intensity over density (I/n) confirms that is due shock.
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 acceleration of electrons injected in a plasma wave generated by the laser wakefield mechanism has been observed. A maximum energy gain 1.6 MeV measured and longitudinal electric field is estimated to 1.5 GV/m. experimental data agree with theoretical predictions when 3D effects are taken into account. duration inferred from number accelerated order 1 ps.
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...
The spatial extent of the plasma wave and spectrum accelerated electrons are simultaneously measured when relativistic associated with Raman forward scattering an intense laser beam reaches breaking limit. maximum observed energy 94 MeV is greater than that expected from phase slippage between accelerating electric field as given by linear theory for preinjected electrons. results in good agreement 2D particle-in-cell code simulations experiment.
Metal foil targets were irradiated with 1 mum wavelength (lambda) laser pulses of 5 ps duration and focused intensities (I) up to 4x10;{19} W cm;{-2}, giving values both Ilambda;{2} pulse comparable those required for fast ignition inertial fusion. The divergence the electrons accelerated into target was determined from spatially resolved measurements x-ray K_{alpha} emission transverse probing plasma formed on back foils. Comparison other published data shows that it increases is...
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 report experimental evidence for a Rayleigh-Taylor-like instability driven by radiation pressure of an ultraintense (${10}^{21}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$) laser pulse. The is witnessed the highly modulated profile accelerated proton beam produced when irradiates 5 nm diamondlike carbon (90% C, 10% H) target. Clear anticorrelation between bubblelike modulations and transmitted further demonstrate role in modulating foil. Measurements modulation wavelength, acceleration...
We show that x-rays from a recently demonstrated table top source of bright, ultrafast, coherent synchrotron radiation [Kneip et al., Nat. Phys. 6, 980 (2010)] can be applied to phase contrast imaging biological specimens. Our scheme is based on focusing high power short pulse laser in tenuous gas jet, setting up plasma wakefield accelerator accelerates and wiggles electrons analogously conventional synchrotron, but the centimeter rather than tens meter scale. use record absorption images...
Abstract Laser wakefield accelerators promise to revolutionize many areas of accelerator science. However, one the greatest challenges their widespread adoption is difficulty in control and optimization outputs due coupling between input parameters dynamic evolution accelerating structure. Here, we use machine learning techniques automate a 100 MeV-scale accelerator, which optimized its by simultaneously varying up six including spectral spatial phase laser plasma density length. Most...
Abstract A bright μm-sized source of hard synchrotron x-rays (critical energy E crit > 30 keV) based on the betatron oscillations laser wakefield accelerated electrons has been developed. The potential this for medical imaging was demonstrated by performing micro-computed tomography a human femoral trabecular bone sample, allowing full 3D reconstruction to resolution below 50 μm. use 1 cm long accelerator means that length beamline (excluding laser) is dominated x-ray distances rather...
The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) aims at studying plasma wakefield generation and electron acceleration driven by proton bunches. It is a proof-of-principle R&D experiment CERN the world׳s first experiment. AWAKE will be installed in former CNGS facility uses 400 GeV/c beam bunches from SPS. experiments focus on self-modulation instability of long (rms ~12 cm) bunch plasma. These are planned for end 2016. Later, 2017/2018, low energy (~15 MeV)...
Laser-driven ion sources are a rapidly developing technology producing high energy, peak current beams. Their suitability for applications, such as compact medical accelerators, motivates development of robust acceleration schemes using widely available repetitive ultraintense femtosecond lasers. These applications not only require beam but also place demanding requirements on the source stability and controllability. This can be seriously affected by laser temporal contrast, precluding...
The spectra of energetic electrons produced by a laser interaction with underdense plasma have been measured at intensities $>3\ifmmode\times\else\texttimes\fi{}{10}^{20}\text{ }\text{ }\mathrm{W}\text{ }{\mathrm{cm}}^{\ensuremath{-}2}$. Electron energies in excess 300 MeV observed. Measurements the transmitted spectrum indicate that there is no correlation between acceleration and wave production. Particle-in-cell simulations show ponderomotive force produces an ion channel. field nonlinear...