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  • Journal article
    Tresca O, Dover NP, Cook N, Maharjan C, Polyanskiy MN, Najmudin Z, Shkolnikov P, Pogorelsky Iet al., 2015,

    Spectral Modification of Shock Accelerated Ions Using a Hydrodynamically Shaped Gas Target

    , PHYSICAL REVIEW LETTERS, Vol: 115, ISSN: 0031-9007
  • Journal article
    Cole JM, Wood J, Lopes NC, Poder K, Abel RL, Alatabi S, Bryant JSJ, Jin A, Kneip S, Mecseki K, Symes DR, Mangles SPD, Najmudin Zet al., 2015,

    Laser-wakefield accelerators as hard x-ray sources for 3D medical imaging of human bone

    , Scientific Reports, Vol: 5, ISSN: 2045-2322

    A bright μm-sized source of hard synchrotron x-rays (critical energy Ecrit > 30 keV) based on the betatron oscillations of laser wakefield accelerated electrons has been developed. The potential of this source for medical imaging was demonstrated by performing micro-computed tomography of a human femoral trabecular bone sample, allowing full 3D reconstruction to a resolution below 50 μm. The use of a 1 cm long wakefield accelerator means that the length of the beamline (excluding the laser) is dominated by the x-ray imaging distances rather than the electron acceleration distances. The source possesses high peak brightness, which allows each image to be recorded with a single exposure and reduces the time required for a full tomographic scan. These properties make this an interesting laboratory source for many tomographic imaging applications.
  • Journal article
    Savert, Mangles SPD, Schnell M, Siminos E, Cole JM, Leier M, Reuter M, Schwab MB, Moller M, Poder K, Jackel O, Paulus GG, Spielmann C, Skupin S, Najmudin Z, Kaluza MCet al., 2015,

    Direct observation of the injection dynamics of a laser wakefield accelerator using few-femtosecond shadowgraphy

    , Physical Review Letters, Vol: 115, ISSN: 1079-7114

    We present few-femtosecond shadowgraphic snapshots taken during the non-linear evolution of the plasma wave in a laser wakefield accelerator with transverse synchronized few-cycle probe pulses. These snapshots can be directly associated with the electron density distribution within the plasma wave and give quantitative information about its size and shape. Our results show that self-injection of electrons into the first plasma wave period is induced by a lengthening of the first plasma period. Three dimensional particle in cell simulations support our observations.
  • Journal article
    Turrell AE, Sherlock M, Rose SJ, 2015,

    Self-consistent inclusion of classical large-angle Coulomb collisions in plasma Monte Carlo simulations

    , Journal of Computational Physics, Vol: 299, Pages: 144-155, ISSN: 1090-2716

    Large-angle Coulomb collisions allow for the exchange of a significant proportion of the energy of a particle in a single collision, but are not included in models of plasmas based on fluids, the Vlasov-Fokker-Planck equation, or currently available plasma Monte Carlo techniques. Their unique effects include the creation of fast ‘knock-on’ ions, which may be more likely to undergo certain reactions, and distortions to ion distribution functions relative to what is predicted by small-angle collision only theories. We present a computational method which uses Monte Carlo techniques to include the effects of large-angle Coulomb collisions in plasmas and which self-consistently evolves distribution functions according to the creation of knock-on ions of any generation. The method is used to demonstrate ion distribution function distortions in an inertial confinement fusion (ICF) relevant scenario of the slowing of fusion products.
  • Journal article
    Pasley J, Bush IA, Robinson APL, Rajeev PP, Mondal S, Lad AD, Ahmed S, Narayanan V, Kumar GR, Kingham RJet al., 2015,

    Generation of shock waves in dense plasmas by high-intensity laser pulses

    , Nukleonika, Vol: 60, Pages: 193-198, ISSN: 1508-5791

    When intense short-pulse laser beams (I > 1022 W/m2, τ < 20 ps) interact with high density plasmas, strong shock waves are launched. These shock waves may be generated by a range of processes, and the relative significance of the various mechanisms driving the formation of these shock waves is not well understood. It is challenging to obtain experimental data on shock waves near the focus of such intense laser–plasma interactions. The hydrodynamics of such interactions is, however, of great importance to fast ignition based inertial confinement fusion schemes as it places limits upon the time available for depositing energy in the compressed fuel, and thereby directly affects the laser requirements. In this manuscript we present the results of magnetohydrodynamic simulations showing the formation of shock waves under such conditions, driven by the j × B force and the thermal pressure gradient (where j is the current density and B the magnetic field strength). The time it takes for shock waves to form is evaluated over a wide range of material and current densities. It is shown that the formation of intense relativistic electron current driven shock waves and other related hydrodynamic phenomena may be expected over time scales of relevance to intense laser–plasma experiments and the fast ignition approach to inertial confinement fusion. A newly emerging technique for studying such interactions is also discussed. This approach is based upon Doppler spectroscopy and offers promise for investigating early time shock wave hydrodynamics launched by intense laser pulses.
  • Journal article
    Rodriguez R, Espinosa G, Gil JM, Stehle C, Suzuki-Vidal F, Rubiano JG, Martel P, Minguez Eet al., 2015,

    Microscopic properties of xenon plasmas for density and temperature regimes of laboratory astrophysics experiments on radiative shocks

    , PHYSICAL REVIEW E, Vol: 91, ISSN: 2470-0045
  • Journal article
    Krygier AG, Morrison JT, Kar S, Ahmed H, Alejo A, Clarke R, Fuchs J, Green A, Jung D, Kleinschmidt A, Najmudin Z, Nakamura H, Norreys P, Notley M, Oliver M, Roth M, Vassura L, Zepf M, Borghesi M, Freeman RRet al., 2015,

    Selective deuterium ion acceleration using the Vulcan petawatt laser

    , Physics of Plasmas, Vol: 22, ISSN: 1089-7674

    We report on the successful demonstration of selective acceleration of deuterium ions by targetnormalsheath acceleration (TNSA) with a high-energy petawatt laser. TNSA typically produces amulti-species ion beam that originates from the intrinsic hydrocarbon and water vapor contaminantson the target surface. Using the method first developed by Morrison et al. [Phys. Plasmas 19,030707 (2012)], an ion beam with >99% deuterium ions and peak energy 14 MeV/nucleon is producedwith a 200 J, 700 fs, >1020W=cm2 laser pulse by cryogenically freezing heavy water (D2O)vapor onto the rear surface of the target prior to the shot. Within the range of our detectors(0!–8.5!), we find laser-to-deuterium-ion energy conversion efficiency of 4.3% above 0.7 MeV/nucleon while a conservative estimate of the total beam gives a conversion efficiency of 9.4%.
  • Journal article
    Sarri G, Poder K, Cole JM, Schumaker W, Di Piazza A, Reville B, Dzelzainis T, Doria D, Gizzi LA, Grittani G, Kar S, Keitel CH, Krushelnick K, Kuschel S, Mangles SP, Najmudin Z, Shukla N, Silva LO, Symes D, Thomas AG, Vargas M, Vieira J, Zepf Met al., 2015,

    Generation of neutral and high-density electron-positron pair plasmas in the laboratory

    , Nature Communications, Vol: 6, ISSN: 2041-1723

    Electron-positron pair plasmas represent a unique state of matter, whereby there exists an intrinsic and complete symmetry between negatively charged (matter) and positively charged (antimatter) particles. These plasmas play a fundamental role in the dynamics of ultra-massive astrophysical objects and are believed to be associated with the emission of ultra-bright gamma-ray bursts. Despite extensive theoretical modelling, our knowledge of this state of matter is still speculative, owing to the extreme difficulty in recreating neutral matter-antimatter plasmas in the laboratory. Here we show that, by using a compact laser-driven setup, ion-free electron-positron plasmas with unique characteristics can be produced. Their charge neutrality (same amount of matter and antimatter), high-density and small divergence finally open up the possibility of studying electron-positron plasmas in controlled laboratory experiments.
  • Journal article
    Bennett MJ, Lebedev SV, Hall GN, Suttle L, Burdiak G, Suzuki-Vidal F, Hare J, Swadling G, Patankar S, Bocchi M, Chittenden JP, Smith R, Frank A, Blackman E, Drake RP, Ciardi Aet al., 2015,

    Formation of radiatively cooled, supersonically rotating, plasma flows in Z-pinch experiments: Towards the development of an experimental platform to study accretion disk physics in the laboratory

    , High Energy Density Physics, Vol: 17, Pages: 63-67, ISSN: 1878-0563

    We present data from the first Z-pinch experiments aiming to simulate aspects of accretion disk physics in the laboratory. Using off axis ablation flows from a wire array z-pinch we demonstrate the formation of a supersonically (M ∼ 2) rotating hollow plasma cylinder of height ∼4 mm and radius 2 mm. Using a combination of diagnostics we measure the rotation speed (∼60 kms−1), electron density (1019 cm−3), ion temperature (Ti ∼ 60 eV) and the product of electron temperature and average ionisation (ZTe ∼ 150 to 200 eV). Using these parameters we calculate the Reynolds number for the plasma on the order 105 and magnetic Reynolds number as 10 – 100. The plasma flow is maintained for 150 ns, corresponding to one rotation period, which should allow for studying fast instabilities which develop on this time-scale.
  • Journal article
    Willingale L, Nagel SR, Thomas AGR, Bellei C, Clarke RJ, Dangor AE, Heathcote R, Kaluza MC, Kamperidis C, Kneip S, Krushelnick K, Lopes N, Mangles SPD, Nazarov W, Nilson PM, Najmudin Zet al., 2015,

    Characterization of laser-driven proton beams from near-critical density targets using copper activation

    , JOURNAL OF PLASMA PHYSICS, Vol: 81, ISSN: 0022-3778
  • Conference paper
    Sarri G, Corvan DJ, Cole JM, Schumaker W, Di Piazza A, Ahmed H, Yeung M, Zhao Z, Harvey C, Keitel CH, Krushelnick K, Mangles SPD, Najmudin Z, Thomas AGR, Zepf Met al., 2015,

    Laser-driven Thomson scattering for the generation of ultra-bright multi-MeV gamma-ray beams

    , Conference on Laser Acceleration of Electrons, Protons, and Ions III and Medical Applications of Laser-Generated Beams of Particles III, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
  • Journal article
    Sherlock, Hill EG, Evans, Rose, W Rozmuset al., 2014,

    In-depth Plasma-Wave Heating of Dense Plasma Irradiated by Short Laser Pulses

    , Physical Review Letters, Vol: 113, ISSN: 1079-7114
  • Journal article
    Hooker SM, Bartolini R, Mangles SPD, Tuennermann A, Corner L, Limpert J, Seryi A, Walczak Ret al., 2014,

    Multi-pulse laser wakefield acceleration: a new route to efficient, high-repetition-rate plasma accelerators and high flux radiation sources

    , JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, Vol: 47, ISSN: 0953-4075
  • Journal article
    Sarri G, Corvan DJ, Schumaker W, Cole JM, Di Piazza A, Ahmed H, Harvey C, Keitel CH, Krushelnick K, Mangles SPD, Najmudin Z, Symes D, Thomas AGR, Yeung M, Zhao Z, Zepf Met al., 2014,

    Ultrahigh brilliance multi-MeV gamma-Ray beams from nonlinear relativistic Thomson scattering

    , Physical Review Letters, Vol: 113, Pages: 1-5, ISSN: 0031-9007

    We report on the generation of a narrow divergence (θγ<2.5  mrad), multi-MeV (Emax≈18  MeV) and ultrahigh peak brilliance (>1.8×1020  photons s−1 mm−2  mrad−2 0.1% BW) γ-ray beam from the scattering of an ultrarelativistic laser-wakefield accelerated electron beam in the field of a relativistically intense laser (dimensionless amplitude a0≈2). The spectrum of the generated γ-ray beam is measured, with MeV resolution, seamlessly from 6 to 18 MeV, giving clear evidence of the onset of nonlinear relativistic Thomson scattering. To the best of our knowledge, this photon source has the highest peak brilliance in the multi-MeV regime ever reported in the literature.
  • Journal article
    Espinosa G, Gil JM, Rodriguez R, Rubiano JG, Mendoza MA, Martel P, Minguez E, Suzuki-Vidal F, Lebedev SV, Swadling GF, Burdiak G, Pickworth LA, Skidmore Jet al., 2014,

    Collisional-radiative simulations of a supersonic and radiatively cooled aluminum plasma jet

    , High Energy Density Physics, Vol: 17, Pages: 74-84, ISSN: 1878-0563

    A computational investigation based on collisionaleradiative simulations of a supersonic and radiativelycooled aluminum plasma jet is presented. The jet, both in vacuum and in argon ambient gas, was producedon the MAGPIE (Mega Ampere Generator for Plasma Implosion Experiments) generator and isformed by ablation of an aluminum foil driven by a 1.4 MA, 250 ns current pulse in a radial foil Z-pinchconfiguration. In this work, population kinetics and radiative properties simulations of the jet in differenttheoretical approximations were performed. In particular, local thermodynamic equilibrium (LTE), nonLTEsteady state (SS) and non-LTE time dependent (TD) models have been considered. This study allowsus to make a convenient microscopic characterization of the aluminum plasma jet.
  • Journal article
    Swadling GF, Lebedev SV, Hall GN, Patankar S, Stewart NH, Smith RA, Harvey-Thompson AJ, Burdiak GC, de Grouchy P, Skidmore J, Suttle L, Suzuki-Vidal F, Bland SN, Kwek KH, Pickworth L, Bennett M, Hare JD, Rozmus W, Yuan Jet al., 2014,

    Diagnosing collisions of magnetized, high energy density plasma flows using a combination of collective Thomson scattering, Faraday rotation, and interferometry

    , REVIEW OF SCIENTIFIC INSTRUMENTS, Vol: 85, ISSN: 0034-6748
  • Journal article
    Albert F, Thomas AGR, Mangles SPD, Banerjee S, Corde S, Flacco A, Litos M, Neely D, Vieira J, Najmudin Z, Bingham R, Joshi C, Katsouleas Tet al., 2014,

    Laser wakefield accelerator based light sources: potential applications and requirements

    , PLASMA PHYSICS AND CONTROLLED FUSION, Vol: 56, ISSN: 0741-3335
  • Journal article
    Kamperidis C, Dimitriou V, Mangles SPD, Dangor AE, Najmudin Zet al., 2014,

    Low energy spread electron beams from ionization injection in a weakly relativistic laser wakefield accelerator

    , PLASMA PHYSICS AND CONTROLLED FUSION, Vol: 56, ISSN: 0741-3335
  • Journal article
    Green JS, Dover NP, Borghesi M, Brenner CM, Cameron FH, Carroll DC, Foster PS, Gallegos P, Gregori G, McKenna P, Murphy CD, Najmudin Z, Palmer CAJ, Prasad R, Romagnani L, Quinn KE, Schreiber J, Streeter MJV, Ter-Avetisyan S, Tresca O, Zepf M, Neely Det al., 2014,

    Enhanced proton beam collimation in the ultra-intense short pulse regime

    , PLASMA PHYSICS AND CONTROLLED FUSION, Vol: 56, ISSN: 0741-3335
  • Journal article
    Hill EG, Rose SJ, 2014,

    Non-thermal enhancement of electron-positron pair creation in burning thermonuclear laboratory plasmas

    , High Energy Density Physics
  • Journal article
    Hall GN, Burdiak GC, Suttle L, Stuart NH, Swadling GF, Lebedev SV, Smith RA, Patankar S, Suzuki Vidal F, de Grouchy P, Harvey-Thompson AJ, Bennett M, Bland SN, Pickworth L, Skidmore Jet al., 2014,

    Monochromatic radiography of high energy density physics experiments on the MAGPIE generator

    , Review of Scientific Instruments, Vol: 85, ISSN: 1089-7623

    A monochromatic X-ray backlighter based on Bragg reflection from a spherically bent quartzcrystal has been developed for the MAGPIE pulsed power generator at Imperial College (1.4 MA,240 ns) [I. H. Mitchell et al., Rev. Sci. Instrum. 67, 1533 (2005)]. This instrument has been usedto diagnose high energy density physics experiments with 1.865 keV radiation (Silicon He-α) froma laser plasma source driven by a ∼7 J, 1 ns pulse from the Cerberus laser. The design of thediagnostic, its characterisation and performance, and initial results in which the instrument was usedto radiograph a shock physics experiment on MAGPIE are discussed.
  • Journal article
    Swadling GF, Lebedev SV, Harvey-Thompson AJ, Rozmus W, Burdiak GC, Suttle L, Patankar S, Smith RA, Bennett M, Hall GN, Suzuki-Vidal F, Yuan Jet al., 2014,

    Interpenetration, Deflection, and Stagnation of Cylindrically Convergent Magnetized Supersonic Tungsten Plasma Flows

    , PHYSICAL REVIEW LETTERS, Vol: 113, ISSN: 0031-9007
  • Journal article
    Pike OJ, Mackenroth F, Hill EG, Rose SJet al., 2014,

    A photon-photon collider in a vacuum hohlraum

    , Nature Photonics, Vol: 8, Pages: 434-436, ISSN: 1749-4885

    The ability to create matter from light is amongst the most striking predictions of quantum electrodynamics. Experimental signatures of this have been reported in the scattering of ultra-relativistic electron beams with laser beams1,2, intense laser–plasma interactions3 and laser-driven solid target scattering4. However, all such routes involve massive particles. The simplest mechanism by which pure light can be transformed into matter, Breit–Wheeler pair production (γγ′ → e+e−)5, has never been observed in the laboratory. Here, we present the design of a new class of photon–photon collider in which a gamma-ray beam is fired into the high-temperature radiation field of a laser-heated hohlraum. Matching experimental parameters to current-generation facilities, Monte Carlo simulations suggest that this scheme is capable of producing of the order of 105 Breit–Wheeler pairs in a single shot. This would provide the first realization of a pure photon–photon collider, representing the advent of a new type of high-energy physics experiment.
  • Journal article
    Pike OJ, Rose SJ, 2014,

    Dynamical friction in a relativistic plasma

    , PHYSICAL REVIEW E, Vol: 89, ISSN: 1539-3755
  • Journal article
    Robinson APL, Strozzi DJ, Davies JR, Gremillet L, Honrubia JJ, Johzaki T, Kingham RJ, Sherlock M, Solodov AAet al., 2014,

    Theory of fast electron transport for fast ignition

    , Nuclear Fusion, Vol: 54, ISSN: 1741-4326

    Fast ignition (FI) inertial confinement fusion is a variant of inertial fusion in which DT fuel is first compressed to high densityand then ignited by a relativistic electron beam generated by a fast (<20 ps) ultra-intense laser pulse, which is usually broughtin to the dense plasma via the inclusion of a re-entrant cone. The transport of this beam from the cone apex into the dense fuelis a critical part of this scheme, as it can strongly influence the overall energetics. Here we review progress in the theory andnumerical simulation of fast electron transport in the context of FI. Important aspects of the basic plasma physics, descriptionsof the numerical methods used, a review of ignition-scale simulations, and a survey of schemes for controlling the propagationof fast electrons are included. Considerable progress has taken place in this area, but the development of a robust, high-gain FI‘point design’ is still an ongoing challenge.
  • Journal article
    Keenan FP, Doyle JG, Madjarska MS, Rose SJ, Bowler LA, Britton J, McCrink L, Mathioudakis Met al., 2014,

    INTENSITY ENHANCEMENT OF O VI ULTRAVIOLET EMISSION LINES IN SOLAR SPECTRA DUE TO OPACITY

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 784, ISSN: 2041-8205
  • Journal article
    Najmudin Z, Kneip S, Bloom MS, Mangles SPD, Chekhlov O, Dangor AE, Doepp A, Ertel K, Hawkes SJ, Holloway J, Hooker CJ, Jiang J, Lopes NC, Nakamura H, Norreys PA, Rajeev PP, Russo C, Streeter MJV, Symes DR, Wing Met al., 2014,

    Compact laser accelerators for X-ray phase-contrast imaging

    , PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 372, ISSN: 1364-503X
  • Conference paper
    Mangles SPD, Bloom MS, Bryant J, Cole JM, Doepp A, Kneip S, Nakamura H, Poder K, Streeter MJV, Wood J, Najmudin Z, Bendoyro R, Jiang J, Lopes NC, Russo C, Cheklov O, Ertel K, Hawkes SJ, Hooker CJ, Neely D, Norreys PA, Rajeev PP, Rusby DR, Scott RHH, Symes DR, Holloway J, Wing M, Seely JFet al., 2014,

    Producing bright X-rays for imaging applications using a laser wakefield accelerator

    , Conference on Lasers and Electro-Optics (CLEO), Publisher: IEEE, ISSN: 2160-9020
  • Conference paper
    Sarri G, Schumaker W, Di Piazza A, Poder K, Cole JM, Vargas M, Doria D, Kushel S, Dromey B, Grittani G, Gizzi L, Dieckmann ME, Green A, Chvykov V, Maksimchuk A, Yanovsky V, He ZH, Hou BX, Nees JA, Kar S, Najmudin Z, Thomas AGR, Keitel CH, Krushelnick K, Zepf Met al., 2013,

    Laser-driven generation of collimated ultra-relativistic positron beams

    , 40th Conference of the European-Physical-Society on Plasma Physics, Publisher: IOP PUBLISHING LTD, ISSN: 0741-3335
  • Conference paper
    Williams BER, Kingham RJ, 2013,

    Hybrid simulations of fast electron propagation including magnetized transport and non-local effects in the background plasma

    , 40th Conference of the European-Physical-Society on Plasma Physics, Publisher: IOP PUBLISHING LTD, ISSN: 0741-3335

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