Publications


Evidence for a glassy state in strongly driven carbon.

Scientific reports 4 (2014) 5214-

CRD Brown, DO Gericke, M Cammarata, BI Cho, T Döppner, K Engelhorn, E Förster, C Fortmann, D Fritz, E Galtier, SH Glenzer, M Harmand, P Heimann, NL Kugland, DQ Lamb, HJ Lee, RW Lee, H Lemke, M Makita, A Moinard, CD Murphy, B Nagler, P Neumayer, K-U Plagemann, R Redmer, D Riley, FB Rosmej, P Sperling, S Toleikis, SM Vinko, J Vorberger, S White, TG White, K Wünsch, U Zastrau, D Zhu, T Tschentscher, G Gregori

Here, we report results of an experiment creating a transient, highly correlated carbon state using a combination of optical and x-ray lasers. Scattered x-rays reveal a highly ordered state with an electrostatic energy significantly exceeding the thermal energy of the ions. Strong Coulomb forces are predicted to induce nucleation into a crystalline ion structure within a few picoseconds. However, we observe no evidence of such phase transition after several tens of picoseconds but strong indications for an over-correlated fluid state. The experiment suggests a much slower nucleation and points to an intermediate glassy state where the ions are frozen close to their original positions in the fluid.


Observations of continuum depression in warm dense matter with x-ray Thomson scattering.

Physical review letters 112 (2014) 145004-

LB Fletcher, AL Kritcher, A Pak, T Ma, T Döppner, C Fortmann, L Divol, OS Jones, OL Landen, HA Scott, J Vorberger, DA Chapman, DO Gericke, BA Mattern, GT Seidler, G Gregori, RW Falcone, SH Glenzer

Detailed measurements of the electron densities, temperatures, and ionization states of compressed CH shells approaching pressures of 50 Mbar are achieved with spectrally resolved x-ray scattering. Laser-produced 9 keV x-rays probe the plasma during the transient state of three-shock coalescence. High signal-to-noise x-ray scattering spectra show direct evidence of continuum depression in highly degenerate warm dense matter states with electron densities ne>1024  cm-3. The measured densities and temperatures agree well with radiation-hydrodynamic modeling when accounting for continuum lowering in calculations that employ detailed configuration accounting.


Laminar shocks in high power laser plasma interactions

Physics of Plasmas 21 (2014)

RA Cairns, R Bingham, P Norreys, R Trines

We propose a theory to describe laminar ion sound structures in a collisionless plasma. Reflection of a small fraction of the upstream ions converts the well known ion acoustic soliton into a structure with a steep potential gradient upstream and with downstream oscillations. The theory provides a simple interpretation of results dating back more than forty years but, more importantly, is shown to provide an explanation for recent observations on laser produced plasmas relevant to inertial fusion and to ion acceleration. © 2014 AIP Publishing LLC.


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

Optics InfoBase Conference Papers (2014)

SPD Mangles, MS Bloom, J Bryant, JM Cole, A Döpp, S Kneip, H Nakamura, K Poder, MJV Streeter, J Wood, Z Najmudin, R Bendoyro, J Jiang, NC Lopes, C Russo, O Cheklov, O Ertel, S Hawkes, CJ Hooker, D Neely, PA Norreys, PP Rajeev, DR Rusby, RHH Scott, DR Symes, J Holloway, M Wing, JF Seely

We report on the generation of bright multi-keV betatron X-ray radiation using a GeV laser wakefield accelerator and investigate the use of these X-rays for various imaging applications. © 2014 Optical Society of America.


Proton-driven plasma wakefield acceleration: a path to the future of high-energy particle physics

PLASMA PHYSICS AND CONTROLLED FUSION 56 (2014) ARTN 084013

R Assmann, R Bingham, T Bohl, C Bracco, B Buttenschoen, A Butterworth, A Caldwell, S Chattopadhyay, S Cipiccia, E Feldbaumer, RA Fonseca, B Goddard, M Gross, O Grulke, E Gschwendtner, J Holloway, C Huang, D Jaroszynski, S Jolly, P Kempkes, N Lopes, K Lotov, J Machacek, SR Mandry, JW McKenzie, M Meddahi, BL Militsyn, N Moschuering, P Muggli, Z Najmudin, TCQ Noakes, PA Norreys, E Oez, A Pardons, A Petrenko, A Pukhov, K Rieger, O Reimann, H Ruhl, E Shaposhnikova, LO Silva, A Sosedkin, R Tarkeshian, RMGN Trines, T Tueckmantel, J Vieira, H Vincke, M Wing, G Xia


Combined Hydrodynamic and Diffraction Simulations of Femtosecond X-ray Scattering from Laser-Shocked Crystals

18TH APS-SCCM AND 24TH AIRAPT, PTS 1-19 500 (2014) UNSP 152016

JS Wark, A Higginbotham, D Milathianaki, A Gleason


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

Optics InfoBase Conference Papers (2014)

SPD Mangles, MS Bloom, J Bryant, JM Cole, A Döpp, S Kneip, H Nakamura, K Poder, MJV Streeter, J Wood, Z Najmudin, R Bendoyro, J Jiang, NC Lopes, C Russo, O Cheklov, K Ertel, SJ Hawkes, CJ Hooker, D Neely, PA Norreys, PP Rajeev, DR Rusby, RHH Scott, DR Symes, J Holloway, M Wing, JF Seely

We report on the generation of bright multi-keV betatron X-ray radiation using a GeV laser wakefield accelerator and investigate the use of these X-rays for various imaging applications. © 2014 Optical Society of America.


Opacity effects in a solid-density aluminium plasma created by photo-excitation with an X-ray laser

HIGH ENERGY DENSITY PHYSICS 11 (2014) 59-69

DS Rackstraw, SM Vinko, O Ciricosta, BI Cho, K Engelhorn, H-K Chung, CRD Brown, T Burian, J Chalupsky, RW Falcone, C Graves, V Hajkova, A Higginbotham, L Juha, J Krzywinski, HJ Lee, M Messerschmidt, C Murphy, Y Ping, A Scherz, W Schlotter, S Toleikis, JJ Turner, L Vysin, T Wang, B Wu, U Zastrau, D Zhu, B Nagler, RW Lee, PA Heimann, JS Wark


Compact laser accelerators for X-ray phase-contrast imaging

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372 (2014)

Z Najmudin, S Kneip, MS Bloom, SPD Mangles, O Chekhlov, AE Dangor, A Dopp, K Ertel, SJ Hawkes, J Holloway, CJ Hooker, J Jiang, NC Lopes, H Nakamura, PA Norreys, PP Rajeev, C Russo, MJV Streeter, DR Symes, M Wing

Advances in X-ray imaging techniques have been driven by advances in novel X-ray sources. The latest fourth-generation X-ray sources can boast large photon fluxes at unprecedented brightness. However, the large size of these facilities means that these sources are not available for everyday applications. With advances in laser plasma acceleration, electron beams can now be generated at energies comparable to those used in light sources, but in university-sized laboratories. By making use of the strong transverse focusing of plasma accelerators, bright sources of betatron radiation have been produced. Here, we demonstrate phase-contrast imaging of a biological sample for the first time by radiation generated by GeV electron beams produced by a laser accelerator. The work was performed using a greater than 300TW laser, which allowed the energy of the synchrotron source to be extended to the 10100 keV range. © 2014 The Author(s) Published by the Royal Society. All rights reserved.


Observations of strong ion-ion correlations in dense plasmas

PHYSICS OF PLASMAS 21 (2014) ARTN 056302

T Ma, L Fletcher, A Pak, DA Chapman, RW Falcone, C Fortmann, E Galtier, DO Gericke, G Gregori, J Hastings, OL Landen, S Le Pape, HJ Lee, B Nagler, P Neumayer, D Turnbull, J Vorberger, TG White, K Wuensch, U Zastrau, SH Glenzer, T Doeppner


Electron-ion equilibration in ultrafast heated graphite.

Physical review letters 112 (2014) 145005-

TG White, NJ Hartley, B Borm, BJB Crowley, JWO Harris, DC Hochhaus, T Kaempfer, K Li, P Neumayer, LK Pattison, F Pfeifer, S Richardson, APL Robinson, I Uschmann, G Gregori

We have employed fast electrons produced by intense laser illumination to isochorically heat thermal electrons in solid density carbon to temperatures of ∼10,000  K. Using time-resolved x-ray diffraction, the temperature evolution of the lattice ions is obtained through the Debye-Waller effect, and this directly relates to the electron-ion equilibration rate. This is shown to be considerably lower than predicted from ideal plasma models. We attribute this to strong ion coupling screening the electron-ion interaction.


Investigations into rapid uniaxial compression of polycrystalline targets using femtosecond X-ray diffraction

18TH APS-SCCM AND 24TH AIRAPT, PTS 1-19 500 (2014) UNSP 112063

D McGonegle, A Higginbotham, E Galtier, EE McBride, MI McMahon, D Milathianaki, HJ Lee, B Nagler, SM Vinko, JS Wark


Prospects for Multi kJ plasma ampliefiers

Optics InfoBase Conference Papers Part F38-FiO 2016 (2014)

J Sadler, R Trines, L Ceurvorst, N Ratan, M Kasim, R Bingham, P Norreys

© OSA 2016.Plasma amplifiers potentially offer a route to low cost, high efficiency, multi-kJ, tunable laser pulses. I will describe numerical simulations underpinning careful experiment design and interpretation to optimize this process at the University of Rochester.


Focus on high energy density physics

New Journal of Physics 16 (2014)

R Paul Drake, P Norreys

High-energy-density physics concerns the behavior of systems at high pressure, often involving the interplay of plasma, relativistic, quantum mechanical and electromagnetic effects. The field is growing rapidly in its scope of activity thanks to advances in experimental, laser and computational technologies. This 'focus on' collection presents papers discussing forefront research that spans the field, providing a sense of its breadth and of the interlinking of its parts. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.


Shock waves in polycrystalline iron: Plasticity and phase transitions

PHYSICAL REVIEW B 89 (2014) ARTN 140102

N Gunkelmann, EM Bringa, DR Tramontina, CJ Ruestes, MJ Suggit, A Higginbotham, JS Wark, HM Urbassek


Ultrafast three-dimensional imaging of lattice dynamics in individual gold nanocrystals.

Science 341 (2013) 56-59

JN Clark, L Beitra, G Xiong, A Higginbotham, DM Fritz, HT Lemke, D Zhu, M Chollet, GJ Williams, M Messerschmidt, B Abbey, RJ Harder, AM Korsunsky, JS Wark, IK Robinson

Key insights into the behavior of materials can be gained by observing their structure as they undergo lattice distortion. Laser pulses on the femtosecond time scale can be used to induce disorder in a "pump-probe" experiment with the ensuing transients being probed stroboscopically with femtosecond pulses of visible light, x-rays, or electrons. Here we report three-dimensional imaging of the generation and subsequent evolution of coherent acoustic phonons on the picosecond time scale within a single gold nanocrystal by means of an x-ray free-electron laser, providing insights into the physics of this phenomenon. Our results allow comparison and confirmation of predictive models based on continuum elasticity theory and molecular dynamics simulations.


Simulation of X-ray scattering diagnostics in multi-dimensional plasma

High Energy Density Physics 9 (2013) 510-515

I Golovkin, JJ MacFarlane, P Woodruff, I Hall, G Gregori, J Bailey, E Harding, T Ao, S Glenzer

X-ray scattering is a powerful diagnostic technique that has been used in a variety of experimental settings to determine the temperature, density, and ionization state of warm dense matter. In order to maximize the intensity of the scattered signal, the x-ray source is often placed in close proximity to the target plasma. Therefore, the interpretation of the experimental data can become complicated by the fact that the detector records photons scattered at different angles from points within the plasma volume. In addition, the target plasma that is scattering the x-rays can have significant temperature and density gradients. To address these issues, we have developed the capability to simulate x-ray scattering for realistic experimental configurations where the effects of plasma non-uniformities and a range of x-ray scattering angles are included. We will discuss the implementation details and show results relevant to previous and ongoing experimental investigations. © 2013 Elsevier B.V.


Radiative shocks produced from spherical cryogenic implosions at the National Ignition Facility

Physics of Plasmas 20 (2013)

A Pak, L Divol, G Gregori, S Weber, J Atherton, R Bennedetti, DK Bradley, D Callahan, DT Casey, E Dewald, T Döppner, MJ Edwards, JA Frenje, S Glenn, GP Grim, D Hicks, WW Hsing, N Izumi, OS Jones, MG Johnson, SF Khan, JD Kilkenny, JL Kline, GA Kyrala, J Lindl, OL Landen, S Le Pape, T Ma, A Macphee, BJ Macgowan, AJ Mackinnon, L Masse, NB Meezan, JD Moody, RE Olson, JE Ralph, HF Robey, HS Park, BA Remington, JS Ross, R Tommasini, RPJ Town, V Smalyuk, SH Glenzer, EI Moses

Spherically expanding radiative shock waves have been observed from inertially confined implosion experiments at the National Ignition Facility. In these experiments, a spherical fusion target, initially 2 mm in diameter, is compressed via the pressure induced from the ablation of the outer target surface. At the peak compression of the capsule, x-ray and nuclear diagnostics indicate the formation of a central core, with a radius and ion temperature of ∼20 μm and ∼ 2 keV, respectively. This central core is surrounded by a cooler compressed shell of deuterium-tritium fuel that has an outer radius of ∼40 μm and a density of > 500 g/cm 3 . Using inputs from multiple diagnostics, the peak pressure of the compressed core has been inferred to be of order 100 Gbar for the implosions discussed here. The shock front, initially located at the interface between the high pressure compressed fuel shell and surrounding in-falling low pressure ablator plasma, begins to propagate outwards after peak compression has been reached. Approximately 200 ps after peak compression, a ring of x-ray emission created by the limb-brightening of a spherical shell of shock-heated matter is observed to appear at a radius of ∼100 μm. Hydrodynamic simulations, which model the experiment and include radiation transport, indicate that the sudden appearance of this emission occurs as the post-shock material temperature increases and upstream density decreases, over a scale length of ∼10 μm, as the shock propagates into the lower density (∼1 g/cc), hot (∼250 eV) plasma that exists at the ablation front. The expansion of the shock-heated matter is temporally and spatially resolved and indicates a shock expansion velocity of ∼300 km/s in the laboratory frame. The magnitude and temporal evolution of the luminosity produced from the shock-heated matter was measured at photon energies between 5.9 and 12.4 keV. The observed radial shock expansion, as well as the magnitude and temporal evolution of the luminosity from the shock-heated matter, is consistent with 1-D radiation hydrodynamic simulations. Analytic estimates indicate that the radiation energy flux from the shock-heated matter is of the same order as the in-flowing material energy flux, and suggests that this radiation energy flux modifies the shock front structure. Simulations support these estimates and show the formation of a radiative shock, with a precursor that raises the temperature ahead of the shock front, a sharp μ m-scale thick spike in temperature at the shock front, followed by a post-shock cooling layer. © 2013 AIP Publishing LLC.


Comparison between x-ray scattering and velocity-interferometry measurements from shocked liquid deuterium

Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 87 (2013)

K Falk, SP Regan, J Vorberger, BJB Crowley, SH Glenzer, SX Hu, CD Murphy, PB Radha, AP Jephcoat, JS Wark, DO Gericke, G Gregori

The equation of state of light elements is essential to understand the structure of Jovian planets and inertial confinement fusion research. The Omega laser was used to drive a planar shock wave in the cryogenically cooled deuterium, creating warm dense matter conditions. X-ray scattering was used to determine the spectrum near the boundary of the collective and noncollective scattering regimes using a narrow band x-ray source in backscattering geometry. Our scattering spectra are thus sensitive to the individual electron motion as well as the collective plasma behavior and provide a measurement of the electron density, temperature, and ionization state. Our data are consistent with velocity-interferometry measurements previously taken on the same shocked deuterium conditions and presented by K. Falk. This work presents a comparison of the two diagnostic systems and offers a detailed discussion of challenges encountered. ©2013 American Physical Society.


Comparison between x-ray scattering and velocity-interferometry measurements from shocked liquid deuterium.

Phys Rev E Stat Nonlin Soft Matter Phys 87 (2013) 043112-

K Falk, SP Regan, J Vorberger, BJB Crowley, SH Glenzer, SX Hu, CD Murphy, PB Radha, AP Jephcoat, JS Wark, DO Gericke, G Gregori

The equation of state of light elements is essential to understand the structure of Jovian planets and inertial confinement fusion research. The Omega laser was used to drive a planar shock wave in the cryogenically cooled deuterium, creating warm dense matter conditions. X-ray scattering was used to determine the spectrum near the boundary of the collective and noncollective scattering regimes using a narrow band x-ray source in backscattering geometry. Our scattering spectra are thus sensitive to the individual electron motion as well as the collective plasma behavior and provide a measurement of the electron density, temperature, and ionization state. Our data are consistent with velocity-interferometry measurements previously taken on the same shocked deuterium conditions and presented by K. Falk et al. [High Energy Density Phys. 8, 76 (2012)]. This work presents a comparison of the two diagnostic systems and offers a detailed discussion of challenges encountered.

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