Publications


Implementation of Hydrodynamic Simulation Code in Shock Experiment Design for Alkali Metals

JOINT AIRAPT-25TH & EHPRG-53RD INTERNATIONAL CONFERENCE ON HIGH PRESSURE SCIENCE AND TECHNOLOGY, 2015 950 (2017) UNSP 042037

AL Coleman, R Briggs, MG Gorman, S Ali, A Lazicki, DC Swift, PG Stubley, EE McBride, G Collins, JS Wark, MI McMahon, IOP


Phase transitions in shock compressed bismuth identified using single photon energy dispersive X-ray diffraction (SPEDX)

JOINT AIRAPT-25TH & EHPRG-53RD INTERNATIONAL CONFERENCE ON HIGH PRESSURE SCIENCE AND TECHNOLOGY, 2015 950 (2017) UNSP 042038

R Briggs, MJ Suggit, MG Gorman, A Coleman, R Heathcote, A Higginbotham, S Patel, JS Wark, MI McMahon, IOP


Atomic processes modeling of X-ray free electron laser produced plasmas using SCFLY code

ATOMIC PROCESSES IN PLASMAS (APIP 2016) 1811 (2017)

H-K Chung, BI Cho, O Ciricosta, SM Vinko, JS Wark, RW Lee


Numerical modeling of laser-driven experiments aiming to demonstrate magnetic field amplification via turbulent dynamo

Physics of Plasmas AIP Publishing 24 (2017) 041404

P Tzeferacos, A Rigby, A Bott, A Bell, R Bingham, A Casner, F Cattaneo, EM Churazov, J Emig, N Flocke, F Fiuza, CB Forest, J Foster, C Graziani, J Katz, M Koenig, C-K Li, J Meinecke, R Petrasso, H-S Park, BA Remington, JS Ross, D Ryu, D Ryutov, TG White

The universe is permeated by magnetic fields, with strengths ranging from a femtogauss in the voids between the filaments of galaxy clusters to several teragauss in black holes and neutron stars. The standard model behind cosmological magnetic fields is the nonlinear amplification of seed fields via turbulent dynamo to the values observed. We have conceived experiments that aim to demonstrate and study the turbulent dynamo mechanism in the laboratory. Here, we describe the design of these experiments through simulation campaigns using FLASH, a highly capable radiation magnetohydrodynamics code that we have developed, and large-scale three-dimensional simulations on the Mira supercomputer at the Argonne National Laboratory. The simulation results indicate that the experimental platform may be capable of reaching a turbulent plasma state and determining the dynamo amplification. We validate and compare our numerical results with a small subset of experimental data using synthetic diagnostics.


Quantitative shadowgraphy and proton radiography for large intensity modulations

Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics American Physical Society (2017)

M Kasim, L Ceurvorst, N Ratan, J Sadler, N Chen, A Savert, R Trines, R Bingham, PN Burrows, MC Kaluza, P Norreys

Shadowgraphy is a technique widely used to diagnose objects or systems in various fields in physics and engineering. In shadowgraphy, an optical beam is deflected by the object and then the intensity modulation is captured on a screen placed some distance away. However, retrieving quantitative information from the shadowgrams themselves is a challenging task because of the non-linear nature of the process. Here, a novel method to retrieve quantitative information from shadowgrams, based on computational geometry, is presented for the first time. This process can also be applied to proton radiography for electric and magnetic field diagnosis in high-energy-density plasmas and has been benchmarked using a toroidal magnetic field as the object, among others. It is shown that the method can accurately retrieve quantitative parameters with error bars less than 10%, even when caustics are present. The method is also shown to be robust enough to process real experimental results with simple pre- and post-processing techniques. This adds a powerful new tool for research in various fields in engineering and physics for both techniques.


A strong diffusive ion mode in dense ionized matter predicted by Langevin dynamics

Nature Communications Springer Nature 8 (2017) 14125

P Mabey, S Richardson, TG White, LB Fletcher, SH Glenzer, NJ Hartley, J Vorberger, DO Gericke, G Gregori

The state and evolution of planets, brown dwarfs and neutron star crusts is determined by the properties of dense and compressed matter. Due to the inherent difficulties in modelling strongly coupled plasmas, however, current predictions of transport coefficients differ by orders of magnitude. Collective modes are a prominent feature, whose spectra may serve as an important tool to validate theoretical predictions for dense matter. With recent advances in free electron laser technology, X-rays with small enough bandwidth have become available, allowing the investigation of the low-frequency ion modes in dense matter. Here, we present numerical predictions for these ion modes and demonstrate significant changes to their strength and dispersion if dissipative processes are included by Langevin dynamics. Notably, a strong diffusive mode around zero frequency arises, which is not present, or much weaker, in standard simulations. Our results have profound consequences in the interpretation of transport coefficients in dense plasmas.


Simulations of the inelastic response of silicon to shock compression

Computational Materials Science Elsevier 128 (2016) 121–126-

P Stubley, A Higginbotham, J Wark

Recent experiments employing nanosecond white-light x-ray di↵raction have demonstrated a complex response of pure, single crystal silicon to shock compression on ultra-fast timescales. We present here details of a Lagrangian code which tracks both longitudinal and transverse strains, and successfully reproduces the experimental response by incorporating a model of the shock-induced, yet kinetically inhibited, phase transition. This model is also shown to reproduce results of classical molecular dynamics simulations of shock compressed silicon.


Measurements of plasma spectra from hot dense elements and mixtures at conditions relevant to the solar radiative zone.

ATOMIC PROCESSES IN PLASMAS (APIP 2016) 1811 (2017)

DJ Hoarty, E Hill, P Beiersdorfer, P Allan, CRD Brown, MP Hill, LMR Hobbs, SF James, J Morton, N Sircombe, L Upcraft, JWO Harris, R Shepherd, E Marley, E Magee, J Emig, J Nilsen, SJ Rose


Ultra-fast x-ray diffraction studies of the phase transitions and equation of state of scandium shock-compressed to 82 GPa

Physical Review Letters American Physical Society 118 (2017) 025501

B Briggs, MG Gorman, AL Coleman, RS McWilliams, EE McBride, D McGonegle, L Peacock, S Rothman, SG Macleod, CA Bolme, AE Gleason, GW Collins, JH Eggert, DE Fratanduono, RF Smith, E Galtier, E Granados, HJ Lee, B Nagler, I Nam, Z Xing, J Wark, MI McMahon

Using x-ray diffraction at the LCLS x-ray free electron laser, we have determined simultaneously and self-consistently the phase transitions and equation-of-state of the lightest transition metal, scandium, under shock compression. On compression scandium undergoes a structural phase transition between 32 and 35 GPa to the same bcc structure seen at high temperatures at ambient pressures, and then a further transition at 46 GPa to the incommensurate host-guest polymorph found above 21 GPa in static compression at room temperature. Shock melting of the host-guest phase is observed between 53 and 72 GPa with the disappearance of Bragg scattering and the growth of a broad asymmetric diffraction peak from the high-density liquid.


Magnetic field generation during intense laser channelling in underdense plasma

Physics of Plasmas AIP Publishing 23 (2016)

AG Smyth, G Sarri, M Vranic, Y Amano, D Doria, E Guillaume, H Habara, R Heathcote, G Hicks, Z Najmudin, H Nakamura, P Norreys, S Kar, LO Silva, KA Tanaka, J Vieira, M Borghesi

Channel formation during the propagation of a high-energy (120 J) and long duration (30 ps) laser pulse through an underdense deuterium plasma has been spatially and temporally resolved via means of a proton imaging technique, with intrinsic resolutions of a few μm and a few ps, respectively. Conclusive proof is provided that strong azimuthally symmetric magnetic fields with a strength of around 0.5 MG are created inside the channel, consistent with the generation of a collimated beam of relativistic electrons. The inferred electron beam characteristics may have implications for the cone-free fast-ignition scheme of inertial confinement fusion.


High Orbital Angular Momentum Harmonic Generation

Physical Review Letters American Physical Society 117 (2016)

J Vieira, RMGM Trines, RA Fonseca, JT Mendonça, R Bingham, P Norreys, LO Silva

We identify and explore a high orbital angular momentum (OAM) harmonics generation and amplification mechanism that manipulates the OAM independently of any other laser property, by preserving the initial laser wavelength, through stimulated Raman backscattering in a plasma. The high OAM harmonics spectra can extend at least up to the limiting value imposed by the paraxial approximation. We show with theory and particle-in-cell simulations that the orders of the OAM harmonics can be tuned according to a selection rule that depends on the initial OAM of the interacting waves. We illustrate the high OAM harmonics generation in a plasma using several examples including the generation of prime OAM harmonics. The process can also be realized in any nonlinear optical Kerr media supporting three-wave interactions.


Scaled laboratory experiments explain the kink behaviour of the Crab Nebula jet

Nature Communications Nature Publishing Group (2016)

CK Li, P Tzeferacos, D Lamb, G Gregori, PA Norreys, MJ Rosenberg, RK Follett, DH Froula, M Koenig, FH Seguin, JA Frenje, HG Rinderknecht, H Sio, AB Zylstra, RD Petrasso, PA Amendt, HS Park, BA Remington, SX Hu, TC Sangster, P Hartigan, RP Drake, CC Kuranz, SV Lebedev, NC Woolsey

The remarkable discovery by the Chandra X-ray observatory that the Crab nebula's jet periodically changes direction provides a challenge to our understanding of astrophysical jet dynamics. It has been suggested that this phenomenon may be the consequence of magnetic fields and magnetohydrodynamic instabilities, but experimental demonstration in a controlled laboratory environment has remained elusive. Here we report experiments that use high-power lasers to create a plasma jet that can be directly compared with the Crab jet through well-defined physical scaling laws. The jet generates its own embedded toroidal magnetic fields; as it moves, plasma instabilities result in multiple deflections of the propagation direction, mimicking the kink behaviour of the Crab jet. The experiment is modelled with three-dimensional numerical simulations that show exactly how the instability develops and results in changes of direction of the jet.


Laboratory analogue of a supersonic accretion column in a binary star system.

Nature Communications Nature Publishing Group 7 (2016) ncomms11899-

JE Cross, G Gregori, JM Foster, P Graham, JM Bonnet-Bidaud, C Busschaert, N Charpentier, CN Danson, HW Doyle, RP Drake, J Fyrth, ET Gumbrell, M Koenig, C Krauland, CC Kuranz, B Loupias, C Michaut, M Mouchet, S Patankar, J Skidmore, C Spindloe, ER Tubman, N Woolsey, R Yurchak, É Falize

Astrophysical flows exhibit rich behaviour resulting from the interplay of different forms of energy-gravitational, thermal, magnetic and radiative. For magnetic cataclysmic variable stars, material from a late, main sequence star is pulled onto a highly magnetized (B>10 MG) white dwarf. The magnetic field is sufficiently large to direct the flow as an accretion column onto the poles of the white dwarf, a star subclass known as AM Herculis. A stationary radiative shock is expected to form 100-1,000 km above the surface of the white dwarf, far too small to be resolved with current telescopes. Here we report the results of a laboratory experiment showing the evolution of a reverse shock when both ionization and radiative losses are important. We find that the stand-off position of the shock agrees with radiation hydrodynamic simulations and is consistent, when scaled to AM Herculis star systems, with theoretical predictions.


Numerical study of neutron beam divergence in a beam-fusion scenario employing laser driven ions

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Elsevier 829 (2016) 176-180

A Alejo, A Green, H Ahmed, APL Robinson, M Cerchez, R Clarke, D Doria, S Dorkings, J Fernandez, P McKenna, SR Mirfayzi, K Naughton, D Neely, P Norreys, C Peth, H Powell, JA Ruiz, J Swain, O Willi, M Borghesi, S Kar

The most established route to create a laser-based neutron source is by employing laser accelerated, low atomic-number ions in fusion reactions. In addition to the high reaction cross-sections at moderate energies of the projectile ions, the anisotropy in neutron emission is another important feature of beam-fusion reactions. Using a simple numerical model based on neutron generation in a pitcher–catcher scenario, anisotropy in neutron emission was studied for the deuterium–deuterium fusion reaction. Simulation results are consistent with the narrow-divergence (∼70° full width at half maximum) neutron beam recently served in an experiment employing multi-MeV deuteron beams of narrow divergence (up to 30° FWHM, depending on the ion energy) accelerated by a sub-petawatt laser pulse from thin deuterated plastic foils via the Target Normal Sheath Acceleration mechanism. By varying the input ion beam parameters, simulations show that a further improvement in the neutron beam directionality (i.e. reduction in the beam divergence) can be obtained by increasing the projectile ion beam temperature and cut-off energy, as expected from interactions employing higher power lasers at upcoming facilities.


Short-pulse laser-driven x-ray radiography

High Power Laser Science and Engineering Cambridge University Press 4 (2016) e30-

E Brambrink, S Baton, M Koenig, R Yurchak, N Bidaut, B Albertazzi, JE Cross, G Gregori, A Rigby, E Falize, A Pelka, F Kroll, S Pikuz, Y Sakawa, N Ozaki, C Kuranz, M Manuel, C Li, P Tzeferacos, D Lamb

We have developed a new radiography setup with a short-pulse laser-driven x-ray source. Using a radiography axis perpendicular to both long- and short-pulse lasers allowed optimizing the incident angle of the short-pulse laser on the x-ray source target. The setup has been tested with various x-ray source target materials and different laser wavelengths. Signal to noise ratios are presented as well as achieved spatial resolutions. The high quality of our technique is illustrated on a plasma flow radiograph obtained during a laboratory astrophysics experiment on POLARs.


Raman scattering for intense high orbital angular momentum harmonic generation

2016 Conference on Lasers and Electro-Optics, CLEO 2016 (2016)

J Vieira, RMGM Trines, EP Alves, RA Fonseca, JT Mendonca, R Bingham, P Norreys, LO Silva

© 2016 OSA. We identify a mechanism, based on Raman scattering, to endow near-infrared laser beams with high orders of orbital angular momentum (OAM). In combination with high-harmonic generation, this could lead to very high OAM harmonics in the soft x-ray region.


Characteristics of betatron radiation from direct-laser-accelerated electrons

Physical Review E American Physical Society 93 (2016) 063203

P Norreys, TW Huang, APL Robinson, CT Zhou, B Qiao, B Liu, SC Ruan, XT He

<p>Betatron radiation from direct-laser-accelerated electrons is characterized analytically and numerically. It is shown here that the electron dynamics is strongly dependent on a self-similar parameter S ( ≡ n e n c a 0 ). Both the electron transverse momentum and energy are proportional to the normalized amplitude of laser field ( a 0 )fora fixed value of S . As a result, the total number of radiated photons scales as a 2 0 / √ S and the energy conversion efficiency of photons from the accelerated electrons scales as a 3 0 /S . The particle-in-cell simulations agree well with the analytical scalings. It is suggested that a tunable high-energy and high-flux radiation source can be achieved by exploiting this regime.</p>


Dynamic X-ray diffraction observation of shocked solid iron up to 170 GPa

Proceedings of the National Academy of Sciences of the United States of America National Academy of Sciences 113 (2016) 7745-7749

A Denoeud, N Ozaki, A Benuzzi-Mounaix, H Uranishi, Y Kondo, R Kodama, E Brambrink, A Ravasio, M Bocoum, J-M Boudenne, M Harmand, F Guyot, S Mazevet, D Riley, M Makita, T Sano, Y Sakawa, Y Inubushi, G Gregori, M Koenig, G Morard

Investigation of the iron phase diagram under high pressure and temperature is crucial for the determination of the composition of the cores of rocky planets and for better understanding the generation of planetary magnetic fields. Here we present X-ray diffraction results from laser-driven shock-compressed single-crystal and polycrystalline iron, indicating the presence of solid hexagonal close-packed iron up to pressure of at least 170 GPa along the principal Hugoniot, corresponding to a temperature of 4,150 K. This is confirmed by the agreement between the pressure obtained from the measurement of the iron volume in the sample and the inferred shock strength from velocimetry deductions. Results presented in this study are of the first importance regarding pure Fe phase diagram probed under dynamic compression and can be applied to study conditions that are relevant to Earth and super-Earth cores.


Experimental measurements of the collisional absorption of XUV radiation in warm dense aluminium.

Physical Review American Physical Society 94 (2016) 023203-

B Kettle, T Dzelzainis, S White, L Li, B Dromey, M Zepf, CL Lewis, G Williams, S Künzel, M Fajardo, H Dacasa, P Zeitoun, A Rigby, G Gregori, C Spindloe, R Heathcote, D Riley

The collisional (or free-free) absorption of soft x rays in warm dense aluminium remains an unsolved problem. Competing descriptions of the process exist, two of which we compare to our experimental data here. One of these is based on a weak scattering model, another uses a corrected classical approach. These two models show distinctly different behaviors with temperature. Here we describe experimental evidence for the absorption of 26-eV photons in solid density warm aluminium (T_{e}≈1 eV). Radiative x-ray heating from palladium-coated CH foils was used to create the warm dense aluminium samples and a laser-driven high-harmonic beam from an argon gas jet provided the probe. The results indicate little or no change in absorption upon heating. This behavior is in agreement with the prediction of the corrected classical approach, although there is not agreement in absolute absorption value. Verifying the correct absorption mechanism is decisive in providing a better understanding of the complex behavior of the warm dense state.


AWAKE, The Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 829 (2016) 76-82

E Gschwendtner, E Adli, L Amorim, R Apsimon, R Assmann, A-M Bachmann, F Batsch, J Bauche, VKB Olsen, M Bernardini, R Bingham, B Biskup, T Bohl, C Bracco, PN Burrows, G Burt, B Buttenschoen, A Butterworth, A Caldwell, M Cascella, E Chevallay, S Cipiccia, H Damerau, L Deacon, R Dirksen, S Doebert, U Dorda, J Farmer, V Fedosseev, E Feldbaumer, R Fiorito, R Fonseca, F Friebel, AA Gorn, O Grulke, J Hansen, C Hessler, W Hofle, J Holloway, M Huether, D Jaroszynski, L Jensen, S Jolly, A Joulaei, M Kasim, F Keeble, Y Li, S Liu, N Lopes, KV Lotov, S Mandry, R Martorelli, M Martyanov, S Mazzoni, O Mete, VA Minakov, J Mitchell, J Moody, P Muggli, Z Najmudin, R Norreys, E Oez, A Pardons, K Pepitone, A Petrenko, G Plyushchev, A Pukhov, K Rieger, H Ruhl, E Salveter, N Savard, J Schmidt, A Seryi, E Shaposhnikova, ZM Sheng, R Sherwood, L Silva, L Soby, AP Sosedkin, RI Spitsyn, R Trines, PV Tuev, M Turner, V Verzilov, J Vieira, H Vincke, Y Wei, CP Welsch, M Wing, G Xia, H Zhang

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