Publications


Phase transition lowering in dynamically compressed silicon

NATURE PHYSICS 15 (2019) 89-+

EE McBride, A Krygier, A Ehnes, E Galtier, M Harmand, Z Konopkova, HJ Lee, H-P Liermann, B Nagler, A Pelka, M Roedel, A Schropp, RF Smith, C Spindloe, D Swift, F Tavella, S Toleikis, T Tschentscher, JS Wark, A Higginbotham


Using Sparse Gaussian Processes for Predicting Robust Inertial Confinement Fusion Implosion Yields

IEEE Transactions on Plasma Science Institute of Electrical and Electronics Engineers (IEEE) (2019) 1-8

P Hatfield, S Rose, R Scott, I Almosallam, S Roberts, M Jarvis


Supersonic plasma turbulence in the laboratory.

Nature communications 10 (2019) 1758-

TG White, MT Oliver, P Mabey, M Kühn-Kauffeldt, AFA Bott, LNK Döhl, AR Bell, R Bingham, R Clarke, J Foster, G Giacinti, P Graham, R Heathcote, M Koenig, Y Kuramitsu, DQ Lamb, J Meinecke, T Michel, F Miniati, M Notley, B Reville, D Ryu, S Sarkar, Y Sakawa, MP Selwood, J Squire, RHH Scott, P Tzeferacos, N Woolsey, AA Schekochihin, G Gregori

The properties of supersonic, compressible plasma turbulence determine the behavior of many terrestrial and astrophysical systems. In the interstellar medium and molecular clouds, compressible turbulence plays a vital role in star formation and the evolution of our galaxy. Observations of the density and velocity power spectra in the Orion B and Perseus molecular clouds show large deviations from those predicted for incompressible turbulence. Hydrodynamic simulations attribute this to the high Mach number in the interstellar medium (ISM), although the exact details of this dependence are not well understood. Here we investigate experimentally the statistical behavior of boundary-free supersonic turbulence created by the collision of two laser-driven high-velocity turbulent plasma jets. The Mach number dependence of the slopes of the density and velocity power spectra agree with astrophysical observations, and supports the notion that the turbulence transitions from being Kolmogorov-like at low Mach number to being more Burgers-like at higher Mach numbers.


First demonstration of ARC-accelerated proton beams at the National Ignition Facility

Physics of Plasmas 26 (2019)

D Mariscal, T Ma, SC Wilks, AJ Kemp, GJ Williams, P Michel, H Chen, PK Patel, BA Remington, M Bowers, L Pelz, MR Hermann, W Hsing, D Martinez, R Sigurdsson, M Prantil, A Conder, J Lawson, M Hamamoto, P Di Nicola, C Widmayer, D Homoelle, R Lowe-Webb, S Herriot, W Williams, D Alessi, D Kalantar, R Zacharias, C Haefner, N Thompson, T Zobrist, D Lord, N Hash, A Pak, N Lemos, M Tabak, C McGuffey, J Kim, FN Beg, MS Wei, P Norreys, A Morace, N Iwata, Y Sentoku, D Neely, GG Scott, K Flippo

© 2019 Author(s). New short-pulse kilojoule, Petawatt-class lasers, which have recently come online and are coupled to large-scale, many-beam long-pulse facilities, undoubtedly serve as very exciting tools to capture transformational science opportunities in high energy density physics. These short-pulse lasers also happen to reside in a unique laser regime: very high-energy (kilojoule), relatively long (multi-picosecond) pulse-lengths, and large (10s of micron) focal spots, where their use in driving energetic particle beams is largely unexplored. Proton acceleration via Target Normal Sheath Acceleration (TNSA) using the Advanced Radiographic Capability (ARC) short-pulse laser at the National Ignition Facility in the Lawrence Livermore National Laboratory is demonstrated for the first time, and protons of up to 18 MeV are measured using laser irradiation of >1 ps pulse-lengths and quasi-relativistic (∼10 18 W/cm 2 ) intensities. This is indicative of a super-ponderomotive electron acceleration mechanism that sustains acceleration over long (multi-picosecond) time-scales and allows for proton energies to be achieved far beyond what the well-established scalings of proton acceleration via TNSA would predict at these modest intensities. Furthermore, the characteristics of the ARC laser (large ∼100 μm diameter focal spot, flat spatial profile, multi-picosecond, relatively low prepulse) provide acceleration conditions that allow for the investigation of 1D-like particle acceleration. A high flux ∼ 50 J of laser-accelerated protons is experimentally demonstrated. A new capability in multi-picosecond particle-in-cell simulation is applied to model the data, corroborating the high proton energies and elucidating the physics of multi-picosecond particle acceleration.


Laboratory measurements of geometrical effects in the x-ray emission of optically thick lines for ICF diagnostics

PHYSICS OF PLASMAS 26 (2019) ARTN 063302

G Perez-Callejo, LC Jarrott, DA Liedahl, EV Marley, GE Kemp, RF Heeter, JA Emig, ME Foord, K Widmann, J Jaquez, H Huang, SJ Rose, JS Wark, MB Schneider


Laboratory study of stationary accretion shock relevant to astrophysical systems.

Scientific reports 9 (2019) 8157-

P Mabey, B Albertazzi, E Falize, T Michel, G Rigon, L Van Box Som, A Pelka, F-E Brack, F Kroll, E Filippov, G Gregori, Y Kuramitsu, DQ Lamb, C Li, N Ozaki, S Pikuz, Y Sakawa, P Tzeferacos, M Koenig

Accretion processes play a crucial role in a wide variety of astrophysical systems. Of particular interest are magnetic cataclysmic variables, where, plasma flow is directed along the star's magnetic field lines onto its poles. A stationary shock is formed, several hundred kilometres above the stellar surface; a distance far too small to be resolved with today's telescopes. Here, we report the results of an analogous laboratory experiment which recreates this astrophysical system. The dynamics of the laboratory system are strongly influenced by the interplay of material, thermal, magnetic and radiative effects, allowing a steady shock to form at a constant distance from a stationary obstacle. Our results demonstrate that a significant amount of plasma is ejected in the lateral direction; a phenomenon that is under-estimated in typical magnetohydrodynamic simulations and often neglected in astrophysical models. This changes the properties of the post-shock region considerably and has important implications for many astrophysical studies.


Recovery of metastable dense Bi synthesized by shock compression

APPLIED PHYSICS LETTERS 114 (2019) ARTN 120601

MG Gorman, AL Coleman, R Briggs, RS McWilliams, A Hermann, D McGonegle, CA Bolme, AE Gleason, E Galtier, HJ Lee, E Granados, EE McBride, S Rothman, DE Fratanduono, RF Smith, GW Collins, JH Eggert, JS Wark, MI McMahon


The use of geometric effects in diagnosing ion density in ICF-related dot spectroscopy experiments

HIGH ENERGY DENSITY PHYSICS 30 (2019) 45-51

G Perez-Callejo, DA Liedahl, MB Schneider, SJ Rose, JS Wark


Maser radiation from collisionless shocks: application to astrophysical jets

HIGH POWER LASER SCIENCE AND ENGINEERING 7 (2019) ARTN e17

DC Speirs, K Ronald, ADR Phelps, ME Koepke, RA Cairns, A Rigby, F Cruz, RMGM Trines, R Bamford, BJ Kellett, B Albertazzi, JE Cross, F Fraschetti, P Graham, PM Kozlowski, Y Kuramitsu, F Miniati, T Morita, M Oliver, B Reville, Y Sakawa, S Sarkar, C Spindloe, M Koenig, LO Silva, DQ Lamb, P Tzeferacos, S Lebedev, G Gregori, R Bingham


A proposal to measure iron opacity at conditions close to the solar convective zone-radiative zone boundary

High Energy Density Physics Elsevier BV (2019)

DJ Hoarty, J Morton, M Jeffery, LK Pattison, A Wardlow, SPD Mangles, SJ Rose, C Iglesias, K Opachich, RF Heeter, TS Perry


Observing thermal Schwinger pair production

Physical Review A American Physical Society (APS) 99 (2019) 052120

O Gould, S Mangles, A Rajantie, S Rose, C Xie


Setup for meV-resolution inelastic X-ray scattering measurements and X-ray diffraction at the Matter in Extreme Conditions endstation at the Linac Coherent Light Source.

The Review of scientific instruments 89 (2018) 10F104-

EE McBride, TG White, A Descamps, LB Fletcher, K Appel, FP Condamine, CB Curry, F Dallari, S Funk, E Galtier, EJ Gamboa, M Gauthier, S Goede, JB Kim, HJ Lee, BK Ofori-Okai, M Oliver, A Rigby, C Schoenwaelder, P Sun, T Tschentscher, BBL Witte, U Zastrau, G Gregori, B Nagler, J Hastings, SH Glenzer, G Monaco

We describe a setup for performing inelastic X-ray scattering and X-ray diffraction measurements at the Matter in Extreme Conditions (MEC) endstation of the Linac Coherent Light Source. This technique is capable of performing high-, meV-resolution measurements of dynamic ion features in both crystalline and non-crystalline materials. A four-bounce silicon (533) monochromator was used in conjunction with three silicon (533) diced crystal analyzers to provide an energy resolution of ∼50 meV over a range of ∼500 meV in single shot measurements. In addition to the instrument resolution function, we demonstrate the measurement of longitudinal acoustic phonon modes in polycrystalline diamond. Furthermore, this setup may be combined with the high intensity laser drivers available at MEC to create warm dense matter and subsequently measure ion acoustic modes.


Comments on A new theory for X-ray diffraction.

Acta crystallographica. Section A, Foundations and advances 74 (2018) 447-456

JT Fraser, JS Wark

In an article entitled A new theory for X-ray diffraction [Fewster (2014). Acta Cryst. A70, 257-282], hereafter referred to as NTXRD, it is claimed that when X-rays are scattered from a small crystallite, whatever its size and shape, the diffraction pattern will contain enhanced scattering at angles of exactly 2θB, whatever the orientation of the crystal. It is claimed that in this way scattering from a powder, with randomly oriented crystals, gives rise to Bragg scattering even if the Bragg condition is never satisfied by an individual crystallite. The claims of the theory put forward in NTXRD are examined and they are found to be in error. Whilst for a certain restricted set of shapes of crystals it is possible to obtain some diffraction close to (but not exactly at) the Bragg angle as the crystallite is oriented away from the Bragg condition, this is generally not the case. Furthermore, contrary to the claims made within NTXRD, the recognition of the origin of the type of effects described is not new, and has been known since the earliest days of X-ray diffraction.


Single-shot frequency-resolved optical gating for retrieving the pulse shape of high energy picosecond pulses.

The Review of scientific instruments 89 (2018) 103509-

R Aboushelbaya, AF Savin, L Ceurvorst, J Sadler, PA Norreys, AS Davies, DH Froula, A Boyle, M Galimberti, P Oliveira, B Parry, Y Katzir, K Glize

Accurate characterization of laser pulses used in experiments is a crucial step to the analysis of their results. In this paper, a novel single-shot frequency-resolved optical gating (FROG) device is described, one that incorporates a dispersive element which allows it to fully characterize pulses up to 25 ps in duration with a 65 fs per pixel temporal resolution. A newly developed phase retrieval routine based on memetic algorithms is implemented and shown to circumvent the stagnation problem that often occurs with traditional FROG analysis programs when they encounter a local minimum.


Erratum: "Setup for meV-resolution inelastic X-ray scattering measurements and X-ray diffraction at the Matter in Extreme Conditions endstation at the Linac Coherent Light Source" [Rev. Sci. Instrum. 89, 10F104 (2018)].

The Review of scientific instruments 89 (2018) 129901-129901

EE McBride, TG White, A Descamps, LB Fletcher, K Appel, F Condamine, CB Curry, F Dallari, S Funk, E Galtier, EJ Gamboa, M Gauthier, S Goede, JB Kim, HJ Lee, BK Ofori-Okai, M Oliver, A Rigby, C Schoenwaelder, P Sun, T Tschentscher, BBL Witte, U Zastrau, G Gregori, B Nagler, J Hastings, SH Glenzer, G Monaco


Analytical estimates of proton acceleration in laser-produced turbulent plasmas

JOURNAL OF PLASMA PHYSICS 84 (2018) ARTN 905840608

KA Beyer, B Reville, AFA Bott, H-S Park, S Sarkar, G Gregori


Femtosecond diffraction studies of solid and liquid phase changes in shock-compressed bismuth.

Scientific reports 8 (2018) 16927-

MG Gorman, AL Coleman, R Briggs, RS McWilliams, D McGonegle, CA Bolme, AE Gleason, E Galtier, HJ Lee, E Granados, M Śliwa, C Sanloup, S Rothman, DE Fratanduono, RF Smith, GW Collins, JH Eggert, JS Wark, MI McMahon

Bismuth has long been a prototypical system for investigating phase transformations and melting at high pressure. Despite decades of experimental study, however, the lattice-level response of Bi to rapid (shock) compression and the relationship between structures occurring dynamically and those observed during slow (static) compression, are still not clearly understood. We have determined the structural response of shock-compressed Bi to 68 GPa using femtosecond X-ray diffraction, thereby revealing the phase transition sequence and equation-of-state in unprecedented detail for the first time. We show that shocked-Bi exhibits a marked departure from equilibrium behavior - the incommensurate Bi-III phase is not observed, but rather a new metastable phase, and the Bi-V phase is formed at significantly lower pressures compared to static compression studies. We also directly measure structural changes in a shocked liquid for the first time. These observations reveal new behaviour in the solid and liquid phases of a shocked material and give important insights into the validity of comparing static and dynamic datasets.


Advantages to a diverging Raman amplifier

Communications Physics 1 (2018)

JD Sadler, LO Silva, RA Fonseca, K Glize, MF Kasim, A Savin, R Aboushelbaya, MW Mayr, B Spiers, RHW Wang, R Bingham, RMGM Trines, PA Norreys

© 2018, The Author(s). The plasma Raman instability can efficiently compress a nanosecond long high-power laser pulse to sub-picosecond duration. Although, many authors envisaged a converging beam geometry for Raman amplification, here we propose the exact opposite geometry; the amplification should start at the intense focus of the seed. We generalise the coupled laser envelope equations to include this non-collimated case. The new geometry completely eradicates the usual trailing secondary peaks of the output pulse, which typically lower the efficiency by half. It also reduces, by orders of magnitude, the initial seed pulse energy required for efficient operation. As in the collimated case, the evolution is self similar, although the temporal pulse envelope is different. A two-dimensional particle-in-cell simulation demonstrates efficient amplification of a diverging seed with only 0.3 mJ energy. The pulse has no secondary peaks and almost constant intensity as it amplifies and diverges.


Soft X-ray backlighter source driven by a short-pulse laser for pump-probe characterization of warm dense matter.

The Review of scientific instruments 89 (2018) 10F122-

C McGuffey, M Dozières, J Kim, A Savin, J Park, J Emig, C Brabetz, L Carlson, RF Heeter, HS McLean, J Moody, MB Schneider, MS Wei, FN Beg

Here we propose a pump-probe X-ray absorption spectroscopy temperature measurement technique appropriate for matter having temperature in the range of 10 to a few 100 eV and density up to solid density. Atomic modeling simulations indicate that for various low- to mid-Z materials in this range the energy and optical depth of bound-bound and bound-free absorption features are sensitive to temperature. We discuss sample thickness and tamp layer considerations. A series of experimental investigations was carried out using a range of laser parameters with pulse duration ≤5 ps and various pure and alloyed materials to identify backlighter sources suitable for the technique.


Implementation of a Faraday rotation diagnostic at the OMEGA laser facility

HIGH POWER LASER SCIENCE AND ENGINEERING 6 (2018) ARTN e49

A Rigby, J Katz, AFA Bott, TG White, P Tzeferacos, DQ Lamb, DH Froula, G Gregori

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