Dense plasma heating by crossing relativistic electron beams

Physical Review E American Physical Society 95 (2016) 013211

N Ratan, NJ Sircombe, LA Ceurvorst, J Sadler, MF Kasim, J Holloway, MC Levy, R Trines, R Bingham, P Norreys

Here we investigate, using relativistic fluid theory and Vlasov-Maxwell simulations, the local heating of a dense plasma by two crossing electron beams. Heating occurs as an instability of the electron beams drives Langmuir waves which couple nonlinearly into damped ion-acoustic waves. Simulations show a factor 2.8 increase in electron kinetic energy with a coupling efficiency of 18%. Our results support applications to the production of warm dense matter and as a driver for inertial fusion plasmas.

Simulations of the time and space-resolved X-ray transmission of a free-electron-laser-heated aluminium plasma

Journal of Physics B: Atomic, Molecular and Optical Physics IOP Publishing 49 (2016) 035603

DS Rackstraw, SM Vinko, O Ciricosta, H-K Chung, RW Lee, JS Wark

<p>We present simulations of the time and space-resolved transmission of a solid-density aluminium plasma as it is created and probed with the focussed output of an x-ray free-electron-laser with photon energies ranging from the K-edge of the cold material (1560 eV) to 1880 eV. We demonstrate how information about the temporal evolution of the charge states within the system can be extracted from the spatially resolved, yet time-integrated transmission images. We propose that such time-resolved measurements could in principle be performed with recently developed split-and-delay techniques.</p>

Amplification and generation of ultra-intense twisted laser pulses via stimulated Raman scattering

Nature Communications Nature Publishing 7 (2016) Article 10371-

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

Twisted Laguerre–Gaussian lasers, with orbital angular momentum and characterized by doughnut-shaped intensity profiles, provide a transformative set of tools and research directions in a growing range of fields and applications, from super-resolution microcopy and ultra-fast optical communications to quantum computing and astrophysics. The impact of twisted light is widening as recent numerical calculations provided solutions to long-standing challenges in plasma-based acceleration by allowing for high-gradient positron acceleration. The production of ultra-high-intensity twisted laser pulses could then also have a broad influence on relativistic laser–matter interactions. Here we show theoretically and with ab initio three-dimensional particle-in-cell simulations that stimulated Raman backscattering can generate and amplify twisted lasers to petawatt intensities in plasmas. This work may open new research directions in nonlinear optics and high–energy-density science, compact plasma-based accelerators and light sources.



S Kerr, MZ Mo, R Masud, X Jin, L Manzoor, HF Tiedje, Y Tsui, R Fedosejevs, A Link, P Patel, HS McLean, A Hazi, H Chen, L Ceurvorst, P Norreys, IEEE

Efficient evaluation of collisional energy transfer terms for plasma particle simulations


AE Turrell, M Sherlock, SJ Rose

Nanosecond formation of diamond and lonsdaleite by shock compression of graphite

Nature Communications Nature Publishing Group 7 (2016) 10970

D Kraus, A Ravasio, M Gauthier, DO Gericke, J Vorberger, S Frydrych, J Helfrich, LB Fletcher, G Schaumann, B Nagler, B Barbrel, B Bachmann, EJ Gamboa, S Göde, E Granados, G Gregori, HJ Lee, P Neumayer, W Schumaker, T Döppner, RW Falcone, SH Glenzer, M Roth

The shock-induced transition from graphite to diamond has been of great scientific and technological interest since the discovery of microscopic diamonds in remnants of explosively driven graphite. Furthermore, shock synthesis of diamond and lonsdaleite, a speculative hexagonal carbon polymorph with unique hardness, is expected to happen during violent meteor impacts. Here, we show unprecedented in situ X-ray diffraction measurements of diamond formation on nanosecond timescales by shock compression of pyrolytic as well as polycrystalline graphite to pressures from 19 GPa up to 228 GPa. While we observe the transition to diamond starting at 50 GPa for both pyrolytic and polycrystalline graphite, we also record the direct formation of lonsdaleite above 170 GPa for pyrolytic samples only. Our experiment provides new insights into the processes of the shock-induced transition from graphite to diamond and uniquely resolves the dynamics that explain the main natural occurrence of the lonsdaleite crystal structure being close to meteor impact sites.

Theory of density fluctuations in strongly radiative plasmas

Physical Review E American Physical Society 93 (2016) 033201

JE Cross, P Mabey, DO Gericke, G Gregori

Derivation of the dynamic structure factor, an important parameter linking experimental and theoretical work in dense plasmas, is possible starting from hydrodynamic equations. Here we obtain, by modifying the governing hydrodynamic equations, a new form of the dynamic structure factor which includes radiative terms. The inclusion of such terms has an effect on the structure factor at high temperatures, which suggests that its effect must be taken into consideration in such regimes.

Path to AWAKE: Evolution of the concept


A Caldwell, E Adli, L Amorim, R Apsimon, T Argyropoulos, R Assmann, A-M Bachmann, E Batsch, J Bauche, VKB Olsen, M Bernardini, R Bingham, B Biskup, T Bohl, C Bracco, PN Burrows, G Burt, B Buttenschoen, A Butterworth, M Cascella, S Chattopadhyay, E Chevallay, S Cipiccia, H Damerau, L Deacon, R Dirksen, S Doebert, U Dorda, E Eisen, J Farmer, S Fartoukh, V Fedosseev, E Feldbaumer, R Fiorito, R Fonseca, F Friebel, G Geschonke, B Goddard, AA Gorn, O Grulke, E Gschwendtner, J Hansen, C Hessler, S Hillenbrand, W Hofle, J Holloway, C Huang, M Huether, D Jaroszynski, L Jensen, S Jolly, A Joulaei, M Kasim, F Keeble, R Kersevan, N Kumar, Y Li, S Liu, N Lopes, KV Lotov, W Lu, J Machacek, S Mandry, I Martin, R Martorelli, M Martyanov, S Mazzoni, M Meddahi, L Merminga, O Mete, VA Minakov, J Mitchell, J Moody, A-S Mueller, Z Najmudin, TCQ Noakes, P Norreys, J Osterhoff, E Oez, A Pardons, K Pepitone, A Petrenko, G Plyushchev, J Pozimski, A Pukhov, O Reimann, K Rieger, S Roesler, H Ruhl, T Rusnak, E Salveter, N Savard, J Schmidt, H von der Schmitt, A Seryi, E Shaposhnikova, ZM Sheng, R Sherwood, L Silva, F Simon, L Soby, AP Sosedkin, RI Spitsyn, T Tajima, R Tarkeshian, H Timko, R Trines, T Tueckmantel, PV Tuev, M Turner, E Velotti, V Verzilov, J Vieira, H Vincke, Y Wei, CP Welsch, M Wing, G Xia, V Yakimenko, H Zhang, F Zimmermann

Calibration of time of flight detectors using laser-driven neutron source.

The Review of scientific instruments 86 (2015) 073308-

SR Mirfayzi, S Kar, H Ahmed, AG Krygier, A Green, A Alejo, R Clarke, RR Freeman, J Fuchs, D Jung, A Kleinschmidt, JT Morrison, Z Najmudin, H Nakamura, P Norreys, M Oliver, M Roth, L Vassura, M Zepf, M Borghesi

Calibration of three scintillators (EJ232Q, BC422Q, and EJ410) in a time-of-flight arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub-MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors is shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil.

From microjoules to megajoules and kilobars to gigabars: Probing matter at extreme states of deformation

PHYSICS OF PLASMAS 22 (2015) ARTN 090501

BA Remington, RE Rudd, JS Wark

Compression of X-ray free electron laser pulses to attosecond duration

Scientific Reports Nature Publishing Group 5 (2015) 16755-16755

JD Sadler, R Nathvani, P Oleśkiewicz, LA Ceurvorst, N Ratan, MF Kasim, RMGM Trines, R Bingham, P Norreys

State of the art X-ray Free Electron Laser facilities currently provide the brightest X-ray pulses available, typically with mJ energy and several hundred femtosecond duration. Here we present one- and two-dimensional Particle-in-Cell simulations, utilising the process of stimulated Raman amplification, showing that these pulses are compressed to a temporally coherent, sub-femtosecond pulse at 8% efficiency. Pulses of this type may pave the way for routine time resolution of electrons in nm size potentials. Furthermore, evidence is presented that significant Landau damping and wave-breaking may be beneficial in distorting the rear of the interaction and further reducing the final pulse duration.

Mitigating the relativistic laser beam filamentation via an elliptical beam profile.

Physical review. E, Statistical, nonlinear, and soft matter physics American Physical Society 92 (2015) 053106-

TW Huang, CT Zhou, AP Robinson, B Qiao, H Zhang, SZ Wu, HB Zhuo, P Norreys, XT He

It is shown that the filamentation instability of relativistically intense laser pulses in plasmas can be mitigated in the case where the laser beam has an elliptically distributed beam profile. A high-power elliptical Gaussian laser beam would break up into a regular filamentation pattern-in contrast to the randomly distributed filaments of a circularly distributed laser beam-and much more laser power would be concentrated in the central region. A highly elliptically distributed laser beam experiences anisotropic self-focusing and diffraction processes in the plasma channel ensuring that the unstable diffractive rings of the circular case cannot be produced. The azimuthal modulational instability is thereby suppressed. These findings are verified by three-dimensional particle-in-cell simulations.

Simulations of in situ x-ray diffraction from uniaxially compressed highly textured polycrystalline targets


D McGonegle, D Milathianaki, BA Remington, JS Wark, A Higginbotham

Laboratory measurements of resistivity in warm dense plasmas relevant to the microphysics of brown dwarfs.

Nature communications 6 (2015) 8742-

N Booth, APL Robinson, P Hakel, RJ Clarke, RJ Dance, D Doria, LA Gizzi, G Gregori, P Koester, L Labate, T Levato, B Li, M Makita, RC Mancini, J Pasley, PP Rajeev, D Riley, E Wagenaars, JN Waugh, NC Woolsey

Since the observation of the first brown dwarf in 1995, numerous studies have led to a better understanding of the structures of these objects. Here we present a method for studying material resistivity in warm dense plasmas in the laboratory, which we relate to the microphysics of brown dwarfs through viscosity and electron collisions. Here we use X-ray polarimetry to determine the resistivity of a sulphur-doped plastic target heated to Brown Dwarf conditions by an ultra-intense laser. The resistivity is determined by matching the plasma physics model to the atomic physics calculations of the measured large, positive, polarization. The inferred resistivity is larger than predicted using standard resistivity models, suggesting that these commonly used models will not adequately describe the resistivity of warm dense plasma related to the viscosity of brown dwarfs.

Direct Observation of Melting in Shock-Compressed Bismuth With Femtosecond X-ray Diffraction.

Physical review letters 115 (2015) 095701-

MG Gorman, R Briggs, EE McBride, A Higginbotham, B Arnold, JH Eggert, DE Fratanduono, E Galtier, AE Lazicki, HJ Lee, HP Liermann, B Nagler, A Rothkirch, RF Smith, DC Swift, GW Collins, JS Wark, MI McMahon

The melting of bismuth in response to shock compression has been studied using in situ femtosecond x-ray diffraction at an x-ray free electron laser. Both solid-solid and solid-liquid phase transitions are documented using changes in discrete diffraction peaks and the emergence of broad, liquid scattering upon release from shock pressures up to 14 GPa. The transformation from the solid state to the liquid is found to occur in less than 3 ns, very much faster than previously believed. These results are the first quantitative measurements of a liquid material obtained on shock release using x-ray diffraction, and provide an upper limit for the time scale of melting of bismuth under shock loading.

X-ray free-electron laser studies of dense plasmas


SM Vinko

Ultra-fast collisional ion heating by electrostatic shocks

Nature Communications Nature Publishing Group 6 (2015) 8905

A Turrell, M Sherlock, SJ Rose

High intensity lasers can be used to generate shockwaves which have found applications in nuclear fusion, proton imaging, cancer therapies, and materials science. Collisionless electrostatic shocks are one type of shockwave widely studied for applications involving ion acceleration. Here we show a novel mechanism for collisionless electrostatic shocks to heat small amounts of solid density matter to temperatures of ∼ keV in tens of femtoseconds. Unusually, electrons play no direct role in the heating, and it is the ions which determine the heating rate. Ions are heated due to an interplay between the electric field of the shock, the local density increase during the passage of the shock, and collisions between different species of ion. In simulations, these factors combine to produce rapid, localised heating of the lighter ion species. Although the heated volume is modest, this would be one of the fastest heating mechanisms discovered if demonstrated in the laboratory.

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


AE Turrell, M Sherlock, SJ Rose

Laser-driven platform for generation and characterization of strong quasi-static magnetic fields


JJ Santos, M Bailly-Grandvaux, L Giuffrida, P Forestier-Colleoni, S Fujioka, Z Zhang, P Korneev, R Bouillaud, S Dorard, D Batani, M Chevrot, JE Cross, R Crowston, J-L Dubois, J Gazave, G Gregori, E d'Humieres, S Hulin, K Ishihara, S Kojima, E Loyez, J-R Marques, A Morace, P Nicolai, O Peyrusse, A Poye, D Raffestin, J Ribolzi, M Roth, G Schaumann, F Serres, VT Tikhonchuk, P Vacar, N Woolsey

The generation and amplification of intergalactic magnetic fields in analogue laboratory experiments with high power lasers

Physics Reports Elsevier 601 (2015) 1-34

G Gregori, B Reville, F Miniati

The advent of high-power laser facilities has, in the past two decades, opened a new field of research where astrophysical environments can be scaled down to laboratory dimensions, while preserving the essential physics. This is due to the invariance of the equations of magneto-hydrodynamics to a class of similarity transformations. Here we review the relevant scaling relations and their application in laboratory astrophysics experiments with a focus on the generation and amplification of magnetic fields at cosmological shock waves. These arise during the collapse of protogalactic structures, resulting in the formation of high Mach number shocks in the intergalactic medium, which act as sources of vorticity in protogalaxies. The standard model for the origin of magnetic fields is via baroclinic generation from the resulting misaligned pressure and temperature gradients (the so-called Biermann battery process). While both experiment and numerical simulation have confirmed the occurrence of this mechanism at shocks, reconciling the resulting weak fields with present day observations is an un-solved problem, although it is generally accepted that turbulent motions of the weakly magnetised plasma plays a key role. Bridging the vast scale differences is a challenge both numerically and experimentally. A summary of novel laboratory experiments aimed at investigating additional processes that may shed light on these and other processes, such us turbulent amplification, resistive and collision-less plasma instabilities will be discussed in this review, particularly in relation to experiments using high power laser systems. The connection between laboratory shock waves and additional mechanisms, such as diffusive shock acceleration will be discussed. Finally, we will summarize the impact of laboratory investigation in furthering our understanding of plasma physics on super-galactic scales.