Observation of magnetic field generation via the Weibel instability in interpenetrating plasma flows

NATURE PHYSICS 11 (2015) 173-176

CM Huntington, F Fiuza, JS Ross, AB Zylstra, RP Drake, DH Froula, G Gregori, NL Kugland, CC Kuranz, MC Levy, CK Li, J Meinecke, T Morita, R Petrasso, C Plechaty, BA Remington, DD Ryutov, Y Sakawa, A Spitkovsky, H Takabe, H-S Park

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.

Weak collisionless shocks in laser-plasmas

Plasma Physics and Controlled Fusion 57 (2015)

RA Cairns, R Bingham, RGM Trines, P Norreys

© 2015 IOP Publishing Ltd. We obtain a theory describing laminar shock-like structures in a collisionless plasma and examine the parameter limits, in terms of the ion sound Mach number and the electron/ion temperature ratio, within which these structures exist. The essential feature is the inclusion of finite ion temperature with the result that some ions are reflected from a potential ramp. This destroys the symmetry between upstream and downstream regions that would otherwise give the well-known ion solitary wave solution. We have shown earlier (Cairns et al 2014 Phys. Plasmas 21 022112) that such structures may be relevant to problems such as the existence of strong, localized electric fields observed in laser compressed pellets and laser acceleration of ions. Here we present results on the way in which these structures may produce species separation in fusion targets and suggest that it may be possible to use shock ion acceleration for fast ignition.

Electron-ion temperature equilibration in warm dense tantalum


NJ Hartley, P Belancourt, DA Chapman, T Doeppner, RP Drake, DO Gericke, SH Glenzer, D Khaghani, S LePape, T Ma, P Neumayer, A Pak, L Peters, S Richardson, J Vorberger, TG White, G Gregori

Investigation of the solid-liquid phase transition of carbon at 150 GPa with spectrally resolved X-ray scattering


J Helfrich, D Kraus, A Ortner, S Frydrych, G Schaumann, NJ Hartley, G Gregori, B Kettle, D Riley, DC Carroll, MM Notley, C Spindloe, M Roth

Single Hit Energy-resolved Laue Diffraction.

The Review of scientific instruments 86 (2015) 053908-

S Patel, MJ Suggit, PG Stubley, JA Hawreliak, O Ciricosta, AJ Comley, GW Collins, JH Eggert, JM Foster, JS Wark, A Higginbotham

In situ white light Laue diffraction has been successfully used to interrogate the structure of single crystal materials undergoing rapid (nanosecond) dynamic compression up to megabar pressures. However, information on strain state accessible via this technique is limited, reducing its applicability for a range of applications. We present an extension to the existing Laue diffraction platform in which we record the photon energy of a subset of diffraction peaks. This allows for a measurement of the longitudinal and transverse strains in situ during compression. Consequently, we demonstrate measurement of volumetric compression of the unit cell, in addition to the limited aspect ratio information accessible in conventional white light Laue. We present preliminary results for silicon, where only an elastic strain is observed. VISAR measurements show the presence of a two wave structure and measurements show that material downstream of the second wave does not contribute to the observed diffraction peaks, supporting the idea that this material may be highly disordered, or has undergone large scale rotation.

Simulation of density measurements in plasma wakefields using photon acceleration


MF Kasim, N Ratan, L Ceurvorst, J Sadler, PN Burrows, R Trines, J Holloway, M Wing, R Bingham, P Norreys

Characterization of x-ray lens for use in probing high energy density states of matter


P Mabey, NJ Hartley, HW Doyle, JE Cross, L Ceurvorst, A Savin, A Rigby, M Oliver, M Calvert, IJ Kim, D Riley, PA Norreys, CH Nam, DC Carroll, C Spindloe, G Gregori

The complex ion structure of warm dense carbon measured by spectrally resolved x-ray scattering

PHYSICS OF PLASMAS 22 (2015) ARTN 056307

D Kraus, J Vorberger, J Helfrich, DO Gericke, B Bachmann, V Bagnoud, B Barbrel, A Blazevic, DC Carroll, W Cayzac, T Doeppner, LB Fletcher, A Frank, S Frydrych, EJ Gamboa, M Gauthier, S Goede, E Granados, G Gregori, NJ Hartley, B Kettle, HJ Lee, B Nagler, P Neumayer, MM Notley, A Ortner, A Otten, A Ravasio, D Riley, F Roth, G Schaumann, D Schumacher, W Schumaker, K Siegenthaler, C Spindloe, F Wagner, K Wuensch, SH Glenzer, M Roth, RW Falcone

Generation of high-flux neutron beam from radiation pressure driven deuterium ion bunches

42nd European Physical Society Conference on Plasma Physics, EPS 2015 (2015)

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

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


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

Ultrabright X-ray laser scattering for dynamic warm dense matter physics

NATURE PHOTONICS 9 (2015) 274-279

LB Fletcher, HJ Lee, T Doeppner, E Galtier, B Nagler, P Heimann, C Fortmann, S LePape, T Ma, M Millot, A Pak, D Turnbull, DA Chapman, DO Gericke, J Vorberger, T White, G Gregori, M Wei, B Barbrel, RW Falcone, C-C Kao, H Nuhn, J Welch, U Zastrau, P Neumayer, JB Hastings, SH Glenzer

Saturable absorption of an x-ray free-electron-laser heated solid-density aluminum plasma.

Physical review letters 114 (2015) 015003-

DS Rackstraw, O Ciricosta, SM Vinko, B Barbrel, T Burian, J Chalupský, BI Cho, H-K Chung, GL Dakovski, K Engelhorn, V Hájková, P Heimann, M Holmes, L Juha, J Krzywinski, RW Lee, S Toleikis, JJ Turner, U Zastrau, JS Wark

High-intensity x-ray pulses from an x-ray free-electron laser are used to heat and probe a solid-density aluminum sample. The photon-energy-dependent transmission of the heating beam is studied through the use of a photodiode. Saturable absorption is observed, with the resulting transmission differing significantly from the cold case, in good agreement with atomic-kinetics simulations.

The creation of large-volume, gradient-free warm dense matter with an x-ray free-electron laser

PHYSICS OF PLASMAS 22 (2015) ARTN 030703

A Levy, P Audebert, R Shepherd, J Dunn, M Cammarata, O Ciricosta, F Deneuville, F Dorchies, M Fajardo, C Fourment, D Fritz, J Fuchs, J Gaudin, M Gauthier, A Graf, HJ Lee, H Lemke, B Nagler, J Park, O Peyrusse, AB Steel, SM Vinko, JS Wark, GO Williams, D Zhu, RW Lee

Selective deuterium ion acceleration using the Vulcan petawatt laser

PHYSICS OF PLASMAS 22 (2015) ARTN 053102

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

Evidence of locally enhanced target heating due to instabilities of counter-streaming fast electron beams

PHYSICS OF PLASMAS 22 (2015) ARTN 020701

P Koester, N Booth, CA Cecchetti, H Chen, RG Evans, G Gregori, L Labate, T Levato, B Li, M Makita, J Mithen, CD Murphy, M Notley, R Pattathil, D Riley, N Woolsey, LA Gizzi

Collisionless shock experiments with lasers and observation of Weibel instabilities

PHYSICS OF PLASMAS 22 (2015) ARTN 056311

H-S Park, CM Huntington, F Fiuza, RP Drake, DH Froula, G Gregori, M Koenig, NL Kugland, CC Kuranz, DQ Lamb, MC Levy, CK Li, J Meinecke, T Morita, RD Petrasso, BB Pollock, BA Remington, HG Rinderknecht, M Rosenberg, JS Ross, DD Ryutov, Y Sakawa, A Spitkovsky, H Takabe, DP Turnbull, P Tzeferacos, SV Weber, AB Zylstra

Developed turbulence and nonlinear amplification of magnetic fields in laboratory and astrophysical plasmas.

Proceedings of the National Academy of Sciences of the United States of America National Academy of Sciences 112 (2015) 8211-8215

J Meinecke, P Tzeferacos, AR Bell, EM Churazov, R Bingham, RJ Clarke, H Doyle, R Crowston, R Heathcote, RP Drake, M Koenig, Y Kuramitsu, CC Kuranz, MJ MacDonald, D Lee, CD Murphy, MM Notley, H-S Park, A Ravasio, A Pelka, B Reville, Y Sakawa, WC Wan, NC Woolsey, R Yurchak

The visible matter in the universe is turbulent and magnetized. Turbulence in galaxy clusters is produced by mergers and by jets of the central galaxies and believed responsible for the amplification of magnetic fields. We report on experiments looking at the collision of two laser-produced plasma clouds, mimicking, in the laboratory, a cluster merger event. By measuring the spectrum of the density fluctuations, we infer developed, Kolmogorov-like turbulence. From spectral line broadening, we estimate a level of turbulence consistent with turbulent heating balancing radiative cooling, as it likely does in galaxy clusters. We show that the magnetic field is amplified by turbulent motions, reaching a nonlinear regime that is a precursor to turbulent dynamo. Thus, our experiment provides a promising platform for understanding the structure of turbulence and the amplification of magnetic fields in the universe.

Target fabrication for the POLAR experiment on the Orion laser facility


C Spindloe, D Wyatt, D Haddock, I East, JE Cross, CN Danson, E Falize, JM Foster, M Koenig, G Gregori

Imaging transient melting of a nanocrystal using an X-ray laser.

Proceedings of the National Academy of Sciences of the United States of America 112 (2015) 7444-7448

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

There is a fundamental interest in studying photoinduced dynamics in nanoparticles and nanostructures as it provides insight into their mechanical and thermal properties out of equilibrium and during phase transitions. Nanoparticles can display significantly different properties from the bulk, which is due to the interplay between their size, morphology, crystallinity, defect concentration, and surface properties. Particularly interesting scenarios arise when nanoparticles undergo phase transitions, such as melting induced by an optical laser. Current theoretical evidence suggests that nanoparticles can undergo reversible nonhomogenous melting with the formation of a core-shell structure consisting of a liquid outer layer. To date, studies from ensembles of nanoparticles have tentatively suggested that such mechanisms are present. Here we demonstrate imaging transient melting and softening of the acoustic phonon modes of an individual gold nanocrystal, using an X-ray free electron laser. The results demonstrate that the transient melting is reversible and nonhomogenous, consistent with a core-shell model of melting. The results have implications for understanding transient processes in nanoparticles and determining their elastic properties as they undergo phase transitions.