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

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.

Imaging Shock Waves in Diamond with Both High Temporal and Spatial Resolution at an XFEL.

Scientific reports 5 (2015) 11089-

A Schropp, R Hoppe, V Meier, J Patommel, F Seiboth, Y Ping, DG Hicks, MA Beckwith, GW Collins, A Higginbotham, JS Wark, HJ Lee, B Nagler, EC Galtier, B Arnold, U Zastrau, JB Hastings, CG Schroer

The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic compression wave in diamond. The elastic wave was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnified x-ray phase-contrast imaging. The temporal evolution of the shock wave can be monitored, yielding detailed information on shock dynamics, such as the shock velocity, the shock front width, and the local compression of the material. The method provides a quantitative perspective on the state of matter in extreme conditions.

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

Pellet ignition using ions shock accelerated in the corona

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

RA Cairns, E Boella, M Vranic, LO Silva, R Trines, P Norreys, R Bingham

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

Physics of Plasmas 22 (2015)

A Lévy, 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

© 2015 AIP Publishing LLC. The efficiency and uniformity of heating induced by hard x-ray free-electron laser pulse is investigated for 0.5 μm silver foils using the X-ray Pump Probe instrument at the Linac Coherent Light Source facility. Intense 8.9 keV x-ray pulses of 60fs duration deposit energy predominantly via inner-shell ionization to create a non-equilibrium Ag solid density plasma. The x-ray pulses are focused to 14 × 17 μm2 by means of beryllium lenses and by varying the total beam energy, the energy deposition is varied over a range of irradiances from 4.4 to 6.5 × 1015 ∼ W/cm2. Two time-and-space resolved interferometers simultaneously probed the expansion of the front and rear sample surfaces and find evidence of a nearly symmetric expansion pointing to the uniformity of energy deposition over the full target thickness. The experimental results are compared with two different hydrodynamic simulations of the sample expansion. The agreement between experimental and theoretical results yields an estimate of the temperature evolution as a function of x-ray irradiance that varies from 8 to 10 eV for the x-ray irradiances studied.

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

Ultrafast collisional ion heating by electrostatic shocks.

Nature communications 6 (2015) 8905-

AE 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 that 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, localized 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.

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

Quantitative single shot and spatially resolved plasma wakefield diagnostics

Physical Review Special Topics: Accelerators and Beams American Physical Society 18 (2015)

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

Diagnosing plasma conditions can give great advantages in optimizing plasma wakefield accelerator experiments. One possible method is that of photon acceleration. By propagating a laser probe pulse through a plasma wakefield and extracting the imposed frequency modulation, one can obtain an image of the density modulation of the wakefield. In order to diagnose the wakefield parameters at a chosen point in the plasma, the probe pulse crosses the plasma at oblique angles relative to the wakefield. In this paper, mathematical expressions relating the frequency modulation of the laser pulse and the wakefield density profile of the plasma for oblique crossing angles are derived. Multidimensional particle-in-cell simulation results presented in this paper confirm that the frequency modulation profiles and the density modulation profiles agree to within 10%. Limitations to the accuracy of the measurement are discussed in this paper. This technique opens new possibilities to quantitatively diagnose the plasma wakefield density at known positions within the plasma column.