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  • Journal article
    Perez-Callejo G, Marley E, Liedahl DA, Jarrott LC, Kemp GE, Heeter RF, Emig JA, Foord ME, Schneider MB, Rose SJ, Wark JSet al., 2021,

    Demonstration of geometric effects and resonant scattering in the X-Ray spectra of high-energy-density plasmas

    , Physical Review Letters, Vol: 126, Pages: 1-7, ISSN: 0031-9007

    In a plasma of sufficient size and density, photons emitted within the system have a probability of being reabsorbed and reemitted multiple times—a phenomenon known in astrophysics as resonant scattering. This effect alters the ratio of optically thick to optically thin lines, depending on the plasma geometry and viewing angle, and has significant implications for the spectra observed in a number of astrophysical scenarios, but has not previously been studied in a controlled laboratory plasma. We demonstrate the effect in the x-ray spectra emitted by cylindrical plasmas generated by high power laser irradiation, and the results confirm the geometrical interpretation of resonant scattering.

  • Journal article
    Rose S, Hatfield P, Scott R, 2020,

    Modelling burning thermonuclear plasma

    , Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol: 378, Pages: 1-8, ISSN: 1364-503X

    Considerable progress towards the achievement ofthermonuclear burn using inertial confinement fusion has beenachieved at the National Ignition Facility (NIF) in the USA inthe last few years. Other drivers, such as the Z-machine atSandia, are also making progress towards this goal. A burningthermonuclear plasma would provide a unique and extremeplasma environment; in this paper we discuss a) differenttheoretical challenges involved in modelling burning plasmasnot currently considered, b) the use of novel machine learningbased methods that might help large facilities reach ignition,and c) the connections that a burning plasma might have tofundamental physics, including QED studies, and the replicationand exploration of conditions that last occurred in the first fewminutes after the Big Bang.

  • Journal article
    Pérez-Callejo G, Jarrott LC, Liedahl DA, Schneider MB, Wark JS, Rose SJet al., 2020,

    Measuring the oscillator strength of intercombination lines of helium-like V ions in a laser-produced-plasma

    , Journal of Quantitative Spectroscopy and Radiative Transfer, Vol: 256, ISSN: 0022-4073

    We present results of measurements of the oscillator strength of intercombination lines of He-like Vanadium ions in high energy density (HED) laser-produced-plasmas and compare them with the simulations from commonly used codes and data from the NIST database. Whilst not yet sufficiently accurate to constrain different trusted atomic-physics models for the particular system studied, our results are in agreement with the available data within experimental error bars, yet differ from cruder approximations of the oscillator strength used in certain atomic-kinetics packages, suggesting that this general method could be further extended to be used as a measurement of the oscillator strength of additional atomic transitions under the extreme conditions that are achieved in HED experiments.

  • Journal article
    Pérez-Callejo G, Barrios MA, Liedahl DA, Schneider MB, Jones O, Landen O, Kauffman RL, Suter LJ, Moody JD, Rose SJ, Wark JSet al., 2020,

    A novel method to measure ion density in ICF experiments using x-ray spectroscopy of cylindrical tracers

    , Physics of Plasmas, Vol: 27, Pages: 112714-1-112714-11, ISSN: 1070-664X

    The indirect drive approach to inertial confinement fusion has undergone important advances in the past few years. Improvements in temperature and density diagnostic methods are leading to more accurate measurements of the plasma conditions inside the Hohlraum and therefore to more efficient experimental designs. The implementation of dot spectroscopy has proven to be a versatile approach to extracting space- and time-dependent electron temperatures. In this method, a microdot of a mid-Z material is placed inside the Hohlraum and its K-shell emission spectrum is used to determine the plasma temperature. However, radiation transport of optically thick lines acting within the cylindrical dot geometry influences the outgoing spectral distribution in a manner that depends on the viewing angle. This angular dependence has recently been studied in the high energy density regime at the OMEGA laser facility, which allowed us to design and benchmark appropriate radiative transfer models that can replicate these geometric effects. By combining these models with the measurements from the dot spectroscopy experiments at the National Ignition Facility, we demonstrate here a novel technique that exploits the transport effects to obtain time-resolved measurements of the ion density of the tracer dots, without the need for additional diagnostics. We find excellent agreement between experiment and simulation, opening the possibility of using these geometric effects as a density diagnostic in future experiments.

  • Conference paper
    White S, Irwin R, Warwick R, Sarri G, Gribakin GF, Keenan FP, Hill E, Rose S, Ferland GJ, Wang F, Zhao G, Han B, Riley Det al., 2020,

    Generation of photoionized plasmas in the laboratory: Analogues to astrophysical sources

    , Laboratory Astrophysics fFrom Observation to Interpretation, Publisher: Cambridge University Press, Pages: 321-325, ISSN: 1743-9213

    Implementation of a novel experimental approach using a bright source of narrowband x-ray emission has enabled the production of a photoionized argon plasma of relevance to astrophysical modelling codes such as Cloudy. We present results showing that the photoionization parameter ζ = 4πF/ne generated using the VULCAN laser was ≈ 50 erg cm s−1, higher than those obtained previously with more powerful facilities. Comparison of our argon emission-line spectra in the 4.15 - 4.25 Å range at varying initial gas pressures with predictions from the Cloudy code and a simple time-dependent code are also presented. Finally we briefly discuss how this proof-of-principle experiment may be scaled to larger facilities such as ORION to produce the closest laboratory analogue to a photoionized plasma.

  • Journal article
    Baggott R, Rose S, Mangles S, 2020,

    Calculating opacity in hot, dense matter using second-order electron-photon and two-photon transitions to approximate line broadening

    , Physical Review Letters, Vol: 125, Pages: 145002 – 1-145002 – 5, ISSN: 0031-9007

    Calculations of the opacity of hot, dense matter require models for plasma line broadening. How-ever, the most general theories are too complex to calculate directly and some approximation is inevitably required. The most widely-used approaches focus on the line centre, where a Lorentzian shape is obtained. Here, we demonstrate that in the opposite limit, far from the line centre, the opacity can be expressed in terms of second-order transitions, such as electron-photon and two-photon processes. We suggest that this insight could form the basis for a new approach to improve calculations of opacity in hot, dense matter. Preliminary calculations suggest that this approach could yield increased opacity away from absorption lines.

  • Journal article
    Yanuka D, Theocharous S, Chittenden JP, Bland SNet al., 2020,

    High velocity outflows along the axis of pulsed power driven rod z-pinches

    , AIP Advances, Vol: 10, Pages: 1-9, ISSN: 2158-3226

    We report on initial observations of high velocity outflows from the ends of a rod compressed using pulsed power. 1 mm and 2 mm diameter copper rods were placed in a water bath and driven by ∼0.6 MA currents with rise times of ∼700 ns. Laser backlit framing images and streak photography showed an outflow of the material from the ends of each rod, of the initial velocity of up to 7 km/s, which began ∼500 ns after the start of the current pulse and continued throughout the experiment. Ballistics gel was used to help separate low density gas/plasma from any solid/liquid component in the outflow, successfully capturing the material from larger diameter rods (enabling an estimate of its energy) and tracing the path of the material that passed straight through the gel with smaller rods. Experimental results were compared to 1D and 2D MHD simulations performed with the Gorgon code. These suggested that the outflow had two different components, resulting from two different physical processes. Differences in the resistivity between the copper rod and stainless steel anode result in the opening of a small gap between them and ablated stainless steel being projected above the rod, which is captured in framing and streak images. Later in time, a dense copper material, pinched by the magnetic pressure, is launched—explaining the ballistics gel results. The simulations also suggest that the tamped explosion of the rod surface plays a small role in any outflow.

  • Journal article
    Sory DR, Amin HD, Chapman D, Proud WG, Rankin SMet al., 2020,

    Replicating landmine blast loading in cellular <i>in Vitro</i> models

    , Physical Biology, Vol: 17, ISSN: 1478-3967

    Trauma arising from landmines and improvised explosive devices promotes heterotopic ossification, the formation of extra-skeletal bone in non-osseous tissue. To date, experimental platforms that can replicate the loading parameter space relevant to improvised explosive device and landmine blast wave exposure have not been available to study the effects of such non-physiological mechanical loading on cells. Here, we present the design and calibration of three distinct in vitro experimental loading platforms that allow us to replicate the spectrum of loading conditions recorded in near-field blast wave exposure. We subjected cells in suspension or in a three-dimensional hydrogel to strain rates up to 6000 s-1and pressure levels up to 45 MPa. Our results highlight that cellular activation is regulated in a non-linear fashion - not by a single mechanical parameter, it is the combined action of the applied mechanical pressure, rate of loading and loading impulse, along with the extracellular environment used to convey the pressure waves. Finally, our research indicates that PO MSCs are finely tuned to respond to mechanical stimuli that fall within defined ranges of loading.

  • Journal article
    Nguyen TT, Carpanen D, Rankin I, Ramasamy A, Breeze J, Proud W, Clasper J, Masouros Set al., 2020,

    Mapping the risk of fracture of the tibia from penetrating fragments

    , Frontiers in Bioengineering and Biotechnology, Vol: 8, Pages: 1-11, ISSN: 2296-4185

    Penetrating injuries are commonly inflicted in attacks with explosive devices. The extremities, and especially the leg, are the most commonly affected body areas, presenting high risk of infection, slow recovery, and threat of amputation. The aim of this study was to quantify the risk of fracture to the anteromedial, posterior, and lateral aspects of the tibia from a metal fragment-simulating projectile (FSP). A gas gun system and a 0.78-g cylindrical FSP were employed to perform tests on an ovine tibia model. The results from the animal study were subsequently scaled to obtain fracture-risk curves for the human tibia using the cortical thickness ratio. The thickness of the surrounding soft tissue was also taken into account when assessing fracture risk. The lateral cortex of the tibia was found to be most susceptible tofracture,whose impact velocity at 50% risk of EF1+, EF2+, EF3+, and EF4+ fracture types –according to the modified Winquist-Hansen classification –were 174, 190, 212,and 282 m/s respectively. The findings of this study will be used to increase the fidelity of predictive models of projectile penetration.

  • Journal article
    Rankin I, Nguyen TT, Carpanen D, Clasper J, Masouros Set al., 2020,

    A new understanding of the mechanism of injury to the pelvis and lower limbs in blast

    , Frontiers in Bioengineering and Biotechnology, Vol: 8, ISSN: 2296-4185

    Dismounted complex blast injury (DCBI) has been one of the most severe forms of trauma sustained in recent conflicts. This injury has been partially attributed to limb flail; however, the full causative mechanism has not yet been fully determined. Soil ejecta has been hypothesized as a significant contributor to the injury but remains untested. In this study, a small-animal model of gas-gun mediated high velocity sand blast was used to investigate this mechanism. The results demonstrated a correlation between increasing sand blast velocity and injury patterns of worsening severity across the trauma range. This study is the first to replicate high velocity sand blast and the first model to reproduce the pattern of injury seen in DCBI. These findings are consistent with clinical and battlefield data. They represent a significant change in the understanding of blast injury, producing a new mechanistic theory of traumatic amputation. This mechanism of traumatic amputation is shown to be high velocity sand blast causing the initial tissue disruption, with the following blast wind and resultant limb flail completing the amputation. These findings implicate high velocity sand blast, in addition to limb flail, as a critical mechanism of injury in the dismounted blast casualty.

  • Journal article
    Millett JCF, Avraam P, Whiteman G, Chapman DJ, Case Set al., 2020,

    The role of orientation on the shock response of single crystal tantalum

    , JOURNAL OF APPLIED PHYSICS, Vol: 128, ISSN: 0021-8979
  • Conference paper
    Proud WG, O'Brien S, Wilson MA, 2020,

    Elicitation of knowledge from a defence expert

    , ISSN: 1742-6588

    The aim of this work is to understand the way that a defence expert defines the concept of importance in relation to the ideas contained in a scientific document. The expert's views on the importance of the concepts in this document were elicited in two phases. In the first phase, the expert was asked to summarise an eight-page document on the effects of electromagnetic fields on propellant combustion. Completion of this task generated a series of 'key points'. Phase two of the methodology was a sit-down interview with the expert. This interview comprised three parts: asking the expert to talk through why each of the key points were important, asking the expert to sort the key points into categories according to how important they are and then asking the expert to generate categories of why the points are important. The techniques used for expert elicitation proved highly successful in relation to this domain of knowledge. Not only were the procedures able to extract the underlying categories through which the expert structured their understanding of the field, but the results indicated reliability in the content of knowledge extracted through different methods. Subsequent papers in this project compare this work to parallel analysis conducted using Natural Language Processing tools.

  • Journal article
    Nguyen TT, Meek G, Breeze J, Masouros Set al., 2020,

    Gelatine backing affects the performance of single-layer ballistic-resistant materials against blast fragments

    , Frontiers in Bioengineering and Biotechnology, Vol: 8, Pages: 1-10, ISSN: 2296-4185

    Penetrating trauma by energized fragments is the most common injury from explosive devices, the main threat in the contemporary battlefield. Such devices produce projectiles dependent upon their design, including preformed fragments, casings, glass, or stones; these are subsequently energized to high velocities and cause serious injuries to the body. Current body armor focuses on the essential coverage, which is mainly the thoracic and abdominal area, and can be heavy and cumbersome. In addition, there may be coverage gaps that can benefit from the additional protection provided by one or more layers of lightweight ballistic fabrics. This study assessed the performance of single layers of commercially available ballistic protective fabrics such as Kevlar®, Twaron®, and Dyneema®, in both woven and knitted configurations. Experiments were carried out using a custom-built gas-gun system, with a 0.78-g cylindrical steel fragment simulating projectile (FSP) as the impactor, and ballistic gelatine as the backing material. FSP velocity at 50% risk of material perforation, gelatine penetration, and high-risk wounding to soft tissue, as well as the depth of penetration (DoP) against impact velocity and the normalized energy absorption were used as metrics to rank the performance of the materials tested. Additional tests were performed to investigate the effect of not including a soft-tissue simulant backing material on the performance of the fabrics. The results show that a thin layer of ballistic material may offer meaningful protection against the penetration of this FSP. Additionally, it is essential to ensure a biofidelic boundary condition as the protective efficacy of fabrics was markedly altered by a gelatine backing.

  • Journal article
    Felten M, Fries M, Pullen A, Proud WG, Jung Aet al., 2020,

    Investigation of Strain-Rate Effects in Ni/PU Hybrid Foams under Low-Impact Velocities

  • Journal article
    Miller SM, Slutz SA, Bland SN, Klein SR, Campbell PC, Woolstrum JM, Kuranz CC, Gomez MR, Jordan NM, McBride RDet al., 2020,

    A pulsed-power implementation of “Laser Gate” for increasing laser energy coupling and fusion yield in magnetized liner inertial fusion (MagLIF)

    , Review of Scientific Instruments, Vol: 91, Pages: 1-9, ISSN: 0034-6748

    Magnetized Liner Inertial Fusion (MagLIF) at Sandia National Laboratories involves a laser preheating stage where a few-ns laser pulse passes through a few-micron-thick plastic window to preheat gaseous fusion fuel contained within the MagLIF target. Interactions with this window reduce heating efficiency and mix window and target materials into the fuel. A recently proposed idea called “Laser Gate” involves removing the window well before the preheating laser is applied. In this article, we present experimental proof-of-principle results for a pulsed-power implementation of Laser Gate, where a thin current-carrying wire weakens the perimeter of the window, allowing the fuel pressure to push the window open and away from the preheating laser path. For this effort, transparent targets were fabricated and a test facility capable of studying this version of Laser Gate was developed. A 12-frame bright-field laser schlieren/shadowgraphy imaging system captured the window opening dynamics on microsecond timescales. The images reveal that the window remains largely intact as it opens and detaches from the target. A column of escaping pressurized gas appears to prevent the detached window from inadvertently moving into the preheating laser path.

  • Journal article
    McLean KW, Rose SJ, 2020,

    Corrections to weighted opacities and energy exchange rate in 3-T radiation-hydrodynamics

    , High Energy Density Physics, Vol: 35, Pages: 1-5, ISSN: 1574-1818

    It is often the case that high energy density systems can be well described and simulated in the 3T approximation, where electrons, ions and the radiation field are defined at unique temperatures given by Te, Ti, Tr. The difference in temperature between the electrons and radiation field is important when calculating weighted opacities and electron-radiation energy exchange rates. Often, it is assumed that Tr ≈ Te, meaning the quantities can be calculated as functions of Te only. This paper explores the consequences that arise when one uses this assumption in regions where Tr ≠ Te. Mutliplicative correction factors are derived for the Rosseland and Planckian mean opacities (κR and κP) and for the electron-radiation energy exchange rate. We find that there exists a very small region of parameter space where the corrections are negligible. However, for the majority of parameter space explored, numerical corrections vary from factors of 2 to multiple orders of magnitude.

  • Journal article
    Behm K, Hussein AE, Zhao TZ, Baggott RA, Cole JM, Hill E, Krushelnick K, Maksimchuk A, Nees J, Rose SJ, Thomas AGR, Watt R, Wood JC, Yanovsky V, Mangles SPDet al., 2020,

    Demonstration of femtosecond broadband X-rays from laser wakefield acceleration as a source for pump-probe X-ray absorption studies

    , High Energy Density Physics, Vol: 35, Pages: 1-5, ISSN: 1574-1818

    We present X-ray absorption measurements near the K-edge of laser heated aluminum in a pump-probe configuration using X-rays generated in a laser wakefield accelerator. A 30 fs duration laser pulse from the Herculeslaser system was split into two beamlines, with one used to heat a 4 µm thickness Al foil and the second to drive a laser wakefield accelerator. The laser-heated plasma was probed at various pump-probe delays using the femtosecond duration X-rays generated by betatron oscillations of the electrons in the wakefield. We observe an apparent blue-shift of the K-edge occurring on a sub-picosecond timescale in the transmission spectra.

  • Journal article
    Hobbs LMR, Burridge D, Hill MP, Hoarty DJ, Brown CRD, Charles R, Cooper G, James SF, Wilson LA, Babbage W, Hatfield PW, Beiersdorfer P, Nilsen J, Scott H, Rose SJet al., 2020,

    X-ray-line coincidence photopumping in a potassium-chlorine mixed plasma

    , Physical Review A, Vol: 101, Pages: 053431-1-053431-8, ISSN: 2469-9926

    Exploiting the multiple long pulse capability and suite of x-ray diagnostics of the Orion laser, we have set out to explore line coincidence photopuming—the enhancement in population of an atomic level brought on by resonant absorption of x rays from a different emitting ion. Unlike previous work, the two ions are in the same plasma and so the experiment is an x-ray analog of the well-known Bowen resonance fluorescence mechanism that operates in astrophysical situations in the optical region. Our measurements have shown enhanced fluorescence in a chlorine plasma, attributable to line coincident photopumping from co-mixed potassium ions. To detect this relatively low signal-to-noise phenomenon, the data from multiple shots are combined, and the statistical method of bootstrapping is used to assign a confidence value to the measured enhancement, resulting in an estimate of the enhancement of 39±1618% compared to the null case, where no pumping occurs. The experimental results have been compared to coupled radiation-transport and radiation hydrodynamics simulations using the cretin code together with the nym radiation hydrodynamics model and agreement has been found, with the simulations also predicting modest enhancement.

  • Journal article
    Escauriza EM, Duarte JP, Chapman DJ, Rutherford ME, Farbaniec L, Jonsson JC, Smith LC, Olbinado MP, Skidmore J, Foster P, Ringrose T, Rack A, Eakins DEet al., 2020,

    Collapse dynamics of spherical cavities in a solid under shock loading

    , SCIENTIFIC REPORTS, Vol: 10, ISSN: 2045-2322
  • Conference paper
    Nilsen J, Burridge D, Hobbs LMR, Hoarty D, Beiersdorfer P, Brown GV, Hell N, Panchenko D, Gu MF, Saunders AM, Scott HA, Hatfield P, Hill MP, Wilson L, Charles R, Brown CRD, Rose Set al., 2020,

    Enhanced fluorescence from X-Ray line coincidence pumping

    , 16th International Conference on X-ray Lasers, Publisher: Springer International Publishing, Pages: 29-35, ISSN: 0930-8989

    Many resonant photo-pumped X-ray laser schemes that use a strong pump line such as Ly-α or He-α to populate the upper laser state of a separate lasing material have been proposed over the last four decades but none have been demonstrated. As a first step to creating a photo-pumped X-ray laser we have decided to reinvestigate some of these schemes at the Orion laser facility with the goal to show enhanced fluorescence. In particular we look at using the Ly-α or He-α K lines to pump the 1s–3p and 4p transitions in H-like Cl and see fluorescence on the 4f–3d line at 65 Å and the 3d–2p line at 23 Å. Preliminary experiments are presented that show a modest enhancement. As an alternative we also look at enhancing the 2p–2s line in Ne-like Ge at 65 Å using the Ly-α Mg line to photo-pump the 2s–3p line of Ne-like Ge. Calculations are presented that suggest modest enhancements of 2.5.

  • Journal article
    Nguyen TT, Carpanen D, Stinner D, Rankin I, Ramasamy A, Breeze J, Proud W, Clasper J, Masouros Set al., 2020,

    The risk of fracture to the tibia from a fragment simulating projectile

    , Journal of The Mechanical Behavior of Biomedical Materials, Vol: 102, ISSN: 1751-6161

    Penetrating injuries due to fragments energised by an explosive event are life threatening and are associated with poor clinical and functional outcomes. The tibia is the long bone most affected in survivors of explosive events, yet the risk of penetrating injury to it has not been quantified. In this study, an injury-risk assessment of penetrating injury to the tibia was conducted using a gas-gun system with a 0.78-g cylindrical fragment simulating projectile. An ovine tibia model was used to generate the injury-risk curves and human cadaveric tests were conducted to validate and scale the results of the ovine model. The impact velocity at 50% risk (±95% confidence intervals) for EF1+, EF2+, EF3+, and EF4+ fractures to the human tibia – using the modified Winquist-Hansen classification – was 271 ± 30, 363 ± 46, 459 ± 102, and 936 ± 182 m/s, respectively. The scaling factor for the impact velocity from cadaveric ovine to human was 2.5. These findings define the protection thresholds to improve the injury outcomes for fragment penetrating injury to the tibia.

  • Journal article
    Bailie D, Hyland C, Singh R, White S, Sarri G, Keenan F, Riley D, Rose S, Hill E, Wang F, Yuan D, Zhao G, Wei H, Han B, Zhu B, Zhu J, Yang Pet al., 2020,

    An investigation of the L-shell X-ray conversion efficiency for laser-irradiated tin foils

    , Plasma Science and Technology, Vol: 22, Pages: 1-7, ISSN: 1009-0630

    We have used the Shenguang II laser in third harmonic (351 nm) to investigate the emission ofL-shell radiation in the 3.3 to 4.4 keV range generated using thin foils of Sn coated onto a parylenesubstrate with irradiation of order 1015 Wcm−2 and nanosecond pulse duration. In our experiment,we have concentrated on assessing the emission on the non-laser irradiated side as this allows anexperimental geometry relevant to experiments on photo-ionised plasmas where a secondary targetmust be placed close to the source, to achieve X-ray fluxes appropriate to astrophysical objects.Overall L-shell conversion efficiencies are estimated to be of order 1%, with little dependence onSn thickness between 400 and 800 nm.

  • Conference paper
    Tear GR, Proud WG, 2020,

    Experimental Methodology for Characterising Microwave Damaged Concrete

    , 21st Biennial American-Physical-Society -Topical-Group Conference on Shock Compression of Condensed Matter (SCCM), Publisher: AMER INST PHYSICS, ISSN: 0094-243X
  • Journal article
    Hatfield P, Rose S, Scott R, Almosallam I, Roberts S, Jarvis Met al., 2020,

    Using sparse Gaussian processes for predicting robust inertial confinement fusion implosion yields

    , IEEE Transactions on Plasma Science, Vol: 48, Pages: 14-21, ISSN: 0093-3813

    Here, we present the application of an advanced sparse Gaussian process-based machine learning algorithm to the challenge of predicting the yields of inertial confinement fusion (ICF) experiments. The algorithm is used to investigate the parameter space of an extremely robust ICF design for the National Ignition Facility, the ``Simplest Design''; deuterium-tritium gas in a plastic ablator with a Gaussian, Planckian drive. In particular, we show that: 1) GPz has the potential to decompose uncertainty on predictions into uncertainty from lack of data and shot-to-shot variation; 2) it permits the incorporation of science-goal-specific cost-sensitive learning (CSL), e.g., focusing on the high-yield parts of parameter space; and 3) it is very fast and effective in high dimensions.

  • Conference paper
    Jonsson JC, Farbaniec L, Escauriza EM, Smith LC, Chapman DJ, Eakins DEet al., 2020,

    Effect of Texture on Elastic Precursor Decay in Magnesium Alloy AZ31B

    , 21st Biennial American-Physical-Society -Topical-Group Conference on Shock Compression of Condensed Matter (SCCM), Publisher: AMER INST PHYSICS, ISSN: 0094-243X
  • Conference paper
    Proud WG, Martin E, Tear GR, Sory DRet al., 2020,

    The Effect of Temperature on the Failure of a Simple Perspex Structure

    , 21st Biennial American-Physical-Society -Topical-Group Conference on Shock Compression of Condensed Matter (SCCM), Publisher: AMER INST PHYSICS, ISSN: 0094-243X
  • Conference paper
    Lee JJ, Sory DR, Proud WG, 2020,

    Simulation of Two-gauge Measurement Method on the SHPB for Testing Soft Materials

    , 21st Biennial American-Physical-Society -Topical-Group Conference on Shock Compression of Condensed Matter (SCCM), Publisher: AMER INST PHYSICS, ISSN: 0094-243X
  • Conference paper
    Magnus D, Sory DR, Lee J, Khan MA, Proud WGet al., 2020,

    Study of Soft Material Blast Mitigation Effects Using a Shock Tube

    , 21st Biennial American-Physical-Society -Topical-Group Conference on Shock Compression of Condensed Matter (SCCM), Publisher: AMER INST PHYSICS, ISSN: 0094-243X
  • Journal article
    Kettle B, Gerstmayr E, Streeter MJV, Albert F, Baggott RA, Bourgeois N, Cole JM, Dann S, Falk K, Gallardo González I, Hussein AE, Lemos N, Lopes NC, Lundh O, Ma Y, Rose SJ, Spindloe C, Symes DR, Šmíd M, Thomas AGR, Watt R, Mangles SPDet al., 2019,

    Single-shot multi-keV X-ray absorption spectroscopy using an ultrashort laser-wakefield accelerator source

    , Physical Review Letters, Vol: 123, Pages: 254801-1-254801-6, ISSN: 0031-9007

    Single-shot absorption measurements have been performed using the multi-keV x rays generated by a laser-wakefield accelerator. A 200 TW laser was used to drive a laser-wakefield accelerator in a mode which produced broadband electron beams with a maximum energy above 1 GeV and a broad divergence of ≈15  mrad FWHM. Betatron oscillations of these electrons generated 1.2±0.2×106  photons/eV in the 5 keV region, with a signal-to-noise ratio of approximately 300∶1. This was sufficient to allow high-resolution x-ray absorption near-edge structure measurements at the K edge of a titanium sample in a single shot. We demonstrate that this source is capable of single-shot, simultaneous measurements of both the electron and ion distributions in matter heated to eV temperatures by comparison with density functional theory simulations. The unique combination of a high-flux, large bandwidth, few femtosecond duration x-ray pulse synchronized to a high-power laser will enable key advances in the study of ultrafast energetic processes such as electron-ion equilibration.

  • Journal article
    Yanuka D, Theocharous S, Bland SN, 2019,

    Pulsed power driven cylindrical wire array explosions in different media

    , PHYSICS OF PLASMAS, Vol: 26, Pages: 1-7, ISSN: 1070-664X

    Cylindrical copper wire array explosions were carried out in de-ionized water, sodium polytungstate solution, nitromethane, and polyester in order to obtain high energy density conditions in the vicinity of implosion using the generated converging shock waves. The use of different materials in which the array is immersed can contribute to this goal with higher density resulting in higher shock velocities and possible combustion. The generated shock waves were captured by a framing and a streak camera, and shock velocities were calculated and compared. The pressure behind the shock front was calculated using the known hydrodynamic relations (for water, polytungstate, and polyester) and compared to two-dimensional hydrodynamic simulations coupled with the equations of state (for water and polyester). It was shown that despite lower shock wave velocity in polytungstate solution than in water, the pressures generated are similar in both materials. In polyester, both shock velocities and generated pressures are 2–4 times higher than in water. It was also shown that it is possible to carry out these explosions in a solid which has several advantages compared to liquids, such as not relying on waterproof systems and easier transportation.

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