High Energy Density Physics Research Research Articles

SPRAY: A smoothed particle radiation hydrodynamics code for modeling high intensity laser-plasma interactions

Here we report the development of SPRAY, a massively parallel GPU accelerated, smoothed particle hydrodynamics (SPH)-based, radiation hydrodynamics (RHD) code designed specifically for simulating high intensity laser-plasma interactions. When a target is irradiated by an intense laser, highly complex fluid deformation occurs due to instabilities, which is challenging to study numerically. SPRAY is particle-based, mesh-free, and Lagrangian, which addresses numerical issues that posed difficulties to existing methods. Its SPH formulations for RHD governing equations are tailored toward accurate and reliable simulations of laser-target irradiation phenomena, and are solved via a time-dependent, flux-limited diffusion method. A new laser energy coupling module, which is based on the Wentzel-Kramers-Brillouin (WKB) approximation, is implemented with a totally mesh-free ray-tracing scheme that is applicable for arbitrary geometry and dimensions. The accuracy and reliability of the code are demonstrated with a series of benchmark problems. To the authors' knowledge, this is the first attempt to employ SPH method for simulations of laser-plasma interactions in high energy density physics research. Possible expansions to the code, such as laser beam-beam interaction modeling and more sophisticated multi-group radiation transport are left for future development.

Ultrafast x-ray imaging of pulsed plasmas in water

Pulsed plasmas in liquids exhibit complex interaction between three phases of matter (liquids, gas, plasmas) and are currently used in a wide range of applications across several fields, however significant knowledge gaps in our understanding of plasma initiation in liquids hinder additional application and control; this area of research currently lacks a comprehensive predictive model. To aid progress in this area experimentally, here we present the first-known ultrafast (50 ps) X-ray images of pulsed plasma initiation processes in water (+25 kV, 10 ns, 5 mJ), courtesy of the X-ray imaging techniques available at Argonne National Laboratory's Advanced Photon Source (APS), with supporting nanosecond optical imaging and a computational X-ray diffraction model. These results clearly resolve narrow (~10 micron) low-density plasma channels during initiation timescales typically obscured by optical emission (<100 ns), a well-known and difficult problem to plasma experiments without access to state-of-the-art X-ray sources such as the APS synchrotron. Images presented in this work speak to several of the prevailing plasma initiation hypotheses, supporting electrostriction and bubble deformation as dominant initiation phenomena. We also demonstrate the plasma setup used in this work as a cheap ($<$US\$100k), compact, and repeatable benchmark imaging target (29.1 km/s, 1 TW/cm$^2$) useful for the development of next-generation ultrafast imaging of high-energy-density physics (HEDP), as well as easier integration of HEDP research into synchrotron-enabled facilities.

Production of warm dense water in the laboratory using intense ion beams at FAIR: Application to planetary physics

This paper presents two-dimensional hydrodynamic simulations of implosion of a water sample, which is enclosed in a cylindrical shell of tungsten that is driven by an intense uranium beam. The considered beam parameters match the characteristics of the beam which will be delivered by the heavy ion synchrotron, SIS100, at the Facility for Antiprotons and Ion Research (FAIR). An experimental scheme based on this concept, which is named LAPLAS, is an important part of the high energy density physics research program at FAIR. The simulations show that the LAPLAS implosion leads to a low-entropy compression of water, which generates core conditions of water-rich planets. The importance of this work is underscored by the fact that more than 30% of the discovered extrasolar planets are Neptune-like water-rich planets. To be able to construct a reliable physical model of the formation and evolution of these planets, it is important to have correct understanding of the equation of state of the exotic states of water that exist in the planetary interior. It is thus expected that the knowledge obtained from the LAPLAS experiments will be a very valuable contribution to the field of planetary physics. We show that x-ray radiographic imaging using a high-intensity laser-driven hard x-ray source would be a suitable diagnostic capable of delivering high-resolution images of the hydrodynamic evolution.

Four-channel toroidal crystal x-ray imager for laser-produced plasmas.

The motion law of complex fluids under extreme conditions is an important aspect of high energy density physics research. It has been demonstrated that using multi-channel curved crystals and a framing camera to observe the laser-produced target pellets doped with tracer elements is an appropriate method for investigating this law. This paper presents a feasible design scheme for a multi-channel toroidal imager, with the ray trace model used to verify the rationality of the evaluation method and the aberration of single toroidal crystal imaging. We demonstrate that the field of view (FOV) consistency of the four-channel Ge(400) toroidal crystal imager is less than 50 µm, while the best spatial resolution is ∼4 µm and the FOV of each channel is >2.2 mm.

Optical and physical properties of hydrocarbons with metal impurities in the warm dense matter regime

The hydrocarbon (CH) polymer is often chosen as the converter material with potential applications to Z-pinch driven dynamic hohlraum implosion experiments. Its physical and optical properties in the warm dense matter regime are important for dynamic hohlraum platform designs. Using the quantum molecular dynamics (QMD) method, we have obtained the equation of state, absorption coefficient, and reflectivity of hydrocarbon and Al–CH mixtures with the temperature and density ranging from 104–106 K and 0.1–0.9 g/cm3, respectively. The QMD-predicted principal Hugoniot data are compared with experiments as well as the theoretical calculations, and both show good agreement. The optical reflectivity from the corresponding dielectric functions is calculated using the corrected refraction index of the ambient (n0 = 1.59). Besides, we have further analyzed the atomic structure and bond dissociation process of polystyrene and Al–CH mixture systems using a bond tracking method with the temperature ranging from 1000 K to 10 000 K. The Al impurities have a slightly promoting effect on the initial stage of polystyrene pyrolysis. The calculation results can be helpful for future theoretical and experimental studies in high energy density physics research.

Progress of intense heavy ion beam driven high energy density physics

Intense ion beams can quasi-isometrically heat any high-density sample and generate warm dense matter (WDM) with large scale, uniform state distribution without any shock wave inside. This kind of driver provides a new opportunity for the laboratory high energy density physics (HEDP) research. The typical intense ion beam accelerators around the world, as well as their critical parameters and research plans of HEDP study are introduced.The progress of ion driven WDM generation and evolution using PIC and hydrodynamic simulations is shown. The high energy electron beam radiography technique with high spatial resolution, high temporal evolution, and high penetrating ability is also introduced. The collisional and charge transfer processes of the interaction between low-to-medium energy ion and plasma are analyzed. The nonlinear effect during the intense ion beam stopping and transportation process are presented.

High-power, low-coherence laser driver facility.

We report the first (to the best of our knowledge) high-power, low-coherence Nd:glass laser delivering kilojoule pulses with a coherent time of 249 fs and a bandwidth of 13 nm, achieving the 63%-efficiency second-harmonic conversion of the large-aperture low-coherence pulse and good beam smoothing effect. It provides a new type of laser driver for laser plasma interaction and high energy density physics research.

Introduction of laboratory astrophysics with intense lasers

Laboratory astrophysics came into being with the advent of modern high-energy density physics research devices that can be used to create extreme physical conditions in the laboratory similar to those of certain celestial bodies or their surroundings, such as high-power lasers or pinch devices to generate extreme astrophysical plasma conditions. Such experimental conditions are unprecedented and correspond directly to many important and critical physical phenomena in astrophysics. They enable people to study the problems with astrophysical background in the laboratory in a close, active and controllable way. This paper introduces the latest progress in this field in recent years, and presents perspectives on future research directions.

Review of pulsed power-driven high energy density physics research on Z at Sandia

Pulsed power accelerators compress electrical energy in space and time to provide versatile experimental platforms for high energy density and inertial confinement fusion science. The 80-TW “Z” pulsed power facility at Sandia National Laboratories is the largest pulsed power device in the world today. Z discharges up to 22 MJ of energy stored in its capacitor banks into a current pulse that rises in 100 ns and peaks at a current as high as 30 MA in low-inductance cylindrical targets. Considerable progress has been made over the past 15 years in the use of pulsed power as a precision scientific tool. This paper reviews developments at Sandia in inertial confinement fusion, dynamic materials science, x-ray radiation science, and pulsed power engineering, with an emphasis on progress since a previous review of research on Z in Physics of Plasmas in 2005.

High-energy-density physics based on HIAF

High-energy-density physics (HEDP) deals with the study of matter under extreme conditions with an energy density higher than 1011 J/m3, corresponding to a pressure of 100 GPa. Such matter exists in abundance in deep interiors of the planets and stars. It also exists for a short duration during nuclear explosion and the loading of high-power-pulsed machines. HEDP is the international frontier of national security, astrophysics and fusion science, and it is also one of the main scientific goals of the high-power laser-facilities, Z-machines and heavy-ion-accelerators. Herein, the HEDP research based on High Intensity heavy-ion Accelerator Facility (HIAF), which is the “12th Five-Year Plan” national major science and technology infrastructure, will be introduced. The HIAF is advocated to provide the world with a heavy-ion beam with utmost high power. The energy and power of one beam pulse is about 100 J and several TW, respectively. With such a high-power heavy-ion beam, heating a solid-state lead sample, for example, could generate homogenous high-energy-density matter with a spatial scale from mm to cm and a temperature of 10 eV, near-solid density, and energy density of 1013 J/m3. Thus, through the HIAF, the generation, properties and evolution of high-energy-density matter can be investigated. This paper also reports the state of the art in the field of HEDP based on HIAF, including the generation and development of high-energy-density matter driven by a high-intensity heavy-ion beam, micro mechanism of interaction between the ion beam and dense matter or plasma, and key diagnostics of the high-energy-density matter driven by a hevy-ion beam.

Towards ultra-intense ultra-short ion beams driven by a multi-PW laser

AbstractThe multi-petawatt (PW) lasers currently being built in Europe as part of the Extreme Light Infrastructure (ELI) project will be capable of generating femtosecond light pulses of ultra-relativistic intensities (~1023–1024 W/cm2) that have been unattainable so far. Such laser pulses can be used for the production of high-energy ion beams with unique features that could be applied in various fields of scientific and technological research. In this paper, the prospect of producing ultra-intense (intensity ≥1020 W/cm2) ultra-short (pico- or femtosecond) high-energy ion beams using multi-PW lasers is outlined. The results of numerical studies on the acceleration of light (carbon) ions, medium-heavy (copper) ions and super-heavy (lead) ions driven by a femtosecond laser pulse of ultra-relativistic intensity, performed with the use of a multi-dimensional (2D3 V) particle-in-cell code, are presented, and the ion acceleration mechanisms and properties of the generated ion beams are discussed. It is shown that both in the case of light ions and in the case of medium-heavy and super-heavy ions, ultra-intense femtosecond multi-GeV ion beams with a beam intensity much higher (by a factor ~102) and ion pulse durations much shorter (by a factor ~104–105) than achievable presently in conventional radio frequency-driven accelerators can be produced at laser intensities of 1023 W/cm2 predicted for the ELI lasers. Such ion beams can open the door to new areas of research in high-energy density physics, nuclear physics and inertial confinement fusion.

Acceleration of carbon ions to high energies by a multi-PW laser

Extreme Light Infrastructure (ELI) is a large-scale European project, still in the development stage, offering parameters of laser drivers required for multiple applications (femtosecond pulse duration, ultra-relativistic laser intensities ∼ 1022 - 1023 W/cm2), however studies of ion acceleration in the given intensity regime are still in the very early stages and require a deeper understanding of the processes occurring during laser-matter interactions to maximize the efficiency of ion acceleration. The purpose of this work is a numerical examination of the properties of carbon ion beams produced during the interaction of an ultra-intense laser beams (of intensities ∼ 1021 – 1023 W/cm2 and pulse duration order of femtoseconds, predicted to be available at ELI-NP, Romania) with C12 target. The dependence of ion beam parameters, such as intensity, energy spectrum, maximum and average ion energy and spatial distribution of ion charge density, on laser pulse parameters (mainly intensity) and the target thickness is investigated. The possibility of generation of high intensity, GeV energy ion beams in the foregoing conditions is demonstrated. The obtained results can be useful for research in high energy-density physics, nuclear physics or medical applications of ion beams.

A Primer on Pulsed Power and Linear Transformer Drivers for High Energy Density Physics Applications

The objectives of this tutorial are as follows: 1) to help students and researchers develop a basic understanding of how pulsed-power systems are used to create high-energy-density (HED) matter; 2) to develop a basic understanding of a new, compact, and efficient pulsed-power technology called linear transformer drivers (LTDs); 3) to understand why LTDs are an attractive technology for driving HED physics (HEDP) experiments; 4) to contrast LTDs with the more traditional Marx-generator/pulse-forming-line approach to driving HEDP experiments; and 5) to briefly review the history of LTD technology as well as some of the LTD-driven HEDP research presently underway at universities and research laboratories across the globe. This invited tutorial is part of the Mini-Course on Charged Particle Beams and High-Powered Pulsed Sources, held in conjunction with the 44th International Conference on Plasma Science in May of 2017.

A time-gated multi-channel x-ray crystal spectrometer on the Shenguang-III laser facility.

An eight-channel x-ray flat crystal spectrometer was developed for high energy density physics research at the Shenguang-III (SG-III) laser facility. The spectrometer uses trihydroxymethylaminomethane crystals (2d = 8.78 Å) to record Ti K-shell emission in the photon energy range of 4.65-5.05 keV. The spectrometer couples to an x-ray framing camera to achieve time-resolution. This has four microstrips, and each strip records two snapshots of the emission image. Based on the intersection positioning system with a dual-charge coupled device, the alignment system is easily operated and efficient. The instrument was tested and used for Au hohlraum plasma diagnosis experiments on SG-III. The He-α line and its Li-like satellites and the Ly-α line of a Ti tracer were detected, from which the spectral resolution of the instrument was analyzed. The spectral resolution E/ΔE at the Ti He-α line ranges from about 500 to 880 and mainly limited by the x-ray source size.

Simulations of the Interaction of High-Velocity Condensed-Matter Liners With Walls

This paper presents an overview of publications on numerical simulations of one of the major 2-D effects observed in magnetically driven implosion of cylindrical condensed-matter liners: their interaction with glide planes. We consider liners accelerated to 8-20 km/s by currents of 30-100 MA delivered by disk explosive magnetic flux compression generators with azimuthal magnetic fields of 1-6 MG (magnetic pressures of 0.04-1.4 Mbar): experimental liners HEL-1, ALT-1, 2, and liners HEL-2, ALT-3 proposed for high energy density physics research.

Hydrodynamic response of solid target heated by heavy ion beams from future facility HIAF

The hydrodynamic response of solid target heated by heavy ion beams at High Intensity Accelerator Facility (HIAF) project was simulated with 1-D computer code. The energy deposition was benchmarked by a 2-D program. The work serves to show the prospect of HIAF project for High Energy Density Physics (HEDP) study, and provide helpful information for the future experiments. Various target materials and schemes are used in the calculation. The results show that in the first phase of HIAF project, the available ion beam is already a powerful tool to generate HED matter with specially designed target, and the second phase of the project will extend the accessible state of matter a big step further. What’s more, the hydrodynamic behavior of the target under direct heating indicates that the beam parameter design for HEDP research should come to a compromise, which means, for example, with higher intensity or smaller focal spot, the beam pulse length must be compressed short enough to avoid the target dispersal before the end of the pulse.

High energy electron radiography scheme with high spatial and temporal resolution in three dimension based on a e-LINAC

AbstractWe present a scheme of electron beam radiography to dynamically diagnose the high energy density (HED) matter in three orthogonal directions simultaneously based on electron Linear Accelerator. The dynamic target information such as, its profile and density could be obtained through imaging the scattered electron beam passing through the target. Using an electron bunch train with flexible time structure, a very high temporal evolution could be achieved. In this proposed scheme, it is possible to obtain 1010 frames/second in one experimental event, and the temporal resolution can go up to 1 ps, spatial resolution to 1 µm. Successful demonstration of this concept will have a major impact for both future inertial confinement fusion science and HED physics research.

High Energy Density Physics Research Using Intense Heavy Ion Beam at FAIR: The HEDgeHOB Program

International project, Facility for Antiprotons and Ion Research (FAIR), has entered in its construction phase at Darmstadt. It is expected that the new powerful heavy ion synchrotron, SIS100 will deliver a strongly bunched intense beam of energetic uranium ions that will provide the scientists with an efficient and novel tool to research High Energy Density (HED) Physics in the laboratory. Over the past 15 years, substantial theoretical work has been done to design numerous experiments that can be done at this facility in this field. This work has resulted in an extensive scientific proposal named HEDgeHOB, that includes experiment proposals addressing various aspects of HED matter, for example, planetary physics, equation of state, hydrodynamic instabilities and others. In this paper we present a summary of this work.

Performance of bent-crystal x-ray microscopes for high energy density physics research.

We present calculations for the field of view (FOV), image fluence, image monochromaticity, spectral acceptance, and image aberrations for spherical crystal microscopes, which are used as self-emission imaging or backlighter systems at large-scale high energy density physics facilities. Our analytic results are benchmarked with ray-tracing calculations as well as with experimental measurements from the 6.151keV backlighter system at Sandia National Laboratories. The analytic expressions can be used for x-ray source positions anywhere between the Rowland circle and object plane. This enables quick optimization of the performance of proposed but untested, bent-crystal microscope systems to find the best compromise between FOV, image fluence, and spatial resolution for a particular application.

High energy density physics research at IMP, Lanzhou, China

Abstract Recent research activities relevant to high energy density physics (HEDP) driven by the heavy ion beam at the Institute of Modern Physics, Chinese Academy of Sciences are presented. Radiography of static objects with the fast extracted high energy carbon ion beam from the Cooling Storage Ring is discussed. Investigation of the low energy heavy ion beam and plasma interaction is reported. With HEDP research as one of the main goals, the project HIAF (High Intensity heavy-ion Accelerator Facility), proposed by the Institute of Modern Physics as the 12th five-year-plan of China, is introduced.