Equilibration dynamics and conductivity of warm dense hydrogen

Zastrau, U.; Sperling, P.; Becker, Andreas; Bornath, Th.; Bredow, R.; Döppner, T.; Dziarzhytski, Siarhei; Fennel, Thomas; Fletcher, L. B.; Förster, E.; Fortmann, C.; Glenzer, S. H.; Göde, S.; Gregori, G.; Harmand, M.; Hilbert,; Holst, Bastian; Laarmann, Tim; Hj, Lee; Ma, T.; Mithen, J.; Mitzner, R.; Murphy, C. D.; Nakatsutsumi, M.; Neumayer, P.; Przystawik, Andreas; Roling, Sebastian; Schulz, Michael; Siemer, B.; Skruszewicz, Slawomir; Tiggesbäumker, J.; Toleikis, S.; Tschentscher, Th.; White, T. G.; Wöstmann, Michael; Zacharias, H.; Redmer, R.

doi:10.1103/physreve.90.013104

Cited by 26 publications

(23 citation statements)

References 51 publications

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“…Ionization was simulated using a multigroup ionization model based on the quotidian equation of state (QEOS) for strongly coupled plasmas [73]. PROPACEOS 4.2 calculates the ionization via a Saha model, while PROPACEOS 5.1 uses a Thomas-Fermi model as implemented in the QEOS [74]. The simulation parameters are taken from the experiment: The 250 µm solid thick lithium foil is driven with the 1 ns long Vulcan laser beam (frequency doubled to 512 nm) and flat-top focal spot size with average irradiance of ≈ 3 × 10 13 W/cm 2 .…”

Section: B Scattering Spectrummentioning

confidence: 99%

Ab initiosimulations of the dynamic ion structure factor of warm dense lithium

et al. 2017

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We present molecular dynamics simulations based on finite-temperature density functional theory that determine self-consistently the dynamic ion structure factor and the electronic form factor in lithium. Our comprehensive data set allows for the calculation of the dispersion relation for collective excitations, the calculation of the sound velocity, and the determination of the ion feature from the total electronic form factor and the ion structure factor. The results are compared with available experimental x-ray and neutron scattering data. Good agreement is found for both the liquid metal and warm dense matter domain. Finally, we study the impact of possible target inhomogeneities on x-ray scattering spectra.

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Section: B Scattering Spectrummentioning

confidence: 99%

Ab initiosimulations of the dynamic ion structure factor of warm dense lithium

et al. 2017

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“…In such photonic experiments energy is delivered directly to electrons, which then transfer energy to the ions (lattice) as the system relaxes toward a state of local thermal equilibrium (LTE), a prerequisite for reaching local thermodynamic equilibrium conditions. The timescale of equilibration between the ions and electrons is typically on the order order of ps 6,[8][9][10] . As electron-ion equilibration occurs roughly coincident with the expansion, melting, and vaporization processes naturally coupled to lattice heating, a loss of high-density conditions and sample confinement can occur before LTE is achieved, leading to study of nonequilibrium matter exclusively.…”

Section: Introductionmentioning

confidence: 99%

Thermomechanical response of thickly tamped targets and diamond anvil cells under pulsed hard x-ray irradiation

Meza-Galvez

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Marshall

et al. 2020

Journal of Applied Physics

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In the laboratory study of extreme conditions of temperature and density, the exposure of matter to high intensity radiation sources has been of central importance. Here we interrogate the performance of multi-layered targets in experiments involving high intensity, hard x-ray irradiation, motivated by the advent of extremely high brightness hard x-ray sources, such as free electron lasers and 4 th-generation synchrotron facilities. Intense hard x-ray beams can deliver significant energy in targets having thick x-ray transparent layers (tampers) around samples of interest, for the study of novel states of matter and materials' dynamics. Heated-state lifetimes in such targets can approach the microsecond level, regardless of radiation pulse duration, enabling the exploration of conditions of local thermal and thermodynamic equilibrium at extreme temperature in solid density matter. The thermal and mechanical response of such thick layered targets following x-ray heating, including hydrodynamic relaxation and heat flow on picosecond to millisecond timescales, is modeled using radiation hydrocode simulation, finite element analysis, and thermodynamic calculations. Assessing the potential for target survival over one or more exposures, and resistance to damage arising from heating and resulting mechanical stresses, this study doubles as an investigation into the performance of diamond-anvil high pressure cells under high x-ray fluences. Long used in conjunction with synchrotron x-ray radiation and high power optical lasers, the strong confinement afforded by such cells suggests novel applications at emerging high intensity x-ray facilities and new routes to studying thermodynamic equilibrium states of warm, very dense matter.

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“…Matter triggered with x-ray radiation to a highly excited state is an object of intense experimental studies with high power laser sources, in particular with free electron lasers (FELs) [1][2][3][4][5][6]. They enable one to follow the nonequilibrium path of plasma formation, also through the transient state of warm-dense matter [7][8][9]. The ultrashort duration of FEL pulses makes it possible to probe the unexplored regime of electronic thermalization, which takes up to several tens of femtoseconds once the exposure starts.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Boltzmann approach adapted for modeling highly ionized matter created by x-ray irradiation of a solid

et al. 2016

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We report on the kinetic Boltzmann approach adapted for simulations of highly ionized matter created from a solid by its x-ray irradiation. X rays can excite inner-shell electrons, which leads to the creation of deeply lying core holes. Their relaxation, especially in heavier elements, can take complicated paths, leading to a large number of active configurations. Their number can be so large that solving the set of respective evolution equations becomes computationally inefficient and another modeling approach should be used instead. To circumvent this complexity, the commonly used continuum models employ a superconfiguration scheme. Here, we propose an alternative approach which still uses "true" atomic configurations but limits their number by restricting the sample relaxation to the predominant relaxation paths. We test its reliability, performing respective calculations for a bulk material consisting of light atoms and comparing the results with a full calculation including all relaxation paths. Prospective application for heavy elements is discussed.

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Equilibration dynamics and conductivity of warm dense hydrogen

Cited by 26 publications

References 51 publications

Ab initiosimulations of the dynamic ion structure factor of warm dense lithium

Ab initiosimulations of the dynamic ion structure factor of warm dense lithium

Thermomechanical response of thickly tamped targets and diamond anvil cells under pulsed hard x-ray irradiation

Kinetic Boltzmann approach adapted for modeling highly ionized matter created by x-ray irradiation of a solid

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