Pressure-produced ionization of nonideal plasma in a megabar range of dynamic pressures

Fortov, V. E.; Ternovoǐ, V. Ya.; Zhernokletov, M. V.; Mochalov, M. A.; Михайлов, А. Л.; Filimonov, A. S.; Pyalling, A. A.; Минцев, В. Б.; Gryaznov, V. K.; Iosilevskii, I. L.

doi:10.1134/1.1608993

Cited by 160 publications

(128 citation statements)

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“…Xe is observed to metallize near room temperature under pressures similar to those at Earth's coremantle boundary (18,19). Ar and He are observed to conduct only at combined high pressure and temperature (12,13,17). Ne is predicted to have the highest metallization pressure of all known materials-10 3 times that of Xe and 10 times that of He (14,18,20,21)-and has never been documented outside of its insulating state.…”

mentioning

confidence: 99%

“…Ne is predicted to have the highest metallization pressure of all known materials-10 3 times that of Xe and 10 times that of He (14,18,20,21)-and has never been documented outside of its insulating state. Experimental probes of extreme densities and temperatures in noble gases have previously relied on dynamic compression by shock waves (12,13,17,(22)(23)(24). However, in such adiabatic experiments, light and compressible noble gases heat up significantly and can ultimately reach density maxima (12,13,17,21,24,25), so that conditions created often lie far from those deep within planets (7,8) and stars (9).…”

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confidence: 99%

“…Dense noble gases are expected to show systematic similarities in their properties at extreme conditions (13)(14)(15)(16)(17); however, a general understanding of their insulator-conductor transformation remains to be established. Xe is observed to metallize near room temperature under pressures similar to those at Earth's coremantle boundary (18,19).…”

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confidence: 99%

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Opacity and conductivity measurements in noble gases at conditions of planetary and stellar interiors

McWilliams

Dalton

Konôpková

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The noble gases are elements of broad importance across science and technology and are primary constituents of planetary and stellar atmospheres, where they segregate into droplets or layers that affect the thermal, chemical, and structural evolution of their host body. We have measured the optical properties of noble gases at relevant high pressures and temperatures in the laserheated diamond anvil cell, observing insulator-to-conductor transformations in dense helium, neon, argon, and xenon at 4,000-15,000 K and pressures of 15-52 GPa. The thermal activation and frequency dependence of conduction reveal an optical character dominated by electrons of low mobility, as in an amorphous semiconductor or poor metal, rather than free electrons as is often assumed for such wide band gap insulators at high temperatures. White dwarf stars having helium outer atmospheres cool slower and may have different color than if atmospheric opacity were controlled by free electrons. Helium rain in Jupiter and Saturn becomes conducting at conditions well correlated with its increased solubility in metallic hydrogen, whereas a deep layer of insulating neon may inhibit core erosion in Saturn.rare gases | extreme conditions | warm dense matter | giant planet | white dwarf

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confidence: 99%

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confidence: 99%

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Opacity and conductivity measurements in noble gases at conditions of planetary and stellar interiors

McWilliams

Dalton

Konôpková

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…Therefore, the multi-shock EOSs were usually obtained with the help of hydrodynamic simulations. [21][22][23] In this paper, we present results of the measurements of the Hugoniots of dense gaseous deuterium-helium (D 2 He) mixtures. A comprehensive diagnostic technique that combines multiple diagnostics enables us to implement (1) an accurate measurement of the single shock state of D 2 He mixtures, and (2) the direct measurements of multi-shock states.…”

Section: -2 LI Et Almentioning

confidence: 99%

“…There has been some creative multi-shock experiments were performed for hydrogen, 21 helium, 21,22 and hydrogen-helium mixtures. 23 In general, the multi-shock (more than twice) states are much more difficult to measure directly.…”

Section: -2 LI Et Almentioning

confidence: 99%

Measurements of the principal Hugoniots of dense gaseous deuterium−helium mixtures: Combined multi-channel optical pyrometry, velocity interferometry, and streak optical pyrometry measurements

Chen²,

Gu³

et al. 2016

AIP Advances

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The accurate hydrodynamic description of an event or system that addresses the equations of state, phase transitions, dissociations, ionizations, and compressions, determines how materials respond to a wide range of physical environments. To understand dense matter behavior in extreme conditions requires the continual development of diagnostic methods for accurate measurements of the physical parameters. Here, we present a comprehensive diagnostic technique that comprises optical pyrometry, velocity interferometry, and time-resolved spectroscopy. This technique was applied to shock compression experiments of dense gaseous deuterium–helium mixtures driven via a two-stage light gas gun. The advantage of this approach lies in providing measurements of multiple physical parameters in a single experiment, such as light radiation histories, particle velocity profiles, and time-resolved spectra, which enables simultaneous measurements of shock velocity, particle velocity, pressure, density, and temperature and expands understanding of dense high pressure shock situations. The combination of multiple diagnostics also allows different experimental observables to be measured and cross-checked. Additionally, it implements an accurate measurement of the principal Hugoniots of deuterium−helium mixtures, which provides a benchmark for the impedance matching measurement technique.

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Exciton Nature of Plasma Phase Transition in Warm Dense Fluid Hydrogen: ROKS Simulation**

Fedorov

Stegaĭlov

2022

ChemPhysChem

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The transition of warm dense fluid hydrogen from an insulator to a conducting state at pressures of about 20–400 GPa and temperatures of 500–5000 K has been the subject of active scientific research over the past few decades. However, various experimental and theoretical methods do not provide consistent results. In this work, we have applied the restricted open‐shell Kohn–Sham (ROKS) method for first principles molecular dynamics of dense hydrogen after thermal excitation to the first singlet excited state. The Wannier localization method has allowed us to analyze the exciton dynamics in this system. The model shows that a key mechanism of the transition is associated with the dissociation of electron‐hole pairs, which allows explaining several stages of the transition of fluid H2 from molecular state to plasma. This mechanism is able to give a quantitative description of several experimental results as well as to resolve the discrepancies between experimental studies.

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Pressure-produced ionization of nonideal plasma in a megabar range of dynamic pressures

Cited by 160 publications

References 40 publications

Opacity and conductivity measurements in noble gases at conditions of planetary and stellar interiors

Opacity and conductivity measurements in noble gases at conditions of planetary and stellar interiors

Measurements of the principal Hugoniots of dense gaseous deuterium−helium mixtures: Combined multi-channel optical pyrometry, velocity interferometry, and streak optical pyrometry measurements

Exciton Nature of Plasma Phase Transition in Warm Dense Fluid Hydrogen: ROKS Simulation**

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