Oxford Centre for High Energy Density Science (OxCHEDS)

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Dielectronic satellite emission from a solid-density Mg plasma: relationship to models of ionisation potential depression

(2023)

Authors:

G Pérez-Callejo, T Gawne, TR Preston, P Hollebon, OS Humphries, H-K Chung, GL Dakovski, J Krzywinski, MP Minitti, T Burian, J Chalupský, V Hájková, L Juha, V Vozda, U Zastrau, SM Vinko, SJ Rose, JS Wark
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Multi-Messenger Measurements of the Static Structure of Shock-Compressed Liquid Silicon at 100 GPa

arXiv:2309.14905

Authors:

H. Poole, M. K. Ginnane, M. Millot, G. W. Collins, S. X. Hu, D. Polsin, R. Saha, J. Topp-Mugglestone, T. G. White, D. A. Chapman, J. R. Rygg, S. P. Regan, G. Gregori

Abstract:

Ionic structure of high pressure, high temperature fluids is a challenging theoretical problem with applications to planetary interiors and fusion capsules. Here we report a multi-messenger platform using velocimetry and in situ angularly and spectrally resolved X-ray scattering to measure the thermodynamic conditions and ion structure factor of materials at extreme pressures. We document the pressure, density, and temperature of shocked silicon near 100 GPa with uncertainties of 6%, 2%, and 20%, respectively. The measurements are sufficient to distinguish between and rule out some ion screening models.
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Investigating mechanisms of state localization in highly ionized dense plasmas

Physical Review E American Physical Society 108:3 (2023) 35210

Authors:

Thomas Gawne, Thomas Campbell, Alessandro Forte, Patrick Hollebon, Gabriel Perez-Callejo, Oliver S Humphries, Oliver Karnbach, Muhammad F Kasim, Thomas R Preston, Hae Ja Lee, Alan Miscampbell, Quincy Y van den Berg, Bob Nagler, Shenyuan Ren, Ryan B Royle, Justin Wark, Sam M Vinko

Abstract:

We present experimental observations of Kβ emission from highly charged Mg ions at solid density, driven by intense x rays from a free electron laser. The presence of Kβ emission indicates the n = 3 atomic shell is relocalized for high charge states, providing an upper constraint on the depression of the ionization potential. We explore the process of state relocalization in dense plasmas from first principles using finite-temperature density functional theory alongside a wave-function localization metric, and find excellent agreement with experimental results.

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Quantifying ionization in hot dense plasmas

(2023)

Authors:

Thomas Gawne, Sam M Vinko, Justin S Wark
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Correlation energy of the spin-polarized electron liquid studied using quantum Monte Carlo simulations

Physical Review B: Condensed Matter and Materials Physics American Physical Society 108 (2023) 115134

Authors:

Sam Azadi, Nd Drummond, Sam Vinko

Abstract:

Variational and diffusion quantum Monte Carlo (VMC and DMC) methods with Slater-Jastrowbackflow trial wave functions are used to study the spin-polarized three-dimensional uniform electron fluid. We report ground state VMC and DMC energies in the density range 0.5 ≤ rs ≤ 20. Finite-size errors are corrected using canonical-ensemble twist-averaged boundary conditions and extrapolation of the twist-averaged energy per particle calculated at three system sizes (N =113, 259, and 387) to the thermodynamic limit of infinite system size. The DMC energies in the thermodynamic limit are used to parameterize a local spin density approximation correlation function for inhomogeneous electron systems.
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