Oxford Centre for High Energy Density Science (OxCHEDS)

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Speed of sound in methane under conditions of planetary interiors

Physical Review Research 6, L022029 (2024)

Authors:

Thomas G White, Hannah Poole, Emma E McBride, Matthew Oliver, Adrien Descamps, Luke B Fletcher, W Alex Angermeier, Cameron H Allen, Karen Appel, Florian P Condamine, Chandra B Curry, Francesco Dallari, Stefan Funk, Eric Galtier, Eliseo J Gamboa, Maxence Gauthier, Peter Graham, Sebastian Goede, Daniel Haden, Jongjin B Kim, Hae Ja Lee, Benjamin K Ofori-Okai, Scott Richardson, Alex Rigby, Christopher Schoenwaelder, Peihao Sun, Bastian L Witte, Thomas Tschentscher, Ulf Zastrau, Bob Nagler, JB Hastings, Giulio Monaco, Dirk O Gericke, Siegfried H Glenzer, Gianluca Gregori

Abstract:

We present direct observations of acoustic waves in warm dense matter. We analyze wave-number- and energy-resolved x-ray spectra taken from warm dense methane created by laser heating a cryogenic liquid jet. X-ray diffraction and inelastic free-electron scattering yield sample conditions of 0.3 ± 0.1 eV and 0.8 ± 0.1 g/cm-3, corresponding to a pressure of ~13 GPa. Inelastic x-ray scattering was used to observe the collective oscillations of the ions. With a highly improved energy resolution of ~50 meV, we could clearly distinguish the Brillouin peaks from the quasielastic Rayleigh feature. Data at different wave numbers were utilized to derive a sound speed of 5.9 ± 0.5 km/s, marking a high-temperature data point for methane and demonstrating consistency with Birch's law in this parameter regime.
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Diffuse scattering from dynamically compressed single-crystal zirconium following the pressure-induced $\alpha\to\omega$ phase transition

(2024)

Authors:

PG Heighway, S Singh, MG Gorman, D McGonegle, JH Eggert, RF Smith
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Bounds on heavy axions with an X-ray free electron laser

(2024)

Authors:

Jack WD Halliday, Giacomo Marocco, Konstantin A Beyer, Charles Heaton, Motoaki Nakatsutsumi, Thomas R Preston, Charles D Arrowsmith, Carsten Baehtz, Sebastian Goede, Oliver Humphries, Alejandro Laso Garcia, Richard Plackett, Pontus Svensson, Georgios Vacalis, Justin Wark, Daniel Wood, Ulf Zastrau, Robert Bingham, Ian Shipsey, Subir Sarkar, Gianluca Gregori
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Statistical theory of the broadband two-plasmon decay instability

(2024)

Authors:

Rusko T Ruskov, Robert Bingham, Luis O Silva, Max Harper, Ramy Aboushelbaya, Jason F Myatt, Peter A Norreys
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Shock compression experiments using the DiPOLE 100-X laser on the high energy density instrument at the European x-ray free electron laser: quantitative structural analysis of liquid Sn

Journal of Applied Physics AIP Publishing 135:16 (2024) 165902

Authors:

Mg Gorman, D McGonegle, Rf Smith, S Singh, T Jenkins, Rs McWilliams, B Albertazzi, Sj Ali, L Antonelli, Mr Armstrong, C Baehtz, Ob Ball, S Banerjee, Ab Belonoshko, A Benuzzi-Mounaix, Ca Bolme, V Bouffetier, R Briggs, K Buakor, T Butcher, S Di Dio Cafiso, V Cerantola, J Chantel, A Di Cicco, S Clarke, Al Coleman, J Collier, Gw Collins, Aj Comley, F Coppari, Te Cowan, G Cristoforetti, H Cynn, A Descamps, F Dorchies, Mj Duff, A Dwivedi, C Edwards, Jh Eggert, D Errandonea, G Fiquet, E Galtier, A Laso Garcia, H Ginestet, L Gizzi, A Gleason, S Goede, Jm Gonzalez, M Harmand, Nj Hartley

Abstract:

X-ray free electron laser (XFEL) sources coupled to high-power laser systems offer an avenue to study the structural dynamics of materials at extreme pressures and temperatures. The recent commissioning of the DiPOLE 100-X laser on the high energy density (HED) instrument at the European XFEL represents the state-of-the-art in combining x-ray diffraction with laser compression, allowing for compressed materials to be probed in unprecedented detail. Here, we report quantitative structural measurements of molten Sn compressed to 85(5) GPa and ∼ 3500 K. The capabilities of the HED instrument enable liquid density measurements with an uncertainty of ∼ 1 % at conditions which are extremely challenging to reach via static compression methods. We discuss best practices for conducting liquid diffraction dynamic compression experiments and the necessary intensity corrections which allow for accurate quantitative analysis. We also provide a polyimide ablation pressure vs input laser energy for the DiPOLE 100-X drive laser which will serve future users of the HED instrument.
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