Experimental study of planetary ices at high pressure using dynamically-driven diamond-anvil cells

• Applicant: Hanns-Peter Liermann, Ph.D., since 9/2018
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 280637173

Planetary ice compounds (e.g. H2O, CH4, NH3) constitute large parts of solar giant ice planets and are likely abundant in the interiors of recently discovered exoplanets. The physical properties and phase diagrams of these compounds at the pressure and temperature conditions of planetary interiors are poorly understood. Previous experimental studies using x-ray diffraction in static diamond-anvil cells were limited to comparably low pressures as a result of experimental dfficulties related to the small scattering effciency of these low-Z compounds and weakening of the high-pressure cell resulting from reactions with the sample materials. In the proposed research, we will employ recently developed dynamically-driven diamond-anvil cells (dDAC and mDAC) to compress planetary ice compounds on short time scales (milliseconds to seconds). The rapid compression will prevent chemical reactions and will allow for reaching pressures that were previously not accessibly by experiments. During compression, we will probe the samples by x-ray diffraction to study their structure, phase stability and equations of state. Such fast diffraction experiments have only recently become possible with the development of new superfast detectors. Initial experiments will be performed at the Extreme Conditions Beamline at PETRA III, DESY. During the course of the project, we will start performing experiments at the High Energy Density instrument at the European XFEL that will become available to users in 2018. The results of our experiments will provide new insights to the stability felds and physical properties of planetary ice compounds in the interiors of solar giant ice planets and exoplanets. The results will also provide key anchor points to constrain computational predictions (carried out in SP3) and serve as input parameters for large-scale numerical models to simulate the dynamics of planets (collaboration with SP4/SP5).

• DFG Programme: Research Units
• Subproject of: FOR 2440: Matter Under Planetary Interior Conditions - High-Pressure, Planetary and Plasma Physics
• Cooperation Partner: Dr. Emma McBride
• Ehemaliger Antragsteller: Dr. Hauke Marquardt, until 9/2018