The Thermal Conductivity of Warm Dense Planetary Interiors

Understanding the thermal conductivity of materials in the cores of rocky planets can help in predicting planetary evolution and understanding the mechanisms necessary for the existence of organic life. However, significant variations in predictions and a scarcity of experimental measurements hamper our understanding of materials under warm dense matter (WDM) conditions. We plan to use our established isochoric heating platform
^1-3
to measure the thermal conductivity of iron-rich alloys in the WDM regime close to the thermodynamic conditions of large rocky exoplanet interiors. Using Fresnel Diffractive Radiography (FDR), we will observe the dynamics of an isochorically heated
$5\ \mu\mathrm{m}$
Fe95/Ni5 alloy wire encased in
$10\ \mu\mathrm{m}$
of borosilicate glass designed to mimic the core-mantle boundary of Earth-like planets
⁴
. After pressure equilibration, the shape of the density profile across the Fe/Ni-glass interface evolves primarily through thermal conductivity. This profile will be measured using FDR with a spatial resolution on the order of
$1\ \mu\mathrm{m}$
. This will enable the accurate extraction of the conductivity scale length, which in turn will be used to validate competing theoretical models.