Investigation of Thermal Transport in Warm Dense Matter

Abstract

Understanding thermal conductivity in the Warm Dense Matter (WDM) regime is essential for modeling the hydrodynamic evolution of complex systems, such as planetary cores and inertial confinement fusion (ICF). In this work, we calculated the electronic thermal conductivity of iron (Fe) by implementing a modified Coulomb logarithm within the Lee-More model framework. To evaluate the validity of various theoretical transport models, I investigated heat transfer dynamics in Fe/Cu double-layer targets, where one side of the Fe layer was irradiated by an ultrafast laser pulse and was used to indirectly heat the Cu layer, creating a temperature gradient that enables the calculation of Fe’s thermal conductivity. The dynamic thermal response was analyzed using the Two-Temperature Model (TTM), incorporating different temperature-dependent conductivity models for comparison. Experimental measurements were performed using time-resolved X-ray absorption spectroscopy (TR-XAS) at the soft X-ray scattering and spectroscopy (SSS) station at PAL-XFEL. By probing near the Cu L3 edge following laser excitation, the changes in the electron temperature of the Cu layer were observed. These measurements provide the necessary benchmarks to compare experimental electron average temperatures against TTM simulations, facilitating a rigorous investigation of competing theoretical models for thermal transport in WDM.