X-ray Absorption Fine Structure (XAFS) experiments may provide a pathway towards thermal conductivity measurements at HED conditions

Directly measuring temperature as well as thermal conductivity at HED conditions is challenging. At the Laboratory for Laser Energetics at (LLE) and the National Ignition Facility (NIF), the X-ray Absorption Fine Structure (XAFS) spectroscopy platform measures simultaneous temperature, density and pressure. Previous XAFS at NIF observed that when ramp compressing Cu adjacent to HDC, the Cu was hotter than when adjacent to LiF or Al and the predominant theory is that conduction may be occurring between the HDC and Cu. An experiment was designed on OMEGA EP to directly observe conduction between iron and diamond. XAFS data of the Fe K-edge were collected along a ~12 ns steady pressure hold at around 140 GPa. Various heating mechanisms during the experiment are investigated including thermal conduction.