Equation of state measurements of isochorically-heated polymer foams with x-ray Thomson scattering and fluorescence*

Inertial Fusion Energy (IFE) research aims to revolutionize energy production, and advancing this field requires precise data on materials under extreme conditions. Here, we present recent experiments designed to enhance IFE research through absolute measurements of the equation of state of isochorically heated polymer foams. Utilizing the short-pulse MEC laser, we heat foam samples and probe them with coherent x-rays from the LCLS. We obtain forward and backward x-ray Thomson scattering (XRTS) spectra and simultaneously perform complementary equation of state measurements via x-ray fluorescence spectroscopy (XFS) from dopant Co atoms in the foam. Our goal is to achieve high-precision measurements of density, temperature, and ionization state populations in high energy density (HED) plasma. These measurements will provide benchmark data at HED conditions, crucial for improving atomic models in atomic kinetic and radiation codes. Specifically, we aim to critically constrain the thermodynamic behavior of polymer foams. Since foams are the proposed means for the delivery of nuclear fuel for many alternative approaches to IFE, our project will deliver precision data that are urgently needed for the development of this field.