Modeling Laser-Plasma Interaction under Extreme Conditions Towards In-Situ Pump-Probe Simulations

Laser-driven solid density plasmas can be used to generate highly energetic electrons and ions. Diagnosing properties within those plasmas at nm length scales and down to fs timescales is crucial in understanding the involved processes. This has recently become feasible through the advent of X-Ray Free Electron Lasers (XFELs). For instance, XFELs allow imaging the electron density distribution within plasmas via Small Angle X-Ray Scattering (SAXS). We present a scalable GPU-based software framework for simulating photon scattering processes of X-ray beams in matter using Monte-Carlo methods. These simulations enable us to produce synthetic SAXS signals from the interaction of a modeled X-ray pulse with an arbitrarily complex, 3D electron density distribution obtained e.g. from detailed particle-in-cell simulations. Additionally, we present radiation transport methods in our 3D3V fully-relativistic PIC code PIConGPU. These methods enhance modeling of self-imaging of solid-density plasmas and lay the foundation for in-situ simulations of pump-probe experiments. Our new framework allows for single and multiple scattering and is extendable to include complex physics processes like ionization, atomic excitation, and de-excitation along the photon path to further enhance its predictive capability.