Experimental Investigation of MeV X-ray Spectra and Dose Scaling in High-Energy-Density Plasmas in the multi-picosecond regime*

X-ray backlighting aids in extracting various physical properties from the system. The use of high-intensity lasers focused on high-Z foil targets produce relativistic electrons that generate MeV photons via Bremsstrahlung, Compton scattering, and synchrotron emission. The advantages over existing sources include smaller spot size, shorter pulse duration, tailorable spectra, and flexible configurations. This enables imaging with higher spatial and temporal resolution and multiple fields of view. However, certain limiting factors such as energy conversion efficiency, spectra optimization, and source stability must be addressed to achieve such a source. Recent experiments with 1 mm thick W targets at the OMEGA-EP laser explore MeV X-ray spectra and dose scaling with intensity (> 10¹⁹ W/cm²), energy (0.125 - 1.25 KJ), and pulse duration (0.5 -10 ps). We also report on shots using CH-coated targets with the goal of increased Bremsstrahlung production from increased laser-energy coupling and enhanced electron temperature. The resulting spectra were obtained using an iterative unfolding algorithm based on VPIC and MNCP transport codes that model the generation of hot-electrons and X-rays. For more details, we encourage you to refer to the contributed talk presented by Dr. Brian J. Albright.