Statistical Analysis of Stark-Broadened Ti Heβ Line Shapes for Diagnosing Solid-Density Plasmas*

This work investigates conditions within solid-density plasma created by high-intensity lasers. These lasers are focused on targets with layered titanium microstructures or "tracers" embedded at varying depths, which when laser-heated, emit x-rays captured by high-resolution spectrometers. With shot repetition rates on the order of 1 Hz, our x-ray spectrometers can now collect hundreds of high-resolution, spatially resolved spectra from these laser-heated targets. This allows us to observe shot-to-shot variations in measured x-ray spectra, in particular of Stark-broadened Ti Heβ, which implies variations in plasma density and electron/ion temperatures. From these spectra, we parametrize line shapes by features commonly associated with Stark-broadening, obtaining distributions of spectral parameters representing a large dataset. These multishot statistical analyses of plasma parameters convey the consistency of laser-solid coupling at high repetition rates and exemplify how high energy density plasmas are diagnosed with big datasets and advanced statistical analyses.