Ultrafast x-ray probing is critical for studying transport properties in warm dense matter and dense plasmas, particularly in astrophysics and inertial confinement fusion. While laser-driven K-alpha sources serve as excellent x-ray probes, their relatively low conversion efficiency compared to He-alpha and Ly-alpha sources limits broader use. Recent studies propose nano- and micro-structured targets to enhance x-ray flux [1-3], though experimental validation remains sparse. We present experiments using low-density copper nanowire foams irradiated by high-power lasers (~ 10²⁰ W/cm²) to develop high-brightness x-ray sources. X-ray spectroscopy revealed improved laser absorption, hot electron generation, and target heating compared to flat foils, with simulations linking enhanced x-ray yields to prominent vacuum heating and localized fields in nanowire structures. These results highlight the potential of structured targets for optimizing x-ray sources while emphasizing unresolved mechanisms, such as volumetric heating, hydrodynamic effects, and electron spectra modifications. This work advances laser-plasma interaction strategies for high-energy-density science.

Ultrafast probing,Laser-driven X-ray sources,Laser-plasma interactions,Structured targets,X-ray spectroscopy,Inertial confinement fusion