Microscopy X-ray Imaging enriched with Small Angle X-ray Scattering for few nanometer resolution reveals shock waves and compression in intense short pulse laser irradiation of solids

TL;DR

This paper introduces a combined X-ray imaging and small-angle X-ray scattering technique to observe shock waves and compression in solids at nanometer resolution during intense laser irradiation, bridging macroscopic and nanoscopic diagnostics.

Contribution

The study presents a novel integrated XRM-SAXS method that enables direct observation of shock formation and decay at solid density with nanometer precision, advancing diagnostics of high-energy-density states.

Findings

Nanometer-sharp shock fronts observed after 18 ps

Shock front velocity approximately 25 km/s

Method applicable to dense plasma diagnostics

Abstract

Understanding how laser pulses compress solids into high-energy-density states requires diagnostics that simultaneously resolve macroscopic geometry and nanometer-scale structure. Here we present a combined X-ray imaging (XRM) and small-angle X-ray scattering (SAXS) approach that bridges this diagnostic gap. Using the Matter in Extreme Conditions end station at LCLS, we irradiated 25-micrometer copper wires with 45-fs, 0.9-J, 800-nm pulses at 3.5e19 W/cm2 while probing with 8.2-keV XFEL pulses. XRM visualizes the evolution of ablation, compression, and inward-propagating fronts with about 200-nm resolution, while SAXS quantifies their nanometer-scale sharpness through the time-resolved evolution of scattering streaks. The joint analysis reveals that an initially smooth compression steepens into a nanometer-sharp shock front after roughly 18 ps, consistent with an analytical steepening model and hydrodynamic simulations. The front reaches a velocity of about 25 km/s and a lateral width of several tens of micrometers, demonstrating for the first time the direct observation of shock formation and decay at solid density with few-nanometer precision. This integrated XRM-SAXS method establishes a quantitative, multiscale diagnostic of laser-driven shocks in dense plasmas relevant to inertial confinement fusion, warm dense matter, and planetary physics.