113 / 2025-03-14 23:11:19

Experimental Validation of Return Current Scaling Laws in Ultrafast Laser-Driven Thin Wire Cylindrical Compression: Dependence on Material, Diameter, and Energy

Return Current Dynamics,Ultrafast Joule Heating,XFEL Imaging,Thin Wire Cylindrical Compression

This study experimentally investigates the cylindrical implosion dynamics of thin metallic wires driven by ultrafast (30 fs) Joule heating from high-intensity laser (10²¹ W/cm²) irradiation, focusing on scaling laws with material properties and wire diameters. Utilizing the HED-HIBEF instrument at EuXFEL, we combined time-resolved X-ray FEL imaging, hydrodynamic simulations, and particle-in-cell (PIC) modeling to analyze cylindrical shock propagation, surface current density, and electron temperature evolution. Results demonstrate that wire compression is governed by ablation pressure, with implosion times following  under strong shock conditions. A key finding validates the return current scaling law , showing slight overestimations (19–47%) for smaller radii due to enhanced hot-electron recirculation. Material dependence (Cu vs. Al) revealed comparable current densities, consistent with Spitzer resistivity models, while laser energy scans confirmed  scaling. The study bridges theoretical predictions with experimental data, offering insights for optimizing high-energy-density platforms with short-pulse J-class lasers. This work advances the understanding of ultrafast laser-driven implosions, which are critical for inertial confinement fusion and laboratory astrophysics applications.