Laser-driven betatron x rays for high-throughput imaging of additively manufactured materials.

This article focuses on optimizing betatron x rays generated by laser wakefield acceleration (LWFA) for high-throughput, high-resolution three-dimensional tomography of micrometer-scale defects in additively manufactured (AM) AlSi10Mg alloys. Using the Advanced Laser Light Source (ALLS) facility, the study compares three gas targets—helium (He), nitrogen (N₂), and a mixed He–N₂ (99.5% He, 0.5% N₂) gas—to evaluate x-ray critical energy, brightness, spatial resolution, beam stability, and emission length at a 2.5 Hz repetition rate. The mixed He–N₂ gas produced the highest critical energy (19 ± 5 keV), greatest average brightness (~3.3 × 10¹⁰ photons/s/mm²/mrad²/0.1% BW), and superior beam stability, enabling acquisition of high-quality images with ~4 µm resolution in 6 seconds using 15 integrated shots. These results demonstrate that LWFA-driven betatron sources with optimized gas mixtures can provide laboratory-scale, high-throughput imaging capabilities comparable to synchrotrons but with greater accessibility for in situ characterization of AM materials.