Laser-induced ablation spectroscopy on a linear plasma device: magnetic field effects on signal and application to fuel retention diagnosis in HL-3 wall samples

In fusion devices, boundary plasma particle and heat fluxes incident on plasma-facing materials (PFMs) lead to plasma–wall interactions (PWI). Real-time, in-situ quantitative diagnosis of wall material composition and fuel retention is critical for the safe and efficient operation of fusion reactors. Linear plasma devices offer a cost-effective platform for PWI studies, featuring extensive diagnostic access, fusion-relevant plasma conditions, and the ability to controllably vary plasma and surface parameters. In this work, a laser-induced ablation spectroscopy (LIAS) diagnostic system was developed on the ‘The Plasma-Surface Interaction Research Platform at Harbin Institute of Technology’ linear plasma device and applied to analyze graphite samples as a representative PFM. The influence of magnetic field conditions on LIAS signals was systematically investigated. Furthermore, the system has been successfully applied to diagnose first-wall samples from the HL-3 fusion device, enabling the acquisition of retention signals for hydrogen qualitatively. These results demonstrate the significant potential of LIAS in diagnosing first-wall composition and assessing fuel retention during fusion device operation.