Tokamak-like dust removal induced by laser irradiation

Abstract

Due to safety constraints, the in situ removal of metallic and carbon micro particles or dust is a critical issue in the framework of the ITER project.Laser processing is a promising technique to lift particles from the walls which is a first step toward an efficient dust collection system, and the present study examines the laser-induced removal of carbon aggregates, tungsten droplets and tungsten nanoparticles.The particle removal efficiencies have been measured for a wide range of laser irradiation conditions. The results show that carbon removal is very efficient and independent of the laser source characteristics, but the ejection of tungsten only occurs for short wavelength (UV) or ultra-short pulse duration (ps, fs).From SEM analysis of the different substrates and particles before and after irradiation, it can be concluded that carbon aggregates are ablated via thermal processes, whereas intact tungsten droplets are ejected without ablation.