Laser decontamination and cleaning of metal surfaces : modelling and experimental studies

• Main Author: Leontyev, Anton
• Language: ENG
• Published: Université Paris Sud - Paris XI 2011
• Subjects: [PHYS:COND:CM_GEN] Physics/Condensed Matter/Other; Decontamination; Cleaning; Laser ablation; Fiber laser; Metal; Stainless steel; Oxide layer; Tungsten; Carbon; Four-flux model; ITER; Tokamak; Deposited layer; Diagnostic mirror; Plasma-facing components
• Online Access: http://tel.archives-ouvertes.fr/tel-00661695; http://tel.archives-ouvertes.fr/docs/00/66/16/95/PDF/VA2_LEONTYEV_ANTON_08112011.pdf

Metal surface cleaning is highly required in different fields of modern industry. Nuclear industry seeks for new methods for oxidized surface decontamination, and thermonuclear installations require the cleaning of plasma facing components from tritium-containing deposited layer. The laser ablation is proposed as an effective and safe method for metal surface cleaning and decontamination. The important factor influencing the laser heating and ablation is the in-depth distribution of laser radiation. The model of light propagation in a scattering layer on a metal substrate is developed and applied to analyse the features of light distribution. To simulate the contaminated surfaces, the stainless steel AISI 304L was oxidized by laser and in a furnace. Radioactive contamination of the oxide layer was simulated by introducing europium and/or sodium. The decontamination factor of more than 300 was demonstrated with found optimal cleaning regime. The decreasing of the corrosion resistance was found after laser cleaning. The ablation thresholds of ITER-like surfaces were measured. The cleaning productivity of 0.07 m2/hour∙W was found. For mirror surfaces, the damage thresholds were determined to avoid damage during laser cleaning. The possibility to restore reflectivity after thin carbon layer deposition was demonstrated. The perspectives of further development of laser cleaning are discussed.