Laser ablation is one of the physical processes that are being considered for paint stripping in possibly contaminated areas, especially for decommissioning and dismantling of nuclear facilities. In this regard, the knowledge of "ablation products", consisting of particles and gases, is an important issue.
The numeric and weight concentration of partcles, their size distribution, their morphology and their density have been determined for laser ablation of two wall paints. The main gas species have also been identified.
The aerosol is composed of nanopartides, of which the number is predominant, and submicronic partides.
Their morphologies and their chemical composition are very distinct: carbon aggregates have been identified, as weil as spherical particles of titanium dioxide. These results show that nanoscale aggregates come from the vaporization of the paint polymer, whereas submicronic partides are due to mechanical ejection of titanium dioxide particles.
The expansion of the plume resulting from laser paint interaction has been monitored by means of three optical techniques: light extinction, scattering and emission. The frames show the propagation of a shockwave followed by the ejection of matter with a specific "mushroom" shape. Measurements based on these results show that the peripheral part of the plume contains the primary particles ofcarbon aggregates; it is the warmest area, which reaches a few thousands Kelvin degrees. Its central part is composed of titanium dioxide spherical particles.