Influence of laser pulse shape on dry laser cleaning

Characterization of carbon and tungsten micro-particles mobilized by laser irradiation in order to develop an ITER dust removal technique

“…However, the slopes of these curves are less sharp than for dielectric particles [14] which could reveal a less deterministic process. The PRE curve obtained for silica substrate is very similar which evidences that the ejection mechanism is not due to substrate motion or ablation [15]. The carbon strongly absorbs the 308 nm wavelength, and it is reasonable to think that the removal process is due to the ablation of the particle [16].…”

Experimental investigation of ablation mechanisms involved in dry laser cleaning

“…In the experiments, the samples were placed in a detachable customized chamber where a residual pressure of 5 Â 10 À2 Pa can be reached. The sample holder was fixed on a long range motorized translation stage that permits a precise repositioning of the irradiated zone in front of an optical microscope (Olympus, BXFM) [14]. Thus, the experimental apparatus allows to perform in situ like measurements of the removal efficiency (PRE) by evaluating the fraction of removed particles, and optical observations (BF, DF, DIC) of the affected materials.…”

“…One was a XeCl (l las = 308 nm) laser (CILAS, UV635) equipped with an electro-optic gating system which is capable of providing pulses of duration varying from 10 to 50 ns [14]. The second was an ArF (l las = 193 nm) laser source (Lambda Physik, LPX220i) delivering pulses of 15-ns duration.…”

Mécanismes d'éjection de particules par laser impulsionnel

“…L'enlèvement de particules de polystyrène de 190nm de rayon, déposées sur une surface de silicium, est réalisé en un seul tir laser et pour des fluences de quelques centaines de mJ/cm 2 . Au cours de ces dernières années, ce procédé a fait l'objet de nombreuses études expérimentales [6,7] et plusieurs descriptions théoriques ont été proposées [8,9]. Ces dernières suggèrent différents mécanismes d'éjection tels que l'expansion rapide du substrat due à son échauffement par le faisceau [10], l'ablation locale du substrat sous la particule induite par une exaltation du champ par celle-ci [11], ou encore l'évaporation explosive de l'humidité résiduelle se trouvant à l'interface particule-substrat [12].…”