Influence of UO2 crystal orientation on laser ablation performance

Three UO2 single crystals of different orientation as well as polycrystalline UO2 were produced and characterized. Subsequently, a ns-laser ablation (LA) system was employed to study laser-matter interaction in detail. Firing the laser continuously at 1 Hz with various single shot fluence (2, 4, 6, 8, 12 J cm-2) for diverse periods created LA craters impacted by cumulative fluence between 50 and 650 J cm-2. Repeated LA experiments on the <100> plane of a UO2 single crystal at the beginning and end of the entire study revealed highly reproducible (<3%) LA rates, only limited by the fluctuation of the laser energy output of the ns-LA system. After thorough cleaning of the ablated samples, surface roughness and average depth of LA craters were determined using confocal laser scanning profilometry. Both LA rate and average depth of craters decreased exponentially with increasing single shot fluence independently of the crystal orientation. Surface roughness increased linearly with increasing cumulative fluence having largest intensification for lowest single shot fluence. Scanning electron microscope (SEM) images not only revealed the conical silhouette of LA craters, but also identified a convex meniscus at its bottom. This particular shape of the crater bottom with a deeper ring surrounding the central region is a result of melted and re-solidified UO2 generated during the LA process and the main limiting factor for the achievable depth resolution.

KRACHLER Michael;  MARTINEZ FERRI Ana;  BULGHERONI Antonio; 

2023-03-27

PERGAMON-ELSEVIER SCIENCE LTD

JRC131851

0968-4328 (online),   

https://www.sciencedirect.com/science/article/pii/S0968432823000434?via%3Dihub,    https://publications.jrc.ec.europa.eu/repository/handle/JRC131851,   

10.1016/j.micron.2023.103445 (online),