20.500.12556/RUL-114833 Propulsion effects after laser ablation in water, confined by different geometries A Nd:YAG laser with 7-ns pulses and pulse energies up to 10 mJ is used to induce an optical breakdown in the front surface of an aluminum rod, covered by a water layer. The rod is part of a ballistic pendulum. In this way, we study the propulsion effects by means of coupling coefficient and energy-conversion efficiency with respect to different confining geometries, volumes of water applied to the front surface of the rod, and the distance of this surface from the laser-beam focus. Holes with different dimensions are drilled on the target surface and filled with different volumes of water to examine the influence of the confinement by the liquid (a free boundary) and a solid-surface geometry on laser ablation effects. The rod movement and the water ejection after laser ablation are acquired by a high-speed camera with 10k frames per second. The results show that the confinement by cavity substantially increases the propulsion effects by shaping the ejected flow of the liquid; while the cavitation bubble, induced inside the water layer, plays a significant role in propulsion efficiency. From the presented results, it follows that the laser-propelled rod carries below 0.5% of the total mechanical energy after propulsion, while the rest of this energy represents the kinetic energy of the ablated water. As expected, moving the target surface away from the focal position decreases the ablative-propulsion efficiency. When the focus is moved inside the solid target, the decrease occurs due to lower conversion of the pulse energy into the energy of the cavitation bubble. If the focus is moved from the surface outward, the bubble moves towards the liquid-gas interface and it is not able to efficiently eject all the liquid from the target. laser ablation laser propulsion cavitation bubbles nanosecond lasers coupling coefficient energyconversion efficiency laserska propulzija laserska ablacija kavitacijski mehurčki true false true Angleški jezik Slovenski jezik Članek v reviji 2020-03-17 15:12:31 2020-03-17 15:12:35 2022-08-26 03:52:46 0000-00-00 00:00:00 2020 0 0 Str. 1-12 iss. 2 Vol. 126 Feb. 2020 0000-00-00 PostprintKoncna Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 2021-03-18 544.53:532.528(045) 0947-8396 10.1007/s00339-020-3309-y 17026587 14196007 RAZ_Senegacnik_Matej_2020.pdf RAZ_Senegacnik_Matej_2020.pdf 1 BECCE002BCA6FE28D3605B09014D16E0 7401b240631b6cd94585db7f34306294a411859081285bd43a68a1498f314dbc 4c52a230-a1b8-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=127284 https://link.springer.com/article/10.1007%2Fs00339-020-3309-y 1 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=127135 Fakulteta za strojništvo 0 0 0