RESUTS OF INTERACTION OF XUV LASER PULSES OF NANOSECOND DURATION WITH DIFFICULT-ABLATED-MATERIALS

0473160 - ÚFP 2017 RIV US eng A - Abstract
Koláček, Karel - Schmidt, Jiří - Frolov, Oleksandr - Štraus, Jaroslav - Matějíček, Jiří - Vilémová, Monika - Choukourov, A. - Kasuya, K.
RESUTS OF INTERACTION OF XUV LASER PULSES OF NANOSECOND DURATION WITH DIFFICULT-ABLATED-MATERIALS.
2016 IEEE International Conference on Plasma Science (ICOPS). Vol. 43. Alberta: IEEE, 2016. s. 16211618. ISBN 978-1-4673-9601-1.
[IEEE - 2016 IEEE International Conference on Plasma Science (ICOPS)/43./. 19.06.2016-23.06.2016, Banff, Alberta]
Institutional support: RVO:61389021
Keywords : Contracts * Silicon carbide * Plasmas * Physics * Photonics * Surface morphology * X-rays
Subject RIV: BL - Plasma and Gas Discharge Physics

Summary form only given. It is well known that each photon of extreme ultraviolet (XUV) radiation carries energy higher than 20 eV, what is more than any binding energy in a solid state. Provided that energy of these photons is deposited in some localized volume (for example in a surface layer - which is true for XUV and soft X-rays) a non-thermal melting can appear1. This contribution presents experimental results of interaction of focused pulsed XUV laser (λ ~ 47 nm/ ~1.5 ns/150-350 μJ) radiation with tungsten (W), molybdenum (Mo), and silicon carbide (SiC) - three materials considered as perspective armour for plasma facing components in future thermonuclear reactors. It was found that W and Mo behave similarly: during the first shot the laser footprint is covered by melted and re-solidified material, in which circular holes appear - residua of just opened pores, from which explosively escaped pressurized (up to atmospheric pressure) air. The W has tendency to peel off its surface layer: semidetached chip is then more intensely heated (due to locally reduced thermal conductivity) and rounded. The SiC has negligible porosity, and at melting point it de-composes to elements; therefore, the crater morphology can be related to local laser-energy-density above ablation threshold. When more shots are superimposed, in all three investigated materials the crater depth remarkably increases up to ~10 accumulated shots, between 10 and 20 accumulated shots this increase is slowed down, and above 20 it is very small.
Permanent Link: http://hdl.handle.net/11104/0270323