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Tomáš Blejchař, Václav Nevrlý, Michal Vašinek, Michal Dostál, Milada Kozubková, Jakub Dlabka, Martin Stachoň, Libor Juha, Petr Bitala, Zdeněk Zelinger, Peter Pira and Jan Wild

Abstract

The availability of reliable modeling tools and input data required for the prediction of surface removal rate from the lithium fluoride targets irradiated by the intense photon beams is essential for many practical aspects. This study is motivated by the practical implementation of soft X-ray (SXR) or extreme ultraviolet (XUV) lasers for the pulsed ablation and thin film deposition. Specifically, it is focused on quantitative description of XUV laser-induced desorption/ablation from lithium fluoride, which is a reference large band-gap dielectric material with ionic crystalline structure. Computational framework was proposed and employed here for the reconstruction of plume expansion dynamics induced by the irradiation of lithium fluoride targets. The morphology of experimentally observed desorption/ablation craters were reproduced using idealized representation (two-zone approximation) of the laser fluence profile. The calculation of desorption/ablation rate was performed using one-dimensional thermomechanic model (XUV-ABLATOR code) taking into account laser heating and surface evaporation of the lithium fluoride target occurring on a nanosecond timescale. This step was followed by the application of two-dimensional hydrodynamic solver for description of laser-produced plasma plume expansion dynamics. The calculated plume lengths determined by numerical simulations were compared with a simple adiabatic expansion (blast-wave) model.

Open access

A. Durán

). 2 The mathematical model 2.1 On the derivation The two-layer interface problem for internal wave propagation, of interest for the present paper, is idealized in Figure 1 . This consists of two inviscid, homogeneous, incompressible fluids of depths d i , i = 1, 2, with d 2 > d 1 and densities ρ i , i = 1, 2 with ρ 2 > ρ 1 . The upper and lower layers are respectively bounded above and below by a rigid horizontal plane, while the deviation of the interface from a level of rest, denoted by ζ , is supposed to be a graph over the bottom

Open access

Marina Esteban, Enrique Ponce and Francisco Torres

dimensional reduction in the analysis of slow-fast systems, see the Appendix. In [ 10 ] two characteristics of hysteresis are emphasized. First, the non-linearity has a dependence on previous values of the input ( memory effect ). Second, hysteretic systems undergo arbitrary quickly transitions, what is an idealization for real systems. The mathematical analysis of hysteretic systems has emphasized its ability for generating chaotic solutions when the involved dynamics are of focus type. See [ 6 , 7 , 9 ]. Here, we consider instead symmetric hysteretic systems having