Florence Garrelie

Monte Carlo simulation of the laser-induced plasma plume expansion under vacuum: Comparison with experiments

The laser induced plasma plume expansion in vacuum is studied by a Monte Carlo simulation. An original method, which allows the simulation with no size restrictions on laser spot width or ablated depth, is presented. The global shape of the plume created above a copper target is followed in time by using a three-dimensional algorithm. Particles evaporation from the sample surface during the laser pulse duration is done by taking into account a radial distribution of laser energy and the influence of vapor pressure on surface temperature. The simulation indicates that, when much more than few monolayers are ablated, the laser energy absorption by the evaporated particles has dominant effects on the plume shape during the expansion process. An approximation of these effects has been done by considering that a fraction of the recombination of ionic and excited species leads to a delayed kinetic energy transfer in the plume. It was found that this contribution has a significant effect on the angular and kinet...

Study of the expansion of the laser ablation plume above a boron nitride target

Abstract The plasma plume created above a boron nitride target irradiated by a pulsed KrF laser beam is investigated by optical emission spectroscopy and fast intensified camera. The light emitting species detected are B*, B+*, N+*, their velocity varies between 20 and 50 km/s depending on the laser fluence and the ambient pressure in the vessel. The motion of the leading edge is studied under various nitrogen pressures ({ce:inline-formula}6 × 10−3{/ce:inline-formula} up to 500 Pa) and for two laser fluences (7 and 200 J/cm2) in order to fit the expansion of the front with different models (shock-wave-like and drag force models).

Study of particles ejected after pulsed laser ablation of a graphite target

Abstract This work is devoted to the study of the micrometer-sized particles ejected after pulsed laser ablation of a graphite target. The motion of these particles is followed from the target surface up to the deposited carbon film surface by fast imaging of the plasma plume and by image processing of optical photographies of various deposited carbon films. The influence of the laser fluence on the particle motion and on the size of the deposited particles are presented for laser fluence ranging 10–5000 J/cm 2 .

New trends in femtosecond pulsed laser deposition and femtosecond produced plasma diagnostics

The availability of compact table top amplified femtosecond lasers and the technical simplicity of experimental design have opened the way to many recent and fast developments towards thin film elaboration by Pulsed Laser Deposition (PLD) with ultra short laser pulses, with the aim of producing materials of high quality previously unattainable or attainable only through more complex means. The first developments of PLD using femtosecond lasers were made on Diamond-Like Carbon thin films elaboration, with the attempt to reach high sp3 content. PLD with ultra short pulses was used recently to deposit several systems such as quasicrystals or oxides with a transfer of the target composition to the deposited films, even for compounds with complex stoechiometry. Femtosecond laser ablation from solid targets has shown its capability in producing nanoparticles of different materials, even in high vacuum conditions. Nanostructured films of doped Diamond-Like Carbon were obtained recently, opening the way to large applications towards functional materials. The characteristics of the plasma are a well-suited signature of the physics of laser-matter interaction and plasma plume creation and expansion. Recent studies on the control of the film growth and femtosecond PLD processes will be reported. Emphasis on actual capability of the existing sources to elaborate high quality materials will be questioned in terms of energy per pulse, time width, repetition rates but also in the need for further source development and beam shaping improvement.

Response to “Comment on ‘Monte Carlo simulation of the laser-induced plasma plume expansion under vacuum: Comparison with experiments’ ” [J. Appl. Phys. 86, 4709 (1999)]

This response recalls the bases of the Monte Carlo methods of gas flow simulations. Basic points and explicit parameters used in both the DSMC method and the method of random trajectories are underlined. Some clarifications are made on the confusion made by the author of the comment on this subject. The justification of the validity of the method is recalled, as already made in the original article.

Simulation Monte-Carlo du transport sous vide et sous gaz ambiant d'un panache plasma créé par ablation laser

Abstract The expansion of the plasma plume created during the interaction between an excimer laser and a copper target is studied by a Monte-Carlo simulation. The global shape of the plume is followed in time using a three dimensional algorithm, allowing the simulation of the expansion both under vacuum and background gas. The laser energy absorption by the plume of evaporated particles is found to have dominant effects on the plume shape. An approximation of these effects is made by taking into account a kinetic energy transfer in the plume through the recombination of ionized and excited particles by collisional recombinative processes. Results of the simulation of the expansion under vacuum are compared with experimental results obtained by fast photography of the plume and time of flight measurements. First results of the simulation by a Monte-Carlo method of the plasma plume expansion under residual pressure show clearly the snowplow of the leading edge of the plume and the background particles deficiency in the dense region of the plume.

Laser-induced plasma plume expansion under vacuum by Monte Carlo simulation

The laser induced plasma plume expansion in vacuum is studied by a Monte Carlo simulation. The global shape of the plume created above a copper target is followed in time by using a 3D algorithm. An original method has allowed the simulation with no restrictions on laser spot width or ablated depth. Particles evaporation from the sample surface during the laser pulse is done by introducing in the model a radial distribution of laser energy and a high surface temperature induced by the vapor pressure. The effects of the later energy absorption by the evaporated particles appear to be dominating parameters on the expansion process. An approximation of these effects has been done by considering a fraction of energetic species, corresponding to the recombination of ionic species by kinetic energy transfer in the cloud. Results of this simulation are compared with experimental results obtained by time of flight measurements and fast photography of the luminous component of the plume.