A. Casavola

Modelling of LIBS plasma expansion

Abstract A one-dimensional time-dependent fluid dynamic model has been developed to describe the expansion of the plume produced by laser ablation. The model includes chemical reactions considered in local thermodynamic equilibrium to describe the expansion of a TiO plasma. The results are discussed in connection with LIBS plasmas.

High-Temperature Thermodynamic Properties of Mars- Atmosphere Components

Methods of calculation of high-temperature thermodynamic properties for some selected Mars-atmosphere components in the temperature range from 200 to 50,000 K and results are discussed and compared with previous works. Aspects such as quasi-bound rotational states, cutoff criteria, and autoionizing states are considered.

Laser Ablation of Titanium Metallic Targets: Comparison Between Theory and Experiment

A model of plasma expansion with chemical kinetics has been developed and compared with the free-flow model describing the laser ablation plume of metallic titanium target. Optical emission spectroscopy has been used to obtain time of flight (TOF) spectra. The measured shift between Ti and Ti + TOF has been theoretically explained on the basis of the recombination process. Particular attention has been also focused on the dependence of TOF on some plume parameters such as initial speed, temperature, pressure, and plume extension.

Non-equilibrium conditions during a laser induced plasma expansion

Abstract A theoretical model to simulate the laser induced plasma (LIP) expansion with chemical kinetics has been developed for a Ti target. Our attention has been also focused on the influence of initial conditions on the plume expansion. In particular, changing the initial speed, temperature, pressure and plume extension, the speed of expansion and the width of the time of flight (TOF) peak change. A systematic study of the effect of all these parameters on the plume expansion can lead to a method that allows the determination of initial conditions of the expansion, which are not available experimentally because of the delay necessary to trigger the measure apparatus with the laser pulse.

Kinetic model of titanium laser induced plasma expansion in nitrogen environment

A theoretical model to investigate the laser induced plasma (LIP) produced by a nanosecond laser pulse interacting with a metallic titanium target in a nitrogen environment is presented. In this work the influence of chemical processes on the plume expansion has been investigated, applying a 2D fluid dynamic code under local thermodynamic equilibrium or chemical non-equilibrium approximations.

Thermodynamic Properties of High-Temperature Jupiter-Atmosphere Components

A study on the thermodynamic properties of Jupiter-atmosphere chemical species important for the high-speed aerodynamics analysis of entry problems is reported. The included species are H 2 , H 2 4 , H 3 + , H + , H - , He, He + , He ++ , e - . Complete tables of thermodynamic properties of these species in the temperature range 50-50000 K have been obtained by using accurate sets of energy levels for both atomic and molecular species. The calculation method is described and relevant results are shown and discussed by comparison with previous data from other sources.

Laser‐Induced Plasma In a Water Bubble

In this work we present a theoretical study concerning the Laser Induced Breakdown Spectroscopy (LIBS) in water. The strong influence of chemical processes on the fluid dynamic expansion has been investigated. To this aim a fluid dynamic code has been developed and coupled with a chemical model, considering the plasma inside the bubble in local thermodynamic equilibrium (LTE).

Experimental and Theoretical Investigation of Nonequilibrium in Laser Induced Plasmas

Expansion of the material ablated from a TiO (titanium oxide) surface with a nanosecond pulsed laser is studied by emission spectroscopy. The quantities measured are the time of flight and a space resolved spectrum. The Boltzmann plot approach is used to obtain temperatures and concentrations of Ti (titanium) atoms and ions. A semi-empirical collisional-radiative model is shown to be very useful to eliminate spurious effects from the spectrum. A self-consistent model coupling collisional/radiative kinetics and fluid dynamic equations of the plume expansion can improve the understanding of the physics during the expansion ad can be used as a powerful tool to extract quantitative information from the emission spectrum even in the absence of LTE (local thermodynamic equilibrium).

Modeling of TiO plume expansion under laser ablation

In this work a theoretical model to describe the expansion of the plume ablated from a monoxide titanium target is presented. The flow expansion has been studied by means of the Euler equations. Consideration of equilibrium and frozen conditions along the plume expansion allows the prediction of film composition on the substrate.

Theoretical modelling of laser induced breakdown spectroscopy in water

In this work we present a theoretical study concerning the Laser Induced Breakdown Spectroscopy (LIBS) in water. A 1D Euler code has been developed and coupled with a complete kinetic model. This study has been applied to the evaporation of a titanium target in water. The strong influence of chemical processes on the fluid dynamic expansion has been shown. Moreover the introduction of two pulses, which is a typically experimental approach in water, has been simulated. The effect of the second pulse on the macroscopic quantities has been deeply discussed.