Author: Stefan-Andrei Irimiciuc
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Laser ablation methods exhibit a fast development in various application fields, as materials processing, medicine, nuclear fusion or analytical sciences. Despite important advances in the knowledge of the complex laser-matter interactions involved in this process, there is still need for better fundamental understanding and modeling. The aim of this work was to experimentally and theoretically investigate the dynamics of transient plasmas generated by laser ablation in various regimes (ns, ps, fs), and to try to correlate the observed behavior with the physical properties of the ablated materials We implemented space- and time-resolved optical, spectroscopic and electrical methods for the study of single-component metallic targets and of complex chalcogenide targets. This led to a space-time mapping of the main plasma parameters. The study performed in actual Pulsed Laser Deposition (PLD) conditions revealed some peculiar effects like ionic oscillations or plume reflection at the substrate. A compact fractal hydrodynamic model was developed to simulate the laser-produced plasma dynamics. The theoretical model accurately describes the spatial and temporal evolution of the main plasma parameters (electronic temperature, expansion velocities, particle number density, Debye length, plasma potential). We report for the first time empirical relations connecting these plasma parameters with the physical properties (electrical/thermal conductivity, atomic mass, heat of vaporization) of the target. These relationships transcend all three ablation regimes (ns, ps, fs).
Author: Petru-Edward Nica
Publisher:
ISBN:
Category : Science
Languages : en
Pages :
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Book Description
During the last decade, our groups have performed systematic experimental studies on the characterization of plasma plumes generated by laser ablation in various temporal regimes (ns, ps, fs) on materials ranging from simple metals (Al, Cu, Mn, Ni, In, W, ...) to more complex compounds (ceramics, chalcogenide glasses, ferrites). Optical (fast imaging and space- and time-resolved emission spectroscopy) and electrical (mainly Langmuir probe) methods have been applied to experimentally investigate the dynamics of the plasma plume and its constituents. Influence of the target physical (thermodynamic and electrical) parameters on the plasma dynamics has been studied. A mathematical correlation between the local and global plasma parameters and the physical properties of the target was proposed for the first time. Peculiar behaviors like plume splitting or plasma oscillations have been evidenced for high laser fluence ablation in vacuum. Along with results from the literature, our findings provide convincing arguments for the existence of multiple double-layers in the laser ablation plasma plume, in a scenario including two-temperature electrons. New fractal-based theoretical approaches have been developed to qualitatively and quantitatively account for the observed phenomena. The space and time evolution of expansion velocity, particle number, current density and plasma temperature were theoretically investigated.
Author: Stefan Andrei Irimiciuc
Publisher: World Scientific
ISBN: 9811270686
Category : Science
Languages : en
Pages : 233
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Book Description
Fourteen years after the first proposal of a fractal theoretical model to understand the dynamics of laser produced plasma, a complete image of the model is projected on a wide range of empirical data related to laser produced plasmas.The book tackles the two sides of laser produced plasmas with experimental data on a wide range of materials, from metallic alloys to geological samples and the associated mathematical model is developed in the multifractal theory of motion. A new perspective is explored in analyzing and interpreting the data collected by electrical or optical methods, focusing especially on the charged particles dynamics and the nature of fractal fluctuations and their influence during measurements as well as to the scattering process and plasma splitting phenomena, all seen through the lens of multifractal physics.The book offers the best presentation of the multifractal theoretical model for the study of transient phenomena in laser produced plasmas, which focus leads to a balanced development of the model showcasing both the flexibility and the unique vision of a multifractal mathematical apparatus.
Author: Tatiana Itina
Publisher: BoD – Books on Demand
ISBN: 9535136992
Category : Science
Languages : en
Pages : 292
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Book Description
Shortly after the demonstration of the first laser, the most intensely studied theoretical topics dealt with laser-matter interactions. Many experiments were undertaken to clarify the major ablation mechanisms. At the same time, numerous theoretical studies, both analytical and numerical, were proposed to describe these interactions. These studies paved the ways toward the development of numerous laser applications, ranging from laser micro- and nanomachining to material analysis, nanoparticle and nanostructure formation, thin-film deposition, etc. Recently, more and more promising novel fields of laser applications have appeared, including biomedicine, catalysis, photovoltaic cells, etc. This book intends to provide the reader with a comprehensive overview of the current state of the art in laser ablation, from its fundamental mechanisms to novel applications.
Author: Maricel Agop
Publisher: MDPI
ISBN: 3039364138
Category : Computers
Languages : en
Pages : 104
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Book Description
The world of laser matter interaction has known great and rapid advancements in the last few years, with a considerable increase in the number of both experimental and theoretical studies. The classical paradigm used to describe the dynamics of laser produced plasmas has been challenged by new peculiar phenomena observed experimentally, like plasma particles’ oscillations, plume splitting and self-structuring behavior during the expansion of the ejected particles. The use of multiple complementary techniques has become a requirement nowadays, as different aspects can be showcased by specific experimental approaches. To balance these non-linear effects and still remain tributary to the classical theoretical, views on laser produced plasma dynamics novel theoretical models that cover the two sides of the ablation plasma (differentiability and non-differentiability) still need to be developed. Plasma is a strongly nonlinear dynamic system, with many degrees of freedom and other symmetries, favorable for the development of ordered structures, instabilities and transitions (from ordered to chaotic states). In such contexts, we showcased research based on global and local symmetries, complexity and invariance. This special number highlighted exciting new phenomena related to laser produced plasma dynamics with the implementation of theoretical models, towards understanding the complex reality of laser matter interaction.
Author: Stefan Andrei Irimiciuc
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 0
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Book Description
Understanding the underline fundamental mechanism behind experimental and industrial technologies embodies one of the foundations of the advances and tailoring new materials. With the pulsed laser deposition being one of the key techniques for obtaining complex biocompatible materials with controllable stoichiometry, there is need for experimental and theoretical advancements towards understanding the dynamics of multi component plasmas. Here we investigate the laser ablation process on Cu-Mn-Al and Fe-Mn-Si by means of space-and time-resolved optical emission spectroscopy and fast camera imaging. In a fractal paradigm the space,Äìtime homographic transformations were correlated with the global dynamics of the ablation plasmas.
Author: Rashid A. Ganeev
Publisher: World Scientific
ISBN: 1848169809
Category : Science
Languages : en
Pages : 250
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Book Description
This book represents the first comprehensive treatment of high-order harmonic generation in laser-produced plumes, covering the principles, past and present experimental status and important applications. It shows how this method of frequency conversion of laser radiation towards the extreme ultraviolet range matured over the course of multiple studies and demonstrated new approaches in the generation of strong coherent short-wavelength radiation for various applications. Significant discoveries and pioneering contributions of researchers in this field carried out in various laser scientific centers worldwide are included in this first attempt to describe the important findings in this area of nonlinear spectroscopy. High-Order Harmonic Generation in Laser Plasma Plumes is a self-contained and unified review of the most recent achievements in the field, such as the application of clusters (fullerenes, nanoparticles, nanotubes) for efficient harmonic generation of ultrashort laser pulses in cluster-containing plumes and resonance-induced enhancement of harmonic yield. It can be used as an advanced monograph for researchers and graduate students working in the field of nonlinear spectroscopy. It is also suitable for researchers in laser physics and nonlinear optics who wish to have an overview of the advanced achievements in laser ablation-induced high-order harmonic generation spectroscopy. The carefully presented details of this book will be of value to research devoted to the understanding and control frequency conversion of laser pulses in plasma plumes. The studies described in this book pave the way for the development of a new method of materials studies using the laser ablation-induced high-order harmonic generation spectroscopy, which can exploit the spectral and structural properties of various solid-state materials through their ablation and further propagation of short laser pulse through laser-produced plasma and generation of high-order harmonics.
Author: Mahmoud Dawood
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Omid A. Ranjbar
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages :
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Book Description
Ablation of materials by nanosecond laser pulses involves expansion of a laser-induced vapor plume into a background gas. The absorption of the incident laser radiation by the plume can substantially decrease the amount of laser energy absorbed directly by the target, and, correspondingly, the amount of the ablated material. This plasma shielding effect limits the overall efficiency of industrial laser systems designed for material removal applications. The goal of the present work is to numerically study the expansion process of plumes induced by irradiation of a metal target by bursts or groups of nanosecond laser pulses and to reveal the implications of the interaction between plumes induced by individual pulses for the efficiency of material removal. The plume expansion induced by irradiation of a copper target in argon background gas is studied based on one- and two-dimensional hybrid computational models that include a hydrodynamic or kinetic model of plasma plumes. The hydrodynamic model is based on finite-difference solution of gas dynamics equations. The kinetic model is implemented in the form of the direct simulation Monte Carlo (DSMC) method. In this work, the generalization of the DSMC method for plasma flows is developed. The effects of laser fluence, spot size, inter-pulse separation, and background gas pressure are thoroughly studied. The numerical simulations of plume expansion induced by a burst of pulses indicate the formation of complicated flow structures with cascades of the primary and secondary shock waves and strong interaction between plumes induced by individual pulses. The simulations reveal the plume accumulation effect when the plumes induced by preceding pulses in a burst change conditions of propagation of plumes generated by subsequent pulses. The degree of plasma shielding increases with increasing number of laser pulses due to the plume accumulation effect. It results in reduction of the effectiveness of material removal by the subsequent pulses. The degrees of the plasma shielding and plume accumulation effects strongly depend on the inter-pulse separation and laser spot size. The trade-off between the plume accumulation and thermal accumulation effects maximizes the ablation depth per pulse at a certain value of the time delay between pulses.
Author:
Publisher:
ISBN:
Category : Lasers
Languages : en
Pages : 624
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