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Descripción
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| The development of this Thesis has been focused specifically on the characterization of the plasma generated in an LSP process. In particular, this work combines a joint study either experimental or theoretical so as to diagnose cold plasmas generated in industrial processes, concretely the LSP on an aluminium alloy of the series 2024. This Thesis is structured in 7 chapters briefly described below: Chapter 1 contains a brief introduction about the state of the art of the processes of superficial treatment for metallic materials, such Shot Peening or the Burnishing, indicating the applications, advantages and disadvantages. Chapter 2 is focused on the LSP process. In the first part the process is described and the background of the evolution is presented. After this, an overview of the industrial applications of the LSP technology is realised. The next point is focused on the work made in the Laser Centre of the UPM for the study of the process. Here is a description of the way of work either in the experimental part or in the simulation of the process. At last a brief revision is presented about the material subject of study. Chapter 3 describes the experimental device used: laser, monochromator, CCD. . . It also explains the experimental assembly and the measure procedure, as well as everything dealing with the calibration of the device: efficiency of the system and calibration in wavelength. Chapter 4 is about the breakdown spectroscopy induced by laser or Laser Induced Breakdown Spectroscopy (LIBS) which is the method chosen for the characterization of the plasma produced. The whole process of the formation of the plasma is explained as well as the spectroscopy characterization. The effects that can modify the results have been described in detail: width and shape of the lines, evolution and homogeneity of the plasma or the effect of the self-absorption in certain spectral lines. Chapter 5 describes in detail the procedure of the quantitative study of the plasma, it is, the calculation of electronic density and the temperature. Full justification will be given to choose line H of Balmer?s series to determine density and the election of Boltzmann?s method for the temperature. Finally, the plasma is confirmed to be on Local Thermodynamic Balance and the results obtained will be presented. Chapter 6 shows the calculation process of the atomic parametres, such as the transition probabilities, whose average life is determined, and also the width and the Stark displacement with the Cowan programme, in particular, the results of the lines of the ions two and three of magnesium (Mg II and Mg III), because they are necessary to realize the calculations of the former chapter. Chapter 7 presents the conclusions and achievements obtained throughout the development of this Thesis, as well as the possible new lines of investigation. | |
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Internacional
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ISBN
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Tipo de Tesis
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Doctoral |
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Calificación
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Sobresaliente cum laude |
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Fecha
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01/06/2017 |