Download or read book Energy Coupling and Plume Dynamics During High Power Laser Heating of Metals written by and published by . This book was released on 1997 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: High power laser heating of metals was studied utilizing experimental and numerical methods with an emphasis on the laser energy coupling with a target and on the dynamics of the laser generated vapor flow. Rigorous theoretical modeling of the heating, melting, and evaporation of metals due to laser radiation with a power density below the plasma shielding threshold was carried out. Experimentally, the probe beam deflection technique was utilized to measure the propagation of a laser induced shock wave. The effects of a cylindrical cavity in a metal surface on the laser energy coupling with a solid were investigated utilizing photothermal deflection measurements. A numerical calculation of target temperature and photothermal deflection was performed to compare with the measured results. Reflection of the heating laser beam inside the cavity was found to increase the photothermal deflection amplitude significantly and to enhance the overall energy coupling between a heating laser beam and a solid. Next, unsteady vaporization of metals due to nanosecond pulsed laser heating with an ambient gas at finite pressure was analyzed with a one dimensional thermal evaporation model for target heating and one dimensional compressible flow equations for inviscid fluid for the vapor flow. Lastly, the propagation of a shock wave during excimer laser heating of aluminum was measured with the probe beam deflection technique. The transit time of the shock wave was measured at the elevation of the probe beam above the target surface; these results were compared with the predicted behavior using ideal blast wave theory. The propagation of a gaseous material plume was also observed from the deflection of the probe beam at later times.
Download or read book Energy Coupling and Plume Dynamics During High Power Laser Heating of Metals written by Sungho Jeong and published by . This book was released on 1997 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laser Heating of Metals written by A. M. Prokhorov and published by CRC Press. This book was released on 2018-01-31 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to ensure efficient use of lasers, and for any large-scale implementation, a thorough knowledge of the fundamental laws governing the interaction of radiation with matter is required. Laser Heating of Metals provides a systematic and comprehensive presentation of the fundamental principles underlying the physical and chemical mechanisms governing the interaction of laser radiation with solid targets, and in particular metals in gaseous environments, for a wide range of beam parameters. The authors have been active in the field of interactions between lasers and materials for many years, and this book summarises the results of their work, in particular concerning the action of CO2 lasers on metals. These results are then discussed at some length. Laser Heating of Materials will be of interest to scientists at all levels with an interest in the interaction of radiation with condensed matter, and in particular to those involved in laser cutting and welding etc, and metal-working.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1998 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the ASME Heat Transfer Division written by and published by . This book was released on 1997 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Modeling of Plume Dynamics in Multiple Pulse Laser Ablation of Carbon written by Kedar Ashok Pathak and published by . This book was released on 2008 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flow field induced by the ablation plume in the presence of background gas is simulated numerically. The study of plume flow that occurs in laser ablation is important for it can yield information on ablation process itself and the properties of end product for which the ablation is carried out. Unsteady compressible axisymmetric Navier-Stokes equations govern the plume flow. The major challenge involved, even in this simplified model of plume dynamics, is twofold: (i) the time scale of simulation spans six orders of magnitude, from nanosecond to millisecond, and (ii) the high nonlinearity of governing equations because of high pressure, temperature and injection velocity of plume. A computational model is developed that can account for the entire range of time scale and high nonlinearity. This model is a combination of numerical methods and includes multi-time step and multi-size grid technique. The uniqueness of model lies in choosing the combination of numerical methods and handling multi-size grid interface in a conservative way. The combination of numerical methods is decided after comparing the results of few numerical methods for a single plume. The plume dynamics for single plume is explained with the help of proposed post-processing model based on vorticity dynamics. The model not only helps in understanding the expansion dynamics of plume but also provides quantitative comparison amongst numerical methods. The validity of nano-to-micro second range viscous and inviscid models of plume dynamics is discussed by means of evaluation of source terms in the vorticity transport equation. The role of turbulence is evaluated by millisecond-scale modeling of plume expanding in surrounding furnace gas with imposed turbulent gust. The results for multiple plumes typical for real life ablation are presented and discussed. Shielding of laser beam by previously ejected plume in multiple laser hits is important because it changes energy deposition of incident laser pulse at the target surface and in turn influences the ablation dynamics and amount of material removed. To account for this shielding effect, shielding models are developed and implemented. The quantity of ablated mass due to the shielding effect is evaluated. Ionization of carbon plume and its impact on plume dynamics and shielding is studied. An iterative procedure is developed to determine the local equilibrium temperature affected by ionization. It is shown that though shielding due to the presence of ionized particles in carbon plume is small, the effect of ionization on plume dynamics can be considerable. Shielding effect is calculated for laser pulses with different time interval between pulses. The effect of high temperature and low density of plume are controversary and cause shielding behavior to be non-monotonic with pulse number. It is shown that the non-monotonic dependence of the delivered laser energy with the pulse number and the difference in shielding characteristics between planar and axisymmetric formulations increase with the time duration between two consecutive pulses. The developed numerical methodology is employed to study the heat transfer modulation between the Thermal Protection Shield (TPS) and the gas flow occurring because of ejection of under-expanded pyrolysis gases through the cracks in the TPS in hypersonic flight. The simulations are performed for an axisymmetric bluff body flying at Mach 7. The influence of the geometry of the TPS on heat transfer pattern is studied for two representative shapes. The results are presented for three different flight altitudes (low-ground level, moderate-20km and high-30km). At the low altitude the plume pressure is lower than the pressure behind the detached front shockwave and the plume propagates slowly along the wall surface. At high and moderate altitudes, the plume path and consequently, convective heat transfer between the TPS and the plume depends on the plume interaction with the bow shock wave. The effect of viscosity for the plume injection conditions and free stream Mach number considered is found to be negligible at simulated altitudes. However, the effect of initial pressure of pyrolysis gas on the plume dynamics is significant. The presence of the blast wave associated with under-expanded plume alters the heat transfer and increases mixing. Finally, the enhanced heat transfer caused by the emergence of multiple pyrolysis plumes is investigated.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laser Heating of Metals written by and published by . This book was released on 1990 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Doctoral Dissertations written by and published by . This book was released on 1999 with total page 848 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the 36th International MATADOR Conference written by Srichand Hinduja and published by Springer Science & Business Media. This book was released on 2010-08-05 with total page 581 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented here are 130 refereed papers given at the 36th MATADOR Conference held at The University of Manchester in July 2010. The MATADOR series of conferences covers the topics of Manufacturing Automation and Systems Technology, Applications, Design, Organisation and Management, and Research. The proceedings of this Conference contain original papers contributed by researchers from many countries on different continents. The papers cover the principles, techniques and applications in aerospace, automotive, biomedical, energy, consumable goods and process industries. The papers in this volume reflect: • the importance of manufacturing to international wealth creation; • the emerging fields of micro- and nano-manufacture; • the increasing trend towards the fabrication of parts using lasers; • the growing demand for precision engineering and part inspection techniques; and • the changing trends in manufacturing within a global environment.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1993 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Handbook of Laser Micro and Nano Engineering written by KOJI SUGIOKA. and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This handbook provides a comprehensive review of the entire field of laser micro and nano processing, including not only a detailed introduction to individual laser processing techniques but also the fundamentals of laser-matter interaction and lasers, optics, equipment, diagnostics, as well as monitoring and measurement techniques for laser processing. Consisting of 11 sections, each composed of 4 to 6 chapters written by leading experts in the relevant field. Each main part of the handbook is supervised by its own part editor(s) so that high-quality content as well as completeness are assured. The book provides essential scientific and technical information to researchers and engineers already working in the field as well as students and young scientists planning to work in the area in the future. Lasers found application in materials processing practically since their invention in 1960, and are currently used widely in manufacturing. The main driving force behind this fact is that the lasers can provide unique solutions in material processing with high quality, high efficiency, high flexibility, high resolution, versatility and low environmental load. Macro-processing based on thermal process using infrared lasers such as CO2 lasers has been the mainstream in the early stages, while research and development of micro- and nano-processing are becoming increasingly more active as short wavelength and/or short pulse width lasers have been developed. In particular, recent advances in ultrafast lasers have opened up a new avenue to laser material processing due to the capabilities of ultrahigh precision micro- and nanofabrication of diverse materials. This handbook is the first book covering the basics, the state-of-the-art and important applications of the dynamic and rapidly expanding discipline of laser micro- and nanoengineering. This comprehensive source makes readers familiar with a broad spectrum of approaches to solve all relevant problems in science and technology. This handbook is the ultimate desk reference for all people working in the field.
Download or read book Multiscale Modeling and Simulation of Laser Interaction with Metals written by Pengfei Ji and published by . This book was released on 2016 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electron temperature dependent electron heat capacity, electron thermal conductivity and effective electron-phonon coupling factor are modeled and computed on the basis of ab initio quantum mechanics (QM) calculation. The obtained electron thermophysical parameters are implemented into energy equation of electron subsystem in two temperature model (TTM). Upon laser irradiation on metal, energy transfer from the electron subsystem to the lattice subsystem is modeled by including electron thermophysical parameters in molecular dynamics (MD) and TTM coupled simulation. Phenomena, such as melting, layer-ablation, vaporization are found in the simulation results. In addition, bond hardening of femtosecond laser irradiated gold is observed. As the first work studying the laser interaction with metallic materials ranging from atomic scale to continuum scale, the successful construction of the QM-MD-TTM integrated simulation provides a general way that is accessible to other metals in laser heating. The simulation results highlight the promising application of the QM-MD-TTM integrated simulation. Obtained results from pure ab initio MD provide a better relation between microscopic processes and material response detected in experiments and serve for improved interpretation of experimental results on ultrafast laser-metal interactions. The results simulated and conclusion drawn will empower the multi-scale modeling of laser material interaction and be quite useful in helping to resolving the heat transfer and energy conversion problem during ultrashort laser processing of metals.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994 with total page 1032 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
Download or read book Laser Induced Breakdown Spectroscopy written by Jagdish P. Singh and published by Elsevier. This book was released on 2007-10-03 with total page 455 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser induced breakdown spectroscopy (LIBS) is basically an emission spectroscopy technique where atoms and ions are primarily formed in their excited states as a result of interaction between a tightly focused laser beam and the material sample. The interaction between matter and high-density photons generates a plasma plume, which evolves with time and may eventually acquire thermodynamic equilibrium. One of the important features of this technique is that it does not require any sample preparation, unlike conventional spectroscopic analytical techniques. Samples in the form of solids, liquids, gels, gases, plasmas and biological materials (like teeth, leaf or blood) can be studied with almost equal ease. LIBS has rapidly developed into a major analytical technology with the capability of detecting all chemical elements in a sample, of real- time response, and of close-contact or stand-off analysis of targets. The present book has been written by active specialists in this field, it includes the basic principles, the latest developments in instrumentation and the applications of LIBS . It will be useful to analytical chemists and spectroscopists as an important source of information and also to graduate students and researchers engaged in the fields of combustion, environmental science, and planetary and space exploration. * Recent research work* Possible future applications* LIBS Principles
Download or read book Non equilibrium Energy Transfer and Phase Change During Intense Picosecond Laser metal Interactions written by Long-Sheng Kuo and published by . This book was released on 2001 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1972 with total page 886 pages. Available in PDF, EPUB and Kindle. Book excerpt:
