In femtosecond laser ablation the plume has two components: a faster-moving plasma part and a slower nanoparticle plume which contains most of the ablated material. This paper describes the results of experiments to comprehensively characterize the plume in laser ablation ...

In femtosecond laser ablation the plume has two components: a faster-moving plasma part and a slower nanoparticle plume which contains most of the ablated material. This paper describes the results of experiments to comprehensively characterize the plume in laser ablation ...

The transport dynamics of laser-ablated neutral/plasma plumes are of significant interest for film growth by pulsed-laser deposition of materials since the magnitude and kinetic energy of the species arriving at the deposition substrate are key processing...

An annealing model is extended to treat the vaporization process, and a hydrodynamic model describes the ablated material. We find that dynamic source and ionization effects accelerate the expansion front of the ablated plume with thermal vaporization tem...

Experimental evidence of the appearance of a proper periodic dynamics in a plasma plume created by pulsed laser ablation is considered as a hint for the presence of a self-organization scenario that explains similar phenomena observed in plasma diodes.

We report time-resolved imaging of a laser-ablated carbon plasma plume to investigate the expansion dynamics of C2 and CN in an ambient atmosphere of nitrogen gas at various pressures. An attempt is made to locate C2 and CN species in the carbon plasma plume and correlate them with the results of spectroscopic ...

An annealing model is extended to treat the vaporization process, and a hydrodynamic model describes the ablated material. We find that dynamic source and ionization effects accelerate the expansion front of the ablated plume with thermal vaporization temperature. The vaporization process and ...

Multiscale computational approach that combines different methods to study laser ablation phenomenon is presented. The methods include the molecular dynamics (MD) breathing sphere model for simulation of the initial stage of laser ablation, a combined MD - finite element method (FEM) approach for simulation of propagation of the ...

The time span of plume dynamics in laser ablation of carbon ranges from nanoseconds to milliseconds. Multi-time step approach is developed to study the plume dynamics over this entire range with minimum requirements of numerical computational resources. This approach is applied to study one of ...

Free-running Er:YAG lasers are used for precise tissue ablation in various clinical applications. The ablated material is ejected into the direction perpendicular to the tissue surface. We investigated the influence of shielding by the ablation plume on the energy deposition into an irradiated sample because it ...

The structure and evolution of the laser-induced vapor plume and shockwave were measured from femtosecond time resolved shadowgraph images. By changing the wavelength of the probe beam (400 and 800 nm), differences in the opacity of the vapor plume were measured as a function of delay time from the ablation laser pulse. The evolution ...

Several physics and computational approaches have been developed to globally characterize phenomena important for film growth by pulsed laser deposition of materials. These include thermal models of laser-solid target interactions that initiate the vapor plume; plume ionization and heating through laser absorption beyond local thermodynamic equilibrium ...

Various physics and computational approaches have been developed to globally characterize phenomena important for film growth by pulsed-laser deposition of materials. These include thermal models of laser-solid target interactions that initiate the vapor plume, plume ionization and heating through laser absorption beyond local thermodynamic equilibrium ...

The dynamics of a conducting laser ablated carbon plume flow in the ablation furnace typical for nanoparticle synthesis is investigated by numerical modeling. The effect of magnetic field on the flow is accounted through the Lorentz body force. The study begins with benchmark calculations of two simple test cases, ...

Gated photon counting spectroscopy and species-resolved ICCD photography were used to study the weak plasma luminescence following the propagation of the initial ablation plume in vacuum and during the rebound of the plume with a substrate during pulsed l...

Thin films of La0.6Ca0.4CoO3 were grown by pulsed laser ablation with nanosecond and femtosecond pulses. The films deposited with femtosecond pulses (248 nm, 500 fs pulse duration) exhibit a higher surface roughness and deficiency in the cobalt content compared to the films deposited with nanosecond pulses (248 nm, 20 ns pulse duration). The origin of these pronounced ...

The behavior of ablated plumes produced by nanosecond scale multiple laser pulses typical for carbon ablation is studied in order to understand the plume expansion dynamics and shielding effect of plume with special interest to ionization of plumes. The ...

The transport dynamics of laser-ablated neutral/plasma plumes are of significant interest for film growth by pulsed-laser deposition of materials since the magnitude and kinetic energy of the species arriving at the deposition substrate are key processing parameters. Dynamical calculations of ...

To study the phase transformation mechanism and gas dynamic process for the laser-ablated plume, direct and indirect evidences of potential laser ablation mechanisms were sought experimentally and analytically. Two phase transformation mechanisms, normal vaporization and phase explosion, were introduced as the ...

We consider the applicability of the isentropic, adiabatic gas dynamical model of plume expansion for laser ablation in vacuum. We show that the model can be applied to ionized plumes and estimate the upper electron temperature limit on the applicability of the isentropic approximation. The model predictions are ...

The dynamic behaviors and optical properties of a ZnO plasma plume produced by pulsed laser ablation using a Nd:YAG laser (wavelength: 532 nm, pulse width: 3 ns) were studied by fast photography using a commercial gated charge coupled device (CCD) camera linked with a delay circuit and by optical emission spectroscopy at various ...

Fundamental gas dynamic and laser-material interactions during pulsed laser deposition are explored through sensitive imaging and plasma spectroscopic diagnostics. Two recent phenomena, plume-splitting in background gases and the unusual dynamics of graph...

Laser ablation of bulk High Temperature Superconductor (HTS) material promises to provide a useful means of producing high quality HTS thin films. Mass spectrometric probes of the ablation plume provide a microscopic understanding of the ablation event and plume development as well as providing ...

We discuss the ablation of aluminum plasma using picosecond pulsed laser in vacuum and in ambient atmosphere of nitrogen. The plume dynamics of picosecond and nanosecond laser-ablated plumes in ambient atmosphere is discussed. The degree of polarization is measured using optical emission ...

The expansion in vacuum of the plume generated by the UV ablation of a LiYF4 crystal was analysed as a function of several parameters: distance from the target along the plume axis, laser fluency and angular dislocation with respect to the plume axis. The study was carried out by the optical time of flight ...

Free running Er:YAG lasers are used for a precise tissue ablation in various clinical application as, for example, laser skin resurfacing. The ablated material is ejected from the tissue surface in the direction of the incident laser beam. We investigated the influence of the shielding by the ablation plume on the ...

Combined diagnostic measurements are employed to characterize the penetration of energetic ablation plumes through background gases during a key transitional regime in which the ion flux is observed to split into distinct fast and slowed components. This ...

Generation and expansion dynamics of aluminum laser plasma plumes generated between parallel plates of varying separation (?Z = 2.0, 3.2, 4.0, and 5.6 mm), which confined plume expansion normal to the ablation surface, were diagnosed. Space and time resolved visible emission spectroscopy in the spectral range ? = ...

The gas dynamics and atomic kinetics of a laser ablation plume of lithium, expanding adiabatically in vacuum, are included in a numerical model, using isothermal and isentropic self-similar analytical solutions and steady-state collisional radiative equations, respectively. Measurements of plume expansion ...

Femtosecond laser ablation and plume evolution of aluminum is investigated for various inhomogeneous laser pulses. For the simulations of the atoms the molecular dynamics code IMD is used. The ablated gas-phase is scanned by a cluster algorithm (DBSCAN), from which we gain a cluster size distribution of the ...

Ablation of molecular solids with pulsed ultraviolet lasers at atmospheric pressure is an important process in (bio-)organic mass spectrometry. Of practical importance for analytical sampling and analysis are the plume formation and expansion. Plumes formed by atmospheric-pressure laser ablation of anthracene and ...

Experimental and theoretical studies on laser ablation of polymers (PMMA, polyimide) have been performed in a wide range of CO2-laser fluences. Evolution of polymer laser plume in air has been investigated with simultaneous registration of radiation spectra of the ablation products, spatial dynamics of plasma ...

Fundamental gas dynamic and laser-material interactions during pulsed laser deposition are explored through sensitive imaging and plasma spectroscopic diagnostics. Two recent phenomena, plume-splitting in background gases and the unusual dynamics of graphite ablation for amorphous diamond film growth, are ...

The effect of ambient gas on the expansion dynamics of the plasma plume generated by excimer laser ablation of a LaMnO{sub 3} target is investigated by using fast photography. The plume propagation in an oxygen environment is examined with pressure ranging from vacuum to a few millibars. Imaging analysis performed ...

The effect of ambient gas on the expansion dynamics of the plasma plume generated by excimer laser ablation of a LaMnO3 target is investigated by using fast photography. The plume propagation in an oxygen environment is examined with pressure ranging from vacuum to a few millibars. Imaging analysis performed over a ...

We present comprehensive experimental and theoretical studies of poly(methyl methacrylate) (PMMA) ablation by single pulses of 9.17 �m laser radiation in a wide range of fluences. Ablation was carried out in a quartz cell through which nitrogen under atmospheric pressure was pumped. The composition of the ablation products was ...

Laser ablation of bulk high-temperature superconductor (HTS) material provides a useful means of producing high-quality HTS thin films. Mass spectrometric probes of the ablation plume provide a microscopic understanding of the ablation event and plume development as well as providing a process ...

We study the temperature evolution of aluminum nanoparticles generated by femtosecond laser ablation with spatiotemporally resolved x-ray-absorption fine-structure spectroscopy. We successfully identify the nanoparticles based on the L-edge absorption fine structure of the ablation plume in combination with the dependence of the edge ...

This paper reports ablation experiments on porcine corneal tissue using the Vanderbilt Mark III Free Electron Laser (FEL) and a tabletop Raman-shifted Alexandrite laser. These experiments were designed to test previous models that suggested wavelength and intensity dependent ablation mechanisms. In one test, we compare ablation ...

This thesis discusses the following on resonant holographic measurements of laser ablation plume expansion: Introduction to laser ablation; applications of laser ablation; The study of plume expansion; holographic interferometry; resonant holographic inte...

This research program had as fundamental objectives: to develop a mathematical model of the physical processes attendant to material deposition, particularly pulsed laser deposition, including the ablation, plume dynamics, and film growth, with a focus on...

A femtosecond laser pulse with power density of 10{sup 13} to 10{sup 14} W/cm{sup 2} incident on a metal target causes ablation and ejection of the surface layer. The ejected laser plume has a complicated structure. At the leading front of the plume, there is a spall layer where the material is in a molten state. The spall layer is a ...

The dynamics of the early stages of the ablation plume formation and the mechanisms of cluster ejection are investigated in large-scale molecular dynamics simulations. The cluster composition of the ablation plume has a strong dependence on the irradiation conditions and is ...

Spectroscopic analysis of the emission plumes of graphite, polyimide, polyethylene terepthalate, and polymethylmethacrylate that have been ablated by using a pulsed CO2 laser operating at 10.6 ?m shows the presence of CN and C2, species not previously reported for CO2 laser ablation. The gross dynamics of the ...

A fluid dynamics model was developed for the ablation of water-rich targets by infrared laser pulses at atmospheric pressure. It incorporates the nonlinear absorption of water and the phase explosion due to superheating. The simulation results show that due to two different phase transition mechanisms, the first, slower plume expansion ...

Laser ablation has proven to be an effective method for generating nanoparticles; particles are produced in the laser induced vapor plume during the cooling stage. To understand the in-situ condensation process, a series of time resolved light scattering images were recorded and analyzed. Significant changes in the condensation rate and the shape of the ...

A study of the gas dynamics of the vapor plume generated during laser ablation was conducted including a counterpropagating internal shock wave. The density, pressure, and temperature distributions between the external shock wave front and the sample surface were determined by solving the integrated conservation equations of mass, ...

Laser ablation plasma plume expanding into the ambient atmosphere may be an efficient way to produce nanoparticles. From that reason it would be interesting to study the properties of these laser induced plasmas formed under conditions that are known to be favorable for nanoparticles production. In general, plume behavior can be ...

Silver and gold thin films were deposited by pulsed laser ablation in a controlled Ar atmosphere at pressures between 10 and 100 Pa. Different morphologies, ranging from isolated nanoparticle arrays up to nanostructured thin films were observed. Fast imaging of the plasma allowed deducing the expansion dynamics of the ablated ...

Silver and gold thin films were deposited by pulsed laser ablation in a controlled Ar atmosphere at pressures between 10 and 100 Pa. Different morphologies, ranging from isolated nanoparticle arrays up to nanostructured thin films were observed. Fast imaging of the plasma allowed deducing the expansion dynamics of the ablated ...

The dynamics of the interaction between two plasmas induced by cross-beam pulsed-laser ablation was analyzed by time resolved optical emission spectroscopy and fast photography. The plasmas were created in vacuum by irradiating two perpendicular graphite targets with an excimer (248 nm) and a Nd:yttrium-aluminum-garnet (1064 nm) laser. In this ...

The dynamics of the interaction between two plasmas induced by cross-beam pulsed-laser ablation was analyzed by time resolved optical emission spectroscopy and fast photography. The plasmas were created in vacuum by irradiating two perpendicular graphite targets with an excimer (248 nm) and a Nd:yttrium-aluminum-garnet (1064 nm) laser. In this ...

The expansion of a plasma plume in a background gas is a key problem for film deposition and laser ablation studies. Combined diagnostic measurements of deposition rates and ion time-of-flight (TOF) signals have been used to study the dynamics of a laser ablation plume in an oxygen gas. This ...

Detection of nickel atom by laser induced fluorescence during carbon nanotube formation in a laser of catalyst nickel atoms by laser induced fluorescence during carbon nanotube formation in a laser that ablation of nickel and plume dynamics are strongly related to the oven temperature. Nickel atoms have

of the ejected plume is modeled by the direct simulation Monte Carlo DSMC method. The presence of clusters, which in the conventional DSMC. A number of analytical models are proposed and verified for the statistical distributions sizes, required for the information transfer from the MD to the DSMC parts of the model. The developed

... Characterization of vapour plume species and deposition residues resulting from pulsed laser ablation of a ... ablation of a graphite/epoxy composite ...

... Pyrolysis gas pressure inside the TPS of Formfted: Endnote Reference Pioneer ... ablation. eleted:__ J_Formatted: Endnote Reference ...

The production of thin films by pulsed laser deposition (PLD) has become a standard method, even though many of the basic processes are not known in detail. The key quantitites are the ablation rate (yield) and the angular distribution of the ablated particles. The starting point for this study is the comparatively simple case of one-component metals ...

We studied the dynamics of the femtosecond laser ablation of aluminum in an energy range well above the ablation threshold with the ultrafast time-resolved x-ray-absorption fine structure imaging technique. Analyzing the spectral structures near the L absorption edge that appeared in one-dimensional images of soft-x-ray absorbance, ...

A study of the gas dynamics of the vapor plume generatedduring laser ablation was conducted including a counterpropagatinginternal shock wave. The density, pressure, and temperature distributionsbetween the external shock wave front and the sample surface weredetermined by solving the integrated conservation equations of mass,momentum, ...

The expansion of a plume in a background gas of pressure comparable to that used in pulsed laser deposition (PLD) has been analyzed in terms of the model of Predtechensky and Mayorov (PM). This approach gives a relatively clear and simple description of the essential hydrodynamics during the expansion. The model also leads to an insightful treatment of the stopping behavior in ...

A two-stage two-dimensional (2D) gas-dynamic model of laser ablation in an ambient gas atmosphere is proposed. The initial one-dimensional stage of the process is related to the ablation plume formation under the action of a laser pulse (duration of the order of 10 ns; fluence about several J/cm2; laser spot ...

In this work we report on the properties of the ablation plume and the characteristics of the films produced by ultra-fast pulsed laser deposition (PLD) of TiO2 in vacuum. Ablation was induced by using pulses with a duration of ?300 fs at 527 nm. We discuss both the composition and the expansion dynamics of the ...

Optical emission of plasma is used to investigate the characteristics of dynamics distribution in the plume generated by ablation of a SiC sample using Nd:YAG laser. The plume expansion dynamics is characterized by time-of-flight measurement. We find that the profiles of Si(I) (390.55 nm) split ...

The expansion dynamics of Sm{sub 1-x}Nd{sub x}NiO{sub 3} excimer laser ablation plume in background oxygen atmosphere has been investigated using a fast ICCD imaging. The laser fluence was fixed at 2 J{center_dot}cm{sup -2} and the surrounding ambient gas pressure was varied from vacuum to 50 mbars. The imaging data is used to create ...

12 A 2D gas-dynamic model of laser ablation an ambient gas atmosphere is proposed. To obtain the boundary conditions at the evaporated target surface, a nonlinear heat transfer problem in the target including the dynamics of the melt and evaporation fronts is considered. Back condensation of the vapor at the target is taken into ...

The laser ablation technique for pulsed laser deposition of thin films has proven extremely successful at growing high-quality films of very complex and novel materials, such as high temperature superconducting compounds and diamond-like carbon. The physics ingredients involved are quite complicated given that they include laser-solid interactions at the target, plasma ...

We present experimental and theoretical studies of nanosecond ArF excimer laser desorption and ablation of silicon with insight into material removal mechanisms. The experimental studies involve a comprehensive analysis of the laser-induced plume dynamics and measurements of the charge gained by the target during irradiation time. At ...

Laser materials processing techniques are expected to have a dramatic impact on materials science and engineering in the near future and beyond. One of the main laser materials processing techniques is Pulsed Laser Deposition (PLD) for thin film growth. While experimentalists search for optimal approaches for thin film growth with pulsed laser deposition (PLD), a systematic effort in theory and ...

Lasers represent an efficient and versatile tool to produce and to arrange in organized dispositions nanometer-sized particles, obtaining extended nanostructures with increasing degrees of complexity. In the first part of the chapter, the basic mechanisms of nanoparticle formation for nanosecond laser ablation in an ambient gas atmosphere and femtosecond ...

We used time-gated optical emission spectroscopy to investigate the characteristics of aluminum plumes and their vacuum expansion after femtosecond laser ablation at different fluences. The prominent feature is the presence of two main classes of species in the plume: very fast Al atoms and ions preceding the plume ...

We have used time and space-resolved optical emission spectroscopy to study the expansion dynamics of the plasma generated by pulsed laser ablation of solid targets of the recently discovered superconducting MgB2 into a background Ar gas at different pressures. Our analysis clearly indicates that, above a fixed pressure, plasma propagation into Ar leads to ...

The dynamics of a laser ablation plume during the first stage of its expansion, just after the termination of the laser pulse is modeled. First, we suppose the laser fluence range low enough to consider a neutral vapor. The expansion of the evaporated material is described by one-component fluid and one-dimensional Euler equations. The ...

The dynamics of a laser ablation plume during the first stage of its expansion, just after the termination of the laser pulse is modeled. First, we suppose the laser fluence range low enough to consider a neutral vapor. The expansion of the evaporated material is described by one-component fluid and one-dimensional Euler equations. The ...

Experiments were performed to understand laser-induced back-ablation of Al film targets with picosecond laser pulses. Al films deposited on the back surface of BK-7 substrates are ablated by picosecond laser pulses propagating into the Al film through the substrate. The ablated Al plume is transversely probed by a ...

The formation, composition and propagation of pulsed laser produced plasma plumes from an AlN target have been studied in real time by spatially and temporally resolved optical spectroscopy. The mean front velocity has been measured and appears to be slightly slower in the presence of added gas than in vacuum. In the initial stage of expansion, this velocity is almost the same ...

We have investigated ultrashort laser micromachining of metals, both from the point of view of the basic physical processes, and the technological implications. The process of hole drilling of Ni with ?300 fs SHG (? = 527 nm) Nd-glass and Al samples with 100 fs Ti:sapphire (? = 800 nm) laser pulses, respectively, has been experimentally addressed by using time-gated optical emission spectroscopy ...

A self-similar theory and numerical hydrodynamic modeling is developed to investigate the effects of dynamic source and partial ionization on the acceleration of the unsteady expansion of laser-ablated material near a solid target surface. The dynamic source effect accelerates the expansion in the direction perpendicular to the target ...

A self-similar theory and numerical hydrodynamic modeling is developed to investigate the effects of dynamic source and partial ionization on the acceleration of the unsteady expansion of laser-ablated material near a solid target surface. The dynamic source effect accelerates the expansion in the direction perpendicular to the target ...

Pulsed laser generated Fe plasma plumes have been studied near the target surface using time-resolved imaging. A fast gated intensified CCD camera is used to capture the images with a gate width of 2 ns. The plasma plumes were generated using a Q-switched Nd-YAG laser at 1064 nm with a fluence of �2 kJ/cm2. The expansion studies were done up to a ...

Laser materials processing has been used in the industry for drilling, cutting, welding, scribing, and etc. In most of the scientific papers, the authors assume that the laser energy imparted to the material is transformed into heat. This induces phase transformation as melting, fusion, sublimation, or vaporization. It is known that the atoms and ions are produced in high density plasma ...

A theoretical study of cluster formation in the plume produced by nanosecond laser pulses of moderate intensity in vacuum is undertaken on the basis of the Smoluchowski rate equations. Dynamics of the laser-induced plume expansion is described in a spherical approximation, taking into account ionization/recombination kinetics, the heat ...

The dynamics of the plume ejected from the surface of solid targets (YSZ, Nd:YAG and graphite) by a CO2 laser pulse with a duration of ~500 ?s (at the 0.03 level), energy of 1.0-1.3 J and peak power of 6-7 kW have been studied using high-speed photography of the plume luminescence and shadow. The targets were used to produce ...

Laser ablation of bulk High Temperature Superconductor (HTS) material promises to provide a useful means of producing high quality HTS thin films. Mass spectrometric probes of the ablation plume provide a microscopic understanding of the ablation event an...

Page 1. AFRL-VA-WP-TP-2006-327 ABLATION MODELING FOR DYNAMIC ... Page 4. Ablation Modeling for Dynamic Simulation of Reentry Vehicles ...

The aim of this study is to find thermal conditions for the formation of carbon annotates in a laser furnace. The proposed model includes a multi-species formulation for concentration of chemical components combined with the compressible Euler equations. An axisymmetric unsteady computational gas dynamic model of plume expansion into ambiance has been ...

Molecular dynamics (MD) simulations are used to study the interactions of photons with a poly(methyl methacrylate), or PMMA, substrate and point thermal absorbers. The point thermal absorbers are embedded within the polymer matrix which can be excited and transfer energy to the surrounding particles through an internal vibrational mode. Using a fluence above the ...

This paper mainly concerns on nanosecond and femtosecond laser spectroscopy of aromatic organic compounds as neurotransmitters, and plume diagnostics of the ablated species, in order to characterize the plasma dynamics, i.e. the temporal and spatial evolution of the plume. Optical emission spectroscopy has been ...

The (0,0) Swan band of the C{sub 2} molecules in a laser ablation plume produced on the surface of graphite target submerged in water was used as a probe to estimate the density of C{sub 2} molecules in the plume. Observed emission spectra were reproduced excellently by introducing a self-absorption parameter to the theoretical ...

In order to synthesis zinc oxide thin films and nanostructures, laser ablation of ZnO target into both vacuum and oxygen atmosphere was performed. The gas effect on the plume dynamics was studied for O{sub 2} pressures varied between 10{sup -2} to 70 mbar. Plasma plume evolution was investigated by ICCD camera fast ...

The structure and expansion characteristics of the plasma plume produced by laser ablation of a bulk tin target in vacuum have been investigated. A Q-switched Nd: YAG laser with 1064 nm wavelength, 5 ns pulse width, and the order of 10^11 W/cm^2 power density was employed to create ablation plasma. Time-of-flight (TOF) measurements ...

... Accession Number : ADD411034. Title : Heat transfer and ablation rate measurement in saturn s-11 ullage motor exhaust plume. ...

... PULSED LASER ABLATION OF A GRAPHITE/ EPOXY COMPOSITE ... Graphite/Epoxy Composite, Laser Ablation, Laser Shock, Time-of-Flight 30 ...

The fundamental physical processes that follow ultraviolet laser ablation of polycarbonate and borosilicate glass in air have been investigated using photodeflection as a function of the distance from the surface to probe laser. Four features were observed in the data sets for each material. Two of these features correlate well with gas dynamical ...

The dynamics of nanoparticle formation, transport, and deposition by pulsed laser ablation of c-Si into 1{endash}10 Torr He and Ar gases are revealed by imaging laser-induced photoluminescence and Rayleigh-scattered light from gas-suspended 1{endash}10 nm SiO{sub x} particles. Two sets of dynamic phenomena are presented for times up to ...

In this paper, the plume expansion dynamics of an ablated Sm2O3, Nd2O3 and NiO mixture oxides target by KrF laser into background oxygen atmosphere has been investigated using a fast ICCD imaging. The laser fluence was fixed at 2 J cm?2 and the surrounding ambient gas pressure was varied from vacuum to 50 mbar. Some effects as double ...

A numerical modelling describing a pulsed nanosecond laser interaction with a titanium target is presented, resulting in the study of the plume expansion in vacuum or in background gas, using the species transport model available in Fluent computational fluid dynamics code. The heat transfers in the solid target and the molten material are modeled using an ...

A numerical modelling describing a pulsed nanosecond laser interaction with a titanium target is presented, resulting in the study of the plume expansion in vacuum or in background gas, using the species transport model available in Fluent computational fluid dynamics code. The heat transfers in the solid target and the molten material are modeled using an ...

This work focuses on the study of the plumes obtained in the double pulse orthogonal Laser Induced Breakdown Spectroscopy (LIBS) in the pre-ablation configuration using both spectroscopic and shadowgraphic approaches. Single and double pulse LIBS experiments were carried out on a brass sample in air. Both the distance of the air plasma from the target ...

This thesis discusses the following on resonant holographic measurements of laser ablation plume expansion: Introduction to laser ablation; applications of laser ablation; The study of plume expansion; holographic interferometry; resonant holographic interferometry; accounting for finite laser ...

... I am involved with a study of plume dynamics as it relates to harmful algal blooms in ... The thesis considers the dynamics of wind-forced river plumes.

Plumes from wildfires and prescribed fires represent a critical aspect of smoke management and air quality assessment, ... to understand the structure and dynamics of these plumes, both with respect t...

Pulsed laser ablation of molecular solids is important for identification and quantification in (bio-)organic mass spectrometry, for example using matrix-assisted laser desorption/ionization (MALDI). Recently, there has been a major shift to using MALDI and related laser ablation/post-ionization methods at atmospheric pressure. However, the underlying ...

... of Carbon Nanotube Formation in a Laser Produced Plume: An Investigation of the Metal Catalyst by Laser Ablation Atomic Fluorescence Spectroscopy ...

... HEATING, GLASS FIBERS, HIGH ALTITUDE, PLUMES, LAUNCHERS, CONVECTION(HEAT TRANSFER), NUMBERS, ALTITUDE, AREA ...

... of Carbon Nanotube Formation in a Laser Produced Plume: An Investigation of the Metal Catalyst by Laser Ablation Atomic Fluorescence Spectroscopy ...

... Descriptors : *MATHEMATICAL MODELS, SIMULATION, ABLATION, PHYSICAL PROPERTIES, FILMS, PULSED LASERS, DEPOSITION, PLUMES ...

... of Carbon Nanotube Formation in a Laser Produced Plume: An Investigation of the Metal Catalyst by Laser Ablation Atomic Fluorescence Spectroscopy ...

The interaction of a laser-generated ablation plume with a background gas is of current interest for several materials-fabrication applications. During pulsed laser deposition (PLD) of thin films by laser ablation, for example, an ambient back ground gas (pressure usually {<=} 300 mTorr) is often employed. The ...

Pulsed laser ablation is a process in which an intense laser pulse interacts with the matter producing plasma. The present work describes the theoretical work being conducted in the past for the pulsed laser ablation phenomenon. It incorporates the theoretical models being proposed by various researchers around the globe for pulsed laser ...

Pulsed laser deposition (PLD) uses laser ablation of a solid target to accelerate atoms and ions in a high-density plasma to superthermal kinetic energies (typically 10-100 eV). These high kinetic energies have proven essential for the nonequilibrium formation of thin films of new ultrahard metastable phases, such as the synthesis of amorphous diamond (ta-C, ...

A laser ablation apparatus having a laser source outputting a laser ablation beam includes an ablation chamber having a sidewall, a beam divider for dividing the laser ablation beam into two substantially equal halves, and a pair of mirrors for converging the two halves on a surface of the target from complementary ...

A laser ablation apparatus having a laser source outputting a laser ablation beam includes an ablation chamber having a sidewall, a beam divider for dividing the laser ablation beam into two substantially equal halves, and a pair of mirrors for converging the two halves on a surface of the target from complementary ...

Laser ablation is now widely used for materials synthesis, removal, and analysis applications in fields from microelectronics to biomedicine with both inorganic and organic targets (e.g. see proceedings contents at COLA'97 - The Fourth International Conference on Laser Ablation - http://cola97.ornl.gov). The ...

The dynamics of a transient laser ablation plasma plume has been investigated by means of space- and time-resolved optical emission spectroscopy (OES), through a high-resolution monochromator and a fast gate ICCD camera. The experiments have been carried out with the third harmonic (355 nm) of a Q-switched (10 ns) Nd:YAG laser focused ...

Laser-induced breakdown spectroscopy (LIBS) has been used to map the distribution of particulate matter inside the plume created by laser ablation of a brass target. The spatial density distribution of the different components of the plume was determined in an attempt to reveal the mechanism of fractionation in the process of the laser ...

We have developed an extreme sensitive trace element detection technique that has been labeled Laser ablation atomic fluorescence (LAAF) spectroscopy, and applied to a nanometer-scale solid surface analysis. The absolute weight of the detection limit of 870 ag (10-18g) and high depth resolution of 3.6 nm had been demonstrated in trace sodium detection of ...

We report evidence of nanoparticles formation in laser ablated carbon plasma created by irradiating a graphite target with nanosecond neodymium doped yttrium aluminum garnet laser. The temporal evolution and spatial distribution of C{sub 2} molecules in the plasma is studied using optical emission spectroscopy, dynamic imaging and laser induced ...

Copper targets are irradiated in the ablation regime by pairs of equal, time-delayed collinear laser pulses separated on a timescale going from ~2 ps to ~2 ns. The ablation plume is characterized by ion probe diagnostic, fast imaging, and temporally and spatially resolved optical emission spectroscopy. The variation in the ...

... coastal/nearshore modeling system for river plume dynamics, sediment ... WAVES, *SEDIMENT TRANSPORT, *RIVERS, *PLUMES, OCEAN TIDES ...

... of centerline-mounted engines acted to produce plume momentum persistence ... mount!i engines produced discrete plumes having development ...

Industrial plumes, particularly those of power plants, have been studied for a considerable period of time. The majority of these studies, however, have concentrated exclusively on either the dynamics or the chemistry of such plumes. The number of studies dealing with the interaction of plume ...

A computational fluid dynamics study is conducted to examine nozzle exhaust jet plume effects on the

... LASER BEAMS, *NUCLEAR FUSION, ABLATION, PLASMAS ... LASERS, MOMENTUM TRANSFER, PLASMA DIAGNOSTICS, FOILS(MATERIALS ...

Plasma plume induced by laser ablation of a hydroxyapatite (Ca10(PO4)6(OH)2) target was studied in different ambient conditions. ArF excimer laser operated at the wavelength of 193 nm with the pulse energy of 300 mJ and 20 ns pulse duration. The emission spectra of the plasma plume were registered with the use of a fast gate, lens ...

Rapid transformations through the liquid and vapor phases induced by laser-solid interactions are described by the authors` thermal model with the Clausius-Clapeyron equation to determine the vaporization temperature under different surface pressure condition. Hydrodynamic behavior of the vapor during and after ablation is described by gas dynamic ...

Rapid transformations through the liquid and vapor phases induced by laser-solid interactions are described by the authors' thermal model with the Clausius-Clapeyron equation to determine the vaporization temperature under different surface pressure condition. Hydrodynamic behavior of the vapor during and after ablation is described by gas dynamic ...

The irradiation of a steel surface in atmospheric pressure ambient was performed to study the surface nanostructuring resulting from the formation of a backward-deposited layer. The dynamics of the plume expansion and of the nanoparticle deposition process were investigated by in situ time-resolved optical analysis. Scanning electron microscopy and atomic ...

Emission from YBCO laser-ablated plumes was studied to characterize the PLD process. A KrF laser was used to ablate a bulk YBCO target at oxygen pressures ranging from 50-400 mTorr. Spectra were collected for the 500-860 nm bandpass at target distances ra...

The time-resolved optical emission studies of laser ablated carbon plasma in nitrogen ambient are carried out to understand the dynamic of formation of C2 and CN for depositing quality thin films. An optimum formation of C2 is observed at 3 mm from the target surface and 350 ns after the initiation of plasma. However, CN is formed at comparatively larger ...

Various physical processes during laser ablation of solids for pulsed-laser deposition (PLD) are studied using a variety of computational techniques. In the course of the authors combined theoretical and experimental effort, they have been trying to work on as many aspects of PLD processes as possible, but with special focus on the following areas: (a) the effects of ...

Combined diagnostic measurements are employed to characterize the penetration of energetic ablation plumes through background gases during a key transitional regime in which the ion flux is observed to split into distinct fast and slowed components. This apparently general phenomenon occurs over a limited range of distances at ambient pressures typically ...

The effects of ablation on re-entry body dynamics is a problem that during recent years has advanced from one of general interest to one of general concern. An exploratory analysis shows that ablation will have opposite effects on static and dynamic stabi...

The handbook summarizes information in the areas of leachate plume dynamics and plume management alternatives. The handbook describes factors that affect leachate plume movement, key considerations in delineating the current and future extent of the leachate plume, technologies for controlling ...

A combined experimental and computational study is performed to investigate the origin and characteristics of the surface features observed in SEM images of thin polymer films deposited in matrix-assisted pulsed laser evaporation (MAPLE). Analysis of high-resolution SEM images of surface morphologies of the films deposited at different fluences reveals that the mass distributions of the surface ...

The physical mechanisms that enable short pulses of high-intensity ultraviolet laser radiation to remove tissue, in a process known as laser ablation, remain obscure. The thermodynamic response of biological tissue to pulsed laser irradiation was investigated by measuring and subsequently analyzing the stress transients generated by pulsed argon fluorine (ArF, lambda = 193 nm) ...

An advanced rarefied gas dynamic capability to simulate plume flow fields, plume surface interactions at high altitudes, and plume chemical mechanisms will provide the AF with the tools to adequately address recent problems critical to several AF programs...

Previous studies have shown that changing the pulse structure of the free electron laser (FEL) from 1 to 200 ps and thus reducing the peak irradiance of the micropulse by 200 times had little or no effect on both the ablation threshold radiant exposure and the ablated crater depth for a defined radiant exposure. This study focuses on the ...

... Accession Number : ADA538313. Title : Passive Ranging of Dynamic Rocket Plumes Using Infrared and Visible Oxygen Attenuation. ...

... Title : MOL Fluid Dynamics Preliminary Data Report: Thrustor Plume Tests. Sequence Number B319. Item Data Number UT-132,. ...

The author's theory of dynamic viscous pressure interaction has been extended to cases with surface ablation by sublimation. It has been shown that the two very large and opposite effects of aftbody ablation and forebody ablation on pitch damping of a sle...

... Accession Number : ADD856147. Title : Surface Composition Changes and Ablation Dynamics in Excimer Laser Irradiated CdTe. ...

Page 1. AFRL-VA-WP-TP-2006-302 ABLATION MODELING FOR DYNAMIC SIMULATION OF REENTRY VEHICLES (PREPRINT) ...

Laser ablation particle plume compositions are characterized using inductively coupled plasma mass spectrometry (ICP/MS). This study evaluates the mass response characteristics peculiar to ICP/MS detection as a function of laser fluence and frequency. Eva...

Page 1. Electronic State Distributions of Y Ba2Cu3O7�x Laser Ablated Plumes DISSERTATION Patrick D. Kee, Lieutenant Colonel, USAF ...

This paper presents an updated review of studies on Ablative Laser Propulsion conducted by the Laser Propulsion Group (LPG) at the University of Alabama in Huntsville. In particular, we describe the experimental technique developed for determination of specific impulses from plasma plume imaging with an intensified CCD camera.

and hydrothermal or impact events. .... angle optical measurement will determine total turbidity. Climate history ... to minimize plume induced surface ablation. ...

... Themicro-laser plasma thruster (uLPT) discussed here ... by focusing the laser through a ... ION DENSITY, *DIODE LASERS, VELOCITY, ABLATION ...

by Laser Ablation Atomic Fluorescence Spectroscopy. Gary De Boer. .... Atomic fluorescence spectroscopy is an extremely sensitive means of ...

Measurements of the angle-dependent ablation rates of polymers that have applications in microdevice fabrication are reported. A simple model based on Beer's law, including plume absorption, is shown to give good agreement with the experimental findings for polycarbonate and SU8, ablated using the 193 and 248 nm excimer ...

Measurements of the angle-dependent ablation rates of polymers that have applications in microdevice fabrication are reported. A simple model based on Beer's law, including plume absorption, is shown to give good agreement with the experimental findings for polycarbonate and SU8, ablated using the 193 and 248 nm excimer lasers, ...

Mechanisms of energy transport during ultrashort laser pulses (USLPs) ablation are investigated in this paper. Nonequilibrium electron-transport, material ionization, as well as density change effects, are studied using atomistic models--the molecular dynamics (MD) and Monte Carlo (MC) methods, in addition to the previously studied laser absorption, heat ...

Mechanisms of energy transport during ultrashort laser pulses (USLPs) ablation are investigated in this paper. Nonequilibrium electron-transport, material ionization, as well as density change effects, are studied using atomistic models�the molecular dynamics (MD) and Monte Carlo (MC) methods, in addition to the previously studied laser absorption, heat ...

A time resolved imaging study of pulsed laser ablated Fe and Al plasma plumes with specific interest in the splitting of plumes into the slow and fast moving components as they expand through the background argon gas at different pressures is reported. The material ablation was achieved using a Q-switched Nd:YAG ...

We report on investigations of plasmas produced by laser ablation of fresh potatoes using infrared nanosecond laser radiation. A twin laser system consisting of two Nd:YAG oscillators was used to generate single or double pulses of adjustable interpulse delay. The potatoes were irradiated under ambient air with moderate pulse energies of about 10 mJ. The expansion ...

Using picosecond time-resolved shadowgrams and interferograms, we measured the lateral expansion of an early stage ablation plasma induced by a 1064 nm, 35 ps laser pulse on a copper target. The plasma was found to have an electron density on the order of 10{sup 20} cm{sup -3} near the target surface. Prior to the expanding material vapor plume, this high ...

A new concept of pulse laser ablation target were proposed. The idea is two-fold; that is, the target material to be ablated is a very thin layer deposited on a surface of some substrate material. As the substrate material, we will choose a transparent material like polymer or glass. Through the transparent material, a pulse laser beam is focused onto the ...

Presented here is a novel ambient ion source termed infrared laser ablation metastable-induced chemical ionization (IR-LAMICI). IR-LAMICI integrates IR laser ablation and direct analysis in real time (DART)-type metastable-induced chemical ionization for open air mass spectrometry (MS) ionization. The ion generation in the IR-LAMICI source is a two step ...

The influence of pulsed laser ablation of an aluminum target on the nitrogen plasma produced by electron cyclotron resonance (ECR) microwave discharge has been studied by optical emission spectroscopy (OES) with time and space resolution. The continuous wave (CW) feature of the optical emissions from the ECR nitrogen plasma turns to vary with time and space due to pulsed laser ...

The plume-in-grid modeling approach for treating the subgrid scale dispersion, transport, and chemistry of pollutants contained in plumes released from major point source stacks is described. A plume dynamics model provides the plume rise height, plume po...

A new two-layer reactive plume model is developed, in which arbitrary crosswind resolution of the emission field of each precursor is preserved, and dynamic plume-plume and plume-background interactions are explictly accomodated. The model has a hybrid fo...

A new two-layer reactive plume model is developed, in which arbitrary crosswind resolution of the emission field of each precursor is preserved, and dynamic plume-plume and plume-background interactions are explictly accomodated. The model has a hybrid formulation, having Lagrang...

Gated photon counting spectroscopy and species-resolved ICCD photography were used to study the weak plasma luminescence following the propagation of the initial ablation plume in vacuum and during the rebound of the plume with a substrate during pulsed laser deposition of amorphous diamond. These methods techniques were required in ...

The ablation of metallic targets from Al, Cu, Nb, Ta has been studied under irradiation with 308 nm excimer XeCl laser. A single-wire electron Langmuir probe has been used in time-of-flight measurements of velocity of plume ions scatter. An investigation has been pursued of the dependence of ion current shape at the probe both on laser radiation flux in ...

... Corporate Author : MACKAY SCHOOL OF MINES RENO NV DEPT OF CHEMICAL AND METALLURGICAL ENGINEERING. ...

... SCIENTIFIC RESEARCH), ABLATION, FLUID DYNAMICS ... AND MAGNETOHYDRODYNAMICS RADIOFREQUENCY WAVE PROPAGATION. ...

Observations of plumes from two or more stacks show that the plumes frequently merge as they rise. If the resultant plume rises higher than the individual plumes would have separately, the rise is enhanced. This report describes a study, conducted under contract to the State of Maryland's Power Plant ...

The plume dynamics in the presence of an ambient gas is very intriguing physics. The expansion of a laser-produced plasma in the presence of an ambient gas leads to internal plume structures, plume splitting, sharpening, confinement, etc. We investigated propagation dynamics of an expanding tin ...

A cerium oxide sample was ablated by 2nd harmonic radiation of Nd:YAG laser at a power density of 0.1 GW/cm2. Time evolution of the ablation plume was investigated by laser absorption time-of-flight (TOF) measurement. It was found that the ablated ionic plume in vacuum consisted of two ...

We report high-order harmonic generation from doubly charged ions in laser-ablation plasma produced by different prepulse intensities. At the prepulse intensity of 3.5x10{sup 10} W cm{sup -2}, harmonics up to the 63rd order (12.62 nm wavelength, 98.3 eV photon energy) were obtained by using a laser-ablation titanium plume. From ...

Mar 1, 2011 ... Results are compared to a computational fluid dynamics (CFD) plume model. The added diagnostic capability at WSTF propulsion facilities will ...

Mar 1, 2011 ... Results are compared to a computational fluid dynamics (CFD) plume model. The added diagnostic capability at WSTF propulsion facilities will ...

Apr 15, 1998 ... Twin jet plumes on aircraft can couple, producing higher dynamic pressures in the internozzle region, which in turn can cause sonic fatigue ...

predict the concentrations correctly, because the initial rise of the hot, dynamic jet plumes is unknown. In this project scanning lidars (or laser radars) with eyesafe, invisible...

OF JET PLUME. MODULES. SUPERSONIC. JET. PLUME. DYNAMICS. SUPERSONIC. HIGH-ALPHA ... FAN RESEARCH. HIGH. REYNOLDS. NUMBER. (HEAT. TRANSFER). DETAILED ...

Nov 16, 2010 ... Description: Plumes from wildfires and prescribed fires represent a critical aspect of smoke mangement and aire quality assessment, ...

May 31, 2011 ... Computational fluid dynamics (CFD) analysis has been performed to study the plume effects on sonic boom signature for isolated nozzle ...

The characteristics of ablation plasma from planar targets, driven by long Nd:glass laser pulses (4 nsec,

The characteristics of ablation plasma from planar targets, driven by long Nd:glass laser pulses (4 nsec,