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 ...
E-print Network
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...
National Technical Information Service (NTIS)
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 plume ...
Energy Citations Database
The propagation of laser-induced shockwaves from ablation inside of cavities was determined from time-resolved shadowgraph images. The temperature and electron number density of the laser-induced plasma was determined from spectroscopic measurements. These properties were compared to those for laser ablation on the flat surface under ...
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 ...
NASA Astrophysics Data System (ADS)
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 plume propagation in ...
DOE Information Bridge
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 ...
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...
We report the effect of 'plasma pipe' formation on pulsed laser ablation of organic polymers in air under normal conditions. Ablation of polymers (PMMA, polyimide) is carried out in a wide range of CO2 laser fluences with special attention to plasma formation in the ablation products. Evolution of laser ablation ...
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, momentum, and energy. The ...
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 ...
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, and energy. The ...
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 configuration, a laser is focused ...
The computational procedure for signal propagation in the presence of an exhaust plume is presented.
NASA Technical Reports Server (NTRS)
... Descriptors : *ABLATION, *ATMOSPHERE ENTRY, *PLASMA ... AND MAGNETOHYDRODYNAMICS RADIOFREQUENCY WAVE PROPAGATION. ...
DTIC Science & Technology
... ANALYSIS, COMPUTER PROGRAMS, ABLATION, ATMOSPHERE ENTRY ... Subject Categories : RADIOFREQUENCY WAVE PROPAGATION ...
... THRUSTERS, STEADY STATE, ABLATION, MATERIALS, SCALING ... NUMERICAL MATHEMATICS RADIOFREQUENCY WAVE PROPAGATION ...
... 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 ...
Generation of low-order harmonics (third and fifth) of the fundamental radiation of a Q-switched Nd:YAG laser (1064 nm, pulse 15 ns) was observed in a CaF{sub 2} laser ablation plume. The ablation process is triggered by a second Q-switched Nd:YAG laser operating at 532 or 266 nm. In the scheme employed, the fundamental laser beam ...
Generation of low-order harmonics (third and fifth) of the fundamental radiation of a Q-switched Nd:YAG laser (1064 nm, pulse 15 ns) was observed in a CaF2 laser ablation plume. The ablation process is triggered by a second Q-switched Nd:YAG laser operating at 532 or 266 nm. In the scheme employed, the fundamental laser beam ...
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 ...
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 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 dynamics of 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 ...
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 diameter about 1 mm) and ...
In an ongoing effort to investigate plasma plume features yielding high quality diamond-like carbon films, we have applied plasma plume diagnosis and film characterization to examine plume character distinction from KrF laser ablation of both amorphous carbon (a-C) and single crystal graphite (SCG) targets. The ...
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 account. At later stages, compete absorption of ...
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 predictions for the expansion ...
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 ...
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...
The KrF-laser ablation of graphite into 300 Torr of He, Ne, Ar, and Xe has been studied by fast imaging of the plasma emission and post-deposition analyses of collected film deposits. In each case, the soot which was redeposited on the irradiated rod following ablation was highly fullerene-deficient compared to the material collected on the sample disk 1.5 ...
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 ...
The vibrational populations of the YO A{sup 2}II-{Chi}{sup 2}{Sigma} system of YO were measured in the plasmas generated after the excimer laser ablation of Y{sub 2}O{sub 3} in oxygen when both continuous and pulsed electric fields were applied. When an electric field is applied antiparallel to the direction of propagation of the ejected electrons, two ...
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 15 s after KrF-laser ...
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 ...
The formation, composition, and propagation of KrF laser-produced plasmas from Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-x} have been studied with emphasis on topics relevant to film growth by pulsed-laser deposition. Spatially and temporally resolved, high-resolution optical absorption and emission spectroscopy, fast ion probes, and fast photography (obtained with a gated, ...
Optical reflectivity, removal rate and ablative recoil pressure magnitudes were measured as a function of laser fluence during high-power UV nanosecond laser ablation of graphite. At low fluences only melting and weak surface vaporization of molten carbon were observed. At moderate fluences there is a very narrow fluence interval where the reflected ...
... 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 ...
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 ...
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, ...
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.
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...
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 ...
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 ...
... of Carbon Nanotube Formation in a Laser Produced Plume: An Investigation of the Metal Catalyst by Laser Ablation Atomic Fluorescence Spectroscopy ...
NASA Website
... HEATING, GLASS FIBERS, HIGH ALTITUDE, PLUMES, LAUNCHERS, CONVECTION(HEAT TRANSFER), NUMBERS, ALTITUDE, AREA ...
... Descriptors : *MATHEMATICAL MODELS, SIMULATION, ABLATION, PHYSICAL PROPERTIES, FILMS, PULSED LASERS, DEPOSITION, PLUMES ...
This work investigates the effect of polymer molecular weight M{sub W} on the plume characteristics of poly(methyl methacrylate) (PMMA) and polystyrene (PS) films doped with iodonaphthalene (NapI) and iodophenanthrene (PhenI) following irradiation in vacuum at 248 nm. Laser-induced fluorescence probing of the plume reveals the presence of ArH products ...
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 ...
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 ...
DOEpatents
... MAGNETIC MATERIALS, FREQUENCY, ABLATION, TEMPERATURE, LOW ... AND MAGNETISM RADIOFREQUENCY WAVE PROPAGATION. ...
... LASERS, ATMOSPHERE ENTRY, ABLATION, IONOSPHERIC PROPAGATION ... MECHANICS THERMODYNAMICS RADIOFREQUENCY WAVE ...
... SCIENTIFIC RESEARCH), ABLATION, FLUID DYNAMICS ... AND MAGNETOHYDRODYNAMICS RADIOFREQUENCY WAVE PROPAGATION. ...
... of hot air and of typical ablation products and ... ELECTRICAL AND ELECTRONIC EQUIPMENT RADIOFREQUENCY WAVE PROPAGATION ...
... techniques of pulsed laser ablation and reactive ... ELECTRICAL AND ELECTRONIC EQUIPMENT RADIOFREQUENCY WAVE PROPAGATION. ...
... REENTRY VEHICLES, SIMULATION, ABLATION, INJECTION, PROBES ... Subject Categories : RADIOFREQUENCY WAVE PROPAGATION ...
... of the ambient gases and ablation of the heat ... PLASMA PHYSICS AND MAGNETOHYDRODYNAMICS RADIOFREQUENCY WAVE PROPAGATION ...
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...
of buoyancy is supplied at a localized source. We studied laminar plumes where buoyancy is supplied reaction produces a sharp propagating front at which buoyancy is produced by exothermicity and composi buoyant fluid is incorporated into the plumes, entrainment in autocatalytic plumes provides a buoyancy
Removal rate, air shock, and ablative recoil pressure parameters were measured as a function of laser intensity I(peak) during nanosecond laser ablation of graphite. Surface vaporization of molten graphite at low intensities I(peak)<0.15 GW/cm(2) was observed to transform into its near-critical phase explosion (intense homogeneous boiling) at the ...
PubMed
Removal rate, air shock, and ablative recoil pressure parameters were measured as a function of laser intensity Ipeak during nanosecond laser ablation of graphite. Surface vaporization of molten graphite at low intensities Ipeak<0.15GW/cm2 was observed to transform into its near-critical phase explosion (intense homogeneous boiling) at the threshold ...
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 ...
Nanosecond pulsed laser irradiation is shown to be effective for cleaning contaminant particles as small as 0.3 ?m in diameter from NiP magnetic hard disk substrates. A micron-thick liquid film is deposited on the disk surface just before the laser irradiation. The cleaning threshold and efficiency are investigated for the fundamental and frequency-tripled Nd:YAG laser harmonics (wavelengths ...
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 ...
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 ...
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 observations. The ...
Disturbances in the Earths�s ionosphere and magnetosphere caused by impacts of small comets and asteroids (with diameters from 50 60 m to 1 2 km) are analyzed. Two-dimensional hydrodynamical computations of the passage of a cosmic body through the atmosphere with allowance for deceleration and destruction due to aerodynamic loading and formation of the wake behind the body are performed. The ...
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 ...
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 ...
... routines of the plume diagnostic code EMABIC. ... study, (1) a formalism and computer code (EM.ABIC ... strains the storage capacity of many computers. ...
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 the important aspects of nanosecond-scale ...
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 patterns of a planar ...
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 ...
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 penetration of energetic pulsed ablation plumes through ambient gases is experimentally characterized to investigate a general phenomenon believed to be important to film growth by pulsed laser deposition (PLD). Under typical PLD conditions involving background gases, the ion flux in the ablation plume is ...
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, the Kelvin-Helmholtz ...
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 ...
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 equations. These two models ...
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 equations. These two models ...
A coupled geochemical transport model (MPATH) which includes chemical reaction kinetics is used to evaluate the alteration of Swiss argillaceous sediments in a high-pH environment and to predict the spatial propagation of the hyperalkaline plume with time...
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 spectroscopy for the Al III ...
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 ...
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.
... YTTRIUM ALUMINUM GARNET, ABLATION, REPETITION RATE ... AND MEDICAL RESEARCH RADIOFREQUENCY WAVE PROPAGATION. ...
The ''plasma bullet'' behavior of atmospheric pressure plasma plumes has recently attracted significant interest. In this paper, a specially designed plasma jet device is used to study this phenomenon. It is found that a helium primary plasma can propagate through the wall of a dielectric tube and keep ...
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 ...
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, ...
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 ...
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 ...
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 ambient oxygen pressures. ...
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 ...
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 conduction, and stress ...
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 conduction, and ...
Plume Ryan M. McCabe, Barbara M. Hickey, and Parker MacCready University of Washington, School River plume are presented. Drifting buoys deployed in ebbing plume water downstream of the lift layer. Drifters released near the river mouth, shoreward of the propagating ocean-plume front, catch up
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 laser ...
The technique of laser-induced ablation of thin films from glass slide substrates has been investigated as a candidate vapor target production method for studies of both tunneling-driven x-ray/xuv recombination lasers and relativistic propagation using intense, ultra-short laser pulses. It is shown by simultaneous two-wavelength interferometry that ...
Spatial and temporal distributions of species emitted from ablation of zinc oxide target by a pulsed-electron beam are studied by the complementary use of optical emission spectroscopy and camera fast imaging. We show that the slowest electrons produced by the accelerating tube in the pulsed-electron beam deposition (PED) system interact with the plasma ...
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 ...
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 ...
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 ...
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 ...
Spatial profile of ablation front is observed under the irradiation of spatially modulated 0.27-..mu..m laser beam. Propagation depth of the ablation front is derived by means of various methods which detect x-ray radiation from aluminum substrates overcoated with polyethylene layers of different thicknesses. A higher mass ...
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 ...
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 compared with Langmuir ...
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 ...
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 ...
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 flare, and temporal ...
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 ? = 355-470 nm and time ...
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 ...
Determination of the rates of laser ablation (etching) of various materials by powerful (up to 1014 W cm-2) pulsed radiation revealed a considerable reduction in the etching efficiency during shaping of deep ablation channels. The optical characteristics of the resultant plasma � vapour plume were measured. These measurements and ...
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 ablated ...
This project involved a systematic study to apply newly discovered isotopic enrichment effects in laser ablation plumes to the fabrication of isotopically engineered thin films, superlattices, and nanostructures. The approach to this program involved using ultrafast lasers as a method for generating ablated plasmas that have ...
The ablation by ultrashort laser pulses at relatively low fluences (i.e., in the thermal regime) of solids wetted by a thin liquid film is studied using a generic numerical model. In comparison with dry targets, the liquid is found to significantly affect ablation by confining the solid and slowing down the expansion of the laser-heated material. These ...
Ablation of gold nanoparticle films on polymer was explored using a nanosecond pulsed laser, with the goal to achieve feature size reduction and functionality not amenable with inkjet printing. The ablation threshold fluence for the unsintered nanoparticle deposit was at least ten times lower than the reported threshold for the bulk film. This could be ...
ablation and the direct simulation Monte Carlo (DSMC) method for simulation of the multi-component ablation description, direct simulation Monte Carlo (DSMC) [18], is chosen for extending the MD breathing sphere model into the larger scale. In order to adopt the results of MD simulation as input for the DSMC calculation, we have
There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface ...
Hook spectroscopy has been used to determine the absolute number density of ground state copper atoms in laser-ablated plasma plumes. An ablation laser power flux of (approximately) 1.5 GW/cm(sup 2) is applied to a solid copper target in a background gas,...
A study was made of the cooling of the laser induced vapor plume in background air. The temperature and size variations of the vapor plume were determined from spectroscopic measurements during the first few tens of microseconds after the laser pulse. Experiments were carried out over a range of laser spot sizes and energies. The energy transport by ...
Electric propulsion systems have now reached a level of maturity where they are being used on operational spacecraft. One concern for the designers however, is the effect of the ion exhaust plumes produced by the systems, on microwave communication with t...
In this study, we obtain simple estimates of 1-D plume propagation velocity taking into account the density and viscosity contrast between CO(sub 2) and brine. Application of the Buckley-Leverett model to describe buoyancy-driven countercurrent flow of tw...
While using a laser to process hard tissue, it is difficult to guarantee, that the laser beam is always perpendicular to the tissue surface. Therefore, it is necessary to know the dependence of ablation depth on angle of incidence for preoperative planning. Considering the propagation of the ablation front, an Addition Model is ...
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 ...
Time development of Sm+ and Sm ablation plume produced by the femtosecond laser irradiation has been investigated. The two-dimensional spatial profiles of Sm and Sm+ emitted from oxidized and non-oxidized Sm surface were visualized using a planar laser-induced fluorescence method. It was observed that the flow velocity of Sm+ is much faster than that of Sm ...
A study has been made of the generation of particles during laser ablation and has included size distribution measurements and observation of the formation processes. The particle size distribution with respect to different laser parameters was obtained in-line using a differential mobility analyzer (DMA) and a particle counter. The experimental results show that the particle ...
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 ...
A comparative experimental study of pulsed laser ablation in vacuum of two binary semiconductors, zinc oxide and indium phosphide, has been performed using IR- and visible laser pulses with particular attention to cluster generation. Neutral and cationic Zn{sub n}O{sub m} and In{sub n}P{sub m} particles of various stoichiometry have been produced and investigated by ...
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. Evaluation of the ICP/MS mass response allows deductions to be made concerning how representative the ...
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 luminous ...
Femtosecond laser ablation of Ti, Zr, and Hf has been investigated by means of in situ plasma diagnostics. Fast imaging was used to characterize the plasma plume expansion on a nanosecond time scale. In addition, time- and space-resolved optical emission spectroscopy was employed to determine the plume composition and the ...
Expansion of ablation plumes created by intense ultrashort lasers is determined by various complicated physical processes which have very different spatial and time scales. Since complete simulation by one model is practically impossible, the authors suggest using two models describing initial and final stages that can be matched at an intermediate time. ...
The emission spectrum of the 3?i-3?i (0-0) AlN band and some N+ and N emission lines have been studied in the visible region for the laser ablated plumes. The Stark-shift and Stark broadening were observed. The component species in the ablated plumes were analyzed by time of flight mass spectroscopy. The electron ...
We have successfully demonstrated intensity enhancement of a single high-order harmonic at a wavelength of 46.76 nm by using low-ionized tin ions in a laser-ablation plume as the nonlinear medium. The ablation plume was produced by irradiating a solid tin target with a 10 mJ energy picosecond laser pulse. Strong ...
The plumes accompanying 1064 nm nanosecond pulsed laser ablation of barium in vacuum at three moderate incident laser fluences in the range of 5.3-10.8 J/cm2 have been studied using both wavelength and time resolved optical emission spectroscopy and time-of-flight laser-induced fluorescence. Neutral atoms and both singly and doubly charged monatomic ...
The pulsed laser deposition of YBa2Cu3O7?x targets by excimer laser at fluences of 4-10 J cm?2 in low pressure oxygen backgrounds yields emissive plumes with kinetic energies of 50-200 eV, driving the formation of a shock front with Mach numbers of M = 10-50. The propagation of the shock front is independent of atomic species and adequately characterized ...
The laser ablation of microparticle (LAM) process was used to study nanoparticles of multi-component materials. The production process utilized laser ablation of a continuously flowing aerosol of micron-sized particles under a gas ambient. An aerosol generator entrained microparticles into a gas flow and directed them through a nozzle into a laser ...
In this paper, laser ablation atomic fluorescence (LAAF) spectroscopy has been applied for a nanometer-scale solid surface analysis of Na-doped polymethyl methacrylate (PMMA). LAAF spectroscopy is a new sensitive element detection technique which involves atomizing of a sample by the laser ablation and detection of the ablated ...
We have studied ultrafast laser ablation of nickel using a pair of identical ~250 fs 527 nm laser pulses separated by ~1 to ~1000 ps. Scanning white light interferometry was used to measure the ablated volume, and an ion probe was used to measure the angular distribution of the ablation plasma plume and the total ...
(2009) showed that Earthward propagating EMIC waves preferentially follow the high density dege of magnetospheric plasma drainage plumes (Morley et al., ...
Jun 28, 2011 ... (2009) showed that Earthward propagating EMIC waves preferentially follow the high density dege of magnetospheric plasma drainage plumes ...
... and BTO films on LaA103 by laser ablation. ... Subject Categories : MECHANICS RADIOFREQUENCY WAVE PROPAGATION COMBUSTION AND ...
The propagation of the laser-induced plasma formed by KrF irradiation of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7} has been characterized in background pressures of oxygen and argon typically used for thin film growth. The ion current transmitted through the background gases was recorded along the normal to the irradiated pellet as a function of distance in order to measure the ...
Numerous atomic analytes in plumes produced by pulsed-laser ablation fluoresced upon ArF laser irradiation. The likely mechanism was photoexcitation to levels near the ionization limit. These levels were dense and were probably broadened by the extreme plume density to allow efficient absorption of 193 nm photons. The excited atoms ...
The time-of-flight probe method was used in investigations of erosion plume in ablation of copper with 308 nm radiation of excimer XeCl laser in vacuum. The time-of-flight curves of electron and ion currents at the probe were obtained in the range from 0.2 to 2.2 J/cm-2 of energy densities at the target with probe-to-target separations from 10 to 133 mm. ...
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 plume. ...
We present observations of shallow ( �0.3 m deep) fresh surface plumes as they propagate across the flooded tidal flats of Skagit Bay. Across-plume salinity, temperature, and velocity transects were obtained using CTDs, and a pair of pulse-coherent ADCPs cantilevered in front of a small boat (0.025~m, 0.05~m, and 0.125~s vertical, ...
Resonant holographic interferometry (RHI) and dye-laser resonance absorption photography (DLRAP) have been utilized to investigate the expansion of the laser ablation plumes produced by a KrF excimer laser beam (248 nm) focused onto an aluminum target (approximately equals 0.1 cm(exp 2), 2-6 J/cm(exp 2)). Plume expansion was studied in ...
The precise characterization of plasmas generated by laser irradiation is needed for the development of ion sources. As the characteristic parameters of the expanding plasma vary with both the distance and the time, an experimental study of their evolution is appropriate for a deeper knowledge of the plasma. The purpose of this work is to study the same characteristics of laser plasma produced by ...
The micro laser plasma thruster (?LPT) is a sub-kilogram thruster that is capable of meeting the Air Force requirements for the Attitude Control System on a 100-kg class small satellite. The ?LPT uses one or more 4W diode lasers to ablate a solid fuel, producing a jet of hot gas or plasma which creates thrust with a high thrust/power ratio. A pre-prototype continuous thrust ...
The results of investigations are presented which are concerned with laser radiation absorption in a target, the plasma state of its ablated material, the energy transfer to the solid target material, the characteristics of the shock wave and craters on the target surface. The investigation involved irradiation of a planar target by a subnanosecond plasma-producing laser ...
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 dynamics using ultrafast ...
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 ...
In laser materials processing, localized evaporation caused by focused laser radiation forms a plume of mixed vapor and ambient gas above the material surface. The beam is refracted and absorbed as it traverses the plume, thus modifying its power density on the surface. In this work, plume-beam interaction is studied using an ...
The propagation of rf waves launched in the end cell and central of the tandem mirror propulsion device has been investigated both theoretically and experimentally. Theoretically, a computer code has been developed to study the wave propagation in a nonho...
In order to give the additional forward thrust to the projectile other than the electromagnetic force, the axial symmetric launcher called ablation mass driver (AMD) has been proposed using sequential z pinches in a cylindrical electrode array. The additional driving force originates from the reaction of ablating hot gas from the ...
Laser Induced Breakdown Spectroscopy LIBS is a fast non-contact technique for the analysis of the elemental composition using spectral information of the emission from a laser-induced plasma. For the LIBS studies in this thesis the focus has been in using very low energy, microjoule pulses in order to give high spatial resolution and minimize the laser system requirements. This is a regime that we ...
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 ...
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 defined by the interplay of a number of ...
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...
of the Lawrence Berkeley National Laboratory. (1) Laser pulse is applied; (2) Induced plasma plume expands into the anbient gas; (3) particle formation occurs from solid-sample...
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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...
target during carbon nanotube production by the double-pulse laser oven method. The in- .... 10 Hz high power pulsed Nd:YAG lasers are used for the ablation ...
New satellite observations reveal lower thermospheric transport of a space shuttle exhaust plume into the southern hemisphere two days after a January, 2003 launch. A day later, ground-based lidar observations in Antarctica identify iron ablated from the ...
The Teflon(TM) ablation in a micro-Pulsed Plasma Thruster is studied with an aim to understand the charring phenomena. Microscopic analysis of the charred areas shows that it contains mainly carbon. It is concluded that the carbon char is formed as result...
Prepared for the 1995 32nd Combustion Subcommittee; Propulsion Systems Hazards Subcommittee, 22nd Exhaust Plume Technology Subcommittee, and 4th SPIRITS ...
Time-dependent buoyant plumes form at the outflow of tidally dominated estuaries. When estuary discharge velocity exceeds plume internal wave speed c, a sharp front forms at the plume's leading edge that expands from the time-dependent source. Using observations of the Columbia River tidal plume from multiple tidal ...
The pulsed laser ablation of aluminium, copper and titanium irradiated with 4.5 ns pulses at 355 nm, 532 nm and 1064 nm wavelengths is investigated in open air at normal atmospheric conditions. The effect of pulse number, which is varied in the range of 5 to 50, on ablation rate in these three wavelength regimes is determined. The results indicate a higher ...
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 study is similar to our ...
Laser desorption/ionization from structured surfaces has been the object of recently renewed interest. Conditions in the plume of material ablated from such surfaces may differ from those of a sample which is ablated in bulk. Since recombination and secondary ion-molecule reactions in the plume play a major role in ...
Using fast imaging and atomic force microscopy, we demonstrate that the fraction of nanoparticles in ablation plumes produced by short pulse laser irradiation of metals is strongly altered when a second laser pulse of sufficiently large delay is applied. Comparing the results obtained for gold and copper, it is shown that a significant nanoparticle ...
Nanostructured thin films were deposited by excimer laser ablation of silver targets in controlled atmospheres of He and Ar. The film structural properties were investigated by means of scanning electron microscope and transmission electron microscope imaging. The film growth mechanism was identified as the result of coalescence of nanometric clusters formed during ...
An extremely sensitive trace element detection technique in water is proposed and demonstrated, in which the excimer laser ablation is used to generate a densely atomized plume and the generated atoms are detected by sensitive laser-induced fluorescence (LIF) spectroscopy with a CW dye laser. Very strong LIF signal is detected without any interference of ...
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...
Resonant holographic interferometry and dye-laser-resonance-absorption photography have been utilized to investigate the expansion of the laser ablation plumes produced by a KrF excimer laser beam (248 nm) focused onto an aluminum target (about = 0.1 sq cm, 2 - 6 J/sq cm). Plume expansion was studied in vacuum and in background argon ...
We are engaged in a comprehensive effort to understand and model the initiation and growth of laser damage initiated by surface contaminants. This includes, for example, the initial absorption by the contaminant, heating and plasma generation, pressure and thermal loading of the transparent substrate, and subsequent shockwave propagation, ``splashing`` of molten material and ...
The fundamental characteristics of a laser ablation microthruster were investigated for a 10 kg-class microspacecraft. A single-shot impulse measurement was performed using a thrust stand on which a prototype thruster was installed and the associate ablated mass was estimated from the pressure increase in the space chamber. The best performance of several ...
The ablation performances of a fine-woven, pierced carbon/carbon (C/C) composite throats for solid rocket motor were investigated by a ground ignition test. The ablation surface morphologies of three regions (entrance, throat and exit) of the throats were examined in detail by scanning electron microscopy. The results show that the C/C composite throats ...
First-of-a-kind experiments on cluster/aerosol formation by colliding ablation plumes have been conducted, radiating Al, Cu and C with 3?-YAG laser at power densities between 2~30 J/cm2/pulse. Visible spectroscopy indicates that the excitation light intensities of Cu and Al plumes are not necessarily be doubled in collision, but can ...
Barium and barium oxide targets were irradiated at 248 nm with fluences ranging from 300 - 600 mJ/cm^2 in vacuum and 25 mTorr atmospheres of O_2, N_2, microwave discharged O_2. Time-integrated optical emission from the resulting plume was examined and compared to determine the fate of the Ba^+ ions produced as a result of the ablation process and/or ...
