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...
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 ...
Energy Citations Database
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 ...
DOE Information Bridge
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 ...
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 ...
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 ...
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 ...
NASA Astrophysics Data System (ADS)
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...
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 ...
... A CHARRING ABLATION THERMAL PROTECTION SYSTEM ... AN ANALYSIS OF A CHARRING ABLATION THERMAL PROTECTION SYSTEM ...
DTIC Science & Technology
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 ...
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 ...
A Hybrid MD-DSMC Model of Picosecond Laser Ablation and Desorption Michael I. Zeifman* , Barbara J of the expanding plume into a mixture of liquid droplets (molecular clusters) and gas phase molecules from that predicted by pure thermal desorption models. For high fluences, the phase explosion
E-print Network
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 ...
... 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 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 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 ...
Lasers are finding expanding applications in the field of dentistry. Cutting in soft tissue, hard dental material ablation, caries removal, and root canal therapy are only a few examples of dental laser uses. In this article, the application of short pulse ArF excimer laser to ablation of dentin and enamel is investigated. In particular, the effect of ...
PubMed
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 ...
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 low laser fluences, ...
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 ...
Semi-analytical approach to a quantitative analysis of thermal ns laser ablation is presented. It permits one to take into account: (1) Arbitrary temperature dependences of material parameters, such as the specific heat, thermal conductivity, absorptivity, absorption coefficient, etc. (2) Arbitrary temporal profiles of the laser pulse. ...
... Title : Effluent Plume Imaging. ... BLACKBODY RADIATION, AMMONIA, GASES, GAS DETECTORS, PLUMES, THERMAL RADIATION, EMISSION ...
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 ...
... HEAT RESISTANT PLASTICS, *ABLATION), (*REINFORCED PLASTICS, ABLATION), (*THERMOGRAVIMETRIC ANALYSIS, HEAT RESISTANT ...
... AND ABLATION PROGRAM (CMA) FOR CARBON ABLATION ANALYSIS C. CH AN DTIC LECTE ... I AND ABLATION PROGRAM (CMA) FOR ...
Phenolic Impregnated Carbon Ablator was the heatshield material for the Stardust probe and is also a
NASA Technical Reports Server (NTRS)
We investigated the process of laser micro-drilling of copper and iron by using nanosecond laser-pulses at 532nm wavelength in atmospheric air. We analyzed the ablated volume, ablation rate, crater diameter, and craters quality as functions of laser-fluence and beam-diameter. The fluence was varied between 10 and 6000 J/cm2 by changing the laserenergy. The ...
In order to illustrate that the finite element method is a viable technique in solving ablation type thermal problems, a 1-dimensional ablation and thermal ...
NASA Website
The expansion of plasma created by laser ablation is investigated using the fluid model. At the first stage of the expansion, electrons are considered in thermal equilibrium. The presence of highly charged impurities is considered through Poisson's equation. The set of nonlinear differential equations is solved using a moving boundary and taken ...
The structure of axisymmetric subsolidus thermal plumes in the earth's lower mantle is inferred from
... PLUMES, *ATMOSPHERE MODELS, THERMAL PROPERTIES, VELOCITY, MATHEMATICAL MODELS, OPTICAL PROPERTIES, TEMPERATURE ...
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 ...
Transient thermal analysis and structural analysis for synthesis of ablating thermostructural panels
... Descriptors : *REENTRY VEHICLES, *ABLATION, DENSITY, TEMPERATURE, PERMEABILITY, DEGRADATION, ENERGY, GASES, THERMAL ...
... ANALYSIS, COMPUTER PROGRAMS, ABLATION, ATMOSPHERE ENTRY ... Subject Categories : RADIOFREQUENCY WAVE PROPAGATION ...
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...
Optical emission spectroscopy of the pulsed laser ablation of spines and glochids from Opuntia (Nopal) cladodes was performed. Nopal cladodes were irradiated with Nd:YAG free-running laser pulses on their body, glochids and spines. Emission spectroscopy analyses in the 350-1000 nm region of the laser induced plasma were made. Plasma plume evolution ...
The Monte Carlo method is used to model the thermal radiation field of the plumes for the dual solid
... Accession Number : AD0282941. Title : Thermal Ionization of Rocket Exhaust Plumes. Descriptive Note : Interim rept. Corporate ...
... Descriptors : *EXHAUST PLUMES, *THERMAL RADIATION, MEASUREMENT, DETECTION, FIRING TESTS(ORDNANCE), GRAVITY WAVES ...
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 ...
... ABLATION, MASS SPECTRA, THERMOGRAVIMETRIC ANALYSIS, DIFFERENTIAL THERMAL ANALYSIS, DEGRADATION, THERMAL STABILITY. ...
... Title : Modifications to the Aerotherm Charring Material Thermal Response and Ablation Program (CMA) for Carbon Ablation Analysis. ...
... Descriptors : *Plastics, *Silicon compounds, *Thermal insulation, *Thermal degradation, Chemical reactions, Thermoplastic resins, Ablative ...
... Accession Number : ADD425673. Title : Ablative Char Characterization for Thermal Conductivity Measurements,. Corporate Author : ...
... Accession Number : AD0668623. Title : ABLATION AND THERMAL EFFECTS IN A VISCOELASTIC CYLINDER. Descriptive Note : Technical rept.,. ...
... Accession Number : AD0670535. Title : A MASS-THERMAL METHOD FOR STUDYING ABLATIVE POLYMER DEGRADATION MECHANISMS,. ...
In a previous report on effects of thermal discharges from power plants into the Great Lakes, we stressed the need for a statistical analysis of the spatial and temporal pattern of the thermal plume. The plume pattern is recognized as stochastic in nature...
... KEYWORDS Temperature profiles Rocket motor plumes Thermal imaging ABSTRACT (R) Temperatures profiles in the plume of the rocket motor of ...
... 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 ...
Thermal Analysis Tricks & Tips. Analysis Notes and Questions. Notes on Simulating Ablation in a PATRAN P/Thermal model. Notes on Simulating Ablation in a ...
Characteristics of laser plasmas used for pulsed laser deposition (PLD) of thin films are examined with four in situ diagnostic techniques: Optical emission spectroscopy, optical absorption spectroscopy, ion probe studies, and gated ICCD (intensified charge-coupled-device array) fast photography. These four techniques are complementary and permit simultaneous views of the transport of ions, ...
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...
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 ...
... 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 ...
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 surface, while the dynamic partial ...
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
The first reported planar laser-induced fluorescence (PLIF) images depicting the relative ground-state, neutral density of Si within a pulsed laser ablation (PLA) plume as it expands into vacuum and 10 mTorr Ar are presented. Several images acquired with the laser detuned incrementally must be superimposed to produce images which compensate for Doppler ...
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 laser-induced pressure ...
Plume Impingement modeling is required whenever an object immersed in a rocket exhaust plume must survive or remain undamaged within specified limits, due to thermal and pressure environments induced by the plume. At high altitudes inviscid plume models, ...
Time-of-flight (TOF) mass spectra for a peptide (Y(6)) were obtained by utilizing matrix-assisted infrared laser desorption ionization (IR-MALDI) with glycerol as the matrix and by ultraviolet MALDI with ?-cyano-4-hydroxycinnamic acid (CHCA), sinapinic acid (SA), and 2,5-dihydroxybenzoic acid (DHB). Collisional activation during ion extraction and exothermicity in the gas-phase proton transfer ...
Time-of-flight (TOF) mass spectra for a peptide (Y6) were obtained by utilizing matrix-assisted infrared laser desorption ionization (IR-MALDI) with glycerol as the matrix and by ultraviolet MALDI with ?-cyano-4-hydroxycinnamic acid (CHCA), sinapinic acid (SA), and 2,5-dihydroxybenzoic acid (DHB). Collisional activation during ion extraction and exothermicity in the gas-phase proton transfer were ...
A computer tool to perform entry vehicle ablative thermal protection systems sizing has been developed. Two options for calculating the thermal response are incorporated into the tool. One, an industry-standard, high-fidelity ablation and thermal response...
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 ...
... Keywords: Solar rocket propulsion; Plume/Mirror interactions; Thermal propulsion systems. Descriptors : *MIRRORS, *PLUMES, *ROCKET ...
... Although the configuration of a rocket exhaust particle plume re- sembles a cone, the emissivity for the cylindrical configuration is used here ...
... Descriptors : *MAGMA, *MATHEMATICAL ANALYSIS, *PLUMES, FLUID FLOW, EARTH MANTLE, VISCOSITY, NAVIER STOKES EQUATIONS ...
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 ...
Sclerotherapy; Laser therapy - varicose veins; Radiofrequency vein ablation; Endovenous thermal ablation; Transilluminated power phlebotomy; Endovenous laser ablation; Varicose vein ...
MedlinePLUS
Aug 6, 2010 ... SUBTOPIC TITLE: Ablative Thermal Protection Systems. PROPOSAL TITLE: Phenolic Impregnated Carbon Ablator (PICA) Gap Filler for Heat Shield ...
