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1.1 Objectives SERDP Project WP1625 was a multi-component effort to understand volatile contributions to particulate matter (PM) emitted from military aircraft engines. Volatile PM formed when condensable gases emitted in the exhaust form new particles or add coatings to emitted soot particles, is getting increasing attention due to potential environmental and health effects, and is coming under increasing regulatory control. Military operations can be constrained if local air quality limits are exceeded. For both these environmental reasons and for the potential impact on aircraft signatures, an improved understanding is sought of volatile PM and the factors that control its formation and evolution. 1.2 Technical Approach WP1625 was structured such that there was an interplay between modeling efforts and several experimental measurement efforts. The project was divided into four components, one focused on modeling and three focused on experimental explorations. Modeling work focused on the development of an advanced particle evolution model considering microphysics involving soot, sulfur, water, and condensable hydrocarbons. Experimental work included a laboratory study on soot interaction with organic species, an oil emissions field study, and a combustor sector rig study of condensation on soot. Experimental and modeling efforts were integrated with experiments providing key parameters needed for model simulations and with model simulations aiding in the interpretation of experimental results. Each of these four components is summarized in further detail below, with a Section of the report dedicated to each. 1.3 Results An existing particle evolution model, which included soot and sulfur/water microphysics has been extended to include hydrocarbon condensable species. This is described in detail in Section 2., Prepared in collaboration with United Technologies Research Center, Pratt and Whitney, and the Massachusetts Institute of Technology.

In the beginning of the jet age, the visibility of the exhaust from airplanes drew attention to the particles being emitted. Whether at altitude in a contrail or near the ground due to visible smoke, the particles in the exhaust made the aircraft engines' emissions visible for all to see. This visibility motivated studies to understand and control the particles being emitted by aircraft, and resulted in some of the first regulations on particle emissions represented by the on-going certification requirement of a smoke number measurement. Scientific understanding of both the measurement of particles and their impact on climate and human health have advanced considerably since then, and there is much active research to continue to better understand Particulate Matter (PM) emissions and their resulting impacts. Important landmarks will be presented that represent steps along the way from earlier interest in contrails and smoke trails to present day understanding of PM emissions and particle microphysics., Presented at the Partners in Environmental Technology Technical Symposium & Workshop, 29 Nov - 1 Dec 2011, Washington, DC. Sponsored by SERDP and ESTCP. U.S. Government or Federal Rights License

The threat of atmospheric contamination by hazardous materials remains a high national security concern. There is a strong need for the development of emerging technologies which can significantly advance risk assessment and response capabilities. In this project, Aerodyne Research Inc. (ARI) has developed and demonstrated an algorithm for source estimation, called AIMS ("Aerodyne Inverse Modeling System"). AIMS takes as input all available observational data and optionally any prior knowledge of the source parameters. The output is the set of source parameters that best describes the observations, including number of sources, emission rates, locations, start and end times. AIMS is also designed to include an a posteriori assessment of its solution quality, providing useful feedback on how much confidence to put in a particular solution and in what ways the solution quality might be improved. A novel feature in AIMS is the ability to integrate multiple observation types in order to maximize information content for source estimation. This capability has been demonstrated for data sets from stationary and mobile sensors., The original document contains color images.

Fine particle and trace gaseous emissions from five weapons systems were characterized during routine training on firing ranges at Ft. Sill, OK between March 16th and March 24th 2007. Real-time trace gas and fine particulate matter (PM) instruments were deployed in the Aerodyne Research, Inc. mobile laboratory to measure muzzle plume and, where feasible, breech plume and soldier breathing zone munitions emission properties from the M109A5 155mm self-propelled howitzer, the M119 105mm howitzer, the M203 40mm grenade launcher, the M249 5.66mm SAW, and the M240 7.62mm machine gun. Fine particle number density, mass loading, black carbon content, and nonrefractory chemical content were characterized along with carbon dioxide, carbon monoxide, nitric oxide, nitrogen dioxide, and selected toxic organic trace gas emissions. Emission indices (mass of pollutant/mass of propellant energetic material) for quantified gaseous and PM chemical species or species classes were computed from emission plume trace species and major carbon gas (CO + CO2) concentrations; propellant carbon mass balances were used to correct for plume dilution by ambient air. Time traces of solider breathing zone trace gas and fine PM emissions concentrations for the relatively high wind conditions present during the sampled firing sequences are also reported along with representative ambient background measurements before and/or after firing sequences. The plume emission indices and breathing zone data have been transmitted to USACHPPM for evaluation of potential health risks for gun crews and/or individual weapons operators under real weapons training conditions., Prepared in collaboration with Montana State University, Bozeman.

Miniature internal combustion engine/generators provide high energy density for portable power applications, potentially exceeding 1500 Whr/kg for a 72 hr mission. Operation on JP-8 from cold startup to steady operation has been demonstrated at the 300 W scale. Miniature engine/generators can be acoustically silenced for low noise operation., See also ADM002187. Presented at the Army Science Conference (26th) held in Orlando, Florida on 1-4 December 2008, Published in the Proceedings of the Army Science Conference (26th), p1-7, Dec 2008. The original document contains color images.

This is the final report for a program to extend an embedded-infrared-fiber propellant strand burning diagnostic by replacing bandpass filter detection by spectral detection. This work builds on previous investigations into the chemical and physical processes occurring in the condensed phases of nitramine advanced composite propellants, in which we observed decomposition product gases by infrared absorption in a small volume below the flame front. Detection of infrared absorption spectra along with video camera and embedded thermocouple records allows characterization of the evolution of decomposition regions by correlating time, spatial location, temperature and decomposition species fractions. Much of the effort of the program went into optimizing the sensitivity of the FTIR spectrometer/fiber optic apparatus, and into constructing test articles. The difficulty of these tasks limited us to only a handful of successful burns. The spectra obtained clearly show N2O and CO2, thus confirming our earlier work and adding a new species to those detected previously. Evidence for other gases is less certain., The original document contains color images.

Our Phase I work demonstrated the feasibility of a mobile LIBS system for the detection of biological agents. This is a very demanding application, in part because of the need to detect threat particles in the presence of a much larger number of benign particles. We believe that the best solution to this problem lies in particle beam focusing technology developed at Aerodyne Research for use in other aerosol analysis devices, most notably a commercially successful aerosol mass spectrometer. Using this aerodynamic lens technology, a large fraction of the total particles sampled can be brought to the focal point of a LIBS excitation laser. Therefore, our goal in Phase I was to demonstrate the feasibility of an aerosol particle sampling/microchip laser LIBS system for biological agent detection. The microchip laser is currently the only LIBS-capable laser that can operate at the kHz repetition rates needed for detection of trace fractions of particles in a reasonable amount of time. Other advantages of microchip lasers include small size, rugged construction, low power consumption and, most importantly, the ability to be triggered. Key issues addressed in Phase I work were the choice of spectral detection regions, an assessment of the microchip laser power requirements, and a demonstration of the use of aerodynamic focusing and laser triggering to enhance sensitivity., Prepared in cooperation with the University of Florida, Gainesville, FL.

A passively Q-switched 214.8-nm Nd:YAG/Cr(4+):YAG microchip-laser system for the detection of NO was designed, constructed, and tested. The system uses the fifth harmonic of the 1.074-micrometers transition in Nd:YAG to detect NO at the few-parts-per-billion level. A significant challenge was the development of an environmentally stable coating to provide the necessary discrimination between the 1.074-micrometers laser line and the stronger transition at 1.064 micrometers. The exact position of the fifth-harmonic frequency was determined using NO fluorescence excitation spectra to be 46556/cm. We observed a detection sensitivity for NO of about 15 ppb(v) in a simple, compact optical system. Earlier observations of SO2 imply a similar or better sensitivity for the current system, while green-light excitation of NO2 fluorescence yielded a detection limit of order 1 ppm(v). Applications of the laser system described here include explosives sensors based on detection of NO from thermal decomposition, and NO(x)/SO(x) monitors for trucks, aircraft and stationary sources.

Site characterization using cone penetrometers is required for efficient and thorough screening of explosives contaminated soils at Army facilities. This report documents a Phase 1 SSTR investigation into a novel class of miniature laser devices for sensitive detection of pyrolysis products of explosives and other nitrogen-containing soil contaminants. The major products, nitric oxide (NO) and nitrogen dioxide (NO2), are detectable by laser-induced fluorescence (LIF) in the ultraviolet (UV) and visible spectral regions. Previous optical fiber-based systems cannot be applied to NO LIF due to poor fiber transmission in the UV. We investigated a detection system based on a diode-pumped microchip laser. This has the advantage that a near-infrared pump laser can be located on the surface, and efficiently transmitted over a fiber to crystals in the penetrometer probe which generate the Nd:YAG laser wavelength (1064 nm) and its harmonics. In Phase 1 we generated fifth harmonic UV light, and demonstrated detection of NO2 fluorescence excited by 532 nm (second harmonic) light. We calculate that coatings can be fabricated which suppress laser oscillation at 1064 nm and allow operation at 1074 nm, whose fifth harmonic at 214.8 nm will overlap the NO absorption band. In Phase 2 we will fabricate this laser and develop and demonstrate a detection system., Prepared in cooperation with Massachusetts Institute of Technology, Lincoln Lab., Lexington.

In this Final Report, we describe research performed on the corrosion inhibitive properties of self-assembled monolayers (SAMs) of stearic acid and 10,12-pentacosadiynoic acid (10,12-PDA) on aluminum. Infrared (IR) and X-ray photoelectron spectroscopy, in addition to wetting measurements, were employed to study the corrosion process. Monolayers of stearic acid on aluminum surfaces were found to profoundly affect the wettability of Al surfaces by concentrated sulfuric acid, but not to act as a significant barrier to corrosion. However, to the extent that the SAM coating limits the wettability of the metal surface, it reduces the degree of corrosion. Toward our goal of creating impermeable organic layers, we studied the adsorption and subsequent UV-induced cross linking of 10,12-PDA acid on aluminum. JR and XPS studies as well as macroscopic wettability and corrosion experiments indicate that the resulting coverage of 10,12-PDA on the aluminum surface is very low. We propose experiments which will focus on improving PDA adsorption on Al and on the effect of UV-induced cross linking on the corrosion resistance.

Hydrazoic acid was shown to be an extremely reactive molecule and an effective precursor species for 'active nitrogen'. At room temperature, hydrazoic acid dissociatively chemisorbed on GaAs(110) surfaces to form the NH radical and N2. At 673 K, an anionic exchange mechanism commenced; the surface became completely depleted in As and a thin film of GaN formed. When the surface was dosed at 773 K, a 20 A thick GaN film was grown. This evidence demonstrates that hydrazoic acid is highly reactive at comparatively low surface temperatures and offers a viable alternative to ammonia as a nitrogen precursor. Experiments which involved growing GaN on sapphire and silicon using a supersonic beam of ammonia and an effusive triethylgallium beam, showed distinct trends in film morphology as a function of the ammonia nozzle and substrate temperature. Stoichiometric GaN films were deposited on Al2O3(0001), Si(001) and Si(111) substrates. Very uniform films were achieved at low substrate temperatures. An improvement in the degree of preferred orientation in the GaN films deposited on Al2O3(0001) substrates with increasing nozzle temperature was observed., Prepared in cooperation with North Carolina State Univ., Raleigh, Dept. of Materials Science and Engineering.

The popular atmospheric transmittance radiance computer code MODTRAN has been upgraded to a model called AURIC-M, with improved ultraviolet capability. The atmospheric profiles were increased to many more layers, and extended to higher altitudes. The solar source irradiance spectrum was improved, and a simple variability model added. An improved Schumann-Runge absorption model with 1/cm resolution was incorporated, along with the ability to compute molecular photodissociation rates.

The sulfuric acid-induced corrosion of smooth (20 A average roughness) aluminum surfaces has been studied in real time using an in situ Fourier transform infrared reflection absorption spectrometer (IRAS) and a quartz crystal microbalance. Submicron-thick, 35 - 55 wt% (5- 12 molal), sulfuric acid films were formed on room temperature metal surfaces by the reaction of gas phase SO3 and H2O vapor in a flowing gas system at a total pressure of approx. 200 Torr. Using changes in spectral features that are linked to the production of Al(3+) as indicators of corrosion, we conclude the rate of corrosion of the metal is strongly enhanced by both higher relative humidities and increased rates of sulfuric acid deposition. Ex situ IRAS measurements on aluminum foils indicated that this technique is suitable for the detection of corrosion on metal surfaces. jg

We report on continued work to develop and demonstrate the use of infrared fiber optics to probe the decomposition processes in burning gun propellant strands. Our experiments involve measuring the absorption across an open gap between two embedded fibers as it fills with gaseous decomposition products. Several improvements have been made to the experimental technique. In the most significant, detection techniques for the nitrogen oxide species NO2 and NO have been added to the N2O detection system developed in earlier work. O2 detection was accomplished by differential absorption of red and green HeNe lasers, while NO detection used a tunable infrared diode laser. We have observed N2O, NO2 and NO evolving into the observation volume during the burning of an RDX-based composite propellant. Observations to date indicate that NO appears at similar times as N2O, that is, while the observation region is relatively cool and far from the burning surface, while NO2 can significantly precede both NO and N2O. These data will provide additional information on the physical and chemical processes in the condensed phases of this composite propellant. (MM)

A kinetic model is presented to describe the high temperature, gas phase B/H/O/C/F chemistry associated with fluoroamino/nitroamino/B(s) mixtures. The results of thermodynamic constant temperature and pressure calculations for a prototypical fluoroamino/nitroamino based oxidizer and solid boron are presented to characterize the equilibrium speciation under boron rich and boron lean conditions. Based on an analysis of the predicted equilibrium speciation, key gas phase reactants are selected and a reaction mechanism describing potential reaction pathways is formulated. Rate parameters for elementary reactions were obtained from published experimental/theoretical data or estimated using transition state arguments and scaling relations. The results of kinetic calculations for several isothermal and adiabatic systems are presented which illustrate the general high temperature mechanistic behavior of B/H/O/C/F systems. Standard reaction flux/pathway and gradient sensitivity analysis techniques are used to identify important reaction pathways.... Boron, Kinetic model, Sensitivity analysis, Combustion., Prepared in cooperation with Princeton Univ., Princeton, NJ.

We report on work to develop and demonstrate a diagnostic technique using infrared fiber optics to probe the decomposition processes in burning gun propellant strands. The experiments reported here involve measuring the absorption across an open gap between two embedded fibers as it fills with gaseous decomposition products. Spectroscopic detection is achieved using pairs of bandpass filters. The absorption record can be correlated with readings from embedded thermocouples and with a high resolution video recording of the burn. We have observed N20, a decomposition product of RDX, evolving into the observation volume. The N20 appearance is often an abrupt event. Coupled with evidence that it can occur while the observation region is relatively cool and far from the burning surface (observed in cases involving burning at 6 atm pressure), these observations suggest hypotheses concerning the physical processes in the condensed phases of this propellant, hypotheses including the development of pressurized voids or matrix-trapped bubbles which can release decomposition gases into the unburnt propellant through suddenly opening cracks. The appearance of N20 after the temperature record suggests that melting and decomposition of RDX have begun (observed in 1 atm cases) implies that N20 formation is indeed not an initial step in RDX decomposition under our conditions. Solid propellant combustion, Infrared fiber optic absorption diagnostic.

The ultraviolet (UV) spectral region has current strong interest for both military and pure scientific studies. Military research, for example, often utilizes the UV emissions from rocket motor exhausts, and the possibility for smaller optical sensors than for the infrared (IR). Wavelengths below 300nm are important because atmospheric ozone and oxygen strongly attenuate the solar irradiance, leaving a dark background for target detection. A major area of scientific interest is in atmospheric photochemistry, in which the UV region is of rime importance. The absorption of O2 and O3 largely determine the extent of penetration of sunlight into the stratosphere and troposphere, where it causes photodissociation of a variety of molecules. The photodissociation of O2 is especially important as the major source of odd oxygen.

We report quantitative measurements of self correcting phase shift produced in phaselocked beam combiners using multiple antireflection coated diode lasers in an external cavity. The major result is the demonstration that the primary automatic phase adjustment is produced by optical frequency changes acting on the difference in pathlengths to the individual diode lasers, and that secondary phase changes are produced by fluctuations of the internal optical power acting on any imbalance among the various diode lasers' saturation behaviors. This suggests that the worst condition for a beam combining external cavity using automatic phaselocking is a near perfect pathlength match of the multiple laser arms. Further, the dynamic instability of a two laser system is measured and shown to be at its worst as the cavity length mismatch approaches zero. A second demonstration is controlled tuning over a frequency range corresponding to the inverse of the cavity length difference by piezo control of the phase error. Finally, the advantage for automatic phaselocking of using geometrically increasing feed lengths for the various diode lasers in the cavity is modeled and demonstrated.

We have developed an electrostatically driven tuning fork chopper which is compatible with an ultrahigh vacuum (UHV) environment. Constructed with a commercially available tuning fork using stainless steel and alumina parts, the chopper is capable of operating while exposed to high temperature samples and corrosive gases. Operation in a UHV environment while modulating both optical and molecular beams is demonstrated. Tuning fork chopper, Ultrahigh vacuum, Molecular beams.

The phase-only Consensus Correlator improves the probability of detection of targets obscured by other objects such as a stand of trees. The technique involves masking out most of the input scene and using a standard correlator to search for small pieces of the expected target shape. The areas of the input scene that are found to contain pieces of the target are combined in a final correlation. The Consensus Correlator reduces the transfer of noise that is interspersed with pieces of the target in the input scene to the vicinity of the correlation spike in the correlation plane. A preliminary investigation of an appropriate figure of merit for comparing correlation spikes produced by different inputs and phase-only filters is also presented.

Experiments were performed in the NASA Lewis Research Center (LeRC) Icing Research Tunnel (IRT) to explore the possible application of a novel icing prevention technique. This technique is based on nucleation ice crystallization in supercooled cloud droplets upstream of the impingement surface and relying on evaporative cooling to remove the latent heat of fusion from the droplet so that it can completely freeze before striking the solid surface. Ice accretion on the impingement surface was measured to quantify the changes due to induced nucleation. A flow duct was designed to provide a uniform, parallel flow from the nucleation excitation volume to the test surface, a simple symmetric airfoil. The distance between the excitation volume and the airfoil in the flow duct could be varied, but the maximum length of over 2 meters (m) was chosen to maximize the time for freezing. Ice accretion was measured over a range of tunnel parameters, including tunnel velocities of 50-100 miles per hour (mph) and temperatures from 0 to -36 OF. At colder temperatures, spontaneous freezing of supercooled droplets led to reductions in observed ice accretion. However, the range of active nucleation parameters explored in this set of experiments had no measurable effect on ice accretion on the subject airfoil. Suggested future work includes expanding the measurement parameter space and obtaining static measurements in a cloud chamber.

This report presents kinetics models for the chemically facilitated gasification of the ubiguitous boron oxide coating that inhibits particulate boron ignition and the second stage high temperature boron surface burning that occurs once the oxide coating has been removed. These models include a homogeneous gas phase oxidation mechanism consisting of 19 chemical species and 58 forward and reverse elementary reactions, multicomponent gas phase diffusion and heterogeneous reactions between gas phase oxidation products and the boron oxide/boron surface. Kinetic mechanisms are formulated to describe the heterogeneous surface reactions for both B203(1) and B(s) surfaces in terms of simple adsorption and desorption reaction steps. Thermochemical parameters for these reaction steps are estimated from the current heats of formation and gas phase bond energies for the major reactants. Reaction rate parameters are estimated from available experimental data or using elementary transition state theory arguments.

We have attempted to develop a patterned etching technique for infrared detector arrays based on photo-induced processes. The technique is based on the efficacy of methyl radical etching of II-VI compounds such as HgCdTe and CdTe. Methyl radicals were produced in a pattern above a HgCdTe substrate by photodissociation a radical precursor such as acetone or nitromethane using an excimer laser operating at 193 nm. Neither optical nor scanning electron microscopy could confirm the presence of any etching action. The failure of the proposed technique is ascribed to surface scavenging and/or reaction quenching mechanisms.

Diamond (100) substrates have been fluorinated with both atomic and molecular fluorine under ultrahigh vacuum conditions using molecular beams. X- ray photoelectron spectra of the resulting samples indicate that atomic fluorine, F, reacts with an initial accommodation coefficient of 0.25 (+ or - 0. 1) at 298 K; a saturation coverage of about three quarters of a monolayer is obtained. The carbon fluoride adlayer is thermally stable to 700 K, but slowly desorbs at temperatures above this. In contrast, molecular fluorine, F2, reacts quite slowly; a saturation coverage of less than one fifth of a monolayer after several hundred monolayers exposure to F2 at temperatures from 300 K to 700 K is achieved. In addition, diamond substrates saturated with fluorine atoms showed no loss of fluorine after exposure to beams of H2 and O2 at temperatures between 300 K and 700 K. Keywords: Diamond thin films; Fluorination; Tribology.

Studies of the thermal and photon-induced surface chemistry of dimethyl cadmium (DMCd) and dimethyl tellurium (DMTe) on GaAs(100) substrates under ultrahigh vacuum conditions have been performed for substrate temperatures in the range of 123 K to 473 K. Results indicate that extremely efficient conversion of admixtures of DMTe and DMCd to CdTe can be obtained using low power 193 nanometers laser pulses at substrate temperatures of 123 K. Subsequent annealing at 473 K produces an epitaxial film. Given the similar electronic structure of other II-VI metal alkyls, such as dimethyl mercury, zinc, and selenium, it is believed that laser induced surface chemical epitaxy is suitable for producing patterned deposits of II-VI quantum well structures. Keywords: II- VI epitaxy, Laser induced chemistry, Deposition, Thin film, Vapor deposition, LCVD, MOMBE, Metalorganic molecular beam epitaxy.

This program constructed and demonstrated an apparatus for the development of laser diagnostics for the gas phase molecules involved in semiconductor fabrication techniques, particularly the organometallic chemical vapor deposition of compound semiconductors like gallium arsenide. Work in this apparatus, a flow tube with mirrors for long path tunable infrared diode laser absorption and electrodes for a radio frequency glow discharge, culminated in observations designed to assess the importance of arsenic hydride radicals in the decomposition of organoarsenic compounds. Preliminary observations of fluorocarbon and methane plasmas produced observations of several species which could be compared with models and other observations and which added to knowledge of these systems with their important applications in silicon etching an diamond deposition. The program also resulted in band strength measurements for the methyl and difluorocarbene radicals, using tunable diode laser, dye laser, and fast flow reactor techniques.

The objective of this program was to analyze infrared emission spectra from solid propellant combustion to obtain a better understanding of the chemical, physical, and radiative processes occurring in these flames. The spectra analyzed were obtained in the High Pressure Combustion Lab. of the Pennsylvania State Univ. using an infrared spectrometer and a strand burner. Comparing measured data with predictive models for emission from a substantial number of molecules whose radiative properties are well known allows determination of temperature and species concentrations in flame hot regions. Observed spectra can also be analyzed to yield radiative parameters for less known radiators. Preliminary work included estimates of flowfield parameters, detailed chemical kinetics calculations to track conversion of initial decomposition products, the construction of line and band radiation models for several molecules. Analysis of observed spectra began with an inspection to determine what molecules contributed spectral features. Several techniques were evaluated which used spectral features to evaluate hot region temperatures. These included using the widths of C02 and H20 bands, the strengths ratios of low resolution H20 bands, and the peak intensities of resolved lines in HCR and HF bands. Relative concentrations were derived for several combustion product molecules which were in accord with propellant compositions. Keywords: Solid rocket propellants.

ArF excimer laser radiation has been used to dissociate dimethylmethylphosphonate (DDMP) and diethylmethylphosphonothioate (DEMPS) into electronically excited fragments. Spectrally resolved UV and visible emission identifies the excited fragments from DMMP as C, C2 nd CH and those from DEMPS as C2, CH, PO and possibly PS and CS. In the few cases tested, the emission intensity is linear with respect to parent molecule concentration and persists in the presence of 100 torr of air. The excited fragment emissions could be the basis of a sensitive detection technique for these or similar molecules.

Spectra of gaseous uranium oxide vibrational-rotational bands have never been observed, in part because of the difficulties in vaporizing uranium. Band strengths are needed by the Defense Nuclear Agency to predict infrared backgrounds as viewed from satellites following atmospheric nuclear bursts. Aerodyne Research, Inc. has developed an apparatus to do these measurements, using multipass diode laser absorption spectroscopy. The goal of measuring line positions and strengths was not achieved, but the apparatus constructed shows good promise of providing at least some infrared data with only minor modifications. In the apparatus, uranium vaporized by an electron beam is entrained in a carrier gas. It reacts with oxygen in the flow before being carried into the observation region, a multipass or White cell where tunable diode laser infrared absorption by the oxide molecules takes place. Hollow cathode lamp absorption measurements of the uranium vapor density are made at right angles. Variations in oxygen concentration and flow velocity allow large variations in the relative amounts of different uranium oxide species. Development of the apparatus has progressed to the point of being able to regularly obtain uranium vapor densities in the observation region of up to 5 x 10 to the 10th power cm to the minus 3rd power, with run times of an hour and more. When the oxygen content of the flow is adjusted for maximum U0 production, the resulting U0 density is predicted to be about 1 x 10 to the 10th power cm to the minus 3rd power.

Few nonintrusive techniques are available for particle measurement in the submicron size range ( o.1 micron diameter), yet measurement of these particles is basic to an understanding of important processes in combustion, such as soot formation and oxidation. The objective of the present research is the development and application of a technique for measurement of individual submicron particles in a gas stream. The approach is to measure the inertial relaxation time of individual particles of Brownian motion, by statistical analysis of the time resolved (100 MHz) heterodyne signal obtained in an interferometer system resembling a more conventional laser Doppler velocimeter. Progress to date has included the development and refinement of an optical system for conducting the experimental studies. This optical system and experimental method are described in detail in conjunction with preliminary measurement of H20 particles which confirm the laser Doppler velocimeter mode of operation of the apparatus. A theory describing the statistical behavior of the signal from such a measurement signal has been developed. From theory, the probability distribution for the time intervals between the zeros of the Brownian motion velocity may be obtained. This program will later focus on measurements of particles of known size suspended in liquids in order to maximize the signal to noise of the optical measuring system, to refine the data acquisition methods, and to verify the theoretical understandin of the acquired signal. Followign the demonstration of the experimental approach, the technique will be applied to measurements of submicron particles suspended in gas flows.

A theoretical and experimental study on the feasibility of determining the size of a single submicron particle by observing its Brownian motion characteristics has been carried out. The method is based on measurement of the particle motion interferometrically using the light scattered from a pair of intersecting laser beams. The particle is assumed to be in thermal equilibrium with a fluid medium. due to the viscous damping of the fluid, the motion of the particle exhibits relaxation behavior. The relaxation time may be obtained from the interference signal. Knowing the temperature and the viscosity of the fluid, the mass, hence the size of the particle may be determined from the relaxation time. Monte Carlo simulation of the Brownian motion detector response has shown that the relaxation time may be obtained from the statistics of the time between extrema of the signal. A proof-of-concept experiment was conducted using latex spheres of known sizes as test particles. The signal to noise ratio of the experimental setup, however, was not adequate for determining the size of the particles.

The reactions of metallic species introduced into the atmosphere by meteor ablation may play a significant role in the chemistry of the lower thermosphere and upper stratosphere. The work described in this report summarizes a series of experimental rate constant measurements for reactions pertinent to these atmospheric regions. Prior to this work, virtually no direct kinetic parameters had been measured for the reactions of alkalis, and in particular sodium, which are believed to occur between 30 and 100 km in altitude. Model predictions of excited sodium emissions, expected concentration levels of the various alkali species, and the potential impact of alkali chemistry on the ozone balance all depended on theoretical estimates of reaction rate constants and product branching rations. Using a high temperature fast flow reactor and a variety of atomic and molecular species source and detection techniques, we have measured rate constants for over a dozen reactions.

The reactions of metallic species introduced into the atmosphere by meteor ablation may play a significant role in mesospheric and stratospheric chemistry. Rate constants for the recombination reactions of alkali atoms with molecular oxygen, K + O2 + M yields KO2 + M and Na + O2 + M yields NaO2 + M, have been measured as a function of temperature from to 300 to 700 K using a fast flow reactor. Laser induced fluorescence is used to monitor the disappearance of Na or K as a function of O2 and M. The reactions are studied in their low pressure third order limit from 1 to 7 torr total pressure with N2, He, and Ar as third bodies. The rate constants are found to have the expected negative temperature dependence. The results are compared with other recent measurements from flame and flash photolysis studies and with theoretical expectations based on an energy transfer RRKM mechanism for the NaO2 activated complex. It has been suggested that the reaction of NaOH with HCl might affect the concentration of odd chlorine, thus having an impact on the ozone balance. This report also describes the first measurement of this reaction rate constant. We have also determined estimates of the same room temperature rate constants.

The reactions of metallic species introduced into the atmosphere by meteor ablation may play a significant role in mesospheric and stratospheric chemistry. During this second year of a three year program to investigate these phenomena, we have completed measurements for the reactions of atomic sodium with ozone, and of NaO with ozone. Preliminary measurements of the rate constant for the reaction of NaO2 + HCl have been done, as well as an initial photodissociation cross section determination for NaCl at 193 nm. We have also begun to investigate the means by which neutral gas phase alkali species may be removed from the mesosphere and stratosphere. Originator supplied keywords include: reaction rates, atomic sodium, mesospheric chemistry, stratospheric chemistry, diffusion, sodium hydroxide, hydrochloric acid, ozone.

The PARCS CODE calculates the coherent, incoherent, and overdense surface radar cross sections of a rocket plume. The modified Born approximation calculation includes attenuation, local index of refraction, Doppler shift and range cell truncation. The program accepts plume data directly from the AeroChem LAPP code, but may be interfaced with other sources of plume definition.

The specific approach taken in this work was to study particle formation in a cooling jet of carbon vapor diluted by an inert carrier gas. Vapor was produced by the evaporation of a resistance heated graphite tube. The carbon vapor, mixed with carrier gas, flowed into a light scattering chamber where spectroscopic measurements were used to monitor concentrations of molecular species. Particles were also collected for electron microscopy. An initial reaction leading to particle formation was identified as C2+C3 yields C5 with a gas kinetic rate. Particulates were found to be spherical, of approximately equal diameter and frequently chained in the manner of hydrocarbon soot.

Two theoretical approaches have been followed to calculate far wing absorption of collision reduced absorption in the infrared. The first approach was a standard time dependent perturbation theory. Two methods of this kind were pursued, using different limits. A second approach was investigated called the Recursive Residue Generation Method. The first approach was applied to water self-broadening. Results are given in 10 micro m region. The second approach was investigated for feasibility and examined in the context of the HCl-Ar wings. Keywords: Atmospheric absorption; Continuum absorption; Atmospheric windows

A microprobe analysis technique which has the potential for quantitative measurements of surface and bulk concentration as well as depth profiles has been investigated. This technique is termed Profile Analysis using Laser Assisted Spectroscopy (PALAS) and uses one pulsed laser to desorb or vaporize a controlled volume of the sample and a second pulsed laser to induce fluorescence in the desorbed species. The intensity of the laser induced fluorescence (LIF) provides a quantitative measure of the desorbed atom species concentration, while the energy density of the vaporizing laser controls the sampling depth. The requisite lateral resolution is provided by focusing the vaporizing laser. The purpose of the Phase I project was to demonstrate the feasibility of PALAS by making measurements of impurity and dopant concentrations in Gallium arsenide, which is a III-V material of interest to the Air Force and other defense agencies. The system did not perform as well as anticipated. A number of deficiencies with the machine as constructed were noted. Keywords: Semiconductors, Ablation.

The use of holographic optical elements has been under investigation for several applications. The success of some of these applications has been limited due to the properties of the holographic material. The polaroid DMP-128 Photopolymer has several characteristics that appear suitable for Military Optical Elements. The purpose of this program is to investigate the Polaroid Photopolymer Material in applications requiring protection of personnel and optical systems from laser beams. This requires highly efficient holographic mirrors exhibiting transmissions in narrow spectral bands at the laser lines of interest and little attenuation of transmitted light in other spectral regions. The Polaroid DMP-128 Photopolymer is normally stored dry (in a container with desiccant) and has a long shelf life. Under these conditions it is not active. It is made active by impregnating the photopolymer with water. The presently recommended method for adding water is to circulate humid air over the surface for several minutes and immediately make a hologram by exposing the material to interfering laser beams.

An intersecting, hyperthermal energy molecular beam apparatus with a liquid nitrogen called infrared radiation detector system designed to measure T- V collisional excitation cross sections for the infrared active modes of small molecules is described in this report. In addition, a novel infrared calibration technique using the self-emission of a molecular beam containing H2O or CO2 formed by supersonic expansion from a high temperature nozzle is presented and the design and testing of a dc arc heated supersonic nozzle source for producing molecular beams of atomic oxygen seeded in noble gases is discussed. Measured upper bounds for T-V excitation of the CO2 and H2O nu 3 vibrational modes in collision with N2 at several relative collision velocities in the range of 4 to 8 km/second are presented and compared to literature values for total scattering cross sections of CO2 and H2O as well as to previous experimental and theoretical determinations of CO2 and H2O nu 3 activation cross sections., Prepared in cooperation with Yale Univ., New Haven, CT. Dept. of Engineering and Applied Science.

Optical pattern recognition is extremely effective for well defined targets, and naturally discriminates against small changes in the target shape. Attempts to reduce the discriminatory power of the Fourier plane filter to permit some adjustments such as size or perspective changes while still identifying the 'overall shape' have been generally unsuccessful. These attempts usually involve reducing the information content in the detection filter through various forms of low pass filtering such as circular or radial smearing. Our research is directed at increasing the information content to obtain optical pattern recognition of distorted or rotated or multiple targets. This is accomplished by combining multiple Fourier plane filters which are non- overlapping in the Fourier plane and therefore do not interfere with each other. This system fills the Fourier plane with useful information for detecting multiple targets. It is most effective when the targets are most dissimilar, therefore having the least overlap in the Fourier plane . This is opposite from past approaches aimed at smearing together several similar targets. (RRH)

This is the first annual report on a program to develop laser spectroscopic diagnostics for detection of gas phase species important in fabrication processes for advanced semi-conductor materials. It has two objectives, to obtain quantitative spectroscopic data for these molecules, and to apply diagnostics to model fabrication systems. This report summarizes progress in the areas of investigation identified in the first year: chlorine atom detection using an infrared tunable diode laser, which will also be used to instrument a plasma etching reactor, and infrared and laser induced fluorescence spectroscopic studies of SiF2, CF2, and SiH2. Keywords: Diagnostic instrumentation; Electronic materials; Infrared absorption; Lasers; Laser- induced fluorescence microelectronic fabrication; Semiconductor processing; Spectroscopy.

It has been proposed that trace addition of ClF3 to conventional gas mixtures in photo-initiated HF/DF pulsed lasers might substantially improve chain reaction initiation and consequently, system electrical efficiency. It has further been proposed that steady flow of a spatially tailored trace addition of ClF3 might improve uniformity of initiation and, hence, cavity homogeneity in reptitively pulsed devices by providing enhanced initiation (F-atom production) in regions of diminished lamp illumination. An argon filled flash lamp with pulse duration (FWHM) of approximately 40 microsec was observed to radiate 3.5% of its initial electrical energy in the absorption band of ClF3 (1750A to 2400A) and 13% of its energy in the absorption band of F2 (2400A to 3400A). Theoretical modeling of flash lamp radiation indicates that short lamp pulses appropriate to pulsed chemical lasers would show equal or better radiation distribution of lamp electrical energy in these absorption bands. The flash lamp was used in photolysis studies which show that absorption of radiation by ClF3 results in dissociation with efficiency of order unity. Photolytic production of F-atoms could not be determined in the present UV attenuation studies due to the occurrence of a strongly absorbing unidentified photolysis product or products.

Rate constants have been determined for gas phase reactions of alkali species which are relevant to flame suppression chemistry by sodium and potassium compounds. Sources and detection methods for gas phase molecular alkali species kO, kO2, Na, NaO2 and NaOH have been developed and applied to kinetic studies of these species using a high temperature fast flow reactor. Rate constants for the recombination reactions of alkali atoms with molecular oxygen, K + O2 + M yields KO2 + M and Na + O2 + M yields NaO2 + M, have been measured as a function of temperature from 300 to 700 K. Laser induced fluorescence is used to monitor the disappearance of Na or K as a function of O2 and M. The reactions of NaOH, NaO2 and NaO with HCl at 300 K are found to proceed at their gas kinetic limits to form NaCl. Other reactions studied include: NaOH + H yield Na + H2O, NaCl + H yields Na + HCl and both Na and K with H2O2. KOH has been detected in the gas phase by infrared absorption at 424/ cm using a tunable diode laser. This method has wide applicability for direct detection of a number of molecular alkali species for laboratory kinetic studies and for in situ combustion flame diagnostics. Theoretical sensitivity estimates are calculated for KOH, KO2, KO, NaOH, NaO2, NaO and NaCl for both high temperature, atmospheric pressure and low pressure flow tube conditions.

Findings from previous wars and the wisdom of the senior leadership of the Army suggest that personnel turbulence within units is a significant obstacle to the development of effective units. This report is intended to summarize some of the substantial literature on personnel turbulence in Army units, provide some current evidence that recent efforts to include COHORT have not sufficiently reduced turbulence, and offer an approach to reduce turbulence through policy change. The report concludes that stability measurements should be instituted as part of the Unit Status Report (USR) and recommends a strawman set of measures for that purpose. Keywords: Combat unit cohesiveness; Cohesion; Turbulence; Leader development; Leadership; Climate; Readiness; Unit manning; Unit status Rpt (USR); Personnel management.

In this report an algebraic criterion to predict the onset of muzzle flash is formulated. The criterion is derived from the detailed analysis of a complex Muzzle Exhaust Flow Field (MEFF) model which includes turbulence and detailed chemical kinetics. The algebraic criterion, therefore, contains the essential features of the complex MEFF model. Additional efforts required for the improvement of the criterion are discussed.

This report is presented in four sections. In Section 1 an analysis of the effects of noise on associative memories is presented. Special emphasis is given to generalized inverse memories. In Section 2 of this report, several algorithms which are appropriate for implementation on the NRL spatial light modulator were compiled. These include nonlinear associative memory models and a pseudo inverse memory model that is optimum for incomplete input patterns. In section 3 of this report an analysis of a memory model that is optimum in the least squares sense for input patterns with missing components was analyzed. This memory was shown to be derivable from a different optimization principle. This optimization produces that memory which has a minimum average noise output for a given error in recall. In Section 4 of this report we discuss projection techniques and subspace methods. These approaches will allow the design of dynamic memory and recall schemes that are nonlinear, have local connectivity and can be robust against distorted input patterns. Partial contents: Analysis of the effects of noise on generalized inverse and correlation matrix associative memories; Adaptive associative memory models with potential optical implementation; On optimal associative recall from an incomplete input vector; and Projection operators and subspace methods of pattern recognition.

Much of the current attention being given to optical computing stems from its new found ability to perform digital operations and hence to achieve high accuracy. In optics as in electronics, digital operations are slower and clumsier than analog operations. On the other hand, digital operations are more flexible and more accurate. These considerations lead us to consider whether some sorts of hybrid optical-electronic, analog-digital systems might be useful for some tasks. In this paper, we consider two closely-related hybrids: analog optics wit digital electronics and analog optics with hybrid analog-digital electronics. Both systems will use analog optics for rapid and moderately accurate solution of complex problems and use the electronics to 'bootstrap' the accuracy. That is each new optical computation should increase the accuracy of the solution. We will call such a system a Bimodal Optical Computer. While many of these concepts appear to be new to optics, they are not new to computing in general. We will attempt to document the most useful of the prior publications, to make isomorphisms with other fields explicit, and to label those contributions which appear to be new. With all of these caveats, our primary purpose is to present a general approach for using optical computers. We will illustrate that approach with one specific problem (linear algebraic equations), but this should not obscure the generality of the concept. (Author)

In a previous RADC contract Aerodyne worked on developing an improved algorithm for reducing the rotational dependency of matched filters for use in optical pattern recognition systems. This present contract takes the final result of that effort, the so-called Generalized Matched Filter (GMF), applies the phase-only filter principle to it, and studies the results. Standard actual noisy IR images are used so the result can be compared to other such studies. Also included in this report is a brief discussion of complexity theory and how it might apply to optical computing efforts in the U.S. and elsewhere. Keywords include: Correlation; Pattern recognition; Spatial filtering; and Phase-only filters.

Multiplication with 16 bit accuracy can be accomplished by optical means and is competitive and superior in speed to fully electronic devices if a sum-of-products algorithm is being implemented. The advantage of optics is not in the multiply function where electronic multipliers will be generally faster due to the extra analog-to-digital converters needed in the optical device. The optics advantage appears when many of the resulting numerical products need to be added which is accomplished by integrating sequential light pulses onto one detector. The bottleneck for digital addition is the arithmetic carry terms which are evaluated sequentially. We also present and analyze a threshold logic analog-to-digital converter intended for the optical multiplier which demonstrates increased speed over a successive approximation A/D without the complexity of a flash converter. We also present a significant step which is the sideways summer. The sideways summer greatly reduces the time required for the one step of electronic addition which is part of the digital-multiplication by analog-convolution algorithm. This electronic addition is needed to convert the resulting mixed binary form of the output into a normal binary number. Keywords include: Optical signal processing, and Computer architecture.