X-ray diffraction can be used as the signal for tomographic reconstruction and provides a cross-sectional map of the
crystallographic phases and related quantities. Diffraction tomography has been developed over the last decade using
monochromatic x-radiation and an area detector. This paper reports tomographic reconstruction with polychromatic
radiation and an energy sensitive detector array. The energy dispersive diffraction (EDD) geometry, the instrumentation
and the reconstruction process are described and related to the expected resolution. Results of EDD tomography are
presented for two samples containing hydroxyapatite (hAp). The first is a 3D-printed sample with an elliptical crosssection
and contains synthetic hAp. The second is a human second metacarpal bone from the Roman-era cemetery at
Ancaster, UK and contains bio-hAp which may have been altered by diagenesis. Reconstructions with different
diffraction peaks are compared. Prospects for future EDD tomography are also discussed.
KEYWORDS: iodine lasers, Chlorine, Chemical species, Fluorine, Iodine, Energy transfer, Chemical oxygen iodine lasers, Combustion, Absorption, Chemical lasers
The measurement of positive small signal gain on the 1.315 micron spin orbit transition of atomic iodine following energy transfer from chemically generated NCl(a1Δ) is reported. Previous instances of gain produced by energy transfer from NCl(a1Δ) used DC discharges to generate F and Cl atoms; this report describes recent progress towards a true chemical laser device which uses a high temperature chemical combustor and a supersonic reactor to generate NCl(a1Δ). These improvements represent a significant step towards the development and demonstration of a scalable All Gas-phase Iodine Laser (AGIL) device.
KEYWORDS: iodine lasers, Temperature metrology, 3D modeling, Chemistry, Process modeling, Chemical reactions, Computer simulations, Chemical species, Chlorine, Optical simulations
This work revisits the finite-rate chemistry mechanism for AGIL in light of recent rate measurements for kinetic processes. The effect of temperature dependence of kinetic processes measured only at room temperature conditions is explored by assuming a square-root dependence upon temperature in line with kinetic theory. A sensitivity study is performed to elucidate the relative impact of each chemical kinetic process modeled with respect to the larger set of modeled chemical kinetic processes. And reactant mixing is examined, with documentation of the effects of the reactant mixing predictions upon recent multi-watt power extraction experiments.
KEYWORDS: Chemical oxygen iodine lasers, Optical simulations, Chemical lasers, 3D modeling, Data modeling, Chemistry, Gas lasers, Chemical reactions, Computer simulations, Physics
Theoretical models for chemical lasers depend on a variety of assumptions and empirical data to provide closure and simplify solution of the governing equations. Among the various assumptions and empirical data that have been built into models for chemical lasers are assumptions regarding flow steadiness in the time domain and geometric similarity of the spatial domain. The work discussed here is directed toward elucidating and increasing the understanding of these assumptions commonly used in chemical laser simulation and the impact of their usage upon the predictions of these models. These efforts in turn are directly linked to efforts to achieve improved chemical laser efficiencies and performances as excursions outside the assumed to be 'well understood' traditional operational parameter space are increasingly necessary.
The demonstration and characterization of a multiwatt All Gas-phase Iodine Laser (AGIL) are described. A 20-cm subsonic reactor was used to produce NCl(a1Δ) for a series parametric studies of the I*(2P1/2) - I(2P3/2) small signal gain and extracted power dependence on reactant flow rates and reaction time. A reduction in the flow channel height led to improved performance. The highest measured gain was 4.2 x 10-4 cm-1 and the highest power observed was 31 W.
A review of recent advances in chemical laser technology is presented. New technology and concepts related to the Chemical Oxygen Iodine Laser (COIL), All Gas-phase Iodine Laser (AGIL), and HF Overtone Laser are discussed.
The demonstration and characterization of a multiwatt All Gas-phase Iodine Laser (AGIL) are described. A 20-cm subsonic reactor was used to produce NCl(a1Δ) for a series parametric studies of the I*(2P1/2) - I(2P3/2) small signal gain and extracted power dependence on reactant flow rates and reaction time. A reduction in the flow channel height led to improved performance. The highest measured gain was 4.2 x 10-4 cm-1 and the highest power observed was 31 W.
KEYWORDS: 3D modeling, Chemical lasers, Chemical oxygen iodine lasers, Chemical reactions, Computer simulations, Data modeling, Gas lasers, Physics, Laser resonators, Particles
Theoretical models for the chemical lasers depend on a variety of assumptions and empirical data to provide closure and simplify solution of the governing equations. Among the various assumptions and empirical data built into models for chemical lasers are assumptions regarding steadiness in the time domain and geometric similarity of the computational domain. The work discussed here is directed toward elucidating and increasing the understanding of the assumptions underlying chemical laser models and the implications for the modeled physical processes underlying the chemical laser, driven by current directions in the development of this technology. This is directly linked to efforts to achieve improved chemical laser efficiencies and performance, as excursions outside the assumed to be ‘well understood’ traditional operational parameter space are increasingly necessary.
KEYWORDS: 3D modeling, Chemical oxygen iodine lasers, Chemical lasers, Chemistry, Optical simulations, Data modeling, Fluid dynamics, Space operations, Throat, Process modeling
Theoretical models for the chemical oxygen-iodine laser (COIL) depend on a variety of assumptions and empirical data to provide closure and simplify solution of the governing equations. Among the various assumptions and empirical data built into models for COIL are assumptions regarding steadiness in the time domain and which kinetic processes are significant in addition to the measured values for the rates at which the kinetic processes occur. The work discussed here is directed toward elucidating and increasing the understanding of the assumptions underlying COIL models and the implications for the modeled physical processes underlying the COIL, driven by current directions in the development of this technology. This is directly linked to efforts to achieve improved COIL efficiencies and performance, since excursions well outside traditional operational parameter space are necessary. As such excursions are made, the distance from the traditional parameter space where COIL models have been baselined and validated becomes much greater, increasing the importance for understanding the factors that influence the accuracy of the simulations. In this role of increasing the level of understanding regarding the limits to the accuracy of COIL models, these simulations provide information important to current work investigating configurations and operating conditions well outside of the traditional parameter space.
The demonstration and characterization of a multi-watt All Gas-phase Iodine Laser (AGIL) are described. A 20-cm subsonic reactor was used to produce NCl(a1Δ) for a series of parametric studies of the I*(2P1/2)-I(2P3/2) small signal gain and extracted power dependence on reactant flow rates and reaction time. The highest measured gain was 2.5x10-4 cm-1 and the highest power observed was 18 W.
CW laser action has been demonstrated on the electronic I* (2P1/2) ? I (2P3/2) transition of atomic iodine at 1 .3 15 ?m from the NC! (a1Æ) + I (2P 3/2) energy transfer reaction. The stimulated emission was generated in a transverse subsonic flow device when hydrogen azide, HN3, was injected into a flow of iodine and chlorine atoms. The measured laser output power was 180 mW.
CW laser action has been demonstrated on the electronic I* (2P1/2) yields I(2P3/2) transition of atomic iodine at 1.315 micrometer from the NCl (a1(Delta) ) + I(2P3/2) energy transfer reaction. The stimulated emission was generated in a transverse subsonic flow device when hydrogen azide, HN3 was injected into a flow of iodine and chlorine atoms. The measured laser output power was 180 mW.
KEYWORDS: Chlorine, Molecules, Chemical species, Temperature metrology, Micro optical fluidics, Chemical lasers, Chemical oxygen iodine lasers, Halogens, Hydrogen, Human-computer interaction
The rate constant for Cl + HN3 over the temperature range 300-480 K has been studied in a flow reactor. Based on the rate of loss of HN3 and the rate of NCL(a1(Delta) ) generation, the temperature dependence of this reaction is described by the collision theory expression 1.2 +/- 0.3 X 10-11 T0.5 exp(-1514 +/- 93/T), with E0 equals 3.0 +/- 0.2 kcal mol-1 or an Arrhenius fit k(T) equals 2.0 +/- 1.0 X 10-10 exp(-1452 +/- 150/T) with Ea equals 2.9 +/- 0.2 kcal mol-1.
A direct measurement of gain on the electronic I (2P3/2) - I*(2Pi/2) transition of atomic iodine at 1.315 jam using tunable diode laser is demonstrated. The population inversion results from the efficient energy transfer between NCI (alA) metastables and I (2P3/2) atoms. Ground state iodine atoms and NCI (a1 A) metastables are produced in a transverse subsonic flow device from the stepwise reaction of Cl atoms with HI followed by the reaction of Cl with azide (N3) radicals, respectively. Under current experimental conditions, a gain of 0.020%/cm is obtained and appears to be limited by reagent number density. A kinetic model was constructed to simulate the experimental gain profile using a mechanism consisting of fully coupled finite rate chemistry and 1-D fluid dynamics. Good agreement with experimental and theoretical calculations are obtained. Keywords: Gain, population inversion, atomic iodine, NCI (a*A) metastables, azides, energy transfer
KEYWORDS: Chemical species, Mirrors, Chemical oxygen iodine lasers, Chemical lasers, Iodine, Resonators, 3D modeling, Computer simulations, Diffusion, Computational fluid dynamics
Simulation of chemical lasers such as the chemical oxygen-iodine laser (COIL) laser is of timely interest due to ongoing commercial and military development programs. Accurate models of the gas dynamics and chemistry within a COIL have been developed using Computational Fluid Dynamics (CFD) codes, matching data from experiments designed to probe these physics. This work details the use of these codes to investigate the supersonic injection of molecular I2 and atomic I into the supersonic region of the O2(1?) flow in the COIL, and compare these results with a simulation of sonic injection of I2 into the subsonic region of the O2(1?) flow. The performance of each of these injection mechanisms is characterized by the theoretical power extracted from a Fabry-Perot resonator model, which then serves as the primary basis for comparison. Additional quantities such as power available and chemical efficiency are used to compare and contrast the performance of each concept. Based on these comparisons, the supersonic-supersonic injection methods demonstrate a performance increase over the traditional subsonic methods, with supersonic injection of I atoms providing the greatest performance increase.
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