UNCOVERING THE UNIQUE AND THE UNSAYABLE : POTENTIALITIES FROM A STUDIO EXERCISE IN BALI

Master'sMASTER OF ARCHITECTURE (M.ARCH

Standoff chemical plume detection in turbulent atmospheric conditions with a swept-wavelength external cavity quantum cascade laser

Rapid and sensitive standoff measurement techniques are needed for detection of trace chemicals in outdoor plume releases, for example from industrial emissions, unintended chemical leaks or spills, burning of biomass materials, or chemical warfare attacks. Here, we present results from 235 m standoff detection of transient plumes for 5 gas-phase chemicals: Freon 152a (1,1-difluoroethane), Freon 134a (1,1,1,2-tetrafluoroethane), methanol (CH3OH), nitrous oxide (N2O), and ammonia (NH3). A swept-wavelength external cavity quantum cascade laser (ECQCL) measures infrared absorption spectra over the range 955-1195 cm(-1) (8.37- 10.47 mu m), from which chemical concentrations are determined via spectral fits. The fast 400 Hz scan rate of the swept-ECQCL enables measurement above the turbulence time-scales, reducing noise and allowing plume fluctuations to be measured. For high-speed plume detection, noise-equivalent column densities of 1-2 ppm*m are demonstrated with 2.5 ms time resolution, improving to 100-400 ppb*m with 100 ms averaging. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing AgreementOpen access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Standoff 250 m Open-path Detection of Chemical Plumes Using a Broadband Swept-ECQCL

We measure chemical plumes at a 250 m standoff distance by sweeping an external cavity quantum cascade laser over a broad spectral range of 920-1220 cm(-1) at a rate of 200 Hz. (C) 2019 The Author(s)U.S. Department of Energy (DOE) [DE-AC05-76RL01830]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Standoff detection of chemical plumes from high explosive open detonations using a swept-wavelength external cavity quantum cascade laser

A swept-wavelength external cavity quantum cascade laser (ECQCL) is used to perform standoff detection of combustion gases in a plume generated from an outdoor high-explosive (HE) open detonation. The swept-ECQCL system was located at a standoff distance of 830m from a 41kg charge of LX-14 (polymer-bonded high explosive) and was used to measure the infrared transmission/absorption through the post-detonation plume as it propagated through the beam path. The swept-ECQCL was operated continuously to record broadband absorption spectra at a 200Hz rate over a spectral range from 2050 to 2230cm(-1) (4.48-4.88 mu m). Fitting of measured spectra was used to determine time-resolved column densities of CO, CO2, H2O, and N2O. Analysis of visible video imagery was used to provide timing correlations and to estimate plume dimensions, from which gas mixing ratios were estimated. Measured emission factors and modified combustion efficiency show good agreement with previously reported values.U.S. Department of Energy12 month embargo; first published online 26 October 2020This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Time-Resolved Dual Frequency Comb Spectroscopy for Broadband Multi-Species Detection in Laser-Induced Plasmas

We present the first results using time-resolved broadband dual-comb spectroscopy in a laser-induced plasma. Preliminary results identifying multiple species in a Nd magnet will be shown. (c) 2019 The Author(s)Air Force Office of Scientific Research [FA9550-15-1-0091]; Defense Threat Reduction Agency [HDTRA 11710030]; U.S. Department of Energy (DOE) by the Battelle Memorial Institute [DE-AC05-76RL01830]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Dual-comb spectroscopy of laser-induced plasmas

Dual-comb spectroscopy has become a powerful spectroscopic technique in applications that rely on its broad spectral coverage combined with high frequency resolution capabilities. Experiments to date have primarily focused on detection and analysis of multiple gas species under semi-static conditions, with applications ranging from environmental monitoring of greenhouse gases to high-resolution molecular spectroscopy. Here, we utilize dual-comb spectroscopy to demonstrate broadband, high-resolution, and time-resolved measurements in a laser-induced plasma. As a demonstration, we simultaneously detect trace amounts of Rb and K in solid samples with a single laser ablation shot, with transitions separated by over 6 THz (13 nm) and spectral resolution sufficient to resolve isotopic and ground state hyperfine splittings of the Rb D-2 line. This new spectroscopic approach offers the broad spectral coverage found in the powerful techniques of laser-induced breakdown spectroscopy (LIBS) while providing the high-resolution and accuracy of cw laser-based spectroscopies.Air Force Office of Scientific Research [FA9550-15-1-0091]; National Nuclear Security Administration, Defense Nuclear Nonproliferation RD Office; National Nuclear Security Administration, Department of Energy [DE-SC0004311]; Physics, Materials and Applied Mathematics Research L.L.C.; U.S. Department of Energy (DOE) [DE-AC05-76RL01830]; UA/NASA Space Grant ProgramThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Characterization of a Laser-Induced Plasma Using Time-Resolved Dual-Frequency-Comb Spectroscopy

We characterize the dynamics of laser-induced plasmas using time-resolved dual-frequency-comb spectroscopy. The temporal evolution of plasma's temperature, population number density are estimated for multiple Fe transitions. (C) 2019 The Author(s)Air Force Office of Scientific Research [FA9550-15-1-0091]; Defense Threat Reduction Agency [HDTRA 11710030]; U.S. Department of Energy (DOE) [DE-AC05-76RL01830]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Time-Resolved Dual Frequency Comb Phase Spectroscopy of Laser-Induced Plasmas

We present the first results using time-resolved dual-comb phase spectroscopy in a laser-induced plasma. It can allow for simultaneous plasma characterization as well as multi-species detection and plasma characterization. (c) 2019 The Author(s)Air Force Office of Scientific Research [FA9550-15-1-0091]; Defense Threat Reduction Agency [HDTRA11710030]; U.S. Department of Energy (DOE) [DE-AC05-76RL01830]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Time-resolved dual-comb measurement of number density and temperature in a laser-induced plasma

We utilize time-resolved dual-comb spectroscopy to measure the temporal evolution of the population number densities and absorption excitation temperature of Fe in a laser-induced plasma. The spectra of three excited-state transitions of Fe around 533 nm are simultaneously measured at different time delays following laser ablation of a stainless steel sample. This Letter probes late-time behaviors of laser-induced ablation plumes during plasma cooling. The high spectral resolution and broad spectral coverage of the dual-comb technique, combined with the time-resolved measurement capability shown here, will aid in the characterization of laser induced plasmas, including species identification and molecule and particle formation that can occur at later times in the plasma evolution. (C) 2019 Optical Society of AmericaAir Force Office of Scientific Research (AFOSR) [FA9550-15-1-0091]; Defense Threat Reduction Agency (DTRA) [11710030]; National Science Foundation (NSF) [1206555]; Office of Defense Nuclear Nonproliferation (DNN); National Nuclear Security Administration (NNSA); U.S. Department of Energy (DOE) [DE-AC05-76RL01830]12 month embargo; published online: 10 July 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]