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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

A Compact Two-Step Laser Time-Of-Flight Mass Spectrometer for In Situ Analysis of Planetary Surfaces

Two-step laser mass spectrometry (L2MS) has proved to be a powerful tool for the analysis of aromatic organics in icy planetary simulants, meteorites, asphaltenes on Earth, and returned cometary particles from the Stardust mission. L2MS employs two lasers to separate the desorption and ionization processes of laser desorption ionization into distinct steps. In the first step, an infrared laser desorbs neutrals from a solid sample surface; in the second step, an ultraviolet laser forms molecular ions within the neutral plume through a resonance-enhanced process to minimize fragment at ion of complex species. We have recently demonstrated that the L2MS technique is compatible with a compact TOF-MS that could form the center piece of a future in situ landed planetary mission emphasizing surface chemistry or astrobiology. The increased sensitivity and selectivity offered by this technique has been demonstrated in analyses of various planetary analog mixtures and meteorite powders, and representative results of these analyses will be presented.

Getty, Stephanie A.↗
NASA NTRS2011

JPL Carbon Dioxide Laser Absorption Spectrometer Data Processing Results for the 2010 Flight Campaign

As a precursor to and validation of the core technology necessary for NASA's Active Sensing of CO2 Emissions over Nights, Days,and Seasons (ASCENDS) mission, we flew JPL's Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) in a campaign of five flights onboard NASA's DC-8 Airborne Laboratory in July 2010. This is the latest in a series of annual flight campaigns that began in 2006, and our first on the DC-8 aircraft.

Lidar↗
NASA NTRSDate not supplied

In-Situ Process Monitoring, Synchronization, and Mapping Laser Powder Bed Fusion Builds of Ti6Al4V

The use of in-situ process monitoring is of interest to lower the cost of inspection for the qualification of laser powder bed fusion (LPBF) parts. Precise monitoring of the LPBF-AM build process constitutes a multi-scale and multi-discipline task. There are several significant challenges to the in-situ approach: the synchronization of sensor signals to process steps, the physical interpretation and classification of sensor signals, managing very large datasets, and comparing the inputs with the observed monitoring signals. At NASA Langley Research Center, a configurable architecture additive testbed has been developed to monitor the build process with synchronized sensors. The philosophy and method adopted for the synchronization of the cameras with laser power & position Ti-6Al-4V LPBF are described. The synchronized in-situ monitoring signals are compared with ex-situ nondestructive inspection and optical microscopy observations. Such comparisons permit a better understanding of how the sequential process actions of LPBF-AM can affect build quality.

Laser Powder Bed Fusion↗
NASA NTRS1979

Simulated electronic heterodyne recording and processing of pulsed-laser holograms

The electronic recording of pulsed-laser holograms is proposed. The polarization sensitivity of each resolution element of the detector is controlled independently to add an arbitrary phase to the image waves. This method which can be used to simulate heterodyne recording and to process three-dimensional optical images, is based on a similar method for heterodyne recording and processing of continuous-wave holograms.

Decker, A. J.↗
NASA NTRS1990

Comparison of UNL laser imaging and sizing system and a phase Doppler system for analyzing sprays from a NASA nozzle

Research was conducted on characteristics of aerosol sprays using a P/DPA and a laser imaging/video processing system on a NASA MOD-1 air assist nozzle being evaluated for use in aircraft icing research. Benchmark tests were performed on monodispersed particles and on the NASA MOD-1 nozzle under identical lab operating conditions. The laser imaging/video processing system and the P/DPA showed agreement on a calibration tests in monodispersed aerosol sprays of + or - 2.6 micron with a standard deviation of + or - 2.6 micron. Benchmark tests were performed on the NASA MOD-1 nozzle on the centerline and radially at 0.5 inch increments to the outer edge of the spray plume at a distance 2 ft downstream from the exit nozzle. Comparative results at two operation conditions of the nozzle are presented for the two instruments. For the 1st case studied, the deviation in arithmetic mean diameters determined by the two instruments was in a range of 0.1 to 2.8 micron, and the deviation in Sauter mean diameters varied from 0 to 2.2 micron. Severe operating conditions in the 2nd case resulted in the arithmetic mean diameter deviating from 1.4 to 7.1 micron and the deviation in the Sauter mean diameters ranging from 0.4 to 6.7 micron.

Alexander, Dennis R.↗
NASA NTRS1988

Comparison of UNL laser imaging and sizing system and a phase/Doppler system for analyzing sprays from a NASA nozzle

Aerosol spray characterization was done using a P/DPA and a laser imaging/video processing system on a NASA MOD-1 air-assist nozzle being evaluated for use in aircraft icing research. Benchmark tests were performed on monodispersed particles and on the NASA MOD-1 nozzle under identical laboratory operating conditions. The laser imaging/video processing system and the P/DPA showed agreement on calibration tests in monodispersed aerosol sprays of + or - 2.6 microns with a standard deviation of + or - 2.6 microns. Tests were performed on the NASA MOD-1 nozzle on the centerline and radially at one-half inch increments to the outer edge of the spray plume at a distance two feet (0.61 m) downstream from the exit of the nozzle. Comparative results at two operating conditions of the nozzle are presented for the two instruments. For the first case, the deviation in arithmetic mean diameters determined by the two instruments was in a range of 0.1 to 2.8 microns, and the deviation in Sauter mean diameters varied from 0 to 2.2 microns. Operating conditions in the second case were more severe which resulted in the arithmetic mean diameter deviating from 1.4 to 7.1 microns and the deviation in the Sauter mean diameters ranging from 0.4 to 6.7 microns.

Alexander, Dennis R.↗
NASA NTRS2004

An Acquisition Control for the Laser Interferometer Space Antenna

The Laser Interferometer Space Antenna (LISA) mission is a planned gravitational wave detector consisting of three spacecraft in heliocentric orbit. Laser interferometry is used to measure distance fluctuations between test masses aboard each spacecraft to the picometer level over a 5 million kilometer separation. Each spacecraft has two incoming and two outgoing laser beams for a total of six laser links. These links will have to be established sequentially at the start of the mission, and the spacecraft control systems must aim their lasers at each other with pointing motions less than 8 nanoradians per root Hertz in the frequency band 0.1-100 mHz. This paper presents a strategy for the laser acquisition process. The outgoing beam on one spacecraft is spoiled to provide a wide beam that encompasses the accuracy (noise and mounting bias) of the star tracker. The control system then takes advantage of an array of sensors with increasing sensitivity to quiet the receiving spacecraft and lock the laser. This process is carried out for each of the six links of LISA. A complete analysis and simulation of the acquisition process are presented.

Maghami, Peiman G.↗
NASA NTRS1997

Gold Coating

Epner Technology Inc. responded to a need from Goddard Space Flight Center for the ultimate in electroplated reflectivity needed for the Mars Global Surveyor Mars Orbiter Laser Altimeter (MOLA). Made of beryllium, the MOLA mirror was coated by Epner Technology Laser Gold process, specially improved for the project. Improved Laser Gold- coated reflectors have found use in an epitaxial reactor built for a large semiconductor manufacturer as well as the waveguide in Braun-Thermoscan tympanic thermometer and lasing cavities in various surgical instruments.

Source record↗
NASA NTRS2020

Miniaturized Laser Absorption Spectrometer for Combustion Calorimetry and Process Monitoring

A miniaturized tunable laser absorption spectrometer capable of measuring gas-phase concentrations of CO, CO2, and O2 has been developed for operation in spacecraft environments. As part of the Spacecraft Fire Safety Demonstration (Saffire) project, we previously demonstrated the Combustion Product Monitor (CPM) instrument to characterize pyrolysis of relevant test materials in low gravity aboard a transfer vehicle returning from low Earth orbit. Here, we adapted the CPM instrument design to achieve detection of CO, CO2, and O2 with improved minimum detection limits and dynamic range as well as reduced instrument size and power. The instrument can be operated in either an open or sealed configureation, allowing for ambient gas composition measuremnts or in-line monitoring of gas streams. By accurately monitoring CO, CO2, and O2 with broad pressure/temperature calibration and response time on the order of 1 s, the instrument can be used to characterize the dynamics of combustion reactions in a variety of environments.

Briggs, Ryan M.↗
NASA NTRS1978

Laser-enhanced dynamics in molecular rate processes

The present discussion deals with some theoretical aspects associated with the description of molecular rate processes in the presence of intense laser radiation, where the radiation actually interacts with the molecular dynamics. Whereas for weak and even moderately intense radiation, the absorption and stimulated emission of photons by a molecular system can be described by perturbative methods, for intense radiation, perturbation theory is usually not adequate. Limiting the analysis to the gas phase, an attempt is made to describe nonperturbative approaches applicable to the description of such processes (in the presence of intense laser radiation) as electronic energy transfer in molecular (in particular atom-atom) collisions; collision-induced ionization and emission; and unimolecular dissociation.

George, T. F.↗
NASA NTRS1991

Computer Processing Of Tunable-Diode-Laser Spectra

Tunable-diode-laser spectrometer measuring transmission spectrum of gas operates under control of computer, which also processes measurement data. Measurements in three channels processed into spectra. Computer controls current supplied to tunable diode laser, stepping it through small increments of wavelength while processing spectral measurements at each step. Program includes library of routines for general manipulation and plotting of spectra, least-squares fitting of direct-transmission and harmonic-absorption spectra, and deconvolution for determination of laser linewidth and for removal of instrumental broadening of spectral lines.

May, Randy D.↗
NASA NTRS1980

Computer simulated rate processes in copper vapor lasers

A computer model for metal vapor lasers has been developed which places emphasis on the change of excited state populations of the lasant through inelastic collisions and radiative interaction. Also included are an energy equation for the pumping electrons and rate equations for laser photon densities. Presented are results of calculations for copper vapor with a neon buffer over a range of conditions. General agreement with experiments was obtained.

Harstad, K. C.↗
NASA NTRS1987

Intelligent laser soldering inspection and process control

Component assembly on printed circuitry keeps making giant strides toward denser packaging and smaller dimensions. From a single layer to multilayer, from through holes to surface mounted components and tape applied bonds, unrelenting progress results in new, difficult problems in assembling, soldering, inspecting and controlling the manufacturing process of the new electronics. Among the major problems are the variables introduced by human operators. The small dimensions and the tight assembly tolerances are now successfully met by machines which are faster and more precise than the human hand. The same is true for soldering. But visual inspection of the solder joints is now so severely limited by the ever shrinking area accessible to the human eye that the inspector's diagnosis cannot be trusted any longer. Solutions to correcting these problems are discussed.

Vanzetti, Riccardo↗
NASA NTRS1989

Computer processing of tunable diode laser spectra

A computer-controlled tunable diode laser spectrometer and spectral analysis software are described. The three-channel system records simultaneously the transmission of a subject gas, a temperature-stabilized etalon, and a calibration gas. The software routines are applied to diode laser spectra of HNO3 and NO2 to illustrate the procedures adopted for conversion of raw spectral data to useful transmission and harmonic spectra. Extraction of line positions, absorption intensities, collisional broadening coefficients, and gas concentrations from recorded spectra is also described.

May, Randy D.↗