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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

NASA Tech Briefs, May 2008

Topics covered inclde: Deployable Wireless Camera Penetrators; Hand-Held Units for Short-Range Wireless Biotelemetry; Wearable Wireless Telemetry System for Implantable BioMEMS Sensors; Electronic Escape Trails for Firefighters; Architecture for a High-to-Medium-Voltage Power Converter; 24-Way Radial Power Combiner/Divider for 31 to 36 GHz; Three-Stage InP Submillimeter-Wave MMIC Amplifier; Fast Electromechanical Switches Based on Carbon Nanotubes; Solid-State High-Temperature Power Cells; Fast Offset Laser Phase-Locking System; Fabricating High-Resolution X-Ray Collimators; Embossed Teflon AF Laminate Membrane Microfluidic Diaphragm Valves; Flipperons for Improved Aerodynamic Performance; System Estimates Radius of Curvature of a Segmented Mirror; Refractory Ceramic Foams for Novel Applications; Self-Deploying Trusses Containing Shape-Memory Polymers; Fuel-Cell Electrolytes Based on Organosilica Hybrid Proton Conductors; Molecules for Fluorescence Detection of Specific Chemicals; Cell-Detection Technique for Automated Patch Clamping; Redesigned Human Metabolic Simulator; Compact, Highly Stable Ion Atomic Clock; LiGa(OTf)(sub 4) as an Electrolyte Salt for Li-Ion Cells; Compact Dielectric-Rod White-Light Delay Lines; Single-Mode WGM Resonators Fabricated by Diamond Turning; Mitigating Photon Jitter in Optical PPM Communication; MACOS Version 3.31; Fiber-Optic Determination of N2, O2, and Fuel Vapor in the Ullage of Liquid-Fuel Tanks; Spiking Neurons for Analysis of Patterns; Symmetric Phase-Only Filtering in Particle-Image Velocimetry; Efficient Coupler for a Bessel Beam Dispersive Element; and Attitude and Translation Control of a Solar Sail Vehicle.

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NASA NTRS2015

Temperature Sensitivity of an Atomic Vapor Cell-Based Dispersion-Enhanced Optical Cavity

Enhancement of the response of an optical cavity to a change in optical path length, through the use of an intracavity fast-light medium, has previously been demonstrated experimentally and described theoretically for an atomic vapor cell as the intracavity resonant absorber. This phenomenon may be used to enhance both the scale factor and sensitivity of an optical cavity mode to the change in path length, e.g. in gyroscopic applications. We study the temperature sensitivity of the on-resonant scale factor enhancement, S(sub o), due to the thermal sensitivity of the lower-level atom density in an atomic vapor cell, specifically for the case of the Rb-87 D(sub 2) transition. A semi-empirical model of the temperature-dependence of the absorption profile, characterized by two parameters, a(sub o)(T) and gamma(sub a)(T) allows the temperature-dependence of the cavity response, S(sub o)(T) and dS(sub o)/dT to be predicted over a range of temperature. We compare the predictions to experiment. Our model will be useful in determining the useful range for S(sub o), given the practical constraints on temperature stability for an atomic vapor cell.

Myneni, K.↗
NASA NTRS1992

Optical Pumping of Mesospheric Sodium: a New Measurement Capability

The first observation of laser-induced optical pumping in a remote sensing application is reported. We have observed a large variation in the amount of laser light resonantly backscattered from the earth's mesospheric sodium layer depending on the laser polarization. This is consistent with optical pumping of the mesospheric sodium atoms. A new lidar capability is being developed based on measurements of the rethermalization rate of the optically pumped sodium atoms. These measurements have potential applications in the fields of global warming research, spacecraft re-entry, and upper atmospheric dynamics.

Heinrichs, R. M.↗
NASA NTRS1982

Identification of resonance features within the rings of Saturn

The Voyager 2 UV spectrometer observed a stellar occultation by the rings of Saturn, which located ring features with an accuracy of 12 km. A high-resolution (3 km) optical depth atlas of the rings shows at least nine features, including four density wave patterns, identified with satellite resonances. Analysis of these density wave patterns yields the first surface mass densities for the A ring and, together with the optical depth atlas, a total ring mass of 6.4 x 10 to the -8th Saturn masses.

Holberg, J. B.↗
NASA NTRS1987

Frequency stabilization in injection controlled pulsed CO2 lasers

Longitudinal mode selection by injection has been demonstrated as a viable technique for tailoring a TEA-CO2 laser with pulse energies of a Joule or greater to fit the requirements of a coherent lidar transmitter. Once reliable generation of single-longitudinal-mode (SLM) pulses is obtained, one can study the intrapulse frequency variation and attempt to determine the sources of frequency sweeping, or chirp. These sources include the effect of the decaying plasma, the thermal gradient due to the energy dissipation associated with the laser mechanism itself, and the pressure shift of the center frequency of the laser transition. The use of the positive-branch unstable resonator as an efficient means of coupling a discharge with transverse spatial dimensions of the order of centimeters to an optical cavity mode introduces another concern: namely, what can be done to emphasize transverse mode discrimination in an unstable resonator cavity while maintaining high coupling efficiency. These issues are briefly discussed in the paper, and representative experimental examples are included.

Menzies, Robert T.↗
NASA NTRS1995

The soft gamma-ray spectrum of A0535+26: Detection of an absorption feature at 110 keV by OSSE

We present soft gamma-ray observations by the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory (GRO) of the transient X-ray binary pulsar A0535+26. The observations were made 1994 February 8-17, immediately prior to the peak of a giant outburst. The phase averaged spectrum is complex and cannot be described by a single-component model. We find that structure in the spectrum above 100 keV can best be modeled by an absorption feature near 110 keV, which we interepret as the signature of cyclotron resonant scattering. Because of OSSE's 45 keV threshold, we are unable to make a definitive statement on the presence of a 55 keV absorption line; however, we can conclude that if this line does exist, it must have a smaller optical depth than the line at 110 keV. A first harmonic (=fundamental) cyclotron resonance at 110 keV corresponds to a magnetic field strength at the surface of the neutron star of approximately 1 x 10(exp 13) G (approximately 5 x 10(exp 12) G if the first harmonic is at 55 keV).

Grove, J. E.↗
NASA NTRS1992

Advanced NDE research in electromagnetic, thermal, and coherent optics

A new inspection technology called magneto-optic/eddy current imaging was investigated. The magneto-optic imager makes readily visible irregularities and inconsistencies in airframe components. Other research observed in electromagnetics included (1) disbond detection via resonant modal analysis; (2) AC magnetic field frequency dependence of magnetoacoustic emission; and (3) multi-view magneto-optic imaging. Research observed in the thermal group included (1) thermographic detection and characterization of corrosion in aircraft aluminum; (2) a multipurpose infrared imaging system for thermoelastic stress detection; (3) thermal diffusivity imaging of stress induced damage in composites; and (4) detection and measurement of ice formation on the space shuttle main fuel tank. Research observed in the optics group included advancements in optical nondestructive evaluation (NDE).

Skinner, S. Ballou↗
NASA NTRS1973

Lunar Science Conference, 4th, Houston, Tex., March 5-8, 1973, Proceedings. Volume 1 - Mineralogy and petrology. Volume 2 - Chemical and isotope analyses. Organic chemistry. Volume 3 - Physical properties

The mineralogy, petrology, chemistry, isotopic composition, and physical properties of lunar materials are described in papers detailing methods, results, and implications of research on samples returned from eight lunar landing sites: Apollo 11, 12, 14, 15, 16, 17, and Luna 16 and 20. The results of experiments conducted or set up on the lunar surface by the astronauts are also described along with observations taken from Command Modules and subsatellites. Major topics include general geology, soil and breccia studies, petrologic studies, mineralogic analyses, elemental compositions, radiometric age determinations, rare gas chemistry, radionuclides, organogenic compounds, particle track records, thermal properties, seismic studies, resonance studies, orbital mapping, lunar atmosphere, magnetic studies, electrical studies, optical properties, and microcratering. Individual items are announced in this issue.

Gose, W. A.↗
NASA NTRS1981

IUE observations of supernova remnants

The ultraviolet emission spectra of several filaments in the Cygnus Loop and the Vela Supernova Remnant, including several which are anomalously bright in the optical lines, are discussed. The effects of internal and interstellar resonance line scattering are estimated. Shock velocities, elemental abundances, and in some cases, filament ages are given.

Raymond, J.↗
NASA NTRS1983

A 10 deg K triple-expansion Stirling-cycle cryocooler

The design of a triple expansion closed cycle Stirling cryocooler optimized for a cooling load of 50 mW at 10 K is described. The cooler was designed with the objectives of low power, low weight, compactness, low mechanical motion, low electromagnetic noise, and low output temperature fluctuations. The design employs a direct drive linear motion piston motor and a triple expansion free displacer. Piston motion is controlled by feedback from an optical position transducer. Mechanical vibrations are attenuated with a passive resonant counterbalance. Electromagnetic noise is attenuated with layered high permeability magnetic shielding. The regenerators move with the displacer within a thin titanium cold finger. The piston and displacer oscillate at 8.33 Hz on bearings and seals of reinforced Teflon. The cooler is designed to provide the desired 50 mW of cooling at 10 K with a power input of less than 100 W. The piston can be driven at a greater stroke to produce up to 200 mW of cooling with an input power of 250 W. A lead and copper cold tip heat exchanger will limit temperature fluctuations to within 0.01 K.

Newman, W.↗
NASA NTRS1990

The transfer of resonance-line radiation in static astrophysical media

An analytic solution is derived for the mean intensity of resonance-line radiation within an absorbing medium of large scattering optical depth but low density. The line profile, the mean number of scatterings before absorption or escape, the mean path length traveled, and the fraction of the photons which escape the medium are derived. Approximate methods are also developed which permit the treatment of media of intermediate optical depth, where scattering takes place in the Doppler core. Astrophysical applications include the absorption of H Ly-alpha radiation by stellar dust, the pumping of H2 Lyman band lines by H Ly-alpha and the Bowen fluorescence.

Neufeld, David A.↗
NASA NTRS1992

Structural design and analysis for an ultra low CTE optical bench for the Hubble Space Telescope corrective optics

The stringent stability requirements of the Corrective Optics Space Telescope Axial Replacement (COSTAR) necessitates a Deployable Optical Bench (DOB) with both a low CTE and high resonant frequency. The DOB design consists of a monocoque thin shell structure which marries metallic machined parts with graphite epoxy formed structure. Structural analysis of the DOB has been integrated into the laminate design and optimization process. Also, the structural analytical results are compared with vibration and thermal test data to assess the reliability of the analysis.

Neam, Douglas C.↗
NASA NTRS1995

High-performance reactionless scan mechanism

A high-performance reactionless scan mirror mechanism was developed for space applications to provide thermal images of the Earth. The design incorporates a unique mechanical means of providing reactionless operation that also minimizes weight, mechanical resonance operation to minimize power, combined use of a single optical encoder to sense coarse and fine angular position, and a new kinematic mount of the mirror. A flex pivot hardware failure and current project status are discussed.

Williams, Ellen I.↗
NASA NTRS2007

NASA Tech Briefs, June 2007

Topics covered include: High-Accuracy, High-Dynamic-Range Phase-Measurement System; Simple, Compact, Safe Impact Tester; Multi-Antenna Radar Systems for Doppler Rain Measurements; 600-GHz Electronically Tunable Vector Measurement System; Modular Architecture for the Measurement of Space Radiation; VLSI Design of a Turbo Decoder; Architecture of an Autonomous Radio Receiver; Improved On-Chip Measurement of Delay in an FPGA or ASIC; Resource Selection and Ranking; Accident/Mishap Investigation System; Simplified Identification of mRNA or DNA in Whole Cells; Printed Multi-Turn Loop Antennas for RF Biotelemetry; Making Ternary Quantum Dots From Single-Source Precursors; Improved Single-Source Precursors for Solar-Cell Absorbers; Spray CVD for Making Solar-Cell Absorber Layers; Glass/BNNT Composite for Sealing Solid Oxide Fuel Cells; A Method of Assembling Compact Coherent Fiber-Optic Bundles; Manufacturing Diamond Under Very High Pressure; Ring-Resonator/Sol-Gel Interferometric Immunosensor; Compact Fuel-Cell System Would Consume Neat Methanol; Algorithm Would Enable Robots to Solve Problems Creatively; Hypothetical Scenario Generator for Fault-Tolerant Diagnosis; Smart Data Node in the Sky; Pseudo-Waypoint Guidance for Proximity Spacecraft Maneuvers; Update on Controlling Herds of Cooperative Robots; and Simulation and Testing of Maneuvering of a Planetary Rover.

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NASA NTRS2009

Multiplexing of Hot-Electron Nanobolometers Using Microwave SQUIDs

We have obtained the first data on the multiplexed operation of titanium hot-electron bolometers (HEB). Because of their low thermal conductance and small electron heat capacity nanobolometers are particularly interesting as sensors for far-infrared spectroscopy and mid- and near-IR calorimetry. However, the short time constant of these devices (approximately microseconds at 300-400 mK) makes time domain or audio-frequency domain multiplexing impractical. The Microwave SQUID (MSQUID) approach pursued in this work uses dc SQUIDs coupled to X-band microresonators which are, in turn, coupled to a transmission line. We used a 4-element array of Ti HEBs operated at 415 mK in a He3 dewar with an optical fiber access. The microwave signal exhibited 10-MHz wide resonances at individual MSQUD frequencies between 9 GHz and 10 GHz. The resonance depth is modulated by the current through the bolometer via a change of the SQUID flux state. The transmitted signal was amplified by a cryogenic amplifier and downconverted to baseband using an IQ mixer. A 1-dB per ??/2 responsivity was sufficient for keeping the system noise at the level of ~ 2 pA/Hz1/2. This is more than an order of magnitude smaller than phonon noise in the HEB. The devices were able to detect single near- IR photons (1550 nm) with a time constant of 3.5 ?s. Follow-on work will scale the array to larger size and will address the microwave frequency signal generation and processing using a digital transceiver.

microwave readout↗
NASA NTRS2007

Design, Qualification, and On Orbit Performance of the CALIPSO Aerosol Lidar Transmitter

The laser transmitter for the CALIPSO aerosol lidar mission has been operating on orbit as planned since June 2006. This document discusses the optical and laser system design and qualification process that led to this success. Space-qualifiable laser design guidelines included the use of mature laser technologies, the use of alignment sensitive resonator designs, the development and practice of stringent contamination control procedures, the operation of all optical components at appropriately derated levels, and the proper budgeting for the space-qualification of the electronics and software.

Hovis, Floyd E.↗
NASA NTRS2009

Spectrum Analyzers Incorporating Tunable WGM Resonators

A photonic instrument is proposed to boost the resolution for ultraviolet/ optical/infrared spectral analysis and spectral imaging allowing the detection of narrow (0.00007-to-0.07-picometer wavelength resolution range) optical spectral signatures of chemical elements in space and planetary atmospheres. The idea underlying the proposal is to exploit the advantageous spectral characteristics of whispering-gallery-mode (WGM) resonators to obtain spectral resolutions at least three orders of magnitude greater than those of optical spectrum analyzers now in use. Such high resolutions would enable measurement of spectral features that could not be resolved by prior instruments.

Savchenkov, Anatoliy↗
NASA NTRS1993

Optical Pathlength Control Experiment on JPL Phase B Testbed

An experimental implementation of a nanometer level optical pathlength control for large baseline space interferometry is presented. The pathlength compensation system is installed on a large flexible experimental truss, thus structural motions play a dominant role in the control system design. The associated control structure interaction problem is addressed to maintain the optical pathlength within the prescribed variation of 10-15 nanometer rms. By a successful blend of a structural control for damping augmentation and a direct pathlength control for the pathlength compensation, the optical pathlength variation has been maintained within 6 nonometer rms under the laboratory ambient disturbance and within 9 nonmeter rms under a severe forced resonant disturbance.

interferometry↗