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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Real time moving scene holographic camera system

A holographic motion picture camera system producing resolution of front surface detail is described. The system utilizes a beam of coherent light and means for dividing the beam into a reference beam for direct transmission to a conventional movie camera and two reflection signal beams for transmission to the movie camera by reflection from the front side of a moving scene. The system is arranged so that critical parts of the system are positioned on the foci of a pair of interrelated, mathematically derived ellipses. The camera has the theoretical capability of producing motion picture holograms of projectiles moving at speeds as high as 900,000 cm/sec (about 21,450 mph).

Kurtz, R. L.↗
NASA NTRS1993

GOPEX: A Laser Uplink to the Galileo Spacecraft on its Way to Jupiter

In the Galileo Optical Experiment (GOPEX), optical transmissions were beamed to the Galilieo spacecraft by Earth-based transmitters at Table Mountain Observatory (TMO), California, and Starfire Optical Range (SOR), New Mexico. The demonstration took place over an eight-day period (December 9 through December 16) as Galileo receded from Earth on its way to Jupiter. At 6 million kilometers (15 times the Earth-Moon distance), the laser beam sent from Table Mountain Observatory eight days after Earth flyby covered the longest known range for laser transmission and detection.

lasers↗
NASA NTRS1985

Earth to space dc to dc power transmission system utilizing a microwave beam as source of energy for electric propelled interorbital vehicles

The paper contributes to the credibility of an electric propelled interorbital transportation system by introducing a new low-mass source of continuous dc power for electric propulsion and illustrating how the source can be economically tied to an electric utility on earth by an electronically steered microwave beam. The new thin-film rectenna, which functions as the receiving end of an earth-to-space microwave power transmission system is described. It is easily fabricated, is over 80 percent efficient, has a specific mass of no more than 2 kilograms per kilowatt of continuous dc power output, and is well adapted for deployment in space. The paper then describes a complete system consisting of the interorbital vehicle and the microwave power transmission system that supplies it with power. A design scenario is used to obtain performance data from the system in terms of vehicle transfer times, payload fractions, and costs. Electric energy costs are found to be less than $1000 per kilogram of payload delivered to geosynchronous orbit from low-earth orbit.

Brown, W. C.↗
DOE OSTI2023

Modeling for the phased injector upgrade for 12 GeV CEBAF

The upcoming Jefferson Lab K-Long experiment at Hall D will require unique beam conditions with a much lower bunch repetition rate and atypically high bunch charge. To optimize the Continuous Electron Beam Accelerator Facility (CEBAF) injector for this experiment, we performed Multi-Objective Genetic Optimization (MGO) using General Particle Tracer (GPT) to determine the magnetic elements and RF settings necessary for the K-long bunch charge (0.64 pC) at 200 kV. We also investigated the transmission and beam characteristics of low to high charge per bunch electron beams through the injector for simultaneous operations of all four CEBAF Halls and characterized the transmission as a function of the photocathode laser spot size and pulse length. Our findings provide valuable insights into optimizing the CEBAF injector for the Jefferson Lab K-Long experiment, as well as for other experiments with similar beam conditions

Kazimi, R.↗
NASA NTRS1999

Low-Pressure Gas Effects on the Potency of an Electron Beam Against Ceramic Cloth

An 8-kv electron beam with a current in the neighborhood of 100 mA from the Ukrainian space welding "Universal Hand Tool" (UHT) burned holes in Nextel AF-62 ceramic cloth designed to withstand temperatures up to 1,427 C. The burnthrough time was on the order of 8 scc at standoff distances between UHT and cloth ranging from 6-24 in. At both closer (2 in.) and farther (48 in.) standoff distances the potency of the beam against the cloth declined and the burnthrough time went up significantly. Prior to the test it had been expected that the beam would lay down a static charge on the cloth and be deflected without damaging the cloth. The burnthrough is thought to be an effect of partial transmission of beam power by a stream of positive ions generated by the high-voltage electron beam from contaminant gas in the "vacuum" chamber. A rough quantitative theoretical computation appears to substantiate this possibility.

Nunes, A. C., Jr.↗
NASA NTRS2001

The Low Pressure Gas Effects On The Potency Of An Electron Beam On Ceramic Fabric Materials For Space Welding

This investigation was undertaken to evaluate if molten metal or electron beam impingement could damage or burn through the fabric of the astronauts Extravehicular Mobility Unit (EMU) during electron beam welding exercises performed in space. An 8 kilovolt electron beam with a current in the neighborhood of 100 milliamps from the Ukrainian space welding "Universal Hand Tool" burned holes in Nextel AF-62 ceramic cloth designed to withstand temperatures up to 1427 C. The burnthrough time was on the order of 8 seconds at standoff distances between UHT and cloth ranging from 6 to 24 inches. At both closer (2") and farther (48") standoff distances the potency of the beam against the cloth declined and the burnthrough time went up significantly. Prior to the test it had been expected that the beam would lay down a static charge on the cloth and be deflected without damaging the cloth. The burnthrough is thought to be an effect of partial transmission of beam power by a stream of positive ions generated by the high voltage electron beam from contaminant gas in the "vacuum" chamber. A rough quantitative theoretical computation appears to substantiate this possibility.

Nunes, Arthur C., Jr.↗
NASA NTRS2006

Full-Duplex Digital Communication on a Single Laser Beam

A proposed free-space optical communication system would operate in a full-duplex mode, using a single constant-power laser beam for transmission and reception of binary signals at both ends of the free-space optical path. The system was conceived for two-way data communication between a ground station and a spacecraft in a low orbit around the Earth. It has been estimated that in this application, a data rate of 10 kb/s could be achieved at a ground-station-to-spacecraft distance of 320 km, using a laser power of only 100 mW. The basic system concept is also applicable to terrestrial free-space optical communications. The system (see figure) would include a diode laser at one end of the link (originally, the ground station) and a liquid-crystal- based retroreflecting modulator at the other end of the link (originally, the spacecraft). At the laser end, the beam to be transmitted would be made to pass through a quarter-wave plate, which would convert its linear polarization to right circular polarization. For transmission of data from the laser end to the retroreflector end, the laser beam would be modulated with subcarrier phase-shift keying (SC-PSK). The transmitted beam would then pass through an aperture- sharing element (ASE) - basically, a mirror with a hole in it, used to separate the paths of the transmitted and received light beams. The transmitted beam would continue outward through a telescope (which, in the original application, would be equipped with a spacecraft-tracking system) that would launch the transmitted beam along the free-space optical path to the retroreflector end.

Hazzard, D. A.↗
DOE OSTI2023

Modeling the CEBAF Injector at 200 kV: Investigating K-Long Beam Conditions with and without Wien Filter

The upcoming K-Long experiment [1] ain Hall D at Jefferson Lab presents unique beam requirements, featuring a significantly low bunch repetition rate and an unusually high bunch charge. This experiment, which utilizes the CEBAF accelerator in conjunction with the GlueX experimental setup, aims to study strange hadron spectroscopy by measuring the differential cross section and polarizations of produced hyperons such as Λ, Σ, Ξ, and Ω. By directing an intense K-Long beam towards the LD2/LH2 target, new and valuable data can be obtained. To optimize the CEBAF injector specifically for this experiment, we employed Multi-Objective Genetic Optimization (MGO) using General Particle Tracer (GPT) simulations. Through this approach, we determined the optimal magnetic elements and radiofrequency (RF) settings required to achieve a K-Long bunch charge of 0.64 pC at an energy of 200 kV. We conducted simulations with both the Wien Filter turned on and off to examine its impact on the beam. Furthermore, we investigated the transmission efficiency and beam characteristics of electron beams with varying charge per bunch through the injector, considering the simultaneous operation of all four CEBAF Halls. The results of our study offer valuable insights and guidance for optimizing the CEBAF injector not only for the Jefferson Lab K-Long experiment but also for other experiments that entail similar beam conditions.

Pokharel, Sunil↗
NASA NTRSDate not supplied

Non-Mechanical Beam Steering for NASA's Navigation Doppler LiDAR

Transparent electro-optic (EO) devices can potentially be used for efficient, high speed, and low mass non-mechanical beam steering. Transmission through EO devices will affect the wavefront quality and aberration of both the transmitted and received laser light. The consequences of wavefront distortions on coherent detection are not fully understood. Therefore, we have tested the performance of coherent detection lidar using liquid crystal polarization grating (LCPG) beam steering device. We will discuss the impact of LCPG beam steering devices on the performance of NASA’s Navigation Doppler Lidar, built for providing altitude and vector velocity data to aerial and space vehicles.

Lidar↗
NASA NTRS2014

Upgrade of the NASA 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) to its Full Science Capability of Sun-Sky-Cloud-Trace Gas Spectrometry in Airborne Science Deployments

The objectives of this task in the AITT (Airborne Instrument Technology Transition) Program are to (1) upgrade the NASA 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) instrument to its full science capability of measuring (a) direct-beam sun transmission to derive aerosol optical depth spectra, (b) sky radiance vs scattering angle to retrieve aerosol absorption and type (via complex refractive index spectra, shape, and mode-resolved size distribution), (c) zenith radiance for cloud properties, and (d) hyperspectral signals for trace gas retrievals, and (2) demonstrate its suitability for deployment in challenging NASA airborne multiinstrument campaigns. 4STAR combines airborne sun tracking, sky scanning, and zenith pointing with diffraction spectroscopy to improve knowledge of atmospheric constituents and their links to air pollution, radiant energy budgets (hence climate), and remote measurements of Earth's surfaces. Direct beam hyperspectral measurement of optical depth improves retrievals of gas constituents and determination of aerosol properties. Sky scanning enhances retrievals of aerosol type and size distribution. 4STAR measurements are intended to tighten the closure between satellite and ground-based measurements. 4STAR incorporates a modular sun-tracking/sky-scanning optical head with fiber optic signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical head, and future detector evolution. 4STAR test flights, as well as science flights in the 2012-13 TCAP (Two-Column Aerosol Project) and 2013 SEAC4RS (Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) have demonstrated that the following are essential for 4STAR to achieve its full science potential: (1) Calibration stability for both direct-beam irradiance and sky radiance, (2) Improved light collection and usage, and (3) Improved flight operability and reliability. A particular challenge for the AITT-4STAR project has been conducting it simultaneously with preparations for, and execution of, ARISE (Arctic Radiation - IceBridge Sea&Ice Experiment), a NASA airborne science deployment (unplanned when AITT-4STAR was selected for funding) in which 4STAR will deploy to Thule, Greenland, and Fairbanks, Alaska, on the NASA C- 130. This presentation describes progress to date in accomplishing AITT-4STAR goals, and plans for project completion.

Sun-Sky-Cloud-Trace↗
DOE OSTI2023

Novel Focused Ion Beam Liftouts for Spatial Characterization of Spherical Biominerals With Transmission Electron Microscopy

Abstract Focused ion beam (FIB) is frequently used to prepare electron- and X-ray-beam-transparent thin sections of samples, called lamellae. Typically, lamellae are prepared from only a subregion of a sample. In this paper, we present a novel approach for FIB lamella preparation of microscopic samples, wherein the entire cross-section of the whole sample can be investigated. The approach was demonstrated using spherical, porous, and often hollow microprecipitates of biologically precipitated calcium carbonate. The microprecipitate morphology made these biogenic samples more fragile and challenging than materials commonly investigated using FIB lamellae. Our method enables the appropriate orientation of the lamellae required for further electron/X-ray analyses after attachment to the transmission electron microscopy (TEM) grid post and facilitates more secure adhesion onto the grid post. We present evidence of autofluorescence in bacterially precipitated vaterite using this lamella preparation method coupled with TEM selected area diffraction. This innovative approach allows studying biomineralization at the micro to nano scales, which can provide novel insights into bacterial responses to microenvironmental conditions.

47 OTHER INSTRUMENTATION↗
NASA NTRS1999

Resonant Transmissive Modulator Construction for Use in Beam Steering Array

An agile electronically configurable optical beam steering device for use in directional free-space transmission of optical signals is described. The device design employs an array of tunable resonant transmissive modulators constructed from multi-layered stacks of electro-optically active dielectric materials. Each modulator may be individually configured to transmit an optical signal with a specific amount of phase and group velocity modulation. The resulting diffractive interactions between modulator outputs provide a method for directional optical signal transmission. Of particular focus within this presentation is the optimized design of the individual modulator. It is widely known that periodic multi-layered stacks of dielectric materials exhibit reflective and transmissive resonances as described by the stack's transmission function. If an electric field is applied normal to the stack's layers, phenomena such as the electro-optic effect and/or the quantum-confined Stark effect may be employed to change the effective refractive index within the stack. This refractive index change alters the stack's transmission function and modulates the phase and group velocity of the transmitted optical signal. By varying the parameters that describe the stack's specific construction and operation, such as number of layers within the stack, refractive indexes of stack materials, layer thicknesses, and combinations of periodic verses non-periodic layer repetitions, custom transmittance functions may be generated. The transmitted optical signal carrier frequency and bandwidth must be carefully selected to maximize transmission and to minimize absorption. A computational optimization of the variables describing the stack's construction strives to maximize the amount of optical signal modulation verses applied voltage. Trade-offs between methods of increasing device performance verses the limitations of fabrication technologies are considered.

Keys, Andrew S.↗
DOE OSTI2021

High-efficiency transmission-mode diamond scintillator for quantitative characterization of X-ray beams

The luminance of a transmission mode X-ray scintillator diamond plate is dominated by induced defect centers having an excited state lifetime less than 10 msec, and in embodiments less than 1 msec, 100 usec, 10 used, 1 used, 100 nsec, or even 50 nsec, thereby providing enhanced X-ray luminance response and an X-ray flux dynamic range that is linear with X-ray flux on a log-log scale over at least three orders of magnitude. The diamond plate can be a single crystal having a dislocation density of less than 104 per square centimeter, and having surfaces that are ion milled instead of mechanically polished. The defect centers can be SiV centers induced by silicon doping during CVD diamond formation, and/or NV0 centers formed by nitrogen doping followed by applying electron beam irradiation of the diamond plate and annealing.

Antipov, Sergey↗
DOE OSTI2022

Secure mmWave Spectrum Sharing with Autonomous Beam Scheduling for 5G and Beyond

Spectrum Sharing (SS) has seen a renewed set of initiatives in 5G with the availability of shared and unlicensed spectrum bands that can be used by multiple cellular service providers and private cellular networks. Beam based transmission, instead of the traditional sector based transmission in conjunction with the spectrum agility of the 5G New Radio (NR) has brought new opportunities to optimized sharing of spectrum. Currently in the U.S., a centralized Spectrum Access Server (SAS) is used to co-ordinate spectrum sharing among networks sharing the same spectrum band. However, SAS becomes a focal point for security attacks and a performance bottleneck. In addition, SAS relies on an Environmental Sensor Network (ESN), separate from the 5G network. Without trusted spectral occupancy information, false reporting of spectrum sensing data can create sub-optimal and unfair spectrum usage. This paper summarizes our recent research findings in using a decentralized scheme for multiple networks to securely share spectrum with autonomous beam scheduling : 1) A new stochastic network framework based on Lyapunov Optimization approach is developed to optimize scheduling at the base stations; 2) Game theoretic (GT) approach is used to formulate the distributed scheduler; 3) Another distributed scheduler with Q-learning is presented that utilizes the Reinforcement Learning (RL) approach; 4) The performance and convergence rate of these distributed solutions to use shared and unlicensed spectrum are compared with existing solutions. Conditions under which the performance of these schedulers approach the theoretical upper bound, which is the performance possible with no interference among the operators sharing the spectrum, are presented; 5) The ability of a base station to use its own user equipment as sensors, for optimal spectrum sharing with base stations in other operator networks, is demonstrated to be an effective approach.

5G↗
DOE OSTI2024

Degradation of a Cr-Mo steel by carbide precipitation over long-term service

Microstructure of the 40-year service-exposed 1Cr-0.5Mo steel extracted from pressure vessels through the boat sampling technique was characterized using x-ray diffraction, field-emission scanning electron microscopy, energy dispersive spectrometry, electron backscatter diffraction, focused ion beam, and transmission electron microscopy. The microstructure degradation during long-term service was identified. Statistical crystal plastic ity models were developed to correlate the microstructure and mechanical properties quantitatively. The steel is found significantly strengthened but slightly embrittled. Nanoscale Mo 2 C carbides have nucleated within the ferrite matrix over the long-term service, resulting in significant strengthening of the matrix. The coarser grain boundary Cr 23 C 6 carbides, on the other hand, act as the damage accumulation sites and lead to the degradation.

36 MATERIALS SCIENCE↗