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At least 505 records · Page 28

All sources NASA NTRS DOE OSTI

NASA NTRS1979

Evaluation of the JPL X-band 32 element active array

Tests performed on an X-band 32-element active array are described. Antenna pattern characteristics of the array were tested in its standard operating mode as well as several degraded performance modes, including failures of 1, 2, 3, 4, 8, 16, and 31 elements. Additionally, the array was characterized with the addition of a metallic shroud, and also characterized versus rf drive level and at a single off-axis electronic beamsteered position. Characterization was performed on several of the 3/4-watt, three-stage, X-band solid-state power amplifier modules. The characterization included swept amplitude response, amplitude and phase versus temperature from -20 to +60 C, and intermodulation distortion of selected modules. The array is described and conclusions and recommendations based upon the experience and results achieved are included.

Boreham, J. F.↗

NASA NTRS1979

The JPL space photovoltaic program

The development of energy efficient solar cells for space applications is discussed. The electrical performance of solar cells as a function of temperature and solar intensity and the influence of radiation and subsequent thermal annealing on the electrical behavior of cells are among the factors studied. Progress in GaAs solar cell development is reported with emphasis on improvement of output power and radiation resistance to demonstrate a solar cell array to meet the specific power and stability requirements of solar power satellites.

Scott-Monck, J. A.↗

NASA NTRS1978

JPL - Small Power Systems Applications Project

The Small Power Systems Applications (SPSA) Project has been established to develop and commercialize small solar thermal power plants. The technologies of interest include all distributed and central receiver technologies which are potentially economically viable in power plant sizes of one to 10 MWe. The paper presents an overview of the SPSA Project and briefly discusses electric utility involvement in the Project.

Ferber, R. R.↗

NASA NTRS1978

Selenide technology evaluation program at JPL

Results are presented for experimental and analytical investigations of the overall performance of a selenide radioisotope thermoelectric generator intended to provide the electrical power for interplanetary spaceprobes such as the Galileo mission to Jupiter. The discussion focuses on technology areas of concern, electrical properties of the selenide thermoelectric materials used, and thermal conductivity of these materials for superior performance. It is shown that the selenide thermoelectric materials offer the advantage of high conversion efficiency. The long-life requirement on the power system for the Galileo mission necessitates proper design, known fabrication techniques, and reproducible assembly techniques in order to ensure stability of the thermoelectric properties. However, the thermophysical properties - sublimation and creep - of the p-material remains an area of considerable concern.

Stapfer, G.↗

NASA NTRS1979

A self pulsed laser ranging system under development at 'JPL'

The performance of large space deployable antenna reflectors to be used for broad-based communications systems is largely dependent on the accuracy with which the surface figure can be constructed and maintained. The paper examines various surface distortion tolerance and measurement requirements for various classes of communication antennas. Several surface measuring methods are described including a self-pulsed laser ranging system.

Berdahl, M.↗

NASA NTRS1979

Recent developments at JPL in the application of image processing to astronomy

Four applications of image processing to astronomy, automated location and analysis of star and galaxy images, geometric and radiometric decalibration of vidicon spectra, display of multiband radio images, and generation of high resolution polarization direction and magnitude maps from images are presented with illustrative examples. The technique by which a digital image can be analyzed automatically to locate and segregate between stars and galaxies and the steps performed by the classifier to determine the nature of each object are outlined. The classification program executed on a 48 inch Schmidt plate of the cluster of galaxies 655 is described. The calibration and decalibration steps to remove geometric and radiometric distortions from a silicon vidicon camera digital spectra are discussed. Three methods of displaying multispectral radio data, generating a mosaic of each image, producing a color coded image to depict radio velocity, and producing a stereo pair with radial velocity as depth are described. The generation of polarization information from images obtained through linear polarizing filters is illustrated, and it is concluded that in each case information was displayed using digital techniques which could not readily have been provided visually.

Lorre, J. J.↗

NASA NTRS1980

JPL self pulsed laser surface measurement system development

The use of a self pulsed laser system for accurately describing the surface shape of large space deployed antenna structures was evaluated. Tests with a breadboard system verified functional operation with short time resolution on the order of .2 mm, nonambiguous ranging, and a maximum range capability on the order of 150 m. The projected capability of the system is resolution of less than .1 mm over a reasonable time period and a range extension to over 300 m.

Berdahl, M.↗

NASA NTRS1980

JPL analytical performance prediction capability

The development of a computer code to simulate and predict the performance of large deployable antenna structures is discussed. The computer code is expected to account for all phases of hardware use, i.e., ground handling, boost, deployment, on orbit station keeping, and transfer from LEO to GEO, if applicable. In addition to accounting for static and dynamic loading of the basic structure, the variation in the precision of the reflector surface and the alignment of the feed support structure as a function orbit are scrutinized in order to accommodate electromagnetic analysis. Specific tasks directed towards the development of the computer code are reported and a number of thermal and structural models are discussed.

Chen, R.↗

NASA NTRS1980

Thermal energy storage effort at JPL

The technical, operational, and economic readiness of parabolic dish systems for electric and thermal applications was investigated. A parabolic dish system was then developed to the point at which subsequent commercialization activities can lead to successful market penetration. The immediate possible applications of the dish system to thermal energy storage are discussed.

Young, D. L.↗

NASA NTRS1980

JPL's parabolic dish test site

A parabolic dish test site (PDTS) was established in the California Mojave Desert to carry out work in testing solar point focusing concentrator systems and related hardware. The site was chosen because of its high solar insolation level and year around clear sky conditions. The various facilities and equipment at the PDTS, and the concentrator experiments being performed are described.

Hagen, T. L.↗

NASA NTRS1980

The JPL flux mapper

The flux mapper is a device that can map the intensity distribution in three dimensions of concentrated solar energy at the focus of a concentrator. Intensities to 10,000 solar constants can be measured. Constructed to assist in concentrator and receiver development, it consists of a radiometer which is moved through the concentrated sunlight in a series of planes perpendicular to the optical axis by means of a mechanical rastering device. Various radiometer probes can be utilized depending on the time and accuracy requirements of the program. Energy levels are recorded as a function of location. Reduction of this data can be in various formats, e.g., contour maps, digital arrays, isometric visualizations and other displays as the user requires.

Owen, W. A.↗

NASA NTRS1980

The JPL isolated application experiment series

A set of small (approximately 60-150 kWe) solar thermal power experiments, each of which is meant to address a separate isolated load application, will employ point focusing distributed receiver technology with emphasis on electric and possibly some thermal power applications. The program will be closely integrated with the technology development element of the thermal power systems project with the objective of utilizing the technologies being developed under that program.

Levin, R. R.↗

NASA NTRS1980

The JPL parabolic dish project

The parabolic dish solar collector is a highly versatile concentrating collector system that can produce heat for many thermal processes and electricity by coupling the collector to a suitable heat engine. This paper discusses a project for the development of these collector systems and summarizes contracts with industry for developing the dish subsystems which include concentrator, receiver, and heat engine. An early market for dishes is the dispersed small community market which depends heavily on oil to operate diesel or steam turbine plants in order to generate electricity. The present contracts with industry for conducting engineering experiments using the developed dish hardware to demonstrate the technology in these early opportunity markets is also discussed.

Truscello, V. C.↗

NASA NTRS1980

JPL's electric and hybrid vehicles project: Project activities and preliminary test results

Efforts to achieve a 100 mile urban range, to reduce petroleum usage 40% to 70%, and to commercialize battery technology are discussed with emphasis on an all plastic body, four passenger car that is flywheel assisted and battery powered, and on an all metal body, four passenger car with front wheel drive and front motor. For the near term case, a parallel hybrid in which the electric motor and the internal combustion engine may directly power the drive wheels, is preferred to a series design. A five passenger car in which the electric motor and the gasoline engine both feed into the same transmission is discussed. Upgraded demonstration vehicles were tested using advanced lead acid, nickel zinc, nickel iron, and zinc chloride batteries to determine maximum acceleration, constant speed, and battery behavior. The near term batteries demonstrated significant improvement relative to current lead acid batteries. The increase in range was due to improved energy density, and ampere hour capacity, with relatively 1 small weight and volume differences.

Barber, T. A.↗

NASA NTRS1980

Status of JPL'S experience with thin 7809 glass for solar energy applications

A shipment of advanced, high transmittance glass for solar thermal power applications is assessed. Results of both mirror and glass inspection are reported. Surface and bulk defects are identified as well as the number broken or chipped during shipment and handling. Of the panels received, the thicker 1.5 mm (0.060 in.) glass exhibited a smaller breakage rate than the thin 1.0 mm (0.040 in.) panels.

Bouquet, F.↗

NASA NTRS1981

JPL self-pulsed laser surface measurement system development

Distances from a fixed reference or scan postion to several locations on the surface of an antenna reflector can be measured by using a self pulsed laser ranging system. Processing the information thus obtained is used to define the shape of the surface upon which antenna operational efficiency is directly dependent. Operation of the system consists of initiating a pulse from the laser emitter which is pointed at the scan mirror. The emitted pulse strikes the scan mirror, is reflected and sent to one of several targets on the surface of the antenna. Upon reflection from the target, the pulse returns to a detector via the scan mirror. The detected pulse is amplified and used to trigger the next emitted pulse. After the first pulse is emitted, received and used to trigger another pulse the process becomes repetitive with a repitition rate uniquely determined by the distance traveled to the target and back. A measure of the repetition rate or frequency thus created provides the means required for determining range since the total distance traveled is inversely proportional to the frequency.

Berdahl, M.↗

NASA NTRS1981

Characterization of point focusing test bed concentrators at JPL

The characterization data were measured using both a flux mapper and a cold water calorimeter. The flux mapper uses a Kendall Radiometer as the sensing device. It is mounted on an x, y, z motor-driven positioning mechanism that allows the sensor to take an x-y flux raster at several Z planes in the vicinity of the concentrators nominal focal plane. Various concepts were tried to protect the concentrator structure from being damaged by the Sun's energy during sun acquisition and deacquisition. A description of both the passive and active protective systems is presented.

Starkey, D. J.↗

NASA NTRS1981

The JPL isolated application experiment series

The technical, operational, and economic readiness of parabolic dish power systems for a variety of applications in the power range below 10 MWe are discussed. Power systems are developed and tested to the point where commercialization efforts lead to successful market penetration. A key element in this strategy is the use of experiments to test hardware and assess operational readiness. The Isolated Application Experiments are described and their objectives discussed.

Levin, R. R.↗