A method of treating the nongray error in total emittance measurements
Total emittance measurements by portable IR reflectometer, tabulating nongray error effects
Heaney, J. B.↗
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Substrate-emitter monolithic inverted transistor structure for low-power high- current-gain applications
Substrate emitter monolithic inverted transistor structure for low-power high-current gain application
Cress, S. B.↗
Total normal emittances of some real surfaces at cryogenic temperatures
Radiometric measurement of total normal emittances of real surfaces at cryogenic temperatures
Cottingham, W. B.↗
The influence of heavy doping on the emitter efficiency of a bipolar transistor
Bipolar junction transistor doping effects on bandgap decrease and emitter efficiency, explaining current gain temperature dependence
De Man, H. J. J.↗
Diminiode performance data with an ASTAR-811C emitter and a niobium - 1-percent-zirconium collector
The performance of a fixed-space planar miniature diode (diminiode) with a guarded collector has been mapped using a computerized data acquisition facility. The electrode materials consisted of a tantalum alloy emitter and a Nb-1Zr collector; the electrode gap was 0.254 mm.
Smith, A. L.↗
Infrared spectral emittance in geological mapping - Airborne spectrometer data from Pisgah Crater, California.
Measurements of spectral emittance in the IR region from 6.8 to 13.3 microns were made with an airborne spectrometer on flights at 650 m above the olivine basalt flows at Pisgah Crater in the southern Californian desert. Readings were taken at a rate of six spectra per second. The spectra show chemical and mineralogical differences that can be related to differences in the terrain below the aircraft.
Lyon, R. J. P.↗
Emittance measurement of Surveyor 3 material.
Calorimetric measurements of the total hemispherical emittance of a section of polished aluminum support tubing from the Surveyor 3 spacecraft are reported. The values found, 0.090 at 25 C and 0.089 at 50 C, are lower than was expected from a visual estimate but are in good agreement with an estimate based upon scanning electron microscopy of the tubing.
Dahms, R. G.↗
Spectral reflectance and emittance of particulate materials. I - Theory. II - Application and results
The sizes, shapes, and complex refractive indices of particles are calculated in a study of the IR spectral reflectance of a semiinfinite medium composed of irregular particles of different materials. Geometric optics techniques with corrections for additional absorption due to particle edges and asperities is used in scattering and absorption calculations for particles larger than the wavelength. A Lorentz-Lorenz model is used to derive the averaged complex index of the medium, assuming that its individual particles are ellipsoids. Experimental results obtained on a Michelson interferometer for the spectral emittance of particulate mineral materials are compared with theoretical results. Good agreement between the experimental and theoretical results suggests the applicability, in remote IR spectroscopy, of the theoretical concepts applied in this study.
Emslie, A. G.↗
Current technology for development of low solar absorptance/high emittance coatings
A comprehensive program to develop low solar absorptance/high emittance coatings, to be successful, must coordinate basic materials preparation, coatings technology, environmental simulation, production, and flight-test evaluation. The prime criteria for 'white' thermal-control coatings are low solar absorptance and, most importantly, solar-absorptance stability. Many variables affect the solar absorptance and its stability. These effects must be discerned and evaluated. The factors involved, however, are not entirely independent; accordingly, the present paper emphasizes the major variables, the relationships among them, and how important they are in improving the properties and performance of the coatings.
Gilligan, J. E.↗
Improving Emittance of High-Temperature Insulating Tile
Simple addition to ceramic insulating tiles provides backup properties that minimize transfer of heat through tiles when their surfaces become damaged. Addition of 3 percent by weight of 320- or 600-grit silicon carbide powder to ceramic during production results in impregnated tile material that resists overheating. Silicon carbide increases emittance and decreases transmittance of ceramic.
Gzowski, E. R.↗
Floating-Emitter Solar-Cell Transistor
Conceptual transistor embedded in photovoltaic diode promises to increase efficiency to more than 20 percent. Solar-cell transistor has front-surface contact, rear contact, and floating emitter. Variety of other contact and junction configurations possible, but do not offer ease of fabrication in combination with high performance.
Sah, C. T.↗
Emitter formation in dendritic web silicon solar cells
The use of liquid dopants and liquid masks for p-n junction formation in dendritic web solar cells was investigated and found to be equivalent to the use of gaseous dopants and CVD SiO2 masks previously used. This results in a projected cost reduction of 0.02 1980$/Watt for a 25 MW/year production line, and makes possible junction formation processes having a higher throughput than more conventional processes. The effect of a low-energy (0.4 keV) hydrogen ion implant on dendritic web solar cells was also investigated. Such an implant was observed to improve Voc and Jsc substantially. Measurements of internal quantum efficiency suggest that it is the base of the cell, rather than the emitter, which benefits from the hydrogen implant. The diffusion length for electrons in the p-type base increased from 53 microns to 150 microns in one case, with dendritic web cell efficiency being boosted to 15.2 percent. The mechanism by which low-energy hydrogen ions can penetrate deeply into the silicon to effect the observed improvement is not known at this time.
Meier, D. L.↗
Microwave Power From Natural Emitters
Signal-to-noise ratio of radiometer system calculated. Publication from NASA's Jet Propulsion Laboratory presents calculations of power radiated from natural emitter on Earth to microwave collecting aperture on aircraft or spacecraft. Analysis develops power-transfer criteria for detection of emitting object by collecting aperture (that is, by antenna and its receiver). Resulting formulas used in design of radiometer systems.
Stacey, J. M.↗
Relation between L-band soil emittance and soil water content
An experimental relation between soil emittance (E) at L-band and soil surface moisture content (M) is compared with a theoretical one. The latter depends on the soil dielectric constant, which is a function of both soil moisture content and of soil texture. It appears that a difference of 10 percent in the surface clay content causes a change in the estimate of M on the order of 0.02 cu m/cu m. This is based on calculations with a model that simulates the flow of water and energy, in combination with a radiative transfer model. It is concluded that an experimental determination of the E-M relation for each soil type is not required, and that a rough estimate of the soil texture will lead to a sufficiently accurate estimate of soil moisture from a general, theoretical relationship obtained by numerical simulation.
Stroosnijder, L.↗
The physical basis for spectral variations in thermal infrared emittance of silicates and application to remote sensing
The use of infrared spectroscopy for the remote characterization of planetary surfaces has received attention due to efforts in the investigation of these bodies from space. In the 8 to 14 micron region, a depression in the emittance spectra of rocks (sometimes called reststrahlen) is related to the fundamental stretching vibrations of Si-O bonds and shifts in the locations of this feature are ascribed to variations in rock composition. Thus, it should be possible to investigate, quantify, and model the relationships of reststrahlen spectral band location through silicate mineralogical composition to rock classification. This concept will be tested first through the use of laboratory-acquired data on the infrared spectra and mineralogy of selected mineral and rock samples. As a suitable classification model is developed, it will be tested through overflights of appropriate rock outcrops using the Thermal Infrared Multispectral Scanner (TIMS).
Walter, Louis S.↗
The GaAs solar cells with V-grooved emitters
Geometrically structured surfaces have become increasingly important to solar cell efficiency improvements and radiation tolerance. Gallium arsenide solar cells with a V-grooved front surface which demonstrate improved optical coupling and higher short-circuit current compared to planar cells were fabricated. GaAs homojunction cells were fabricated by organometallic chemical vapor deposition (OMCVD) on an n+ substrate. The V-grooves were formed on the surface with an anisotropic etch, and an n-type buffer and p-type emitter were grown by OMCVD, followed by ohmic contacts. Reflectivity measurements show significantly lower reflectance for the microgrooved cell compared to the planar structure. The short circuit current of the V-grooved solar cell is consistently higher than that of the planar controls.
Bailey, Sheila G.↗
Arc-textured high emittance radiator surfaces
High emittance radiator surfaces are produced by arc-texturing. This process produces such a surface on a metal by scanning it with a low voltage electric arc from a carbon electrode in an inert environment.
Banks, Bruce A.↗
Passive ranging of an airborne emitter by a single non-maneuvering or stationary sensor
A method for passively determining the range of a target vehicle relative to a non-cooperating moving test platform is disclosed. The method includes the steps of moving the test platform along a single linear path at a constant speed, while simultaneously performing a succession of bearing and frequency measurements on a radiant signal emitted by the moving target vehicle. Similarly, the test platform may remain stationary so that its velocity is zero. The measured parameters, along with knowledge of the test platform's own position and velocity, permit the range to the emitter, its velocity and its transmitted frequency to be determined.
Martin Golinsky↗