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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Hollow-cylinder waveguide isolators for use at millimeter wavelengths

The device considered in this study is a semiconductor waveguide isolator consisting of a hollow column of a semiconductor mounted coaxially in a circular waveguide in a longitudinal dc magnetic field. An elementary and physical analysis based on the excitation of plane waves in the guide and a more rigorous mode-matching analysis (MMA) are presented. These theoretical predictions are compared with experimental results for an InSb isolator at 94 GHz and 75 K.

Kanda, M.↗
NASA NTRS1975

Skylab M518 multipurpose furnace convection analysis

An analysis was performed of the convection which existed on ground tests and during skylab processing of two experiments: vapor growth of IV-VI compounds growth of spherical crystals. A parallel analysis was also performed on Skylab experiment indium antimonide crystals because indium antimonide (InSb) was used and a free surface existed in the tellurium-doped Skylab III sample. In addition, brief analyses were also performed of the microsegregation in germanium experiment because the Skylab crystals indicated turbulent convection effects. Simple dimensional analysis calculations and a more accurate, but complex, convection computer model, were used in the analysis.

Bourgeois, S. V.↗
NASA NTRS1976

J, H, K photometry of 433 Eros and other asteroids

Results are reported for IR photometry of nine bright asteroids, including 433 Eros, which was conducted in the J, H, K, and (for Eros) L bands with an InSb photometer on the 1.3-m Kitt Peak telescope. It is found that the J-H and H-K color indices of all nine asteroids are slightly redder than those of the sun and that three C-type objects are somewhat redder in the same color indices than four S-types and an E-type. Eros is shown to have an unusually red J-K index; the shape of its IR spectral reflectance curve is attributed in part to the presence of the weak 2-micron pyroxene absorption band in the spectrum. The results show that JHK photometry is less diagnostic of asteroidal composition than higher-resolution IR spectrophotometry.

Chapman, C. R.↗
NASA NTRS1978

Laboratory studies of the diffuse reflectance spectra of frosts and minerals occurring on astronomical objects

A vacuum monochromator was integrated into the system and optics chosen to increase data collection in the infrared spectral region. Using a InSb detector, good reflectance data was obtained to 5.5 micron from a variety of samples including magnesium oxide, barium sulfate, water frost and Bloedite. Magnesium oxide was found to be a poorer reflector than the barium sulfate throughout the visible and near infrared region. The barium sulfate material was shown to be a Lambert reflector in the visible region and over an angular range of 60 deg. Several samples of water frost were prepared and in reflectance measured from 0.3 micron to 5.5 microm. The fine grained frosts were better reflectors than the coarse grained frosts, usually by 20 percent or more, over the entire spectral range. The minerals Bloedite and sulfur were also investigated further.

Glaser, F. M.↗
NASA NTRS1978

Effects of systemic and non-systemic stresses on the thermal characteristics of corn

Experiments were conducted on corn plants using a calibrated spectroradiometer under field conditions in the indium antimonide channel (InSb, 2.8 to 5.6 mm) and the mercury cadmium telluride channel (HgCdTe, 7 to 14 mm). A ground cover experiment, an experiment on nonsystemic corn plants, and an experiment on systemic-stressed corn plants were included. The average spectral radiance temperature of corn plant populations was found (1) to be statistically significantly different for four healthy corn plant populations, (2) to increase with increased blight severity, and (3) to be statistically significantly different for varying rates of nitrogen applications.

Kumar, R.↗
NASA NTRS1978

Portable He-3 detector cryostat for the far infrared

The design of a portable He-3 cryostat for far infrared detection applications is described, with a cutaway drawing of the cryostat, including bolometer and cooled optics, provided. Consideration is given to the selection and testing of various bolometer materials, including Ge:Ga and Ge:InSb; the resistance-temperature coefficients of the materials examined are presented. The absolute flux calibration of the detector system using a new temperature-modulated cold source method is described.

Radostitz, J. V.↗
NASA NTRS1978

Germane in the atmosphere of Jupiter

Germane, GeH4, is a tetrahedral molecule like methane. The nu 3 fundamental mode of GeH4 falls in the middle of the 5-micrometer Jupiter window. Jupiter observations were made in December 1975 during three flights with the 0.9-m telescope of the Kuiper Airborne Observatory. The spectrometer is a rapid-scanning Michelson interferometer having InSb detectors at each of the two outputs. The germane identification procedure is based on a comparison of the obtained Jupiter spectrum with that of laboratory germane. It appears that the detection of GeH4 in Jupiter's atmosphere with a mixing ratio of 0.6 ppb is the smallest concentration of a trace constituent yet detected in a nonterrestrial planetary atmosphere. It is pointed out that a strict interpretation of thermochemical equilibrium predictions for the spectral line forming regions of Jupiter's atmosphere does not explain the observation of GeH4.

Fink, U.↗
NASA NTRS1979

Support for joint infrared and Copernicus X-Ray observations of Cygnus X-3

Simultaneous X-ray and infrared measurements were carried out of the flares from Cygnus X-3 from the Copernicus spacecraft observatory. The detectors, InSb, were arranged so that 1.65 and 2.2 micrometer broadbend photometry was performed through a common diaphragm. The measurements were used to determine the energy distribution during a flare and thus learn about the infrared spectrum and its changes during the flare.

Source record↗
NASA NTRS1979

The TIROS-N high resolution infrared radiation sounder

The high-resolution infrared radiation sounder (HIRS/2) was developed and flown on the Television and Infrared Observation Satellite, N Series (TIROS-N) as one means of obtaining atmospheric vertical profile information. The HIRS/2 receives visible and infrared spectrum radiation through a single telescope and selects 20 narrow spectral channels by means of a rotating filter wheel. A passive radiant cooler provides an operating temperature of 106.7K for the HgCdTe and InSb detectors while the visible detector operates at instrument frame temperature. Low noise amplifiers and digital processing provide 13 bit data for spacecraft data multiplexing and transmission. The qualities of system performance that determine sounding capability are the dynamic range of data collection, the noise equivalent radiance of the system, the registration of the air columns sampled in each channel, and the ability to upgrade the calibration of the instrument to maintain the performance standard throughout life. The basic performance of the instrument in test is described. Early orbital information from the TIROS-N launched on October 13, 1978 are given and some observations on system quality are made.

Koenig, E. W.↗
NASA NTRS1980

Far infrared heterodyne systems

Three far infrared detectors, the InSb hot electron bolometer, the GaAs Schottky diode and the Josephson point contact junction, were incorporated as mixers into sensitive heterodyne systems. The performances of existing heterodyne receivers/radiometers using these detectors are described and compared. Other applications of submillimeter heterodyne techniques are discussed.

Tannenwald, P. E.↗
NASA NTRS1980

Bulk submillimeter-wave mixers: Strain and superlattices

Strained germanium crystals, doped with gallium, were used as heterodyne mixers at THz frequencies, with infrared bandwidths approaching a GHz. The mixer performance (conversion loss and mixer noise) was analyzed in terms of nonlinearities associated with acceptor levels and with relaxation rates of free holes. Comparison was made with similar mixers employing low lying donor levels in high purity GaAs and with hot electron InSb mixers.

Litvak, M. M.↗
NASA NTRS1979

The IR energy distribution of SS433

The infrared energy distribution of the emission-line object SS 433 in the range 1 to 10 microns is determined. Photometric measurements were made with a 2.2-m telescope using an InSb detector and a 6-arcsec diaphragm for 1.2- to 4.8-micron observations and a gallium-doped germanium bolometer with a 6-arcsec diaphragm for 8- to 13-micron observations. Results indicate the presence of substantial night-to-night flux density and color variations, and a decrease in flux density at wavelengths greater than 5 microns. The energy cut-off is used to estimate a physical size of 1 AU for the emitting region and an electron density of 10 to the 11th/cu cm on the basis of a model of reddened free-free emission from an ionized plasma, with self-absorption of radiation over 5 microns. The greater variability observed at longer wavelengths is also interpreted in terms of this model.

Wynn-Williams, C. G.↗
NASA NTRS1980

Titan - Suspected near-infrared variability

Observations were made of Titan with InSb photometers using standard J (1.25 micron), H (1.6 micron), and K (2.2 micron) filters over a 70 day interval with 0.61 m, 2.2 m, and 4 m telescopes. A beam-switching, sky-subtract mode was used with all telescopes, and evidence appears for variation at approximately the 3 sigma level of confidence. There is some indication that, if periodic, the variation may have a period twice that of the satellite's orbital period.

Cruikshank, D. P.↗
NASA NTRS1979

Design and test of the Near Infrared Mapping Spectrometer /NIMS/ focal plane for the Galileo Jupiter Orbiter mission

A Near Infrared Mapping Spectrometer (NIMS) will fly past Jupiter on the Galileo spacecraft in 1982. The infrared detector assembly (focal plane) used in the NIMS instrument is to be passively cooled to 80 K by radiation into space. The focal plane contains 15 InSb and two silicon detectors, each with an associated dual J-FET preamp and feedback resistor. Preliminary fabrication and test experience will be described for an experimental five-channel hybrid detector assembly. Measurements of spectral noise density along with a plasma cleaning technique will also be described. The final NIMS focal plane will contain much of the design experience gained from the experimental hybrid detector assembly.

Bailey, G.↗
NASA NTRS1979

Integrated infrared detector arrays for low-background astronomy

Existing integrated infrared detector array technology is being evaluated under low-background conditions to determine its applicability in orbiting astronomical applications where extended integration times and photometric accuracy are of interest. Preliminary performance results of a 1 x 20 elements InSb CCD array under simulated astronomical conditions are presented. Using the findings of these tests, improved linear- and area-array technology will be developed for use in NASA programs such as the Shuttle Infrared Telescope Facility. For wavelengths less than 30 microns, extrinsic silicon and intrinsic arrays with CCD readout will be evaluated and improved as required, while multiplexed arrays of Ge:Ga for wavelengths in the range 30 to 120 microns will be developed as fundamental understanding of this material improves. Future efforts will include development of improved drive and readout circuitry, and consideration of alternate multiplexing schemes.

Mccreight, C. R.↗
NASA NTRS1980

Detection of the 610 micron /492 GHz/ line of interstellar atomic carbon

The ground-state transition of neutral atomic carbon, 3P1-3P0, has been detected in the interstellar medium at the frequency of 492.162 GHz determined in the laboratory by Saykally and Evenson (1980). The observations were made from the NASA Kuiper Airborne Observatory using an InSb heterodyne bolometer receiver. The line was detected as strong emission from eight molecular clouds and apparently provides a widely useful probe of the interstellar medium.

Phillips, T. G.↗
NASA NTRS1980

Infrared Fourier spectrometer for airborne and ground-based astronomy

A unique high resolving power near-infrared, astronomical Fourier spectrometer has been constructed for use at both ground-based and airborne telescopes. Its capabilities include a limiting resolution of 0.01/cm and spectral coverage over the InSb detector sensitivity region (0.8-5.6 micron). The instrument is optimized for operation in environments inaccessible to other high-resolution Fourier spectrometers, namely, the Cassegrain focuses of conventional telescopes and the NASA Kuiper Airborne Observatory's 91-cm telescope. Details of the spectrometer are discussed, and various astronomical and laboratory spectra are presented.

Davis, D. S.↗
NASA NTRS1981

Infrared observations of AE Aquarii

Broadband infrared observations of the cataclysmic variable AE Aquarii are reported. The observations were obtained in the J, H, K and L filters with the InSb photometer attached to the 1-m telescope of the European Southern Observatory. The infrared energy distribution observed from 0.35 to 3.5 microns for phase 0.5 suggests a spectral type of K5 V for the secondary and a distance to the system of approximately 70 pc if an absolute magnitude of 7.3 is assumed. Monitoring of the flux at 2.2 microns reveals a variability with an amplitude of approximately 0.3 magnitude over one third of the orbital period, the nature of which is under investigation.

Tanzi, E. G.↗