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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Analytical design of a parasitic-loading digital speed controller for a 400-hertz turbine driven alternator

A design for a solid-state parasitic speed controller using digital logic was analyzed. Parasitic speed controllers are used in space power electrical generating systems to control the speed of turbine-driven alternators within specified limits. The analysis included the performance characteristics of the speed controller and the generation of timing functions. The speed controller using digital logic applies step loads to the alternator. The step loads conduct for a full half wave starting at either zero or 180 electrical degrees.

Ingle, B. D.↗
NASA NTRS1972

Experimental determination of cosmic ray charged particle intensity profiles in the atmosphere

Absolute cosmic-ray free air ionization and charged particle fluxes and dose rates throughout the atmosphere were measured on a series of balloon flights that commenced in 1968. Argon-filled ionization chambers equipped with solid-state electrometers, with different gas pressures and steel wall thicknesses, and a pair of aluminum-wall Gm counters have provided the basic data. These data are supplemented by measurements with air-filled and tissue equivalent ionization chambers and a scintillation spectrometer. Laboratory experiments together with analyses of the theoretical aspects of the detector responses to cosmic radiation indicate that these profiles can be determined to an overall accuracy of + or - 5 percent.

Lowder, W. M.↗
NASA NTRS1972

Solid state ku-band power amplifiers, phase 1

A proposed solid-state K sub u-band power amplifier utilizing a circularly symmetric array of IMPATT diodes mounted in a single radial line power combiner is discussed and its performance predicted. The proposed amplifier configuration consists of a TM sub 030 mode radial line cavity containing 20 IMPATT diodes, with separate input and output ports provided by a ferrite circulator. Conventional IMPATT amplifier techniques preclude the achievement of gain, power output, efficiency, and IMP suppression specifications simultaneously; there fore, several novel techniques with the potential of reducing the intermodulation product level are discussed.

Cohn, M.↗
NASA NTRS1972

Precise linear sun sensor

An evaluation of the precise linear sun sensor relating to future mission applications was performed. The test procedures, data, and results of the dual-axis, solid-state system are included. Brief descriptions of the sensing head and of the system's operational characteristics are presented. A unique feature of the system is that multiple sensor heads with various fields of view may be used with the same electronics.

Johnston, D. D.↗
NASA NTRS1972

S-band microcircuit power amplifier

Research, design, development, and fabrication of a two-stage, solid-state, microcircuit power amplifier operating in the 2.25 GHz region of the S-band are summarized. Output is typically 7.0 watts for an input of approximately 400 mw. Input stage is an MSC 3001 transistor; output stage is an MSC 3005 transistor. Input VSWR is 1.4:1.0, or less. Efficiency of 33.3 percent or more is achieved. Second and third harmonic suppression is 30 db. Operating power is 28 VDC. The entire unit has a length of 3.80 inches, a width of 2.08 inches, and a height of 1.00 inch.

Mcgann, W. E.↗
NASA NTRS1971

Observations of low-energy /0.3- to 1.8-MeV/ differential spectrums of trapped protons.

Measurements of differential energy spectrums of trapped protons obtained from several passes during the period January to November 1969 using the polar orbiting, low-altitude Injun 5 satellite equipped with a special solid-state detector proton-electron telescope are presented. Results reveal the existence of a quasi-persistent peak in the differential energy spectrum in the McIlwain shell parameter (L) range 2 to 2.6 and in the energy range of approximately 0.32 to 0.72 MeV. The fact that the shape of the spectrum is stable for several days or can change with time scales as small as 4 hours suggests an impulsive acceleration mechanism deep in the radiation belts. Other features of the spectrum show that if the spectrum is represented by an exponential form in energy, the dependence of the spectral parameter is in general agreement with diffusion theory over the L range of approximately 2 to 4.

Venkatesan, D.↗
NASA NTRS1972

Enrichment of very heavy nuclei in the composition of solar accelerated particles.

Measurement of the abundances of the nuclei C, N, O, Ne, Mg, Si, Ar, and Ca and the group Cr-Co relative to oxygen from seven solar energetic-particle events in the energy range from about 14 to 61 MeV per nucleon with a solid-state detector telescope on the OGO-5 satellite, 1968-1971. The differential energy spectra of O (14 to 29 MeV per nucleon) and Cr-Co (3 to 61 MeV per nucleon) have a spectral index of about (-3) for a power law in kinetic energy. The relative abundances of C, N, O, and Ne are in excellent agreement with emulsion studies. However, when compared with the solar photospheric and coronal abundances, the OGO-5 measurements show a large enhancement of relative abundances beginning with Si, and extending to the Cr-Co group. The enhancement over the solar and universal abundances is in rough agreement with the composition of the galactic cosmic radiation.

Mogro-Campero, A.↗
NASA NTRS1972

The quiet-time spectra of cosmic-ray electrons of energies between 10 and 200 MeV observed on OGO-5.

Measurement of spectra of cosmic-ray electrons of energies between 10 and 200 MeV over a one-year period starting 1968 March. The measurement was made with a detector system on board the OGO-5 satellite. The instrument consists of a solid-state dE/dx detector, a total-energy CsI detector, a gas Cerenkov threshold detector, and two scintillation guard counters. Time periods during which no solar-flare events were recorded were selected for the study. It was found that during these quiet periods there were numerous intensity variations of the electron flux. These variations, which are seen only below 25 MeV, do not show marked correlation with any solar or interplanetary-medium parameters. The flux of the electrons of energies above 25 MeV, on the other hand, showed a gradual decrease over the one-year period, paralleling the neutron monitor intensity. The parameter describing this long-term modulation is almost independent of the rigidity of the electrons in the reported energy range. The physical implication of the finding is discussed.

L'Heureux, J.↗
NASA NTRS1972

Changes in the distribution of low-energy trapped protons associated with the April 17, 1965, magnetic storm.

The absolute intensity of geomagnetically trapped protons in the energy ranges from 0.52 to 4.0 MeV and from 0.90 to 1.8 MeV has been measured with the solid-state proton detector on the satellite Injun 4 for the period from Mar. 1 to May 31, 1965. A study of the temporal variations of these fluxes associated with the Apr. 17, 1965, magnetic storm shows a general redistribution of these protons for L greater than 2.5. The effect of the sudden commencement was a general depression in the intensities and a hardening of the energy spectra, although the intensities recovered to their prestorm level during the initial phase. The major redistribution was apparently initiated by the polar substorm. During the recovery phase, a secondary peak developed in the intensity profile at L of about 3.5 for 0.52-MeV protons that had no counterpart at this energy at the equator. No such peak was observed for 0.9-MeV protons.

Burns, A. L.↗
NASA NTRS1972

Enhanced diffusion welding of TD-NiCr sheet.

A method termed 'enhanced diffusion welding' has been developed to produce solid-state welds in TD-NiCr (Ni-20Cr-2ThO2) alloy sheet with weld strengths of 100% of the parent metal strength. Diffusion welded joints were made in specially processed TD-NiCr that equaled the tensile-shear and creep-rupture shear strengths of the parent material at 1090 deg C. The following observations have been made: specially processed TD-NiCr is preferred over commercial TD-NiCr for diffusion welding; the weld line can be eliminated when joining specially processed TD-NiCr by 600-grit sanding and electropolishing the faying surfaces prior to welding; and, a two-step weld cycle is preferred for diffusion welding of this alloy.

Holko, K. H.↗
NASA NTRS1972

Development of dispersion-strengthened Ni-Cr-ThO2 alloys for the space shuttle thermal protection system.

An improved manufacturing process has been developed for TD-NiCr that provides sheet of improved quality, better gage control, and reproducible properties. A standard manufacturing process has been developed for the alternate alloy, DS-NiCr, produced by pack-chromizing Ni-2ThO2 sheet. Extension of forming and joining technology for TD-NiCr is in process. Formability criteria are being established for basic sheet forming processes related to the manufacture of Shuttle TPS panels. They include brake forming, corrugation forming, joggling, dimpling, and beading. Joining processes applicable to TPS panels are being optimized with emphasis on establishment of joint efficiencies. Resistance spot welding (fusion and solid state), resistance seam welding, solid-state diffusion welding, and brazing are included in the joining programs. Development of improved manufacturing technology for TD-NiCr fasteners is also being accomplished. Mechanical and physical properties of TD-NiCr are being characterized to provide design-allowable data.

Blankenship, C. P.↗
NASA NTRS1972

Polyimidazopyrrolone model compounds.

Study of model reactions between phthalic anhydride and o-phenylenediamine under conditions analogous to the polymerization and post cyclization of dianhydrides with bis(o-diamines) to form polyimidazopyrrolones (Pyrrones). Solid-state thermal conversion of the amide-acid-amine affords a unique dimeric species containing amide, imide, and benzimidazole functions. It was confirmed that melt techniques lead to disproportionation products. The application of these findings to related polymer syntheses is discussed.

Young, P. R.↗
NASA NTRS1972

Measurements of electron detection efficiencies in solid state detectors.

Detailed laboratory measurement of the electron response of solid state detectors as a function of incident electron energy, detector depletion depth, and energy-loss discriminator threshold. These response functions were determined by exposing totally depleted silicon surface barrier detectors with depletion depths between 50 and 1000 microns to the beam from a magnetic beta-ray spectrometer. The data were extended to 5000 microns depletion depth using the results of previously published Monte Carlo electron calculations. When the electron counting efficiency of a given detector is plotted as a function of energy-loss threshold for various incident energies, the efficiency curves are bounded by a smooth envelope which represents the upper limit to the detection efficiency. These upper limit curves, which scale in a simple way, make it possible to easily estimate the electron sensitivity of solid-state detector systems.

Lupton, J. E.↗
NASA NTRS1972

Techniques in balloon X-ray astronomy.

Since the first balloon observation of the Crab Nebula balloon data have provided much information on the positions, spectra, time variability and pulsed nature of localized sources, and on the spectrum and isotropy of diffuse galactic and universal components. Measurements are limited to energies above about 20 keV by atmospheric attenuation at 2 to 3 g/sq cm depth and to below several hundred keV by detector sensitivity. Detectors usually consist of large-area Na I or Cs I scintillation counters with anticoincidence collimators for rejection of charged particles and scattered X-rays. Proportional counters are occasionally used at lower energies and solid-state detectors are used where extreme energy resolution is important. The instruments require a pointing capability on the order of 1.0 to 0.1 deg, depending on the collimator aperture. Digital data is either recorded on board or telemetered using a PCM technique.

Peterson, L. E.↗
NASA NTRS1972

A solid state multispectral imager.

Photodiode arrays used as image sensors in satellite remote imaging systems offer the advantages of geometric accuracy, precise registration of scene elements, enhanced operational reliability, and wide spectral response. Principles of photodiode-array operation are reviewed, and the latest developments in self-scanned array chip technology are described along with optical system requirements for multispectral coverage. Results of development efforts with a spaceborne solid-state multispectral camera based on linear sensing array technology are outlined to demonstrate the capabilities of this approach to multispectral sensing.

Green, A.↗
NASA NTRS1972

Holographic interferometry.

Review of the techniques and applications of holographic interferometry. The recording of a 'reflected-light' hologram with a gas laser is described in order to illustrate the unique optical properties of a hologram. Special types of interferometric measurement, such as stored-beam holographic interferometry and double-exposure holographic interferometry, are then discussed. Applications of gas-laser holographic interferometry to the detection of internal flaws in steel tubing are cited, as well as applications involving the testing of aircraft and automotive tires and aircraft honeycomb composites for bond integrity and the prediction of failure in mechanical components. Finally, applications of the pulsed solid-state ruby laser in holographic interferometry are considered.

Wuerker, R. F.↗
NASA NTRS1961

Neutralization of Hydroxide Ion in Melt-Grown NaCl Crystals

Many recent studies of solid-state phenomena, particularly in the area of crystal imperfections, have involved the use of melt-grown NaCl single crystals. Quite often trace impurities in these materials have had a prominent effect on these phenomena. Trace amounts of hydroxide ion have been found in melt-grown NaCl crystals. This paper describes a nondestructive method of neutralizing the hydroxide ion in such crystals. Crystals of similar hydroxide content are maintained at an elevated temperature below the melting point of NaCl in a flowing atmosphere containing. dry hydrogen chloride. Heat treatment is continued until an analysis of the test specimens shows no excess hydroxide ion. A colorimetric method previously described4 is used for this analysis.

Otterson, Dumas A.↗