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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
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NASA NTRS1973

Image enhancement by holography.

The speed of the holographic image deblurring method has recently been further enhanced by a new speed in the realization of the powerful holographic image-deblurring filter. The filter makes it possible to carry out the deblurring, in the optical computer used, in times of the order of one second. The experimental achievements using the holographic image-enhancement method are illustrated with examples ranging from out-of-focus or motion-blurred photographs, including 'amateur' photos recorded on Polaroid film, to the sharpening of the best available electron micrographs of viruses. Images recorded with X-rays, notably from rocket-borne photos of the sun, and out-of-focus photographs from cameras in NASA satellites have been similarly deblurred.

Stroke, G. W.↗
NASA NTRS1973

Some aspects of cosmic synchrotron sources

Synchrotron emission is considered from individual particles which have small pitch angles and the general properties of synchrotron sources which mainly contain such particles, as well as the emissivities and degrees of circular polarization for specific source distributions. The limitation of synchrotron source models for optical pulsars and compact extragalactic objects are discussed, and it is shown that several existing models for the pulsar NP 0532 are inconsistent with the measured time variations and polarizations of the optical emission. Discussion is made also of whether the low frequency falloffs in the extragalactic objects PKS 2134 + 004, OQ 208, and NGC 1068 is due to emission from particles with small pitch angles or absorption by a thermal plasma or synchrotron self-absorption. It is concluded that the absorption interpretations cannot account for the turnover in the spectrum of PKS 2134 + 004. Measurements of polarization, angular structure, and X-ray flux are also described.

Epstein, R. I.↗
NASA NTRS1971

Photoemf in cadmium sulfide

Theoretical and experimental investigations on CdS single crystals and CuxS:CdS photovoltaic cells prepared from CdS single crystals by a chemical-dip procedure are described. The studies are aimed at clarifying cell mechanisms which affect key cell properties (efficiency, reliability, and lifetime) by examining the properties of intrinsic and extrinsic defects in the junction and surface regions and their effects on carrier transport through these regions. The experimental research described includes studies of thermal, infrared, and field quenching of acceptor-doped CdS crystals; investigation of optical and electrical properties of CuxS:CdS photovoltaic cells (current-voltage characteristics, spectral distribution of photocurrent and photovoltage) and the dependence of these properties on temperature and light intensity; measurement of changes, as a result of heat treatment in ultrahigh vacuum, in the spectral distribution of photoconductivity at room temperature and liquid nitrogen temperature, the luminescence spectrum at liquid nitrogen temperature, and the thermally stimulated current curves of CdS crystals; determination of the effect of irradiation with 150 keV (maximum) X-rays on the spectral distribution of photoconductivity and thermally-stimulated current of CdS crystals; and studies of the effect of growth conditions on the photoconductive properties of CdS crystals.

Boeer, K. W.↗
NASA NTRSDate not supplied

The HEROIX Broadband X-Ray Space Telescope Mission Concept

The High EneRgy Observatory for Imaging X-rays (HEROIX) Medium-Class Mission concept envisions a next-generation broadband X-ray observatory designed to meet the astrophysics community’s need for high-angular-resolution studies of the Cosmic X-ray Background. Building on the science legacy of NASA’s NuSTAR mission and more than 30 years of advances in replicated NiCo shell technology at NASA Marshall, HEROIX proposes a space observatory comprising four co-aligned telescopes achieving 5 arcsecond half-power diameter (HPD) angular resolution. This capability, approached by the resolution demonstrated in the FOXSI-4 sounding rocket mission and under development through the SuperHERO balloon mission, will be extended to energies up to 80 keV through multilayer coatings. Marshall’s inhouse precision optics manufacturing enables an integrated effective area of 380 cm² at 30 keV, which, combined with high-resolution optics, opens new windows into extreme astrophysical non-thermal processes.

Nick Thomas↗
NASA NTRS1973

Optical observations of the August 1972 flares

The optical appearance of the solar flares in McMath 11976 is described. The region showed complex, twisted magnetic fields from its birth on July 11, 1972. The flares occurred because of high field gradients and sheared field lines, which made transitions to lower energy field configurations possible. The H-alpha emission comes mainly from intense kernels about 10,000 kilometers across in each magnetic polarity. The measurement of the spectra and its relationship to the emission of impulsive flares is discussed. The peak emission of H-alpha from the kernels and the peak 3835 Angstrom flashes agree well with the hard X-ray peak.

Tanaka, K.↗
NASA NTRS1969

X-ray pulsar in the Crab Nebula.

X ray pulsations in Crab Nebula at frequency closely matching radio and optical pulsations, noting energy distribution

Chubb, T. A.↗
NASA NTRS1972

Microscopic observations of X-ray and gamma-ray induced decomposition of ammonium perchlorate crystals

The X-ray and gamma-ray induced decomposition of ammonium perchlorate was studied by optical, transmission, and scanning electron microscopy. This material is a commonly used oxidizer in solid propellents which could be employed in deep-space probes, and where they will be subjected to a variety of radiations for as long as ten years. In some respects the radiation-induced damage closely resembles the effects produced by thermal decomposition, but in other respects the results differ markedly. Similar radiation and thermal effects include the following: (1) irregular or ill-defined circular etch pits are formed in both cases; (2) approximately the same size pits are produced; (3) the pit density is similar; (4) the c face is considerably more reactive than the m face; and (5) most importantly, many of the etch pits are aligned in crystallographic directions which are the same for thermal or radiolytic decomposition. Thus, dislocations play an important role in the radiolytic decomposition process.

Herley, P. J.↗
NASA NTRS1972

Noncontacting device to indicate deflection of turbopump internal rotating parts

Phase 2 (development) which was concluded for the ultrasonic Doppler device and the light-pipe-reflectance device is reported. An ultrasonic Doppler breadboard system was assembled which accurately measured runout in the J-2 LOX pump impeller during operation. The transducer was mounted on the outside of the pump volute using a C-clamp. Vibration was measured by conducting the ultrasonic wave through the volute housing and through the fluid in the volute to the impeller surface. The impeller vibration was also measured accurately using the light-pipe probe mounted in an elastomeric-gland fitting in the pump case. A special epoxy resin developed for cryogenic applications was forced into the end of the fiber-optic probe to retain the fibers. Subsequently, the probe suffered no damage after simultaneous exposure to 2150 psi and 77 F. Preliminary flash X-radiographs were taken of the turbine wheel and the shaft-bearing-seal assembly, using a 2-megavolt X-ray unit. Reasonable resolution and contrast was obtained. A fast-neutron detector was fabricated and sensitivity was measured. The results demonstrated that the technique is feasible for integrated-time measurements requiring, perhaps, 240 revolutions to obtain sufficient exposure at 35,000 rpm. The experimental verification plans are included.

Hamilton, D. B.↗
NASA NTRS1972

The optical polarization of Scorpius X-1.

The X-ray source Sco X-1 is known to have a slight linear polarization in visible light. An investigation was conducted to determine whether the origin of the polarization is intrinsic to the source or interstellar. No evidence could be found for unusual polarization properties in Sco X-1 that would point to an intrinsically polarized source, although this cannot be excluded. It is pointed out that the case for interstellar polarization would become very strong if stars in the immediate vicinity are found to be polarized with the same position angle.

Landstreet, J. D.↗
NASA NTRS1972

On the optical identification of Centaurus X-3.

It is suggested that the previously photographed emission-line star WRA 795 is the optical counterpart of Cen X-3, the X-ray pulsar which is a member of an occulting binary system. The star falls in the X-ray error box, which measures only 0.01 square degrees, and shows strong emission variability on a timescale of days, similar to HDE 226868, the suggested Cyg X-1 counterpart.

Margon, B.↗
NASA NTRS1972

Soft X-rays from Cygnus X-2 and from Cygnus X-1 /in eclipse/.

Observations of Cygnus X-1 (probably in eclipse) and Cygnus X-2 on Oct. 23, 1971, show quite low absorption in their spectrum, and yet they are thought to be in a double or multiple star system from the optical data. The lack of intrinsic absorption in their spectra may be taken to mean that they lie sufficiently far from their primaries for a reduction to virtually zero of their interaction with the atmosphere of the primaries.

Stevens, J. C.↗
NASA NTRS1972

Proceedings of the Space Shuttle Sortie Workshop. Volume 2: Working group reports

Details are presented on the mission planning progress in each of the working paper reports. The general topics covered are the following: space technology; materials processing and space manufacturing; communications and navigation; earth and ocean physics; oceanography; earth resources and surface environmental quality; meteorology and atmospheric environmental quality; life sciences; atmospheric and space physics; solar physics; high energy cosmic rays; X-ray and gamma ray astronomy; ultraviolet-optical astronomy; planetary astronomy; and infrared astronomy.

Source record↗
NASA NTRS1973

Spectroscopic observations of the Cygnus X-1 optical candidate.

Data from nine high-dispersion spectra of HDE 226868, the optical candidate for Cyg X-1, are presented. The line profiles at He II (4686 A) show marked changes from night to night. Our data are not compatible with models where the emission line arises from the unseen secondary component of the system, as has been suggested by other observers. We propose that the emission originates in a gas stream falling toward the secondary; this provides observational evidence that the X-ray source is powered by accretion. We also see changes in spectral type and luminosity class with phase, further complicating attempts to make mass estimates for the system.

Smith, H. E.↗