Adhesion and friction of transition metals in contact with non-metallic hard materials
(Previously announced in STAR as N81-28233)
Miyoshi, K.↗
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Results for “HARDNESS”
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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Tool Enlarges Hard-to-Reach Holes
Tool centers itself and cuts precise depth. Tool consists of crosscut carbide bur; sleeve that serves as depth stop and pilot; length of flexible, strong piano wire; and standard drive socket. Parts brazed together. Piano wire transmits torque and axial force to cutting tool.
Geddes, J. P.↗
Radiation hardness of Efratom M-100 rubidium frequency standard
The effects of nuclear radiation on rubidium gas cell frequency standards and components are presented, including the results of recent tests where a continuously operating rubidium frequency standard (Effratom, Model M-100) was subjected to simultaneous neutron/gamma radiation. At the highest neutron fluence 7.5 10 to the 12th power n/sq cm and total dose 11 krad(Si) tested, the unit operated satisfactorily; the total frequency change over the 2 1/2 hour test period due to all causes, including repeated retraction from and insertion into the reactor, was less than 1 x 10 to the -10th power. The effects of combined neutron/gamma radiation on rubidium frequency standard physics package components were also studied, and the results are presented.
English, T. C.↗
Simultaneous ultraviolet line and hard X-ray bursts in the impulsive phase of solar flares
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Woodgate, B. E.↗
High throughput non-dispersive hard X-ray spectrograph with angular resolution for cosmic bursts, transients, and sources
An instrument concept which offers high throughput nondispersive spectroscopy in the 35-150 keV band for measuring line intensities and widths of faint supernovae is described. The design is based on existing xenon filled, two-dimensional, position sensitive, multiwired proportional counters. Effective detector areas of 1000 sq cm are readily achievable, and expansion to 10,000 sq cm per unit is feasible. Either single-unit or array operation to provide all-sky coverage with one arcmin resolution is possible. The instrument could be used to record gamma ray bursts and would have the capability of distinguishing particle events. Observations could also be made of X ray cyclotron lines and the Ti-44 lines expected to issue from a supernova explosion.
Gorenstein, P.↗
Hard X-ray observations of the Crab Nebula and A0535+26 with a high energy resolution spectrometer
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Hameury, J. M.↗
He D3 as a diagnostic for the hard and soft X-rays from solar flares
The time comparison of He D3 and X-ray emission has been studied in a number of medium-sized flares. In most cases there is a good agreement between the time histories of the He D3 emission and the high-temperature (about 2 keV) thermal source. The most intense He D3 emission comes from two small regions on either side of the neutral line, which are identified with the footpoints of magnetic structures in which a hot (2.3 x 10 to the 7th K) thermal plasma is formed. The impulsive X-ray event is marked by the transient brightening of a number of (usually weaker) He D3 sources. The two types of sources are well displaced from each other, which is an indication that they are produced in two different volumes. In some cases a long-lived third He D3 source is seen.
Feldman, U.↗
Correlation of hard X-ray and type III bursts in solar flares
Correlations between X-ray and type 3 radio emission of solar bursts are described through a bivariate distribution function. Procedures for determining the form of this distribution are described. A model is constructed to explain the correlation between the X-ray spectral index and the ratio of X-ray to radio intensities. Implications of the model are discussed. Previously announced in STAR as N82-32243
Petrosian, V.↗
Hardness of dense beta-Si3N4
The effects of small changes in the concentration of an oxygen content densification aid on the room temperature microhardness of hot isostatically pressed and sintered beta-Si3N4 ceramics are studied. The compositions studied were Si3N4 containing 7 wt. pct BeSiN2, a fixed nonoxide densification aid, and 1.9-3.7 wt. pct oxygen as a second, variable densification aid. A proportional relationship between high density and high oxygen content, regardless of heat treatment type, is noted.
Greskovich, C.↗
Long-term, hard X-ray observations of Scorpius X-1 from HEAO 1
The results of observations of Sco X-1 from three separate scanning epochs during 1977 and 1978 by the UCSD/MIT instruments aboard HEAO 1 in the 15-200 keV range are reported. Intensity and spectral variations have been studied on three time scales: 33-minute scans, daily averages, and weekly averages. No relationship was found between intensity and temperature over the very narrow range of temperatures observed, but comparison of the variability of the intensity, emission measure, and temperature implies at least two different emission mechanisms are at work. It is found that the spectral data are best fitted by either a thin-thermal-bremsstrahlung model of about 5 keV or a Comptonized thermal model of temperature about 3 keV. At higher energies (50-200 keV), no flux is found in excess of the thermal (as claimed by previous observers), and a 2-sigma upper limit from scanning data of 10 to the -5th photons/sq cm sec keV is set. This is an order of magnitude lower than reported detections. Using the distance derived from optical and UV measurements, X-ray luminosities from Sco X-1 incompatible with predictions for spherical accretion onto a white dwarf and emission volumes inconsistent with polar caps of white dwarfs are found.
Soong, Y.↗
Balloon observations of hard X-rays from some galactic X-ray sources
An X-ray telescope consisting of 400 cm phoswich detectors (NaI(T1)/CsI(Na)) was flown from Hyderabad (India) on 18 December 1984. The field of view was 5 deg x 5 deg FWHM. In a 10 hour float at 4 MB several galactic X-ray sources were tracked by the telescope using an on-board microprocessor. Fluxes and spectra in 18-120 keV X-rays for SCO X-1, GX 1+4, Gx 5-1, GX 17+2, SCT X-1, CYC X-1 an CYG X-3 will be presented.
Damle, S. V.↗
Balloon observations of hard X-rays from NGC 4151 and an X-ray transient source
An X-ray telescope consisting of 400 sq cm phoswich detectors (NaI(Tl)/CsI(Na)) was flown from Hyderabad (India) on 31 October 1980; the field of view was 11 deg x 1 deg FWHM. During a five hour observation at 5 millibars two X-ray sources were seen: (1) the variable Seyfert Galaxy NGC 4151; and (2) a transident of approximately 8 minutes duration in the vicinity of the variable source 4U1444 43 which may be associated with the galaxy NGC 5608. X-ray fluxes and spectra in 18-120 keV X-rays are presented.
Kunte, P. K.↗
A coded aperture imaging system optimized for hard X-ray and gamma ray astronomy
A coded aperture imaging system was designed for the Gamma-Ray imaging spectrometer (GRIS). The system is optimized for imaging 511 keV positron-annihilation photons. For a galactic center 511-keV source strength of 0.001 sq/s, the source location accuracy is expected to be + or - 0.2 deg.
Gehrels, N.↗
A 154-day periodicity in the occurrence of hard solar flares?
An analysis of the temporal distribution of 139 solar flares monitored by the Gamma Ray Spectrometer aboard the Solar Maximum Mission is reported. It is found that, instead of being randomly distributed in time, these events have a tendency to occur in groups with a mean spacing of about 154 days (75 nHz) over the observing interval. A larger sample of flares with an X-ray classification of M 2.5 or larger recorded by the GOES satellite showed a similar regularity.
Rieger, E.↗
A high energy resolution experiment in the hard X-ray range
The Low Energy Gamma-Ray Spectrometer (LEGS), a joint project among NASA/GSFC, CEN-SACLAY, and Rice University, is designed to perform fine energy resolution measurements of astrophysical sources. In its low energy configuration (20-800 keV energy range) the instrument uses three planar detectors (effective area of 53 sq cm) surrounded by a combination of passive Fe and active NaI for shielding and collimation (FOW of about 5 x 10 deg FWHM). In a typical one-day balloon flight, LEGS sensitivity limit (3 sigma) for narrow line features is not greater than about 0.0003 ph/sq cm s (at 100 kev).
Paciesas, W.↗
Repairing Hard-to-Reach Cracks in Heat-Exchanger Tubes
Inaccessible leaks repaired from accessible side of tube. Fish-Mouth insert placed in cut in leaky heat-exchanger tube. Insert welded or brazed to tube, and remaining open area of cut patched. Method developed for repairing leaks in nozzle coolant tubes of Space Shuttle main engine. Method also used on other types of tubular heat exchangers.
Mills, R. C., Sr.↗
Depletion layer recombination effects on the radiation damage hardness of gallium arsenide cells
The significant effect of junction depletion layer recombination on the efficiency of windowed GaAs cells was demonstrated. The effect becomes more pronounced as radiation damage occurs. The depletion is considered for 1 MeV electron fluences up to 10 to the 16th power e/sq m. The cell modeling separates damage in emitter and base or buffer layers using different damage coefficients is reported. The lower coefficient for the emitter predicts less loss of performance at fluences greater than 10 to the 15th power e/sq cm. A method for obtaining information on junction recombination effects as damage proceeds is described; this enables a more complete diagnosis of damage to be made.
Garlick, G. F. J.↗
Radiation-hard analog-to-digital converters for space and strategic applications
During the course of the Jet Propulsion Laboratory's program to study radiation-hardened analog-to-digital converters (ADCs), numerous milestones have been reached in manufacturers' awareness and technology development and transfer, as well as in user awareness of these developments. The testing of ADCs has also continued with twenty different ADCs from seven manufacturers, all tested for total radiation dose and three tested for neutron effects. Results from these tests are reported.
Gauthier, M. K.↗