Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Flux Measurement”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

A note on the Gledhill model of the magnetosphere of Jupiter

Free-free emission from a constant density, isothermal rectangular of thickness 2 Jupiter radii and side dimensions 2 x 8 radii is considered. It is determined that the free-free emission from the Gledhill model exceeds the flux measured from the planet over the entire microwave spectrum. Consequently the electron density must be considerably less than Gledhill assumed (10 to the 9th power electrons/cu cm). The upper limit to the electron density which can be set by comparing free-free emission with the observed spectrum is approximately 10 to the 7th power electrons/cu cm.

Gulkis, S.↗
NASA NTRS1971

The present state of gamma-ray astronomy.

The current state of gamma-ray astronomy is reviewed in terms of the most recent experimental results that define, in either measured fluxes or upper limits, the cosmic photon spectrum in the energy range from 0.5 MeV to 10,000 TeV. Methods of research developed during the last 10 yr are discussed and specific results are cited. Cosmic gamma rays have been observed in two regions of the spectrum - from 0.5 to 6 MeV and from about 50 MeV to several hundred mega-electronvolts. Above 50 MeV, a strong concentration of intensity is observed in a band of directions around the galactic equator. In both spectral regions a diffuse background gamma ray flux, apparently isotropic and of extragalactic origin, is observed. Evidence of 50 MeV gamma-ray pulses from the Crab pulsar has been reported. No definite evidence of any other discrete gamma-ray source besides the galaxy itself has been observed at any energy.

Clark, G.↗
NASA NTRS1972

Circumstellar shells in the young cluster NGC 2264. II - Infrared and further optical observations.

Flux measurements at 1.6, 2.2, and 3.4 microns for 42 stars in the young cluster NGC 2264 suggest that a significant number of these stars are surrounded by circumstellar material which produces observable infrared excesses. Hydrogen line profiles are used to estimate surface gravities and thereby to predict visual luminosities for a number of pre-main-sequence A stars. Those stars which appear faintest as compared with their predicted luminosities all have infrared excesses.

Strom, S. E.↗
NASA NTRS1972

21-micron observations of H II regions.

The 21-micron contour map of M17 is similar to radio maps with three components. Measured flux densities give color temperatures of both 240 and 75 K for the two principal components of M17 and 44 to 63 K for Sgr B2, NGC 2024, and DR-21.

Lemke, D.↗
NASA NTRS1972

Flight evaluation of a quartz-fiberfrax heat shield.

The results of temperature and base heat flux measurements made on two heat-shield evaluation flights of six-solid-motor Delta boosters are reviewed. Curtains made of quartz cloth and Fiberfrax felt sandwiches formed the heat shield. A comparison is presented of the flight data to ground test results and to an analytical thermal model of the curtain material. In general, the results obtained have confirmed the excellent suitability of the proposed material as a heat shield for the application considered.

Greenwald, G. F.↗
NASA NTRS1973

Further measurements of the submillimeter background at balloon altitude.

Results of measurements of the far-infrared background radiation made with a balloon-borne radiometer at an altitude of 44 km. Equivalent blackbody temperatures were obtained for the background radiation in three bandwidths: 1 to 11.5 per cm, 1 to 13.5 per cm, and 1 to 18.5 per cm. The total measured flux in the largest of these bandwidths is dominated by the atmospheric emission by ozone and water. The data obtained confirm the results of prior flights, in particular, that a substantial amount, and perhaps all, of the radiation above 13 per cm is due to the atmosphere.

Muehlner, D. J.↗
NASA NTRS1974

Thermal performance of multilayer insulations

Experimental and analytical studies were conducted in order to extend previous knowledge of the thermal performance and gas evacuation characteristics of three selected multilayer insulation (MLI) composites. Flat plate calorimeter heat flux measurements were obtained for 20- and 80- shield specimens using three representative layer densities over boundary temperatures ranging from 39 K (70 R) to 389 K (700 R). Laboratory gas evacuation tests were performed on representative specimens of each MLI composite after initially purging them with helium, nitrogen, or argon gases. In these tests, the specimens were maintained at temperatures between 128 K (230 R) and 300 K (540 R). Based on the results of the laboratory-scale tests, a composite MLI system consisting of 112 unperforated, double-aluminized Mylar reflective shields and 113 water preconditioned silk net spacer pairs was fabricated and installed on a 1.22-m-(4-ft-) diameter calorimeter tank.

Keller, C. W.↗
NASA NTRS1974

Instruments for measuring radiant thermal fluxes

An absolute two-sided radiometer, designed on the principle of replacing absorbed radiant energy with electrical energy, is described. The sensitive element of the detector is a thermoelectric transducer of thermal flux. The fabrication technology, methods of measurement, technical characteristics, and general operation of the instrument are presented.

Gerashenko, O. A.↗
NASA NTRS1974

Observation of soft X-ray emission from a region near Per X-1

Soft X-ray emission from the X-ray source Per X-1 was observed in the 0.4-2 keV energy interval from a rocket-borne X-ray detector. Spectral analysis of the data indicates that in the 0.4-2 keV band the X-ray emission from Per X-1 can be fitted either with a power law or a steep thermal bremsstrahlung spectrum. This steep spectrum is inconsistent with the spectrum measured above 2 keV. The measured flux in 0.4-2 keV band corresponds to X-ray luminosity of 3 times 10 to the 45th ergs per second for Per X-1.

Agrawal, P. C.↗
NASA NTRS1974

Relation of solar wind fluctuations to differential flow between protons and alphas

An analysis is made of the difference between the alpha particle and proton flow velocities in the solar wind as observed by the OGO 5 satellite. The alpha and proton velocities from each of 962 spectral scans are compared with the variance of 32 solar wind flux measurements made during the scans. The average velocity difference is plotted for each of 10 logarithmic variance intervals and is seen to decrease and approach zero when the variance is high. It is shown that such an anticorrelation may be due to the fact the wave/particle interactions provide the drag force between two streams of different velocity in a collisionless plasma.

Neugebauer, M.↗
NASA NTRS1975

Pioneer 7 observations of plasma flow and field reversal regions in the distant geomagnetic tail

The present paper gives the results of an extensive analysis of plasma and magnetic-field data from Pioneer 7 taken in the geomagnetic tail approximately 1000 earth radii downstream from earth. The principal observations are: (1) measurable fluxes of protons in the tail, flowing away from earth, sometimes with a double-peaked velocity distribution; (2) field reversal regions in which the field changes from radial to antiradial by a vector rotation in the north-south plane; and (3) general characteristics of the tail similar to those observed near earth with good correlation between taillike magnetic fields and plasma.

Walker, R. C.↗
NASA NTRS1976

Low latitude middle atmosphere ionization studies

Low latitude middle atmosphere ionization was studied with data obtained from three blunt conductivity probes and one Gerdien condenser. An investigation was conducted into the effects of various ionization sources in the 40 to 65 Km altitude range. An observed enhancement of positive ion conductivity taking place during the night can be explained by an atmsopheric effect, with cosmic rays being the only source of ionization only if the ion-ion recombination coefficient (alpha sub i) is small(10 to the -7 power cu cm/s) and varies greatly with altitude. More generally accepted values of alpha sub i ( approximately equal to 3x10 to the -7 power cu cm/s) require an additional source of ionization peaking at about 65 Km, and corresponding approximately to the integrated effect of an X-ray flux measured on a rocket flown in conjunction with the ionization measurements. The reasonable assumption of an alpha sub i which does not vary with altitude in the 50-70 Km range implies an even greater value alpha sub i and a more intense and harder X-ray spectrum.

Bassi, J. P.↗
NASA NTRS1976

Turbine vane leading edge gas film cooling with spanwise angled coolant holes

An experimental film cooling study was conducted on a 3x size model turbine vane. Injection at the leading edge was from a single row of holes angled in a spanwise direction for two configurations of holes at 18 or 35 deg to the surface. The reduction in the local Stanton number for injection at a coolant-to-mainstream density ratio of 2.18 was calculated from heat flux measurements downstream of injection. Results indicate that optimum cooling occurs near a coolant-to-mainstream velocity ratio of 0.5. Shallow injection angles appear to be most beneficial when injecting into a highly accelerated mainstream.

Hanus, G. J.↗
NASA NTRS1976

Space shuttle cavity assessment test program

In order to obtain basic radiation properties of the radiator/payload bay door cavity, three tests were conducted on a full-size structural simulator of the cavity. There were three tests conducted: (1) CATA used for determination of exchange factors, absorbed solar flux, and door covering influences, (2) quartz lamp array calibrated to provide IR flux distribution on CATA, and (3) retest with radiometer array for background flux measurement.

Scheps, P. B.↗
NASA NTRS1976

EUV fluxes in the solar spectrum below 2000 A

The list of EUV fluxes presented at the 1969 IAGA review in Madrid (Hinteregger, 1970) has served as a useful reference in many aeronomical studies, leading to a wide range of opinions regarding both the absolute values in that reference list and the question of estimating EUV fluxes from the only routinely obtained data, i.e., the solar 10.7 cm flux. Advances made since 1969 will be reviewed including previously unpublished observations of the variability of solar EUV for the period from January 1974 to May 1975 which were obtained from the EUV spectrophotometer experiment on the AE-C satellite. The review is concluded by a discussion of current and future needs of solar EUV flux measurements for aeronomical applications.

Hinteregger, H. E.↗
NASA NTRS1976

Absolute flux calibration for the Mg II observations near 2800 angstroms

Observations of the Mg II features near 2800 A, obtained with a balloon-borne ultraviolet stellar spectrometer for five stars, have been calibrated against the absolute flux measures from OAO-2 spectrometer results. Equivalent widths of the Mg II resonance doublet and their respective subordinate lines, as well as the emission intensities, were evaluated where applicable.

Kondo, Y.↗
NASA NTRS1976

Determination of the energy or pressure of a solar X-ray structure using X-ray filtergrams from a single filter

While the X-ray fluxes measured through two different broadband filters can be used to derive the temperatures and emission measures of solar plasmas, it is generally assumed that no plasma parameters can be measured quantitatively with a single filtergram alone. It is shown that the thermal energy density (or pressure) of a solar plasma can be measured with an ideal single filtergram. Calculations have been done to compare the properties of the Skylab S-054 X-ray telescope filters with those of the ideal filter.

Kahler, S.↗