SNAP-8 corrosion program Quarterly progress report, period ending 31 May 1965
Differences in corrosion and mass transfer rates in corrosion loops for SNAP-8 system and effectiveness of cold trapping in reducing hydrogen concentration
CORROSION TEST↗
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Further examination of the hydrogen content in the upper atmosphere of Venus.
Molecular hydrogen concentration in Venus upper atmosphere by solving numerically heat conduction equation in conjunction with separate diffusion equation for each constituent
Mcgovern, W. E.↗
Electrical resistivity of PdHx system for H/Pd atom ratios to 0.97
PdH system electrical resistivity, studying hydrogen concentration role
Otterson, D. A.↗
Temporal variations of thermospheric hydrogen derived from in situ measurements
Thermospheric atomic hydrogen concentration temporal variations in situ measurement by Explorer 32 satellite
Brinton, H. C.↗
Techniques for lithium removal from 1040 C aged tantalum alloy, T-111
The liquid ammonia and vacuum distillation techniques were found to be satisfactory for removing lithium from 1040 C aged T-111 (tantalum - 8-percent tungsten- 2-percent hafnium). Results of ductility tests and chemical analysis show that these two methods are adequate for removing lithium without embrittlement or contamination of the T-111. Moist air exposure of T-111 with traces of lithium on the surface produced mixed results. Some specimens were ductile; others were brittle. Brittle T-111 had an increased hydrogen content. Water removal of lithium from T-111 caused brittleness and an increased hydrogen concentration.
Gahn, R. F.↗
Gas-phase hydrogen permeation through alpha iron, 4130 steel, and 304 stainless steel from less than 100 C to near 600 C
Gas phase hydrogen permeation studies were conducted on hollow, cylindrical membranes of triply zone-refined alpha iron, AISI 304 austenitic stainless steel, and AISI-SAE 4130 steel in both the normalized (ferrite and carbide) and quenched and tempered (martensite) conditions. Membrane temperature was varied from less than 100 C to near 600 C and hydrogen pressure was varied. For one membrane material, normalized 4130 steel, gas phase hydrogen transport under both steady state and nonsteady state conditions was demonstrated to be controlled by lattice diffusion. Additionally, Sievert's law was shown to be applicable. For all membrane materials, expressions for the coefficients for hydrogen permeation were determined by analysis of steady state transport; the coefficients for diffusion were determined by the lag time technique applied to nonsteady state transport; and through a knowledge of the Sievert's constants, the subsurface equilibrium lattice hydrogen concentrations were determined.
Nelson, H. G.↗
Observed effects of earth-reflected radiation and hydrogen drag on the orbital accelerations of balloon satellites.
From March through May 1967, the high-altitude balloon satellites Pageos (1966 56A) and Dash 2 (1963 30D) were both in continuous sunlight orbits. Observed variations in the orbital accelerations of both satellites are found to be due primarily to a combination of the perturbing effects of earth albedo radiation and atmospheric drag. An equation based on diffuse Lambertian reflection of sunlight from the earth predicts quite well the observed trend of orbital accelerations for both satellites due to the force of earth albedo radiation. After correcting for this effect, the remaining orbital energy changes are found to be consistent with atmospheric drag perturbations, making it possible to deduce mean exospheric densities above 2300 km. The results indicate that hydrogen concentrations during the observation period were about three times greater than that given by the U.S. Standard Atmosphere Supplements (1966).
Prior, E. J.↗
Galactic gamma rays: Models involving variable cosmic-ray density
Mathematical models were developed to determine variable cosmic ray flux around the galactic plane. Data indicate point sources, molecular hydrogen concentration, increased cosmic ray density toward the galactic center, and neutral pion production combine to cause radiation density variables in the galactic plane.
Strong, A. W.↗
Stress corrosion cracking of titanium alloys
The effect of hydrogen on the properties of metals, including titanium and its alloys, was investigated. The basic theories of stress corrosion of titanium alloys are reviewed along with the literature concerned with the effect of absorbed hydrogen on the mechanical properties of metals. Finally, the basic modes of metal fracture and their importance to this study is considered. The experimental work was designed to determine the effects of hydrogen concentration on the critical strain at which plastic instability along pure shear directions occurs. The materials used were titanium alloys Ti-8Al-lMo-lV and Ti-5Al-2.5Sn.
Statler, G. R.↗
Combustion of hydrogen-air jets in local chemical equilibrium: A guide to the CHARNAL computer program
A guide to a computer program, written in FORTRAN 4, for predicting the flow properties of turbulent mixing with combustion of a circular jet of hydrogen into a co-flowing stream of air is presented. The program, which is based upon the Imperial College group's PASSA series, solves differential equations for diffusion and dissipation of turbulent kinetic energy and also of the R.M.S. fluctuation of hydrogen concentration. The effective turbulent viscosity for use in the shear stress equation is computed. Chemical equilibrium is assumed throughout the flow.
Spalding, D. B.↗
Helium and hydrogen in the lunar atmosphere
Of the gas species supplied by the solar wind, only helium and hydrogen are light enough to be lost from the moon by Jeans' thermal escape mechanism. To study the behavior of helium and hydrogen, a Monte Carlo technique has been used, in which random ballistic trajectories of individual molecules are traced over a spherical moon. In the computation, a particle is 'created' on the sunlit surface, and the locations of its subsequent encounters with the surface are recorded until it escapes. Global distributions of helium and hydrogen concentrations have been computed, based on the hypothesis that the release of neutral gases from the lunar surface is confined to daytime and is correlated with the solar wind influx. The resulting helium model is in good agreement with the measurements from the Apollo 17 lunar surface mass spectrometer.
Hodges, R. R., Jr.↗
Infrared emission from H II regions
Analysis of observations made at infrared wavelengths of a large number of H II regions. Several types of IR sources are found associated with H II regions, and a single region can contain a number of varied IR emitting objects. The main sources of IR emission are ionized hydrogen concentrations, heated dust particles, and OH/H2O masers. Flux density maps for both radio and IR emission suggest that there is a physical association between the IR and radio-emitting regions. The properties of several H II regions indicate that they may be protostellar objects at various stages of evolution.
Wynn-Williams, C. G.↗
The development of an electrochemical technique for in situ calibrating of combustible gas detectors
A program to determine the feasibility of performing in situ calibration of combustible gas detectors was successfully completed. Several possible techniques for performing the in situ calibration were proposed. The approach that showed the most promise involved the use of a miniature water vapor electrolysis cell for the generation of hydrogen within the flame arrestor of a combustible gas detector to be used for the purpose of calibrating the combustible gas detectors. A preliminary breadboard of the in situ calibration hardware was designed, fabricated and assembled. The breadboard equipment consisted of a commercially available combustible gas detector, modified to incorporate a water vapor electrolysis cell, and the instrumentation required for controlling the water vapor electrolysis and controlling and calibrating the combustible gas detector. The results showed that operation of the water vapor electrolysis at a given current density for a specific time period resulted in the attainment of a hydrogen concentration plateau within the flame arrestor of the combustible gas detector.
Shumar, J. W.↗
Development of a nitrogen generation system
An eight-stage nitrogen generation module was developed. The design integrated a hydrazine catalytic dissociator, three ammonia dissociation stages and four palladium/silver hydrogen separator stages. Alternating ammonia dissociation and hydrogen separation stages are used to remove hydrogen and ammonia formed in the dissociation of hydrazine which results in negligible ammonia and hydrogen concentrations in the product nitrogen stream. An engineering breadboard nitrogen supply subsystem was also developed. It was developed as an integratable subsystem for a central spacecraft air revitalization system. The subsystem consists of the hydrazine storage and feed mechanism, the nitrogen generation module, the peripheral mechanical and electrical components required to control and monitor subsystem performance, and the instrumentation required to interface with other subsystems of an air revitalization system. The breadboard nitrogen supply subsystem was integrated and tested with a one-person capacity experimental air revitalization system. The integration, checkout and testing was successfully accomplished.
Heppner, D. B.↗
IUE observations of the Jovian HI Lyman alpha emission (1979 - 1982)
Observations of the Jovian H ion Lyman emission made with the IUE observatory beginning in December 1978 just before the time of the Voyager encounters and extending through January 1982 are presented. A constant disk center brightness of about 8 kR is observed for the central meridian longitude range wavelength III approximately equal 200 deg to 360 deg and a variable brightness 9-15 kR is found for the range lambda III approximately 50 deg to 150 deg. These brightness values persisted throughout the three years of observation. The hydrogen bulge near wavelength III approximately equal 100 deg appears to be a permanent feature of the Jovian atmosphere, and no long term change of the planetary Lyman emission is seen. Since the early IUE observations were made near the two Voyager encounters, this indicates that no substantial changes in the atomic hydrogen concentration or the average atmospheric conditions took place between then and now.
Skinner, T. E.↗
Temporal variation of the Jovian H I Lyman-alpha emission /1979-1982/
Observations of the Jovian H I Lyman-alpha emission have been made with the International Ultraviolet Explorer (IUE) observatory beginning in 1978 December, just before the time of the Voyager encounters, and extending through 1982 January. A nearly constant disk center brightness of about 8.5 kilorayleighs is observed for the central meridian longitude range lambda(III) = 200 to 360 deg and a variable brightness of between 9 and 15 kilorayleighs is found for the range lambda(III) = 50 to 150 deg. These brightness values have persisted throughout the three years of observation, and the hydrogen bulge near lambda(III) = 100 deg appears to be a fixed feature of the Jovian atmosphere. These results indicate that no substantial changes in the Jovian atomic hydrogen concentration or the average atmospheric conditions have taken place between the time immediately preceding the Voyager encounters and the present. The question of Jovian Lyman-alpha variability prior to 1978 is reexamined in the light of the IUE results.
Skinner, T. E.↗
Optical properties of hydrogenated amorphous carbon films grown from methane plasma
A 30 kHz ac glow discharge formed from methane gas was used to grow carbon films on InP substrates. Both the growth rate, and the realitive Ar ion sputtering rate at 3 keV varied monotonically with deposition power. Results from the N-15 nuclear reaction profile experiments indicated a slight drop in the hydrogen concentration as more energy was dissipated in the ac discharge. Values for the index of refraction and extinction coefficient ranged from 1.721 to 1.910 and 0 to -0.188, respectively. Optical bandgaps as high as 2.34 eV were determined.
Pouch, J. J.↗
In situ measurement of atomic hydrogen in the upper mesosphere
In situ measurements of H abundance between 73 and 93 km are reported for conditions of winter solstice, magnetic quiet, and a solar depression angle of 12 deg. The data were obtained by a rocket-borne instrument using the resonance fluorescence technique. A discharge source emitting photons at 1216 A was an integral part of the instrument. The instrument was radially deployed 80 cm by a boom from the front of the payload in order to avoid the shock created by the gas flow over the front of the payload. An attitude control system oriented the payload so that the gas flow was nearly perpendicular to the plane containing the incident and scattered photons, thus minimizing any correction for Doppler shift. The resonance radiation detector viewed a black backstop in order to minimize background radiation from the hydrogen geocorona; however, the background was not entirely eliminated. The signal-to-noise ratio was improved by summing the data in 1.8-s bins. The observed hydrogen concentration maximized at 85 km at 1.5 + or - 1.1 x 10 to the 8th atoms/cu cm.
Sharp, W. E.↗