Showing papers on "Atmospheric pressure published in 1972"
TL;DR: Mariner-9 S-band radio occultation measurements conducted during November and December 1971 are described in terms of new information that was obtained about the shape and atmosphere of Mars as mentioned in this paper.
185 citations
TL;DR: In this article, the viscosity of all the noble gases at atmospheric pressure and at zero density at 25°C were derived by means of a single empirical correlation, and a careful analysis of the long-term reproducibility of the oscillating disk viscometer employed in the work was presented.
Abstract: New relative measurements of the viscosity of xenon at a pressure P=1 atm and in the temperature range T=25–700°C are reported. The viscosity of argon has also been remeasured. A careful analysis of the long‐term reproducibility of the oscillating‐disk viscometer employed in the work is presented together with best estimates of the viscosity of all the noble gases. Standard reference values of the viscosity of the gases at atmospheric pressure and at zero density at 25°C are given. The data for all the monatomic gases are represented by means of a single empirical correlation.
180 citations
TL;DR: In this paper, an experimental investigation was made of the turbulent vapor cavity formed by a steam jet discharging into a subcooled liquid water both considering both constant area and convergent-divergent steam injectors of various external geometries.
Abstract: An experimental investigation was made of the lenght of the turbulent vapor cavity formed by a steam jet discharging into a subcooled liquid water both. The experiments considered both constant area and convergent-divergent steam injectors of various external geometries. The tests were conducted with the bath at atmospheric pressure, bath temperatures in the range 301–358K, injector exit diameters in the range 0.00040–0.0112 m, for choked injector flows having mass velocities in the range 332–2050 kg/m2.s. These conditions yielded injector exit Reynolds numbers from 2 to 150 × 104. Over this range a correlation was developed to yield the length of the vapor cavity as a function of the injector diameter, exit mass velocity, and a driving potential for the condensation process. The heat transfer coefficients for this condensation process were found to be significantly greater than those encountered in turbulent film condensation processes in the vicinity of tubes and walls.
173 citations
TL;DR: In this paper, an electron-beam-controlled discharge has been used to pump a variety of CO2 laser gas mixtures at atmospheric pressure in substantial volumes, and the electrical and laser properties of the pumped medium have been measured.
Abstract: An electron‐beam‐controlled discharge has been used to pump a variety of CO2 laser gas mixtures at atmospheric pressure in substantial volumes. Electrical and laser properties of the pumped medium have been measured. Small‐signal‐gain coefficients up to 0.045 cm−1 were achieved at field strengths of 3 kV/cm.
141 citations
Patent•
02 Feb 1972TL;DR: Sulfonated polyxylylene oxide membranes are very effective for the separation of water vapor from other gases as discussed by the authors, and such a gas separation is very selective and may be readily accomplished at atmospheric pressure.
Abstract: Sulfonated polyxylylene oxide membranes are very effective for the separation of water vapor from other gases. Such a gas separation is very selective and may be readily accomplished at atmospheric pressure. Membrane devices for humidifying or drying an air stream are described.
140 citations
TL;DR: The pressure dependence of the elastic constants of various halides, hard tissues and synthetic apatites have been examined using a solid media, pressure apparatus coupled with an ultrasonic interferometer to assess the effects of porosity in aggregate samples and to make measurements on specimens of ideal density.
Abstract: The pressure dependence of the elastic constants of various halides, hard tissues and synthetic apatites have been examined in the 0- to 50-kilobar range using a solid media, pressure apparatus coupled with an ultrasonic interferometer. The samples includ: hydroxy-, fluor-, and chlor-apatite, NaCl, CaF2, mollusc shell (aragonite), ivory, dentin and enamel, and fish, bovine, and human bones. High pressures were used in order to assess the effects of porosity in aggregate samples and to make measurements on specimens of ideal density. Computer analysis of the measured longitudinal and shear ultrasonic velocities yields the pressure dependence of the bulk, shear, and Young's moduli and Poisson's ratio. Atmospheric pressure values at ideal density are obtained by back extrapolation from the high pressure measurements.
108 citations
TL;DR: In this article, the authors measured the burning velocity in the central stream-tube of a button-shaped flame with the particle track method and compared it with data from cone-shaped flames.
101 citations
TL;DR: In this article, the authors presented new relative measurements of the viscosity of the binary mixtures He-Ne and Ne-N2, as well as repeated determinations of viscosities of the pure gases.
Abstract: The paper presents new relative measurements of the viscosity of the binary mixtures He–Ne and Ne–N2, as well as repeated determinations of the viscosity of the pure gases. The experiments were performed using an oscillating‐disk viscometer; they were made at atmospheric pressure and in the nominal temperature range 25–700°C. The accuracy of the measurements is one of ± 0.1% at 25°C, deteriorating to ± 0.3% at 700°C. Tables of the thermal conductivity of the monatomic‐gas mixture are provided together with values for pure nitrogen. The binary diffusion coefficients for the mixtures have also been computed.
69 citations
TL;DR: In this article, the authors present new relative measurements of the viscosity of binary mixtures of helium and nitrogen, together with repeated determinations of the viscous properties of the pure gases.
Abstract: The paper presents new relative measurements of the viscosity of binary mixtures of helium and nitrogen, together with repeated determinations of the viscosity of the pure gases. The experiments were performed, using an oscillating disk viscometer; they were made at atmospheric pressure and in the nominal temperature range 25–700°C, the precision being one of ±0.1%. Tables of thermodynamically consistent values of the thermal conductivity of the pure gases are given. The binary diffusion coefficient for the mixture has also been computed.
67 citations
TL;DR: In this paper, a simple high-power nitrogen laser was described giving a peak power of 1.2 MW in an active length of only 30 cm, and the results for operation with air and with a helium-nitrogen mixture at atmospheric pressure.
Abstract: A simple high-power nitrogen laser is described giving a peak power of 1.2 MW in an active length of only 30 cm. We also report results for operation with air and for operation with a helium-nitrogen mixture at atmospheric pressure.
62 citations
TL;DR: The dynamical processes responsible for laser emission in the pulsed pumping of a transversely excited atmospheric (TEA) CO2 laser are investigated in this article, where an explanation for the formation of the giant pulse is proposed on the basis of a gain-switching mechanism in which it is assumed that with short strong-current pulses a high population inversion can be achieved prior to the onset of laser action.
Abstract: The dynamical processes responsible for laser emission in the pulsed pumping of a transversely excited atmospheric (TEA) CO2 laser are investigated An explanation for the formation of the giant pulse is proposed on the basis of a gain-switching mechanism in which it is assumed that with short strong-current pulses a high population inversion can be achieved prior to the onset of laser action The kinetics of the mechanism are described by means of a set of nonlinear rate equations idealized to a four-energy-state system With suitable initial conditions on the populations, the transient solution of these equations for the mixtures CO2–He and CO–N2–He appears to be consistent with the major features of experimental observation
TL;DR: In this article, the P1(1) line of the v = 0 → 1 branch of the lowest electronic transition of OH at 2822 A was resonantly excited with radiation from a doubled dye laser.
Abstract: Preliminary experiments suggesting the feasibility of using a resonance fluorescence scheme to detect ambient concentrations of OH in the atmosphere (106 molecules/cm3) were carried out using OH concentrations near 1012 molecules/cm3. The P1(1) line of the v = 0 → 1 branch of the lowest electronic transition of OH at 2822 A was resonantly excited with radiation from a doubled dye laser. The subsequent fluorescence from the v = 0 → 0 branch with Δν ≅ 3050 cm−1 was observed to have a fluorescence efficiency of 0.6 × 10−3 in N2 at atmospheric pressure with a 10‐mm partial pressure of H2O. This fluorescence occurs 500 cm−1 away from any strong Raman line in the atmosphere.
TL;DR: A liquid may be superheated beyond its normal boiling point without vaporizing by isolating the liquid from solid container surfaces and minimizing the number of solid impurities in the sample as mentioned in this paper.
Abstract: A LIQUID may be heated beyond its normal boiling point without vaporizing by isolating the liquid from solid container surfaces and by minimizing the number of solid impurities in the sample. This avoids imperfectly wetted solids which act as sites for the formation of vapour cavities. One successful technique1−4 is to heat a droplet of the liquid rising slowly in a host liquid in which the droplet is nearly insoluble, but the application of this technique to the superheating of water has suffered from problems of repeatability.
TL;DR: In this paper, large amplitude fluctuations in the arc potential in the initial phase of an arc have been examined for a low-current resistive break arc at atmospheric pressure, and these fluctuations were accompanied by an increase in the emitted intensity of the light coming from Pd I, N2+, and N2*, suggesting that the initial metallic vapor arc maintains itself by ionizing the surrounding gas.
Abstract: Large amplitude fluctuations in the arc potential in the initial phase of an arc have been examined for a low‐current resistive break arc at atmospheric pressure. These fluctuations were accompanied by an increase in the emitted intensity of the light coming from Pd I, N2+, and N2*, and a leveling of the light from Pd II, suggesting that the initial metallic vapor arc maintains itself by ionizing the surrounding gas. As the gap increases, the arc characteristically enters a second phase in which the discharge is maintained in the gaseous environment.
TL;DR: The vapour pressure of mercury has been determined ebulliometrically over the range 0.05 to 800 kPa (380 to 770 K) by the comparative method with water as the standard, and below 5 kPa by direct measurement of the pressure with a manometer.
TL;DR: In this article, a double-discharge transversely excited atmospheric pressure (TEA) CO2 laser with a Marx bank system at high output energies and efficiencies over a large discharge volume was operated.
Abstract: We have operated a double‐discharge transversely excited atmospheric pressure (TEA) CO2 laser with a Marx bank system at high output energies and efficiencies over a large discharge volume. The typical laser energy output is approximately 17 J/liter at an efficiency of 24% and a pulse‐to‐pulse variation of less than 10%. The parameters that govern the operation of the system are discussed.
Patent•
08 May 1972
TL;DR: In this paper, a plurality of stored bags which can be rapidly inflated with an inflating medium having a combustion suppressing agent to form a barrier to the propagation of a combustion reaction of a fuel-air mixture, such as a mixture of coal dust and/or methane and air.
Abstract: In a coal mine passage, a plurality of stored bags which can be rapidly inflated with an inflating medium having a combustion suppressing agent to form a barrier to the propagation of a combustion reaction of a fuel-air mixture, such as a mixture of coal dust and/or methane and air. To detect an incipient propagating combustion reaction, there is a radiation sensor, a static pressure sensor and a dynamic pressure sensor. There is a data analysis computer comprising a discriminator which determines a condition where radiation is above a certain predetermined level, and static and dynamic pressure are below a predetermined level within an initial short time period (e.g. 0.15 seconds) of sensing such increased radiation. When such a condition exists, the discriminating means arms an activating means which inflates the barrier bags in response to a predetermined level of increase of any one of the following five values: static pressure, dynamic pressure, rate of dynamic air pressure increase, rate of static pressure increase, and rate of radiation increase. Thus the apparatus discriminates between an actual condition of a possible rapidly propagating combustion reaction and such other disturbances as a stationary flame, electrical spark or a blast wave that do not result in such reaction. By initially containing the combustion suppressing medium in an inflatable, a more effective barrier is formed.
TL;DR: In this paper, the origin of nonuniform discharge paths is discussed, and a means for maximizing the energy input to the plasma prior to filamentation is presented, which is of relevance to the design of TEA lasers.
Abstract: A photographic and oscillographic study of discharges in helium‐carbon‐dioxide mixtures at atmospheric pressure has shown that fine filaments develop in the discharge column. The origin of these nonuniform discharge paths is discussed, and a means for maximizing the energy input to the plasma prior to filamentation is presented. This process is of relevance to the design of TEA lasers.
TL;DR: In this paper, a TEA HBr laser was used to pump pure CO2 gas at pressures up to 1 atm by optically pumping with the 4.23μm line of the TEA-HBr laser.
Abstract: Laser action at 10.6 μm has been obtained in pure CO2 gas at pressures up to 1 atm by optically pumping with the 4.23μm line of a TEA HBr laser. The potential usefulness of this method for pumping very high density CO2 is discussed.
TL;DR: In this article, a folded-type single crystal of hexagonal shape was obtained from dilute solution of p-xylene and that of irregular shape has been obtained from the melt of dispersion powder.
Abstract: Crystallizations of poly(chlorotrifluoroethylene)(PCTFE) from dilute solution and from the melt of dispersion powder at atmospheric pressure and from the melt of the bulk material under high pressure have been carried out and examined by electron microscope. A folded-type single crystal of hexagonal shape has been obtained from dilute solution of p-xylene and that of irregular shape has been obtained from the melt of dispersion powder.To determine the optimum crystallization temperature under high pressure, DTA measurements have been carried out and the melting and recrystallization curves have been obtained. Remarkable increase of Tm with respect to pressure (dTm/dP=60°C/1000 kg/cm2) has been observed. Experiments on the crystallization have been performed on the basis of these data. The fracture surface of the bulk sample crystallized under high pressure shows a completely developed band structure. In this polymer this structure has been obtained easily by the application of pressure of only a few hundred kg/cm2. From the examination of X-ray fibre pattern of stretched film crystallized under high pressure, a 17 monomer 1 turn helix configuration has been determined.
TL;DR: The importance of allowing for the variation in the absorption cross-section of oxygen across the width of the Lyman-α line profile is discussed in this paper, and an allowance has been made for the absorption produced by other atmospheric constituents.
TL;DR: In this paper, a determination of the self-broadened linewidth of methane at 2947.88 cm −1 has been made using a stabilized, singlemode helium-neon laser.
Abstract: A determination of the self-broadened linewidth of methane at 2947.88 cm −1 has been made using a stabilized, single-mode helium-neon laser. The width at half-maximum has been found to be 0.16±0.01 cm −1 at atmospheric pressure. By taking into account neighbouring methane components, the variation of the absorption coefficient in the high-pressure region can also be accounted for. The variation of the linewidth with temperature T has also been determined and was found to be close to T −1 . The strength of the methane line nearest the laser emission is 1.76±0.04 atm −1 cm −2 ; this line was found to be located 0.002±0.001 cm −1 from the laser emission.
TL;DR: In this paper, a range of carbon-, oxygen-, nitrogen-and halogen-containing compounds was investigated in order to optimize the sensitivity, linear working range and plasma operating conditions, and the limit of detection for these compounds at 247.9 nm was 1.94·10 -l0 g of carbon per sec.
TL;DR: In this article, the first two zonal harmonics, zonal wave numbers 1 and 2, were correlated with the corresponding harmonics of the atmospheric pressure fields for the stratosphere, and the observed relationship was tentatively explained as due to approximately vertical planetary-scale disturbances of the temperature field which are associated with the fluctuations of the planetary scale waves in the constant pressure surfaces.
Journal Article•
TL;DR: In this paper, Spectroscopic observations of an atmospheric-pressure argon plasma generated inductively by a high-power RF oscillator were reported, and the excitation temperature Tex, obtained from measurement of the relative intensities of spectral lines, were substantially greater than temperature values Teq, determined from absolute continuum and line intensities on the assumption of local thermodynamic equilibrium (LTE).
Abstract: Spectroscopic observations are reported of an atmospheric-pressure argon plasma generated inductively by a high-power RF oscillator. Values of the excitation temperature Tex, obtained from measurement of the relative intensities of spectral lines, were substantially greater than temperature values Teq, determined from absolute continuum and line intensities on the assumption of local thermodynamic equilibrium (LTE). If a “collisional-radiative” plasma model is used, the absolute intensity measurements yield temperatures Tcr, which are in better agreement with the Tex values.
TL;DR: In this paper, the construction and operation of a simple atmospheric pressure CO 2 laser that uses a fast voltage doubling was described, and the operation of the laser was described in detail.
Abstract: The construction and operation of a particularly simple atmospheric pressure CO 2 laser that uses a fast voltage doubling is described.
TL;DR: In this article, the authors used xylene as an additive with a concentration of 0 5% in a 90/5/5 gas mixture of He/N2/CO2 and achieved uniform pulsed discharges with current densities over 3 A/cm2.
Abstract: Uniform direct‐current discharges in atmospheric‐pressure mixtures of He/N2/CO2 have been achieved by the use of an organic gas additive Best results were obtained using xylene as an additive with a concentration of 0 5% in a 90/5/5 gas mixture Observed current densities were limited by external circuitry, but uniform pulsed discharges with current densities over 3 A/cm2 were obtained when the dc discharge was pulsed
Patent•
04 Dec 1972
TL;DR: In this article, a two-stage pressure reducing nozzle is fitted to the vent of a pressure gun to reduce the effective pressure of the jet discharged from the pressure gun downstream from the tube, and a vent in the passageway at this tube aids in forming the second stage pressure reduction.
Abstract: A pressure reducing nozzle for a pressure gun of the type which discharges a jet of air for cleaning and blowing away purposes. When air pressure guns are used with an air supply in the range of 100 to 125 P.S.I., a means for reducing the effective pressure of the jet discharged from the pressure gun is necessary. The present invention is a two-stage pressure reducing nozzle which is fitted to the vent of a pressure gun. A short tube is located at the entrance of the passageway of the pressure reducing nozzle. The entrance end of this tube is reduced in diameter to form a restrictive orifice and to create a first stage of pressure reduction within the tube. The exit end of this tube is also reduced in diameter to form a second restrictive orifice and to create a second stage of pressure reduction within the passageway of the pressure reducing nozzle downstream from the tube. A vent in the passageway at this tube aides in forming the second stage pressure reduction.