scholarly journals Influence of diffusion and viscosity on the field asymmetry of the effect of gravity in the critical fluid

2021 ◽  
pp. 8-16
Author(s):  
A.D. Alekhin
Keyword(s):  
Critical Temperature ◽  
Light Intensity ◽  
Density Gradient ◽  
Critical Field ◽  
Chemical Potential ◽  
Scattered Light ◽  
Critical Density ◽  
Scattered Light Intensity ◽  
Gravity Effect ◽  
Critical Temperature Tc

A brief review of the results of studies of the effect of gravity in inhomogeneous substance near a critical state of a critical fluid (CF) has been presented in paper, based on the data of light scattering, refractometry, and slow neutron transmission methods.Based on these data, the field-altitude asymmetry of various properties of an inhomogeneous substance has been analyzed, namely order parameter Dr(z), scattered light intensity I(z), density gradient dr(z)/dz of the substance. It had been shown that the field-altitude asymmetries of the scattered light intensity I(z)~dr/dm(h) and the density gradient dr(z)/dz~dr/dh(h) of the substance are diametrically opposite. The different altitudinal asymmetry of these quantities dr/dh(h) and dr/dm(h) is explained in paper by the altitude asymmetry of the derivative of the chemical potential dm/dh, and hence with the altitude asymmetry of the chemical potential Dm(h)>>h in the external field h.To the present time, the physical mechanism of the altitude asymmetry of the gravity effect has not been studied. In this regard the mechanism of the formation of the vertical asymmetry of the internal critical field Dm(h) has proposed in paper to be associated with the kinetic characteristics of the inhomogeneous critical fluid: the diffusion coefficients D (h) and viscosity coefficients h(h), when the system passes from a homogeneous state to an inhomogeneous one under the action of an internal asymmetric fields |DU(z)|= |Dm(z)|>>|h=rcgz/Pc|. For this purpose, a high-pressure cell with a height L, with a critical filling density of the substance is considered in paper.It has been shown that when the system is under critical density filling by substance =rc  the critical level of substance z = 0 with the critical density rc  at the critical temperature Tc is realized above the middle of the sample with an inhomogeneous substance. Based on the literature data of P-V-T-measurements and the gravity effect in benzene and ethane, the values of the altitudinal change in the internal critical field have been found. It has been shown that the value of the critical internal inhomogeneous field in the inhomogeneous critical fluid significantly exceeds the variable of the Earth's gravity |DU(h,Tc)|= |Dm(h,Tc)>>|h|  It has been also shown that the magnitude of this field according to the cubic law depends on the critical temperature Tc of the substance: |Dm(z,Tc1)/|Dm(z,Tc2) » (Tc1/Tc2)3.

scholarly journals Planar droplet sizing: Application to a spray of Jet A1 kerosene

2017 ◽  
Author(s):  
Pierre Doublet ◽  
Christine Lempereur ◽  
Virginel Bodoc ◽  
Mikael Orain ◽  
Pierre Gajan
Keyword(s):  
Light Intensity ◽  
Scattered Light ◽  
Droplet Surface ◽  
Scattered Light Intensity ◽  
Field Of View ◽  
Fluorescence Signal ◽  
Droplet Volume ◽  
Image Processing Algorithm ◽  
Two Phase ◽  
Scattering Angle

Optical techniques are  widely employed for their non-intrusive behavior and are applied to two-phase flowinvestigations. Until now, the most commonly used technique to determine the droplet size is the Phase Doppler Anemogranulometry, although it is time consuming for an overall injector characterization. An imaging technique called Planar Droplet Sizing has been used to offer an alternative and provide a spatially-resolved 2D map of the Sauter Mean Diameter (SMD). The measurement is based on the ratio between laser-induced fluorescence and scattered light intensities which are assumed to be proportional respectively to the droplet volume and droplet surface area. However, previous studies revealed that the dependence of fluorescence intensity on the droplet volume can be altered by the absorption of light in the liquid. The scattered light intensity depends on the scattering angle and intensity variations within the field of view must be avoided.The aim of this study is to make the PDS technique operational for a Jet A-1 kerosene spray. A strong absorption of liquid kerosene appears under UV excitation at 266 nm making the technique unsuitable. Under visible excitation at 532 nm, a fluorescent tracer (Pyrromethene 597) must be added to the kerosene to enhance the fluorescence signal. To prevent scattered light intensity variations within the field of view, an optimal scattering angle close to 115° is required. An image processing algorithm is proposed in order to reduce the effects ofmultiple scattering.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4698

scholarly journals Method for the Determination of Density and Phase Functions of Interplanetary Dust

1980 ◽  
Vol 90 ◽  
pp. 55-60
Author(s):  
A. Mujica ◽  
G. Lôpez ◽  
F. Sánchez
Keyword(s):  
Light Intensity ◽  
Unit Volume ◽  
Interplanetary Space ◽  
Scattered Light ◽  
Interplanetary Dust ◽  
Scattered Light Intensity ◽  
Zodiacal Light ◽  
Method Of Determination ◽  
Phase Functions

SummaryA method of determination of the scattered light intensity, , by a unit-volume of interplanetary space is presented. From ground base Zodiacal Light measurements and the experimental results of Pioneer X the density, ρ(r), and phase, σ(θ), functions are obtained without any previous assumptions about them.

Correlation between Powder in the Plasma and Stability of High Rate Deposited a-Si:H

2005 ◽  
Vol 862 ◽  
Author(s):  
Guozhen Yue ◽  
Gautam Ganguly ◽  
Baojie Yan ◽  
Jeffrey Yang ◽  
Subhendu Guha
Keyword(s):  
Solar Cells ◽  
Light Intensity ◽  
Scattered Light ◽  
Scattered Light Intensity ◽  
High Rate ◽  
Invasive Technique ◽  
High Deposition Rate ◽  
Very High Frequency ◽  
Silicon Photodiode ◽  
Non Invasive

AbstractHydrogenated amorphous silicon (a-Si:H) solar cells incorporating high deposition rate (8-10Å/s) intrinsic layers were deposited using modified very high frequency (MVHF) plasma. We have monitored the light scattered from powder generated in the plasma using an Ar-laser and a silicon photodiode. This simple, non-invasive technique allows us to make measurements on the same reactor used to make the solar cells. First, we have varied the total flow rate and observed a maximum in the scattered light intensity from powder in the plasma during the deposition of the intrinsic layer, and correlated this with the degradation, as well as the stabilized performance of the solar cells. Then, we have studied the effects of varying the deposition temperature and/or the addition of germane to the gas mixture on the scattered light intensity due to powder in the plasma.

scholarly journals Optimum Angles for Multi-Angle Elastic Light Scattering Experiments

2011 ◽  
Author(s):  
D. W. Burr ◽  
K. J. Daun ◽  
K. A. Thomson ◽  
G. J. Smallwood
Keyword(s):  
Inverse Problem ◽  
Light Scattering ◽  
Light Intensity ◽  
Size Distribution ◽  
Design Of Experiment ◽  
Scattered Light ◽  
Scattered Light Intensity ◽  
Elastic Light Scattering ◽  
Optimal Angle ◽  
Ill Posed

In multiangle elastic light scattering (MAELS) experiments, the morphology of aerosolized particles is inferred by shining collimated radiation through the aerosol and then measuring the scattered light intensity over a set of angles. In the case of soot-laden aerosols MAELS can be used to recover, among other things, the size distribution of soot aggregates. This involves solving an ill-posed set of equations, however. While previous work focused on regularizing the inverse problem using Bayesian priors, this paper presents a design-of-experiment methodology for identifying the set of measurement angles that minimizes its ill-posedness. The inverse problem produced by the optimal angle set requires less regularization and is less sensitive to noise, compared with two other measurement angle sets commonly used to carry out MAELS experiments.

Opalescence and concentration fluctuations in binary liquid mixtures near the critical mixing point. - II. Theoretical

1954 ◽  
Vol 224 (1156) ◽  
pp. 104-119 ◽  
Keyword(s):  
Correlation Function ◽  
Light Intensity ◽  
Scattered Light ◽  
Wave Length ◽  
Liquid Mixtures ◽  
Density Fluctuations ◽  
Concentration Fluctuations ◽  
Scattered Light Intensity ◽  
Gaussian Shape ◽  
Critical Mixing

A theory of light scattering in fluids produced by local fluctuations of refractive index is developed from the theory of X-ray scattering in fluids which is applied to the phenomena of critical opalescence in one-component liquids due to density fluctuations and in two-component liquid mixtures due to concentration fluctuations. The dependence of the scattered light intensity on wave-length and scattering angle can be derived from the theoretical expressions when the correlation of the fluctuations in two volume elements as a function of the distance of these elements is known. The theory is used for determining the shape of the correlation function for a number of binary mixtures from the measured angular distribution of the scattered light intensity, as described in part I by means of numerical computation of Fourier integrals. It is found that the mixtures belonging to class I (as defined in part I) are characterized by a correlation function with a range of negative correlation, and those belonging to class II by a correlation function of nearly Gaussian shape. The absolute magnitude of the concentration fluctuations near the critical mixing point is also calculated from the observational material. A tentative qualitative explanation for the different shapes of the correlation function for the two classes of mixtures is presented.

Density Matrix Description of Fast and Slow Light Propagation in Sodium Vapour

2009 ◽  
Vol 16 (02n03) ◽  
pp. 103-125 ◽  
Author(s):  
Abu Mohamed Alhasan
Keyword(s):  
Light Intensity ◽  
Density Matrix ◽  
Light Propagation ◽  
Arrival Time ◽  
Slow Light ◽  
Scattered Light ◽  
Scattered Light Intensity ◽  
Field Equations ◽  
Von Neumann ◽  
Radiation Fields

The dual-colour excitation for D1 transition is analysed taking into account the hyperfine structure of sodium atomic vapour. The advancement of the probe and restoring fields are calculated through different time average schemes. The first scheme depends on the arrival time of the pulse. The other one depends explicitly on the arrival time of photons. The evolution of atomic states is described by the Liouville-von Neumann equation for the density matrix of the dressed atom. The spatiotemporal behaviour of radiation fields is described by the reduced Maxwell's field equations. We monitor the populations of atomic levels and calculate the scattered light intensity. The mean arrival time of photons is suitably defined in terms of the scattered light intensity and the total scattered light at a given distance.

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