scholarly journals Антикорреляция интенсивности стимулированного пикосекундного излучения GaAs и характерного времени остывания носителей заряда

2020 ◽  
Vol 54 (1) ◽  
pp. 25
Author(s):  
Н.Н. Агеева ◽  
И.Л. Броневой ◽  
Д.Н. Забегаев ◽  
А.Н. Кривоносов
Keyword(s):  
Relaxation Time ◽  
Energy Density ◽  
Emission Intensity ◽  
Pump Beam ◽  
Optical Pumping ◽  
Pump Energy ◽  
Gaas Layer ◽  
Charge Carriers ◽  
Characteristic Relaxation Time ◽  
Maximum Emission

During the powerful picosecond optical pumping, intense stimulated picosecond emission arises in a thin GaAs layer. It was found that, firstly, the maximum emission intensity decreases with increasing diameter of the pump beam (the pump energy density is fixed). Secondly, this dependence is anticorrelated with the dependence on the diameter of the characteristic relaxation time of the emission. And this time, in turn, is associated with the characteristic cooling time of charge carriers, which is slowed down due to heating of the carriers by emission. As a result, the autocorrelation indicated in the title is revealed.

scholarly journals Связь релаксации собственного стимулированного пикосекундного излучения GaAs с характерным временем остывания носителей заряда

2019 ◽  
Vol 53 (11) ◽  
pp. 1471
Author(s):  
Н.Н. Агеева ◽  
И.Л. Броневой ◽  
Д.Н. Забегаев ◽  
А.Н. Кривоносов
Keyword(s):  
Relaxation Time ◽  
Carrier Density ◽  
Optical Pumping ◽  
Characteristic Temperature ◽  
Gaas Layer ◽  
Saturation State ◽  
Carrier Heating ◽  
Pump Pulse Energy ◽  
Temperature Relaxation ◽  
Analytical Expressions

During the powerful picosecond optical pumping of a thin (~ 1 µm) GaAs layer, a stimulated intense (up to 1 GW/cm^2) picosecond emission appeared. As was found, for a fixed density of the pump pulse energy, with an increase of its diameter the characteristic picosecond time τr of the emission and carrier density n relaxation increases. Due to interrelation of the density and the temperature of the carriers at high-intensity emission (in the saturation state of the emission amplification), time τr is associated with the characteristic temperature relaxation time τT of the photo-pumped carriers, which was determined earlier theoretically with the emission-caused carrier heating taken into account. The corresponding analytical expressions for τr as a functions of τT are consistent with the above experimental results.

Induced polarization and pore radius — A discussion

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. D519-D526 ◽  
Author(s):  
Andreas Weller ◽  
Zeyu Zhang ◽  
Lee Slater ◽  
Sabine Kruschwitz ◽  
Matthias Halisch
Keyword(s):  
Diffusion Coefficient ◽  
Relaxation Time ◽  
Diffusion Coefficients ◽  
Pore Radius ◽  
Mercury Porosimetry ◽  
Induced Polarization ◽  
Reliable Estimate ◽  
Characteristic Relaxation Time ◽  
A Value ◽  
Apparent Diffusion

Permeability estimation from induced polarization (IP) measurements is based on a fundamental premise that the characteristic relaxation time [Formula: see text] is related to the effective hydraulic radius [Formula: see text] controlling fluid flow. The approach requires a reliable estimate of the diffusion coefficient of the ions in the electrical double layer. Others have assumed a value for the diffusion coefficient, or postulated different values for clay versus clay-free rocks. We have examined the link between a widely used single estimate of [Formula: see text] and [Formula: see text] for an extensive database of sandstone samples, in which mercury porosimetry data confirm that [Formula: see text] is reliably determined from a modification of the Hagen-Poiseuille equation assuming that the electrical tortuosity is equal to the hydraulic tortuosity. Our database does not support the existence of one or two distinct representative diffusion coefficients but instead demonstrates strong evidence for six orders of magnitude of variation in an apparent diffusion coefficient that is well-correlated with [Formula: see text] and the specific surface area per unit pore volume [Formula: see text]. Two scenarios can explain our findings: (1) the length scale defined by [Formula: see text] is not equal to [Formula: see text] and is likely much longer due to the control of pore-surface roughness or (2) the range of diffusion coefficients is large and likely determined by the relative proportions of the different minerals (e.g., silica and clays) making up the rock. In either case, the estimation of [Formula: see text] (and hence permeability) is inherently uncertain from a single characteristic IP relaxation time as considered in this study.

scholarly journals Thermodynamic Analysis of Relaxation Model for Non-Equilibrium Phase Behavior of Hydrocarbon Mixtures

2021 ◽  
Vol 2090 (1) ◽  
pp. 012138
Author(s):  
I M Indrupskiy ◽  
P A Chageeva
Keyword(s):  
Relaxation Time ◽  
Phase Behavior ◽  
Relaxation Process ◽  
Thermodynamic Analysis ◽  
Balance Equation ◽  
Equilibrium Phase ◽  
Characteristic Relaxation Time ◽  
Relaxation Model ◽  
Entropy Balance ◽  
Non Equilibrium

Abstract Mathematical models of phase behavior are widely used to describe multiphase oil and gas-condensate systems during hydrocarbon recovery from natural petroleum reservoirs. Previously a non-equilibrium phase behavior model was proposed as an extension over generally adopted equilibrium models. It is based on relaxation of component chemical potentials difference between phases and provides accurate calculations in some typical situations when non-instantaneous changing of phase fractions and compositions in response to variations of pressure or total composition is to be considered. In this paper we present a thermodynamic analysis of the relaxation model. General equations of non-equilibrium thermodynamics for multiphase flows in porous media are considered, and reduced entropy balance equation for the relaxation process is obtained. Isotropic relaxation process is simulated for a real multicomponent hydrocarbon system with different values of characteristic relaxation time using the non-equilibrium model implemented in the PVT Designer module of the RFD tNavigator simulation software. The results are processed with a special algorithm implemented in Matlab to calculate graphs of the total entropy time derivative and its constituents in the entropy balance equation. It is shown that the constituents have different signs, and the greatest influence on the entropy is associated with the interphase flow of the major component of the mixture and the change of the total system volume in the isotropic process. The characteristic relaxation time affects the rate at which the entropy is approaching its maximum value.

Relaxation Time of Phonons Interacting with Charge Carriers in GaAs

1975 ◽  
Vol 71 (2) ◽  
pp. 719-729
Author(s):  
A. F. Kravchenko ◽  
L. I. Magarill ◽  
A. A. Romanov ◽  
N. F. Semchukov ◽  
E. M. Skok
Keyword(s):  
Relaxation Time ◽  
Charge Carriers

Relaxation Time and Effective Masses for Charge Carriers in Semimetallic BiSb Alloys versus Alloy Composition

1981 ◽  
Vol 106 (2) ◽  
pp. 587-592 ◽  
Author(s):  
W. Braune ◽  
U. Straubel ◽  
N. Kubicki ◽  
J. Lebech ◽  
K. Saermark
Keyword(s):  
Relaxation Time ◽  
Alloy Composition ◽  
Charge Carriers ◽  
Versus Alloy ◽  
Effective Masses

CS Optical Pumping Magnetic Sensor Spectrum Lamp Drive Circuit Design Based on PI Feedback Controller

2014 ◽  
Vol 568-570 ◽  
pp. 473-477 ◽  
Author(s):  
Chao Tan ◽  
Li Fang ◽  
Xue Bai
Keyword(s):  
Emission Intensity ◽  
Optical Pumping ◽  
Spectral Width ◽  
Control Measures ◽  
Experimental Result ◽  
Crystal Oscillator ◽  
Optical Source ◽  
Optical Pump ◽  
Rf Power Amplifier ◽  
Drive Circuit

The optical source is one of the key components for the optical pump magnetic field sensor, its spectral width, stability and emission intensity directly related to the sensitivity of the sensor. The CS Spectral Lamp drive signal source was produced by crystal oscillator and amplified by the power controllable RF power amplifier. For achieving the aim of luminous intensity controllable and more stability, the reference controllable analog PI negative feedback control measures were used in the drive circuit. Contrast experimental result show that: the emission intensity of CS spectrum lamp is more stable and less affected by temperature if using the drive circuit which discussed in this paper.

Cooperative Domain Model for Yield Phenomenon

1990 ◽  
Vol 215 ◽  
Author(s):  
S. Matsuoka
Keyword(s):  
Relaxation Time ◽  
Strain Rate ◽  
Yield Stress ◽  
Molecular Model ◽  
Configurational Entropy ◽  
Domain Model ◽  
Characteristic Relaxation Time ◽  
Viscoelastic Relaxation ◽  
Classical Plasticity ◽  
Linear Viscoelastic

AbstractA molecular model for cooperative segmental relaxation has been proposed, which leads to the Adam-Gibbs type dependence of the characteristic relaxation time on temperature and the configurational entropy. When the size distribution for the cooperative domains is introduced, the resulting relaxation spectrum is similar to the Kohlrausch-Williams-Watts (KWW) equation in the frequency range near the loss maximum, but the fit is actually better in the high frequency extremes where the KWW equation always underpredicts the intensity. The model also predicts the broad spread of the spectrum in the non-equilibrium state from the distribution of the apparent activation energy arising from the different sizes of domains.We now extend this model to the yield phenomenon in glassy polymers. Under the stress, a domain has two alternatives to dissipate the strain energy. One way is to relieve the stress at the rate dictated by the linear viscoelastic relaxation time. This process is possible only when the strain rate is low. At above a certain strain rate, the stress reaches the strength of the domain, forcing to irreversibly break up the domain structure in the manner that can be described by the classical plasticity. It can be shown that the yield stress of a real polymer is a combination of the above two types of stresses. Namely, at a given strain rate, the small domains with short relaxation time will attain the linear viscoelastic steady stress while the larger domains reach the (limiting) plastic yield stress. Thus, the strain rate dependence of yield stress can be predicted from the linear viscoelastic relaxation spectra, even though the yield phenomenon is clearly in the realm of nonlinear viscoelasticity.

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