Showing papers on "Thermal equilibrium published in 1986"
TL;DR: In this article, an ideal thermodynamic treatment was proposed for a tephra-water interaction, in which the magma and external water are allowed to come to thermal equilibrium before explosive expansion, and the maximum system pressure and entropy were determined by the mass ratio of water and magma interacting.
Abstract: Physical analysis of explosive, magma-water interaction is complicated by several important controls: (1) the initial geometry and location of the contact between magma and water; (2) the process by which thermal energy is transferred from the magma to the water; (3) the degree to and manner by which the magma and water become intermingled prior to eruption; (4) the thermodynamic equation of state for mixtures of magma fragments and water; (5) the dynamic metastability of superheated water; and (6) the propagation of shock waves through the system. All of these controls can be analyzed while addressing aspects of tephra emplacement from the eruptive column by fallout, surge, and flow processes. An ideal thermodynamic treatment, in which the magma and external water are allowed to come to thermal equilibrium before explosive expansion, shows that the maximum system pressure and entropy are determined by the mass ratio of water and magma interacting. Explosive (thermodynamic) efficiency, measured by the ratio of maximum work potential to thermal energy of the magma, depends upon heat transfer from the pyroclasts to the vapor during the expansion stage. The adiabatic case, in which steam immediately separates from the tephra during ejection, produces lower efficiencies than does the isothermal case, in which heat is continually transferred from tephra to steam as it expands. Mechanisms by which thermal equilibrium between water and magma can be obtained require intimate mixing of the two. Interface instabilities of the Landau and Taylor type have been documented by experiments to cause fine-scale mixing prior to vapor explosion. In these cases, water is heated rapidly to a metastable state of superheat where vapor explosion occurs by spontaneous nucleation when a temperature limit is exceeded. Mixing may also be promoted by shock wave propagation. If the shock is of sufficient strength to break the magma into small pieces, thermal equilibrium and vapor production in its wake may drive the shock as a thermal detonation. Because these mechanisms of magma fragmentation allow calculation of grain size, vapor temperature and pressure, and pressure rise times, detailed emplacement models can be developed by critical field and laboratory analysis of the resulting tephra deposits. Deposits left by dense flows of tephra and wet steam as opposed to those left by dilute flows of dry steam and tephra show contrasts in median grain size, dispersal area, grain shape, grain surface chemistry, and bed form.
403 citations
TL;DR: In this paper, the influence of ocean thermo-dynamics on unstable modal behavior is systematically explored, and the free equatorial modes for several simple coupled ocean-atmosphere models are determined.
Abstract: Free equatorial modes for several simple coupled ocean-atmosphere models are determined. They are found to include unstable and damped modes of large zonal scale and long period. The influence of ocean thermo-dynamics on unstable modal behavior is systematically explored. The Model I ocean features a local thermal equilibrium. In Model II, linearized temperature advection is the sole ocean thermal process. The Model III ocean features both advective and local thermal processes, while that of Model IV features only local thermal processes. The ocean and atmosphere are each represented by linear shallow water equations on the equatorial β-plane, and are linked by traditional couplings. A finite difference method with variable resolution is used to find eigenvalues and eigenvectors of the coupled systems. Key results are checked via a series method. Ocean modes are influenced most strongly by coupling, and are damped or destabilized depending on the configuration of induced atmospheric motion relati...
273 citations
TL;DR: In this article, the authors show that for a system staying in thermal equilibrium with its environment, this hypothesis leads to a violation of the KMS condition, the fluctuation dissipation theorem, and under certain conditions to a fundamental principle of detailed balancing.
128 citations
PARC1
TL;DR: The structure of doped amorphous silicon is shown to be in metastable thermal equilibrium above 130°C, having temperature-dependent densities of dangling bonds and donors.
Abstract: The structure of doped amorphous silicon is shown to be in metastable thermal equilibrium above 130\ifmmode^\circ\else\textdegree\fi{}C, having temperature-dependent densities of dangling bonds and donors. The time to reach equilibrium is thermally activated, so that cooling establishes a slowly relaxing nonequilibrium state resembling a glass. The results are interpreted in terms of the recent defect-compensation model of doping.
119 citations
CERN1
TL;DR: In this paper, a lowest order calculation of the partition function of strings in thermal equilibrium is done, by first computing the world sheet σ-model at finite temperature (with topology of a torus) and then using the light-cone gauge to obtain string quantities.
90 citations
PARC1
TL;DR: The temperature dependence of the dc dark conductivity of doped hydrogenated amorphous silicon is explained by the defect-compensation model of doping with the proposal that the structure is in metastable thermal equilibrium.
Abstract: The temperature dependence of the dc dark conductivity of doped hydrogenated amorphous silicon is explained by the defect-compensation model of doping with the proposal that the structure is in metastable thermal equilibrium. Observed conductivity activation energies and preexponential factors can be accounted for quantitatively. When the localized state distribution is in thermal equilibrium, the conductivity preexponential factor is the Mott minimum metallic conductivity.
81 citations
TL;DR: In this article, the Lie group invariance properties of the one-dimensional radiation hydrodynamic equations with the equilibrium diffusion approximation, a local thermodynamical equilibrium assumption, and an arbitrary material equation of state are derived.
Abstract: The Lie group invariance properties of the one‐dimensional radiation hydrodynamic equations with the equilibrium diffusion approximation, a local thermodynamical equilibrium assumption, and an arbitrary material equation of state are derived. These properties are used systematically to generate similarity solutions of these equations for a given form of the equation of state. A comprehensive list of allowed similarity solutions for a perfect gas is presented. Several special cases that have been found previously by other authors appear in the list. Many other cases not reported previously are also presented. An example numerical solution is given for a piston‐driven shock with a thermal precursor.
56 citations
TL;DR: In this paper, the process of heat transfer in a packed bed catalytic reactor is analyzed in terms of the method of volume averaging, and the results of this analysis provide guidelines for the use of either homogeneous or heterogeneous models and clearly indicate the parameters that must be considered in making the choice between these two models.
53 citations
TL;DR: In this article, the thermal equilibrium electric field fluctuation energy of the gyrokinetic model of magnetized plasmas is computed and found to be smaller than the well-known result δE⋅δE(k)/8π= 1/2 T/[1+kλD)2.
Abstract: The thermal equilibrium electric field fluctuation energy of the gyrokinetic model of magnetized plasma is computed and found to be smaller than the well‐known result 〈δE⋅δE〉(k)/8π= 1/2 T/[1+(kλD)2] valid for arbitrarily magnetized plasmas. It is shown that, in a certain sense, the equilibrium electric field energy is minimum in the gyrokinetic regime.
38 citations
Patent•
28 Mar 1986
TL;DR: In this paper, the surface of the substrate positioned in the reaction chamber is exposed to at least one of the radiation and the active species generated from the LTE plasma for performing the surface processing.
Abstract: In a surface processing apparatus, the LTE (Local Thermal Equilibrium) plasma is produced, instead of the glow discharge, in the discharge chamber. Then the LTE plasma is conducted into the reaction chamber. The surface of the substrate positioned in the reaction chamber is exposed to at least one of the radiation and the active species generated from the LTE plasma for performing the surface processing.
37 citations
TL;DR: In this article, the authors derived an adjoint equation to the inhomogeneous, linearized, dynamic Boltzmann equation to describe the driven plasma in contact with an external source of power, especially a source that interacts specifically with highvelocity electrons.
Abstract: A plasma in contact with an external source of power, especially a source that interacts specifically with highvelocity electrons, exhibits transport properties, such as conductivity, different from those of an isolated plasma near thermal equilibrium. This is true even when the bulk of the particles in the driven plasma is near thermal equilibrium. To describe the driven plasma, we derive an adjoint equation to the inhomogeneous, linearized, dynamic Boltzmann equation. The Green’s functions for a variety of plasma responses can then be generated. It is possible to modify the Chapman–Enskog [Mathematical Theory of Nonuniform Gases, 3rd ed., (Cambridge U.P., Cambridge, MA, 1970)] expansion in order to incorporate the response functions derived here.
TL;DR: In this paper, the authors derived a theory for small amplitude motion about states in thermal equilibrium, which contains the effects of two-body collisions treated beyond the Markov approximation, and studied the damping of collective modes in a stochastic two-level model.
TL;DR: In this paper, the boil-off method for measuring a.c. loss in superconductors is developed, making it possible to conduct experimental measurements regardless of thermal equilibrium in the cryostat.
TL;DR: In this article, the incoherent scatter technique was used to estimate the neutral temperature in the low thermosphere and compare the results to models, finding that the observed neutral temperature at 100 km is lower by about 15k than predicted by the MSIS model and closer to the temperature predicted by Jacchia 71 model.
TL;DR: An algorithm is presented for the detailed computation of the spectral lines in hot, partially ionized plasmas in local thermodynamic equilibrium using the wave functions and state probabilities determined from the average atom model for microscopic configuration accounting.
Abstract: An algorithm is presented for the detailed computation of the spectral lines in hot, partially ionized plasmas in local thermodynamic equilibrium. The procedure uses the wave functions and state probabilities determined from the average atom model for microscopic configuration accounting. We use intermediate coupling to include the detailed structure of the bound-bound transition arrays. The model is applied to bromine plasma under such temperature and density conditions that partially filled L shells occur.
TL;DR: In this article, the energy-relaxation time τ ϵ from 0.3 K to 2 K was derived for a sandwich consisting of a thin Au film and a thin Bi film insulated by a SiO layer.
TL;DR: In this article, it was shown that the entropy of a system constituted by a massive Schwarzschild black hole in stable thermal equilibrium with black body radiation is superadditive in Landsberg's sense.
Abstract: We show that the entropy of a system constituted by a massive Schwarzschild black hole in stable thermal equilibrium with black body radiation is superadditive in Landsberg's sense. Furthermore, we comment on some consequences arising from the negative character of the heat capacity of that system.
TL;DR: In this article, the authors investigate simple model systems in contact with an infinite heat bath and show that starting from almost any initial configuration, the system approaches, ast → ∞, the appropriate Gibbs distribution.
Abstract: We investigate simple model systems in contact with an infinite heat bath. The former consists of a finite number of particles in a bounded regionλ ofℝd,d=1,2. The heat baths are infinite particle systems which can penetrateλ and interact with the system via elastic collisions. Outsideλ the particles move freely and have a Gibbs probability measure prior to enteringλ. We show that starting from almost any initial configuration, the system approaches, ast → ∞, the appropriate Gibbs distribution. The combined system plus bath is Bernoulli.
TL;DR: In this article, the multiple-trapping model is used in order to analyse space-charge perturbed dispersive transport in disordered materials, where traps are considered to be distributed over a wide energy region in the gap.
TL;DR: In this paper, the thermal equilibrium correlation properties of a magnetically confined pure electron plasma (McPEP) are related to those of a one-component plasma (OCP), where the electron gyromotion is allowed to be fully quantized while the guiding center motion is quasi-classical.
Abstract: The thermal equilibrium correlation properties of a magnetically confined pure electron plasma (McPEP) are related to those of a one-component plasma (OCP). The N-particle spatial distribution rho sub s and the Helmholtz free energy F are evaluated for the McPEP to O(lambda sub d-squared/a-squared), where lambda sub d is the thermal de Broglie wavelength and is an interparticle spacing. The electron gyromotion is allowed to be fully quantized while the guiding center motion is quasi-classical. The distribution rho sub s is shown to be identical to that of a classical OCP with a slightly modified potential. To O(lambda sub d-squared/a-squared) this modification does not affect that part of F that is caused by correlations, as long as certain requirements concerning the size of the plasma are met. This theory is motivated by a current series of experiments that involve the cooling of a magnetically confined pure electron plasma to the cryogenic temperature range.
TL;DR: In this paper, the evolution with the temperature of the relative Fe1+ transient state population in ZnS was analyzed with the coherent relaxation model with an activation energy of 0.24 eV.
Abstract: The evolution with the temperature of the relative Fe1+ transient state population in ZnS is analyzed with the coherent relaxation model. The evolution of the Fe1+ life time is compatible with an activation energy of 0.24 eV. The quadrupolar coupling observed at low temperature may be due to the population out of thermal equilibrium of an electronic excited state of Fe1+. These results are in agreement with optical measurements on impurities in semiconductors.
TL;DR: In this article, a non-linear fitting method of these models for obtaining equilibrium temperature and calculating the results from observed data is presented. But the authors assume that the real formation temperature is a very useful parameter in geothermal investigations and hydrocarbon maturation studies.
TL;DR: In this paper, a non-uniform fluid in thermal equilibrium, described by free energy as a functional of particle density, is considered, and the property of locality is defined, and both local chemical potential and local pressure tensor are constructed.
TL;DR: In this article, the authors investigated the rate at which a particle decays out of a metastable potential well by quantum tunneling and calculated the leading corrections to the exponent and the prefactor of the rate, due to coupling to the heat bath and finite temperatures.
Abstract: We investigate the rate at which a particle decays out of a metastable potential well by quantum tunneling. We calculate the leading corrections to the exponent and the prefactor of the rate, due to coupling to the heat bath and finite temperatures. Since the results are essentially equivalent to those employing the transition state assumption, namely maintaining thermal equilibrium, we argue for the lower on the damping strength above which these results should be valid. These results are in good accord with recently reported experiments.
TL;DR: In this article, a self-organized chemical system is described by a set of rate equations for a primary and a partial system, where the partial system acts as an internal driving force to regulate the primary system.
01 Jan 1986
TL;DR: In this paper, a review of the status of the experimental determination of the equilibrium concentration of point defects in metals is given and it is argued that the question whether, in addition to vacancies, self-interstitials contribute significantly must be considered open and that accurate simultaneous measurements of the macroscopic and microscopic thermal expansion might help in answering it.
Abstract: A brief critical review is given of the status of the experimental determination of the equilibrium concentration of point defects in metals. It is argued that the question whether, in addition to vacancies, self-interstitials contribute significantly must be considered open and that accurate simultaneous measurements of the macroscopic and microscopic (unit-cell) thermal expansion might help in answering it. For high-accuracy determination of the differential thermal expansion at high temperatures (melting points of Cu, Ag, Au and above) a laser-interferometry-neutron diffraction experiment is being built up at the Institute Laue-Langevin. Preliminary experiments on Cu are reported, indicating that the desired accuracy may be achieved.
TL;DR: In this article, the authors measured the magnet spin precession frequencies and transverse relaxation rates on demagnetized iron, cobalt, and FeCo alloys (3 at%−50 at% Co) between room temperature and the Curie temperature.
Abstract: Muon spin precession frequencies and transverse relaxation rates have been measured on demagnetized iron, cobalt, and FeCo alloys (3 at%–50 at% Co) between room temperature and the Curie temperatureT
c. The increase of the relaxation rate in iron between 930 K and 1010 K could be quantitatively attributed to the trapping of positive muons by vacancies in thermal equilibrium, resulting in an enthalpy of monovacancy formation ofH
1V
F
=(1.7±0.1) eV. the smallest vacancy concentrations detected are = 10−8.
Journal Article•
TL;DR: In this paper, conditions can be realized such that a free photon gas could be appropriately described by a canonical ensemble with constrained particle number density, then, above Planck's mean photon density for black body radiation, Bose-Einstein condensation is implied.
Abstract: If conditions can be realized such that a free photon gas could be appropriately described by a canonical ensemble with constrained particle number density, then, above Planck's mean photon density for black body radiation, Bose-Einstein condensation is implied. For a finite reflecting cavity the excess photons would occupy the Dirichlet ground state thereby forming an approximately monochromatic radio wave. A rigorous formalism, developed by Lewis et al., is applied. The thermodynamic functions are calculated in the infinite volume limit where the particle number density is fixed.
TL;DR: In this paper, a method for deconvoluting incompletely resolved CARS spectra to obtain quantum state population distributions is described, where the population of each quantum state is treated as an independent quantity.
Abstract: We describe a method for deconvoluting incompletely resolved CARS spectra to obtain quantum state population distributions. No particular form for the rotational and vibrational state distribution is assumed, the population of each quantum state is treated as an independent quantity. This method of analysis differs from previously developed approaches for the deconvolution of CARS spectra, all of which assume that the population distribution is Boltzmann, and thus are limited to the analysis of CARS spectra taken under conditions of thermal equilibrium. The method of analysis reported here has been developed to deconvolute CARS spectra of photofragments and chemical reaction products obtained in chemical dynamics experiments under nonequilibrium conditions. The deconvolution procedure has been incorporated into a computer code. The application of that code to the deconvolution of CARS spectra obtained for samples at thermal equilibrium and not at thermal equilibrium is reported. The method is accurate and computationally efficient.