Plasma In Thermal Equilibrium Research Articles

Perturbative Peculiarities of Quantum Field Theories at High Temperatures

Revisiting the fast fermion damping rate calculation in a thermalized QED and/or QCD plasma in thermal equilibrium at four-loop order, focus is put on a peculiar perturbative structure which has no equivalent at zero-temperature. Not surprisingly, and in agreement with previous C ☆ -algebraic analyses, this structure renders the use of thermal perturbation theory more than questionable.

Momentum Distribution Functions in Quark-Gluon Plasma

Based on the constituent quasiparticle model of the quark-gluon plasma (QGP), the Wigner function is presented in the form of a color path integral. The Monte Carlo calculations of the quark and gluon densities, pair correlation functions and the momentum distribution functions for strongly coupled QGP plasma in thermal equilibrium at barion chemical potential equal to zero have been carried out. Analysis of the pair correlation functions points out on arising glueballs and related gluon bound states. Comparison results between the momentum distribution functions and Maxwell-Boltzmann distributions show the significant influence of the interparticle interaction on the high energy asymptotics of the momentum distribution functions resulting in the appearance of quantum “tails”.

Estimation of temperature and electron density of laser-induced breakdown spectroscopy (libs) on river clam shell using hydrogen emissionlines

The physical characteristic in term of temperature and electron density of the laser-induced plasma produced on a river shell sample has been investigated. The plasma was produced by an Nd: YAG laser beam (1064 nm) at low pressure (5 Torr) of air surrounding gas. Multi-elemental panoramic line spectra (200-900 nm) have been analysed at different delay times (0.1-5 μs) and gate width of 50 μs. The hydrogen emission lines namely Hα at 656.27, Hβ at 486.13 and Hγ at 434.04 nm were identified and utilized to evaluate the plasma parameters. The temperature and electron density of the produced plasma were estimated by means of Boltzmann Plot and Saha-Boltzmann method using the hydrogen emission lines. The result shows that the plasma temperature and electron density vary from about 5633 K to 8810 K and 3.7 × 1020 cm−3 to 9.7 × 1020 cm−3, respectively. The temperature and electron density of the plasma produced on the river shell sample conform the Maxwell distribution and Mc Whriter criteria for the laser induced plasma in local thermal equilibrium (LTE) condition.

Approach to equilibrium of a quarkonium in a quark-gluon plasma

We derive equations of motion for the reduced density matrix of a heavy quarkonium in contact with a quark-gluon plasma in thermal equilibrium. These equations allow in particular a proper treatment of the regime when the temperature of the plasma is comparable to the binding energy of the quarkonium. These equations are used to study how the quarkonium approaches equilibrium with the plasma, and we discuss the corresponding entropy increase, or free energy decrease, depending on the temperature regime. The effect of collisions can be accounted for by the generalization of the imaginary potential introduced in previous studies, and from which collision rates are derived. An important outcome of the present analysis is that this imaginary potential has a sizeable dependence on the energy of the relevant transitions.

Using L-shell x-ray spectra to determine conditions of non-local thermal dynamic equilibrium plasmas.

K-shell x-ray spectra of Li- to H-like ions have long been used to determine plasma conditions. The ratio of integrated line intensities is used to determine the temperature. At the density of non-local thermal dynamic equilibrium (NLTE) plasmas (n e ≈ 1021 cm-3), the K-shell spectrum is not very sensitive to density. We propose using the L-shell emission of open L-shell ions (C- to Li-like) as an alternative to determine both temperature and density of NLTE plasmas. First, the L-shell models of a mid-Z material need to be verified against the temperatures obtained using a K-shell spectrum of a low-Z material. A buried layer platform is being developed at the OMEGA laser to study the open L-shell spectra of NLTE plasmas of mid-Z materials. Studies have been done using a 250 μm diameter dot composed of a layer of 1200 Å thick Zn between two 600 Å thick layers of Ti, in the center of a 1000 μm diameter, 13 μm thick beryllium tamper. Lasers heat the target from both sides for up to 3 ns. The size of the emitting volume vs time was measured with x-ray imaging (face-on and side-on) to determine the density. The temperature was measured from the Ti K-shell spectra. The use of this platform for the verification of atomic L-shell models is discussed.

The quantum equation of state until the fourth virial coefficient for many‐component plasmas

The aim of the present article is to calculate the quantum excess free energy until the fourth virial coefficient in terms of Slater sums for neutral many‐component plasmas. We used the results to calculate the equation of state; we used the thermal equilibrium plasma. Bound states are not taken into account in this work.

Giant increase in cross-magnetic-field transport rate as an electron-positron plasma cools

An electron-positron plasma in thermal equilibrium within a uniform magnetic field is studied using a classical trajectory Monte Carlo simulation. The cross-magnetic-field single-particle diffusion coefficient is evaluated as a function of the magnetic field strength and plasma temperature. The transport rate is found to increase by many orders of magnitude as the plasma temperature is lowered, for a magnetic field strength of 1 T. The sharp dependence on temperature is due to electrons and positrons becoming temporarily correlated and drifting across the magnetic field before dissociating.

On the spectrum of plasma modes in a field-free pair plasma: Dispersion and Landau damping in Tsallis statistics

The full spectrum of possible plasma modes and their Landau damping in a field-free pair plasma are examined analytically in the context of Tsallis statistics. This study is based on the solving the linearized Vlasov equation and Maxwell’s equations by employing the general method of characteristics, i.e., integrating along unperturbed orbits. Three types of plasma modes are confirmed: two of them are electrostatic waves with Landau damping, i.e., ion plasma waves (IPWs) and ion-acoustic waves (IAWs); and one mode is the transverse electromagnetic waves (light waves) without Landau damping. Our analysis shows that the Landau damping time for IAWs is negligible for most of wave lengths, and so these modes are heavily damped. Furthermore, Landau damping time for IPWs are considerable and these modes are of a great importance. Comparison of Landau damping in the case of a supra-thermal background distribution (confirmed by considering q<1 for spectral index) with the ones for a Maxwellian plasma in thermal equilibrium (confirmed by considering the asymptotic limit q→1) shows that the supra-thermal background makes the Landau damping more effective and prominent and also shifts the normal modes to the regions with less wave numbers. Basically, the damping rate in a supra-thermal plasma is stronger than a Maxwellian plasma. Moreover, the electromagnetic modes are comparatively less sensitive to the background distribution.

Spontaneous emission of Alfvénic fluctuations

Low-frequency fluctuations are pervasively observed in the solar wind. The present paper theoretically calculates the steady state spectra of low-frequency electromagnetic (EM) fluctuations of the Alfvénic type for thermal equilibrium plasma. The analysis is based upon a recently formulated theory of spontaneously emitted EM fluctuations in magnetized thermal plasmas. It is found that the fluctuations in the magnetosonic mode branch is constant, while the kinetic Alfvénic mode spectrum is dependent on a form factor that is a function of perpendicular wave number. Potential applicability of the present work in the wider context of heliospheric research is also discussed.

Fundamental investigation of dry electrical discharge machining (DEDM) by optical emission spectroscopy and its numerical interpretation

Dry electrical discharge machining (DEDM) has been developed as an alternative manufacturing process to the traditional EDM in liquid dielectric media. The absence of the liquid dielectric allows DEDM to be performed by simpler and environmentally friendlier machines. The erosion in DEDM mainly occurs due to the bombardment of the workpiece electrode surface by charged particles produced by micro electric discharges. Thus, the understanding of the fundamental properties of the micro plasma is necessary to explain the erosion mechanisms in this process. Optical emission spectroscopy of DEDM single discharges and its numerical interpretation by emission spectra simulation are developed in the present work. The hypothesis of plasmas in local thermal equilibrium (LTE) is developed, whereas the formation of an electron beam in non-LTE plasmas is also considered and briefly introduced. The simulations show that large amount of different ionic species is produced from the anode workpiece material, and the estimated electron temperature profile is peaking at the plasma centre. Moreover, hot anode spots formed on the workpiece surface due to the plasma-material interactions seem to be considerably smaller than the total plasma diameter and the respective eroded crater. These characteristics indicate that DEDM produces discharges similar to anode dominated vacuum arcs, which present properties very different from EDM discharges in liquid dielectric.

Stark broadening measurements in plasmas produced by laser ablation of hydrogen containing compounds

We present a method for the measurement of Stark broadening parameters of atomic and ionic spectral lines based on laser ablation of hydrogen containing compounds. Therefore, plume emission spectra, recorded with an echelle spectrometer coupled to a gated detector, were compared to the spectral radiance of a plasma in local thermal equilibrium. Producing material ablation with ultraviolet nanosecond laser pulses in argon at near atmospheric pressure, the recordings take advantage of the spatially uniform distributions of electron density and temperature within the ablated vapor. By changing the delay between laser pulse and detector gate, the electron density could be varied by more than two orders of magnitude while the temperature was altered in the range from 6,000 to 14,000K. The Stark broadening parameters of transitions were derived from their simultaneous observation with the hydrogen Balmer alpha line. In addition, assuming a linear increase of Stark widths and shifts with electron density for non-hydrogenic lines, our measurements indicate a change of the Stark broadening-dependence of Hα over the considered electron density range. The presented results obtained for hydrated calcium sulfate (CaSO4⋅2H2O) can be extended to any kind of hydrogen containing compounds.

Off-equilibrium sphaleron transitions in the glasma

We perform first classical-statistical real time lattice simulations of topological transitions in the non-equilibrium Glasma of weakly coupled but highly occupied gauge fields created immediately after the collision of ultra-relativistic nuclei. Simplifying our description by employing SU(2) gauge fields, and neglecting their longitudinal expansion, we find that the rate of topological transitions is initially strongly enhanced relative to the thermal sphaleron transition rate and decays with time during the thermalization process. Qualitative features of the time dependence of this non-equilibrium transition rate can be understood when expressed in terms of the magnetic screening length, which we also extract non-perturbatively. A detailed investigation of auto-correlation functions of the Chern-Simons number ($N_{CS}$) reveals non-Markovian features of the evolution distinct from previous simulations of non-Abelian plasmas in thermal equilibrium.

On determining absolute entropy without quantum theory or the third law of thermodynamics

We employ classical thermodynamics to gain information about absolute entropy, without recourse to statistical methods, quantum mechanics or the third law of thermodynamics. The Gibbs–Duhem equation yields various simple methods to determine the absolute entropy of a fluid. We also study the entropy of an ideal gas and the ionization of a plasma in thermal equilibrium. A single measurement of the degree of ionization can be used to determine an unknown constant in the entropy equation, and thus determine the absolute entropy of a gas. It follows from all these examples that the value of entropy at absolute zero temperature does not need to be assigned by postulate, but can be deduced empirically.

N2O Decomposed by Discharge Plasma with Catalysts**supported by National Natural Science Foundation of China (No. 50677026) and the Applied Basic Research Program of Wuhan, China (No. 2015060101010068)

A great deal of attention has been focused on discharge plasma as it can rapidly decompose N2O without additives, which is not only a kind of greenhouse gas but also a kind of damages to the ozone layer. The thermal equilibrium plasma is chosen to combine with catalysts to decompose N2O, and its characteristics are analyzed in the present paper. The results indicate that NO and NO2 were formed besides N2 and O2 during N2O decomposition when N2O was treated merely by discharge plasma. Concentration of NO declined greatly when the discharge plasma was combined with catalysts. Results of Raman spectra analysis on CeO2, Ce0.75Zr0.25O2 and Ce0.5Zr0.5O2 imply that the products selectivity has been obviously improved in discharge plasma decomposing N2O because of the existence of massive oxygen vacancies over the composite oxide catalysts.

Gravitational wave background from Standard Model physics: qualitative features

Because of physical processes ranging from microscopic particle collisions to macroscopic hydrodynamic fluctuations, any plasma in thermal equilibrium emits gravitational waves. For the largest wavelengths the emission rate is proportional to the shear viscosity of the plasma. In the Standard Model at 0T > 16 GeV, the shear viscosity is dominated by the most weakly interacting particles, right-handed leptons, and is relatively large. We estimate the order of magnitude of the corresponding spectrum of gravitational waves. Even though at small frequencies (corresponding to the sub-Hz range relevant for planned observatories such as eLISA) this background is tiny compared with that from non-equilibrium sources, the total energy carried by the high-frequency part of the spectrum is non-negligible if the production continues for a long time. We suggest that this may constrain (weakly) the highest temperature of the radiation epoch. Observing the high-frequency part directly sets a very ambitious goal for future generations of GHz-range detectors.

Calculation of a plasma HgDyI3 transport coefficients

This work is devoted to the calculation of the chemical composition and transport coefficients of HgDyI3 plasmas in thermal equilibrium. These calculations are performed for pressures equal to 2MP and for temperatures varying from 1000 to 10 000 K. The thermal and electrical conductivity as well as viscosity have been computed as a function of temperature at different atomic ratios. The computational method proposed by Devoto from the classical formalism described by Hirschfelder et al. [Molecular Theory of Gases and Liquids (John Wiley and Sons, New York, 1954)] is used.

Multi-average ion model for hot dense plasmas derived from finite temperature density-functional theory

We present a formulation for plasmas in local thermal equilibrium (LTE) as a system of consisting of (ZA + 1) kinds of average ions, i.e., one for each charge state 0; 1; 2; …; ZA and each with a uniform electronic charge, thus generating a multi-average ion model or Multi-AIM model. Here the bound electron density of average atoms and their pair correlation functions is obtained self-consistently by means of minimizing the free energy of the whole system established by the finite temperature density functional theory (FTDFT). The pair correlation function is obtained by solving the hypernetted chain equation (HNC). We show the charge state distribution of Al and Fe plasmas for several temperatures and densities determined by the Multi-AIM.

Time-resolved spatial distribution of plasma in the ablation of a Ba0.6Sr0.4TiO3 target by 25 ns KrF ultraviolet laser

We performed radially and longitudinally time-resolved plasma analysis during pulsed laser deposition of Ba0.6Sr0.4TiO3 thin films. The plasma is shown to be optically thick and strongly non-uniform during the early expansion phase and the resonance line Ba II (455.4 nm) is strongly self-reversed during this time. Plasma temperature and electron density were obtained by comparing experimental emission spectra with the spectral radiance computed for a non-uniform plasma in local thermal equilibrium.

Statistical charge distribution over dust particles in a non-Maxwellian Lorentzian plasma

On the basis of statistical mechanics and charging kinetics, the charge distribution over uniform size spherical dust particles in a non-Maxwellian Lorentzian plasma is investigated. Two specific situations, viz., (i) the plasma in thermal equilibrium and (ii) non-equilibrium state where the plasma is dark (no emission) or irradiated by laser light (including photoemission) are taken into account. The formulation includes the population balance equation for the charged particles along with number and energy balance of the complex plasma constituents. The departure of the results for the Lorentzian plasma, from that in case of Maxwellian plasma, is graphically illustrated and discussed; it is shown that the charge distribution tends to results corresponding to Maxwellian plasma for large spectral index. The charge distribution predicts the opposite charging of the dust particles in certain cases.

Quantitative analysis of amorphous indium zinc oxide thin films synthesized by Combinatorial Pulsed Laser Deposition

The use of amorphous and transparent oxides is a key for the development of new thin film transistors and displays. Recently, indium zinc oxide (IZO) was shown to exhibit high transparency in the visible range, low resistivity, and high mobility. Since the properties and the cost of these films depend on the In/(In + Zn) values, the measurement of this ratio is paramount for future developments and applications. We report on accurate analysis of the elemental composition of IZO thin films synthesized using a Combinatorial Pulsed Laser Deposition technique. The monitoring of the thin films elemental composition by Laser-Induced Breakdown Spectroscopy was chosen in view of further in situ and real-time technological developments and process control during IZO fabrication. Our analytical approach is based on plasma modeling, the recorded spectra being then compared to the spectral radiance computed for plasmas in local thermal equilibrium. The cation fractions measured were compared to values obtained by complementary measurements using energy dispersive X-ray spectroscopy and Rutherford backscattering spectrometry. Spectroscopic ellipsometry assisted the scientific discussion. A good agreement between methods was found, independently of the relative fraction of indium and zinc that varied from about 65 to 90 and 35 to 10 at%, respectively, and the measurement uncertainties associated to each analytical method.