Conformal symmetry of classical electromagnetic zero-point radiation

The two-point correlation functions of classical electromagnetic zero-point radiation fields are evaluated in four-vector notation. The manifestly Lorentz-covariant expressions are then shown to be invariant under scale transformations and under the conformal transformations of Bateman and Cunningham. As a preliminary to the electromagnetic work, analogous results are obtained for a scalar Gaussian random classical field with a Lorentz-invariant spectrum.     

Acceleration and classical electromagnetic radiation

Classical radiation from an accelerated charge is reviewed along with the reciprocal topic of accelerated observers detecting radiation from a static charge. This review commemerates Bahram Mashhoon’s 60th birthday.     

Classical electrodynamic systems interacting with classical electromagnetic random radiation

In the past, a few researchers have presented arguments indicating that a statistical equilibrium state of classical charged particles necessarily demands the existence of a temperature-independent, incident classical electromagnetic random radiation. Indeed, when classical electromagnetic zero-point radiation is included in the analysis of problems with macroscopic boundaries, or in the analysis of charged particles in linear force fields, then good agreement with nature is obtained. In general, however, this agreement has not been found to hold for charged particles bound in nonlinear force fields. The point is raised here that this disagreement arising for nonlinear force fields may be a premature conclusion on this classical theory for describing atomic systems, because past calculations have not directed strict attention to electromagnetic interactions between charges. This point is illustrated here by examining the classical hydrogen atom and showing that this problem has still not been adequately solved.     

Validity conditions for local thermodynamic equilibrium

Validity criteria for partial and complete local thermodynamic equilibrium (L.T.E.) are re-examinated on the basis of generalized cross section formulas which are in agreement with experiments and with quantum mechanical results. The validity conditions for L.T.E. obtained deviate both in the absolute values and in the temperature dependence from those given by other authors. The influence of resonance absorption on the establishment of L.T.E. is considered and quantitatively taken into account. The influence of atom-atom collisions on the population densities of highly excited levels is also discussed. A general formula is derived permitting an estimate wether the excited levels are populated due to electronic or due to atomic collisions. The condition obtained is quite severe for plasmas in which the electron temperature is different from the gas temperature. For example: In a helium non-L.T.E. plasma of 1% ionization degree (forT _e=2×10⁴ °K) all levels of principal quantum numbersn>12 will essentially be populated due to atomic collisions at a gas temperature ofT _a=1.6×10⁴ °K. The influence of diffusion on the L.T.E. conditions is discussed for the various kinds of particle interactions. It is found that deviations from L.T.E. due to particle diffusion may be more severe than is generally assumed.     

Zero energy and thermodynamic equilibrium

Using path integral techniques, it is shown that the real time formalism for finite temperature field theory requires an extra Feynman rule for Feynman diagrams carrying zero-external energies. This is related to a general principle governing the use of equilibrium finite temperature field theory. It is shown that only with this extra Feynman rule does the real time formalism become consistent for zero energy calculations. It is also used to understand the problem of the lack of analyticity at zero external four-momenta encountered in finite temperature field theory diagrams.     

Influence of radiation resorption on criteria of the existence of local thermodynamic equilibrium

The emission of radiation from a plasma volume upsets the Boltzmann equilibrium. A number of authors have proposed criteria for approximate testing of the existence of local thermodynamic equilibrium on the basis of collision and radiation processes. However, those criteria give excessive values, because they do not take into account radiation resorption, which can moderate the test conditions. The present article is concerned with the influence of radiation resorption on the criterion of the existence of local thermodynamic equilibrium in a low-temperature plasma. The domain of existence of local thermodynamic equilibrium (in the sense of Saha-Boltzmann equilibrium) is calculated for electric arcs.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 20–24, June 1986.     

电磁轨道发射器的模型化研究方法

为了更高效地对电磁轨道发射进行大量的实验研究,分析改进了使用中小口径发射器作为研究对象的模型化研究方法。考虑到材料属性等实验条件的可行性,对电磁轨道发射器进行模型化,分析其电磁场、温度场等物理场以及速度、带载能力等性能指标,提出较为可行的模型化研究方案,并利用Ansoft Maxwell等软件对瞬态情况下的发射器三维模型进行仿真验证。理论推导和仿真结果表明：电磁轨道发射器的模型化研究方法有很多种,在大口径原型发射器中采用电导率相对较低的材料,即可实现与现有的、采用电导率较高材料的中小口径发射器的物理场匹配,且保证速度和单位体积带载能力相同。     

A complementary thermodynamic limit for classical Coulomb matter

The canonical equilibrium measure of classical two-component Coulomb matter with regularized interactions is analyzed in a finite volume. It is shown that, in the mean-field regime, the one-particle density is inhomogeneous on a new characteristic length scale _inh. For a system ofN positive andN negative particles, _inh and the characteristic length scale of correlations _corr (=Debye screening length) are related via _inh=(2N)^1/2 _corr. The major conceptual conclusion that is drawn from this is that one needs two nontrivial complementary thermodynamic limits to define the equilibrium thermodynamics of two-component Coulomb systems. One of them is the standard thermodynamic limit (infinite volume), where one takesN, _corr fixed. Its complementary limit is characterized byN, _inh fixed, and is a finite-volume inhomogeneous mean-field limit. The most prominent new feature in the mean-field thermodynamic limit, which is absent in the standard thermodynamic limit, is an anomalous first-order phase transition where the Coulomb system explodes or implodes, respectively. The phase transition is connected with the existence of a metastable plasma phase far below the ionization temperature.     

电磁轨道发射器的模型化研究方法北大核心CSCD

为了更高效地对电磁轨道发射进行大量的实验研究,分析改进了使用中小口径发射器作为研究对象的模型化研究方法。考虑到材料属性等实验条件的可行性,对电磁轨道发射器进行模型化,分析其电磁场、温度场等物理场以及速度、带载能力等性能指标,提出较为可行的模型化研究方案,并利用Ansoft Maxwell等软件对瞬态情况下的发射器三维模型进行仿真验证。理论推导和仿真结果表明:电磁轨道发射器的模型化研究方法有很多种,在大口径原型发射器中采用电导率相对较低的材料,即可实现与现有的、采用电导率较高材料的中小口径发射器的物理场匹配,且保证速度和单位体积带载能力相同。     

Scaling of electromagnetic transducers for shunt damping and energy harvesting

In order for an electromagnetic transducer to operate well as either a mechanical shunt damper or as a vibration energy harvester, it must have good electromechanical coupling. A simple two-port analysis is used to derive a non-dimensional measure of electromechanical coupling, which must be large compared with unity for efficient operation in both of these applications. The two-port parameters for an inertial electromagnetic transducer are derived, from which this non-dimensional coupling parameter can be evaluated. The largest value that this parameter takes is approximately equal to the square of the magnetic flux density times the length of wire in the field, divided by the mechanical damping times the electrical resistance. This parameter is found to be only of the order of one for voice coil devices that weigh approximately 1 kg, and so such devices are generally not efficient, within the definition used here, in either of these applications. The non-dimensional coupling parameter is found to scale in approximate proportion to the device's characteristic length, however, and so although miniaturised devices are less efficient, greater efficiency can be obtained with large devices, such as those used to control civil engineering structures.     

Nanocomposites for electromagnetic radiation protection

Specific features that characterize nanoparticles and which are due to their small size and allow one to enhance the interaction between the electromagnetic radiation and nanostructured materials and to develop the effective protection of man and equipment against harmful uncontrolled radiation are reported. Examples of the development of nanocomposite radar absorbing materials that can be used for protection of man and equipment are presented.     

A Hilbert space for the classical electromagnetic field

The synthetic Maxwell equation, uniting all Maxwell equations within the framework of a Clifford algebra, can be treated as a first-order wave equation. A Hilbert space of its solutions describing classical free electromagnetic fields is introduced. This Hilbert space can be called classical, which means that the Planck constant is absent. The scalar square of an element of this space is the total energy of the field. The time independence of the scalar product is demonstrated. The time and space translation generators are found; they are shown to not coincide with the energy and momentum operators.     

Homogeneous perturbed classical states and equilibrium conditions

For infinite classical systems a class of spatially homogeneous perturbed states is defined, and used to give a direct proof of the fact that global thermodynamical stability implies the (classical) KMS-condition.The author thank Professor H. Araki for numerous suggestions to improve the paper.     

On thermodynamic equilibrium of nonextensive systems

The law of energy composition is defined, and the thermodynamic equilibrium condition of nonextensive systems described by the Havrda-Charvat-Daroczy entropy is considered. A statistic criterion for equilibrium stability is formulated. Equations for the equilibrium distribution and density operator are presented.     

Fluctuations in thermodynamic non equilibrium states

In a statistical theory an expression is derived for the probability of fluctuations in a thermodynamic non equilibrium state. It is a generalization of the Einstein formula, respectively the formula of Greene and Callen for fluctuations in a thermal equilibrium. The application to steady transport processes is discussed in connection with stability conditions.     

Dual symmetry in classical and quantum spin theory

Apropos the continuing discussion of the observability of the magnetic charge (the Dirac monopole [1]), there is interest in investigating the dual symmetry of the spin equations of motion in classical and quantum theory. It is known that in dual symmetry theory the presence of a magnetic charge is a simple consequence of the dual invariance of the equations of electrodynamics [2], The matter of the observability of a magnetic charge is not tackled there, and becomes only experimentally verifiable [2, p. 64].Translated from Izvestiya Vysshikh Uchebnkh, Zavedenii, Fizika, No. 7, pp. 56–59, July, 1932.     

Opacity calculations for high-Z plasma in non-local thermodynamic equilibrium

Opacity of high-Z element plasma in non-local thermodynamic equilibrium (NLTE) is calculated. In the calculation, a collisional radiative model in detailed-configuration-accounting (DCA) is applied to population calculations for NLTE plasmas. Configuration-averaged rate coefficients that needed in the rate equations are obtained based on the first order perturbation theory. The Hatree-Fock-Slater self-consistent-field method is used to calculate the electron wave functions. The spin-orbit splitting is included in the spectrum calculations. The unresolved transition array method is used in the opacity calculations. The calculated frequency-dependent opacity of high-Z plasma Lu is presented. The comparison shows that the present spectrum agrees with another theoretical result well except that the present one shifts a little to the lower energy due to its lower mean ionization stage. The effects of highly doubly excited states on ionization balance and on the opacity are investigated. The mean ionization stage increases more than three stages when doubly excited states 5l6l′ and 5l5l′ are not included in the population calculations and the absorption spectrum also shifts to the higher energy.