Effective Dielectric Response of Composites with Graded Material

The effective dielectric response of linear composites containing graded material is investigated under an applied electric field E₀. For the cylindrical inclusion with gradient dielectric function, ε_i(r)=b+cr, randomly embedded in a host with dielectric constant ε_m, we have obtained the exact solution of local electric potential of the composite media regions, which obeys a linear constitutive relation D=εE, using hypergeometric function. In dilute limit, we have derived the effective dielectric response of the linear composite media. Furthermore, for larger volume fraction, the formulas of effective dielectric response of the graded composite media are given.     

Complex Response Function of Whispering Gallery Dielectric Resonators

A whispering gallery resonator coupled to a dielectric waveguide is experimentally investigated around 86 GHz using a vectorial network analyzer. The resulting complex response function is compared with a theoretical model, simplified assuming negligible stationary waves; indeed their presence can be effectively compensated by a proper normalization procedure, made possible by a suitable analysis in the complex field. It is demonstrated that the proposed approach well reproduce the experimental results in a wide range of coupling conditions. Moreover, some outcomes of the model concerning the power flowing into the resonator are briefly discussed.     

Renormalization of the Quantum Theory of the Solid State

The perturbative structure of a quantum field theory of the solid state, including allradiative corrections, is applied for the calculation of renormaiization factors and counterterms. After a general outline, approximation schemes for the explicit evaluation of renormalization parameters are developed.     

Local Field Corrections Effect on Equation of State in Dense Hydrogen Plasma: Plasma Phase Transition

We present calculations of Hydrogen plasma pressure including local field correction (LFC) effects modelled in the Singwi Tosi Land and Sjölander model extended to arbitrary temperature (ATSTLS), neutrals contributions are not included. We show that LFC induces thermodynamic instabilities (phase transition) in the vicinity of the maximum electron coupling parameter which corresponds to maximum departure of the ATSTLS electron polarizability from the Random Phase Approximation one. Comparison of our results to Monte‐Carlo calculations induced us to think that free electron coupling plays a dominant role in plasma phase transition. Critical temperature is estimated and compared to existing values (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Looking for an Optimal Ground State Within Quasiparticle Random Phase Approximation

A new ansatz for the correlated ground state of the many-nucleon system is proposed which results in obtaining a modified Quasiparticle Random Phase Approximation (QRPA). An additional degree of freedom is introduced which allows to determine variationally the ground state simultaneously with solving the QRPA equations. This new approach, QRPA with an optimal ground state, is studied within the proton-neutron Lipkin model. New solutions have been found, in the range of the interaction strength where the standard QRPA formalism does not work. A relation between one of them and the solution obtained within a semi-classical approach is established. A detailed study of the expectation value of the quasiparticle number operator in the ground state and the transition amplitude for the two-neutrino double beta Fermi decay, is also presented.     

圆柱形介质阻挡放电等离子体光谱诊断

在350~1150 nm范围内对开放空间Ar气介质阻挡放电等离子体的发射光谱进行测量,表明Ar发射谱线主要集中在680 nm~950 nm,且都为Ar原子谱线。采用发射光谱相对强度对比法,选取相距较近且有相同下能级的727.29 nm(2P2-1S4),738.40 nm(2P3-1S4)和751.47 nm(2P5-1S4)三条光谱测量电子温度。通过对在Ar气和空气中放电谱线的对比和分析,得出发射光谱相对强度与电源功率的关系。最终得出若要便于工业应用和光谱测量,需要选择特定的气体流量和电源功率。     

Calculation of Dielectric Function of a Quark-Gluon Plasma

With the hard thermal loop （HTL） resummation technique, we calculate the dielectric function excited by hard gluon in quark-gluon plasma （QCP）. We find that in a section of the space-like region po/p ∈ [0.78, 0.95], there are two extremum structures on the dielectric function curve, while the dielectric function in the HTL approximation decreases monotonously without these properties. Through the analyses of the imaginary part of the dielectric function, we conclude that the character of the dielectric function in this region reflects effects of the Landau damping.     

Quantum Discord of Non-X State

The level surfaces of quantum discord for a class of two-qubit states are investigated when the Bloch vectors and are perpendicularly oriented. The geometric objects of tetrahedron T and octahedron O are deformed. The level surfaces of constant discord are formed by three interaction "tubes" along three orthogonal directions. They shrink to the center when the Bloch vectors are increased and are expanded and cut off by the state tetrahedron T when the quantum discord is increased. In the phase damping channel, the quantum discord keeps approximately a constant when the time increases.     

Effective Anisotropic Dielectric Properties of Crystal Composites

Transformation fieM method （TFM） is developed to estimate the anisotropic dielectric properties of crystal composites having arbitrary shapes and dielectric properties of crystal inclusions, whose principal dielectric axis are different from those of anisotropic crystal matrix. The complicated boundary-value problem caused by inclusion shapes is circumvented by introducing a transformation electric field into the crystal composites regions, and the effective anisotropic dielectric responses are formulated in terms of the transformation field. Furthermore, the numerical results show that the effective anisotropie dielectric responses of crystal composites periodically vary as a function of the rotating angle between the principal dielectric axes of inclusion and matrix crystal materials. It is found that at larger inclusion volume fraction the inclusion shapes induce profound effect on the effective anisotropic dielectric responses.     

On the Nonlinear Theory of Surface Wave Excitation in a Collisional Solid State Plasma

The nonlinear equations governing relativistic electron beam-surface wave dynamics in dissipative P-S-plasma are derived. The influence of P-plasma on time saturation, amplitude of the wave at saturation and damping factor is analyzed. The obtained results are discussed from the physical point of view.     

The Nonlinear Optical Response of Hashin-Shtrikman Geometric Composite Materials

The nonlinear optical response of composite materials consisting of metal grains with insulator shells at finite frequency is investigated. It is found that the surface plasmon peak is stronger and the position of surface plasmon peak is "red-shifted" with the shell being thinner. We also found that the nonlinear optical response is related to the shape of the particles and the dielectric property of the shells.     

Dielectric properties of ferroelectric diisopropylammonium iodide

Temperature dependences of dielectric constant, amplitude of the third harmonic and heat capacity for the organic ferroelectric of diisopropylammonium iodide (C₆H₁₆NI) have been investigated. The measurements were carried out through heating and cooling cycles in the range of 300–400?K. It was found that upon the first heating, only one phase transition occurred without the presence of the ferroelectric phase. For samples preheated over 420?K, two phase transitions at 363 and 378?K appeared in the heating process, and the ferroelectric state was also observed between them. Upon cooling, the ferroelectric phase was detected in the range of lower 361?K and persisted up to room temperature.     

Dielectric characteristics of La-modified PbTiO3 nanoceramics

The nanoceramics of lanthanum (La³⁺)-modified lead titanate (PbTiO₃) with a general formula Pb_1?yLa_yTi_(1?y/4)O₃ (y = 0.00, 0.06, 0.08, 0.10, 0.12 Lead Lanthanum Titanate (PLT)) were synthesized by a mechanothermal method. Thermal analysis of the PLT samples exhibits their nature of the reaction and thermal stability. The incorporation of La at the Pb site of lead titanate (PT) not only changes the ratios of its unit cell parameters but also reduces the grain and particle size to nanoscale. The dielectric constant of PLT is dependent on La concentration. The La concentration-dependent phase transition temperature of PbTiO₃ is one of the main characteristics of the material.     

Ab Initio Simulation of Complex Dielectric Function for Dense Aluminum Plasma

We present calculations of frequency‐dependent complex dielectric function of dense aluminum plasma by quantum molecular dynamics method for temperatures up to 20 kK. Analysis shows that the dependencies for real and imaginary parts can be interpolated by the Drude formula with two effective parameters: the mean charge of ions and the effective frequency of collisions. The rise of these parameters with temperature deviates from simple theoretical predictions (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dielectric properties of LC mixture with induced antiferroelectric phase

Mixture of two liquid crystalline components exhibits the antiferroelectric phase in a broad temperature range at room temperatures, though the two components separately do not show an antiferroelectric phase in a temperature range applied. The dielectric spectroscopy technique combined with measurements of the selective light reflection was used for identification and characterization of the phases and subphases existing in the mixture. In the SmC*_A phase, the low frequency mode characteristic of antiferroelectric phase has been detected. In the broad temperature range between SmC*_A and SmA* phases, no relaxation mode has been detected. The soft mode registered near the phase transition to SmA* phase follows the Curie-Weiss law.     

固氖高压物态方程的量子理论计算

 运用Hartree-Fock计算方法和原子团簇理论,研究了高压下面心立方晶体氖中的二体相互作用、三体相互作用对中心原子势能及冷能的贡献。结合零点振动能,计算得到了固氖在4~208 GPa压强范围内的等温物态方程。结果表明,在较高压强区域内,等温压缩线与高压实验数据符合得非常好;在压强超过100 GPa的区域内,计算得到的等温压缩线较目前已有的理论研究结果系统地改善并提高了3%~5%,精确地解释了固氖的高压实验数据。     

Spectral Representation Theory for Dielectric Behavior of Nonspherical Cell Suspensions

Recent experiments revealed that the dielectric dispersion spectrum of fission yeast cells in a suspension was mainly composed of two sub-dispersions. The low-frequency sub-dispersion depended on the cell length, while the high-frequency one was independent of it. The cell shape effect was simulated by an ellipsoidal cell model but the comparison between theory and experiment was far from being satisfactory. Prompted by the discrepancy, we proposed the use of spectral representation to analyze more realistic cell models. We adopted a shell-spheroidal model to analyze the effects of the cell membrane. It is found that the dielectric property of the cell membrane has only a minor effect on the dispersion magnitude ratio and the characteristic frequency ratio. We further included the effect of rotation of dipole induced by an external electric field, and solved the dipole-rotation spheroidal model in the spectral representation.Good agreement between theory and experiment has been obtained.     

沿面型介质阻挡放电喷枪的发光特性及气体温度研究

利用氩气作为工作气体,采用正弦电压驱动沿面型等离子体喷枪,在大气压空气环境中产生了均匀的等离子体羽。电学和光学测量结果表明,等离子体羽放电只存在于外加峰值电压的正半周期,并且正半周期的放电脉冲个数随气体流量的增加而增加。通过对正半周期不同位置的发光脉冲信号进行比较,发现等离子体羽均按子弹形式传播,其中每一个发光脉冲均对应一次等离子体子弹传播过程。通过对比放电电流和等离子体羽的发光信号,发现等离子体羽的发光脉冲滞后于放电电流脉冲,且该延迟时间基本服从正态分布。该延迟时间随着外加电压峰值及气体流量的增大而减小。利用光纤测温仪测量了等离子体羽的气体温度,发现气体温度随外加峰值电压的增大而升高,随工作气体流量的增大而降低。通过分析放电过程,对上述现象进行了定性解释。     

Quantum Theory of Surface Polaritons in Semi-Infinite Dielectric Systems

The interaction system of a semi-infinite diatomic dielectric and the electromagnetic field propagating parallelly to the surface is studied. The long-wave optical phonon modes of the semi-infinite dielectric are calculated including the electronic polarizability by a quantum-mechanical theory. Retardation effects are neglected. A quantum field theory method of surface polaritons is developed to calculate the operator describing the interaction between a photon and the phonon polarization fields of the semi-infinite crystal, with explicit inclusion of surface effects. The dispersion relations of the surface phonon-polaritons are derived and discussed. The results are in good agreement with those obtained by the conventional, macroscopic dielectric theory of surface polaritons and experimental ATR (attenuated total reflection) spectra. The dispersion cuwes of polariton leaking modes caused by the interaction between bulk TO mode with surface effect and photons are presented in a graphical form. The k_||-dependence of the electric field strength in each polariton branch is calculated and presented also in a graphical form. We also research the spatial dependence of the field strength in each polariton branch. It is found that these properties are influenced and modulated by the surface phonons because of the interaction between photons and the surface phonon modes of the semi-infinite dielectric system. Hence the divergent nature (diffraction effect) of light propagating along the fib& and waveguides is restrained. We present a method how to use the boundary conditions in the quantum theory, which will be discussed in detail.     

Structure factor of liquid metals in one-component plasma system

We present the analytical expression to determine the static structure factorS(q) of liquid alkali metals based on the semi-analytic theory of Baus and Hansen. The calculations were motivated to point out the anomalies exhibited by one-component plasma system (ocp) in describing the structure factor. The numerical example of Na illustrates our results.ocp structure factor is also compared with those obtained by the hard sphere system.