非均匀介质球颗粒的等效介电常量

从求解拉普拉斯方程的边值问题出发,讨论了非均匀介质球颗粒的等效介电常量,给出了多种介质组成的多壳层介质球颗粒的等效介电常量的一般递推公式,推导了壳层的介电常量随半径连续变化的梯度介质球的等效介电常量的微分方程．并以壳层的介电常量为幂函数为例,得到了梯度壳层介质球的等效介电常量．     

Anisotropic dielectric constant of TTF-TCNQ observed by dielectric resonance

Independent measurements at low temperatures of the anisotropic dielectric constant (∈₁) of TTF-TCNQ are reported. The measurements utilize dielectric resonance techniques to determine ∈^B₁ and ∈^a₁ on the same crystal. The results confirm the unusually large value for ∈^b₁(4.2 K) > 10³ and the anisotropic behavior ∈^b₁(4.2 K) > 10² found earlier in cavity perturbation studies of TTF-TCNQ.     

不同电介质结构下介质阻挡放电特性研究

设计制作了单面有氧化铟锡(ITO)导电介质层的双玻璃介质层的介质阻挡放电装置,研究了其放电特性,并将其与双玻璃介质层和单玻璃介质层的介质阻挡放电进行了比较.从电荷输运的角度分析,上述三种装置分别实现了电荷的二维、零维和三维输运.采用两种不同的双玻璃介质层装置,获得了单个稳定的放电丝.与无ITO导电层的双玻璃结构得到的单个放电丝相比,单面有导电ITO介质的双玻璃结构中,单放电丝呈"T"字型,其光晕是前者光晕的2倍,其放电电流大于前者电流,其放电时间间隔长短交替现象更为明显,且存在强度大小交替的现象.分析表明,壁电荷输运及二次电子发射的不同导致了不同电介质结构放电特性的不同. 关键词： 介质阻挡放电 壁电荷 二次电子发射     

Temperature dependence of the dielectric constant of acrylic dielectric elastomer

The dielectric constant is an essential electrical parameter to the achievable voltage-induced deformation of the dielectric elastomer. This paper primarily focuses on the temperature dependence of the dielectric constant (within the range of 173 K to 373 K) for the most widely used acrylic dielectric elastomer (VHB 4910). First the dielectric constant was investigated experimentally with the broadband dielectric spectrometer (BDS). Results showed that the dielectric constant first increased with temperature up to a peak value and then dropped to a relative small value. Then by analyzing the fitted curves, the Cole–Cole dispersion equation was found better to characterize the rising process before the peak values than the Debye dispersion equation, while the decrease process afterward can be well described by the simple Debye model. Finally, a mathematical model of dielectric constant of VHB 4910 was obtained from the fitted results which can be used to further probe the electromechanical stability of the dielectric elastomers.     

Neutralization of charged dielectric materials using a dielectric barrier discharge

Safety and efficiency are two characteristics that must be satisfied by an electric charge neutralizer. The dielectric barrier discharge (DBD), which has the advantage of preventing arc transition, is an interesting tool to safely neutralize unwanted charge. This paper is aimed at studying the efficiency of neutralizing charged polyethylene (PE) granules by using a dielectric barrier discharge. During this study, several factors were considered such as the amplitude and the frequency of the AC voltage, the polarity and the charging mode of the samples, as well as the electrode configuration. Two DBD electrode configurations were considered: simple DBD and a DBD with installed metallic grid. The obtained results show that using the DBD can lead to excellent neutralization results when the grid is installed. With the appropriate voltage amplitude and frequency and with grid installed, the elimination of nearly 99% of the initial surface charges can be achieved. The metallic grid placed between the DBD electrode and the target enhances significantly the neutralization efficiency.     

The elastic dielectric

Macroscopic field equations, boundary conditions and equations of state are derived for the non-linear, macroscopic elastic and dielectric response of an insulator. A centrosymmetric polynomial representation of order four is introduced for the energy density; the equations of state for the electric field and stress tensor are then deduced as polynomials of degree three in the displacement gradients and electric displacement field. The results are applied to the special case of m3m material symmetry.

A finite, point-charge model of a centrosymmetric ionic crystal is introduced and used to determine 0°K microscopic expressions for the electric field and stress tensor equation of state coefficients introduced in the macroscopic analysis. The results are used to calculate the full set of second and third-order non-linear coefficients for NaI, based on a Born-Mayer potential and the 4·2°K elastic stiffness data of Claytor and Marshall.     

Thermal dielectric function

Thermal dielectric functions ε(k, ω) for homogeneous electron gas were determined and discussed. The ground state of the gas is described by the Fermi-Dirac momentum distribution. The low and high temperature limits of ε(k,ω) were related to the Lind-hard dielectric function and to ε(k,ω) derived for Boltzmann and for classical momentum distributions, respectively.     

Mechanistic model for the dielectric spectrum of a simple dielectric material

ABSTRACT

In this paper, we perform molecular dynamics simulations of a dielectric fluidic material composed of permanent molecular dipoles. The dielectric spectrum features two peaks at lower frequencies than the system phonon frequency. The primary peak is observed at all temperatures studied and shifts toward lower frequencies as the temperature decreases. During this shift, the secondary peak emerges with a higher peak frequency than the primary peak. The secondary peak amplitude increases as the temperature decreases. Both peaks are dependent on the wavevector; in the small wavevector regime, the primary peak is shifted to higher frequencies as the wavevector squared and the secondary peak amplitude increases as the wavevector increases, but shows no shift in frequency. From the polarisation balance equation, we propose a model for the dielectric spectrum. This captures the spectrum features, and we conjecture that the primary peak is due to dipole moment correlations (Debye-type) and the secondary peak is due to the correlation between the dipole moment and a microscopic local field.     

On the dispersion of the dielectric constant of an inhomogeneous dielectric

The influence of an inhomogeneity, smoothly distributed through the thickness of a sample, on the dielectric properties of the sample is discussed. An estimate is made of the degree of inhomogeneity in a dielectric film on a base of manganese oxide.In conclusion I wish to thank I. A. Karpovich for his interest in this work.     

介质阻挡放电中电介质参量对放电时间特性的影响

采用介质参量不对称的装置,在大气压氩气介质阻挡放电中,研究了不同电介质温度及不同电介质材料对放电时间特性的影响.实验发现,外加电压较低时,正负半周的放电时间波形没有明显的差别;外加电压较高时,正负半周的放电脉冲个数不同.分析表明,电介质温度以及材料均影响壁电荷的积累,进而使放电特性发生改变. 关键词： 介质阻挡放电 时间特性 壁电荷 介电常数     

Shielded suspended dielectric guide

The dispersion characteristics of a shielded suspended dielectric are computed using mode matching technique. From the dispersion characteristics the dielectric and conductor loss, quality factor and wave impedances are derived. The dimensions of shielded suspended dielectric are same as that of a rectangular metallic wave guide at K_a band.     

Simulating nanoscale dielectric response

We introduce a constrained energy functional to describe dielectric response. We demonstrate that the local functional is a generalization of the long-ranged Marcus energy. Our reformulation is used to implement a cluster Monte Carlo algorithm for the simulation of dielectric media. The algorithm avoids solving the Poisson equation and remains efficient in the presence of spatial heterogeneity, nonlinearity, and scale dependent dielectric properties.     

测量电介质的电容率

简述了应用计算机技术改进测量电介质电容率的一种方法。