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Electrical degradation and electric field distortion in polymers are inherently determined by their charge transfer and charge injection properties. In this contribution, we have proposed a first-principles-based multi-scale modeling approach for describing charge injection into dielectric polymers. First-principles calculations and molecular dynamics (MD) simulations are performed to determine the microscopic physical quantities that enter the non-empirical formula describing charge injection. It is shown that, among the several well-known charge injection models, the disorder-based injection model is relatively appropriate for modeling carrier injection from the electrode into dielectric polymers. From a theoretical point of view, the field emission (FE) and the thermal emission (TE) models are unsuitable for describing charge injection into dielectrics, and the agreement between experimental data and the injection current predicted by these models is most likely accidental. According to the disorder-based injection model, in line with the experimental findings, the simulated injection current increases rapidly at the field above $10^{{2}}$ kV/mm. The computational results indicate that the carriers would be injected from the amorphous region rather than from the crystalline region and that the impurity or interface states play a crucial role in charge injection. Novel non-empirical theoretical models taking into account these mid-gap states are required to describe the injection current into dielectric polymers.

Cu I (Cu neutrals) excitation temperature is usually measured by researchers while analyzing vacuum arcs (ignited by CuCr electrodes). Since ions may have information that neutrals do not have, measuring Cu II (Cu $^{+}$ ) might reveal some new features of the vacuum arc. In this article, Cu II excitation temperature is measured by observing seven Cu II lines. Measurement results show the existence or not of a Cr component in a vacuum arc can greatly change the 2-D distribution pattern of Cu II excitation temperature (researchers suggest no influence on Cu I); from a “flat” shape changes to a “columnar” or a “bowl” shape (related to gap length). However, the Cr ratio in CuCr electrodes does not cause a noticeable difference both in Cu II excitation temperature value and in 2-D distribution shape. In the case of CuCr electrodes, before the arc mode change to anode spot mode, a new phenomenon occurs under diffuse mode; as the arc current grows higher than a critical value under a certain length of the gap, the temperature starts to drop in the area near the anode surface, forming a temperature valley. This temperature valley can be interpreted as a local increase in Cu II density. The local ion eruption caused by the Cr component might be a trigger or a pre-process for arc mode changing to anode spot mode.

In the above article [1], (7) is incorrect because (7) is for the esu-cgs unit. The authors have solved the collisionalradiative model equations in the following excitation rate in the SI unit.

In recent years, excess electron transfer in organic liquids has attracted increasing interest owing to the emerging class of liquid organic semiconductors. In this study, to achieve a comprehensive understanding of electron conduction in liquids, we investigate hopping electron conduction in liquids from an atomistic viewpoint. High-pressure liquid benzene is chosen as a simple model system. Hopping electron mobility is computed using a combination of molecular dynamics simulations, quantum chemical calculations, and kinetic Monte Carlo methods. The computed electron mobility is in good agreement with the experimental values. Because the amplitude of the intermolecular vibration observed in liquids is larger compared to that in solids, the effect of dynamic disorder on electron mobility is investigated. The time scale of the change in electronic couplings due to the rotation of molecules is comparable to that of the electron residence time at each benzene molecule at the absence of change in the arrangement of a benzene dimer. Thus, the effect of dynamic disorder is evaluated by a Monte Carlo-based analysis. It is shown that the effect of dynamic disorder on electron mobility is small even though electronic couplings between molecules fluctuate by more than an order of magnitude.

AbstractThe electrical discharge gaps called S type horn are applied to the ground fault detection and protection in AC traction power supply system for high speed railway called Shinkansen. In this method, the earth resistance of the steel pipe pillar is an important factor for the ground fault protection by the electrical discharge. In this study, the analyses of the transient characteristics of grounding fault are carried out by using EMTP, and the ground resistance value required to trigger discharge at S type horn was calculated. Moreover, the protection effect of a discharge gap called GP the substation equipment that is a discharge gap which is inserted between rails and substation mesh is evaluated.

The erosion of the stress grading system of converter-fed rotating machines may occur by partial discharges and heat generation. There remain unclear issues in the formation of the potential and temperature distributions along the stress grading system of coils. In this paper, the potential distributions on the stress grading system of the model coil bar are measured under the application of 1 kHz square wave voltages of 10 kV in peak to peak value with/without 5 kV DC biased voltage. It turns out that DC bias voltage has little effect on potential distribution on a coil surface.

Helical deformations of a plasma column in a reversed field pinch experiment have been investigated using stereoscopic framing and/or streak photographs together with magnetic search-coils. A toroidal-mode number of 6 was found to be dominant in this experiment. This number agrees with the mode number predicted by a growth-rate calculation based on an ideal magnetohydrodynamic equation. It was observed that the plasma center moved around in a circular arc in the poloidal direction with a frequency of 100 kHz. Moreover, it could be seen that the displacement of the plasma center in the major radial direction traveled in a toroidal direction with a velocity of 0.9×104m/s.

An optical electric field sensor using a Pockels crystal which has the advantage of directly measuring the electric field in a space with limited disturbance of its distribution has been studied. We present an optical waveguide technique which has been developed to miniaturize the sensor. In a prototype sensor a light beam is propagated along a z-direction waveguide in a y-cut LiNbO3crystal. The width of the waveguide is 7 µ m and its length is 4.39 mm. The sensor is not based on an interferometer but on a single waveguide. The sensor has a simple and optimum configuration, and its output has good linearity to applied electric fields. Its frequency and temperature characteristics are presented. A new and smaller sensor with a waveguide 1 mm in length has been developed. It has almost the same configuration as the prototype sensor except for a smaller size. Results of measurement of ac and step electric fields using this sensor are presented.

This paper describes a new optical high voltage measurement technique to realize optical voltage transformers (optical VTs) through which high voltages up to 400 kV can be directly measured. A prototype of an optical VT using Pockels device in a multi-segmented arrangement is designed based on the numerical calculation of the electric field distribution. The response characteristics of the developed prototype are examined for ac, dc, and lightning impulse voltages, and these experimental results showed good agreement with theoretical estimations. An oscillatory component appearing on the output signal of the sensor for the impulse voltage application is successfully eliminated using a fast Fourier transform (FFT) digital filter. It is also found that the sensor can respond to fast transients with a rising time of 40 ns, which defines the frequency response bandwidth of the system from dc to several MHz.