Kiyomitsu Arii

Electrooptic Measurement of Three-Dimensional Nonuniform Electric Field Mapping in Nitrobenzene

An electrooptic method is useful for measuring electric fields without disturbing them. Our investigations have been concerned with measurements of electric field distribution. Three-dimensional nonuniform electric field distributions were measured in nitrobenzene using the Kerr electrooptic measurement. The field distributions to be measured were produced in a sphere-to-sphere electrode system. The optical system consisted of a He–Ne laser, a polarizer, a quarter-wave plate, an experimental cell, an analyzer, and a photodetector. When a negative high voltage pulse was applied to the electrode system, the light intensity transmitted to the analyzer was measured using the photodetector. Intensity measurements were carried out at many points from θ= 0 to π around the electrode system. From the data obtained, the electric field distribution, i.e., the strength and direction of each electric field vector in the measured plane, was reconstructed using a computed tomography (CT) technique. The measured distributions were compared with the theoretical ones calculated using an analytical method.

Fractal Structure of Electrochemically Polymerized Polypyrrole and Growth Process as Function of Monomer Concentration, Electrolyte Concentration and Applied Voltage

By the electrochemical method in the needle-circle electrode configuration, polypyrrole has been found to grow with two kinds of growth patterns; three-dimensional and two-dimensional growth patterns depending on the polymerization conditions such as condition of electrolyte and monomer and applied voltage. The conditions of pattern formation are found to be classified into three regions, 3-D growth, 2-D growth and 3-D+2-D growth regions. Three-dimensional growth model has been proposed from the growth condition. Influence of protuberance at the surface on the growth pattern by the electrochemical polymerization has been taken into consideration for the understanding of the patterns. The pattern of 3-D growth has been found to be fractal in the small scale region using the density correlation function.

Current Injection and Light Emission in Liquid Argon and Xenon in a Divergent Electric Field

Unipolar injection currents originating from a point electrode immersed in LAr or LXe have been observed as functions of voltage and polarity. The dependence was found to be governed by space charge limitation. Ion mobilities were deduced from the analysis of the positive injection currents. Time resolved measurements of the light emission demonstrated that the negative injection current consisted of pulses, similar to Trichel pulses in air corona. Positive currents produced continuous light emission. The results are discussed on the assumption that a gaseous discharge is formed around the point electrode.

Measurement of Nonsymmetrical Electric Field Vector Distribution in Nitrobenzene Using Electrooptic Method

The three-dimensional nonuniform electric field vector distribution was measured in a nonsymmetrical electrode system using the Kerr electrooptic effect with the reconstruction technique modified by computed tomography (CT). The intensity of the light transmitted through a dielectric liquid in nonuniform field was detected at many points on one plane. It was found that the nonuniform electric field in the liquid can be measured three-dimensionally and visualized.

Analysis of Anomalous Discharge Current in Low-Density Polyethylene

An anomalous discharge current flowing in the same direction as the charging current was observed in a low-density polyethylene film with evaporated silver electrodes at room temperature (25°C) after the application of a very high field above 2×108 V/m. The discharge transient current was computer-analyzed numerically by an explicit difference method. The anomalous current was attributed to the large amount of two types of injected space charge (electrons and holes) with ohmic electrodes, and not to one type of injected space charge (electrons or holes) with blocking electrodes.

Very Faint Light Emission in Low-Density Polyethylene Films under dc Field

Faint light emission in low-density polyethylene films was detected by using a photon-counting system. The photoncount response rose to a maximum value at a time greater than 1 minute after a step voltage was applied. The emission spectra ranged between 300 and 540 nm. The light-emission process was attributed to a recombination between trapped electrons and trapped holes.

Three-Dimensional Electric Field Vector Measurements in Nitrobenzene Using Kerr Effect

We have been investigating a nonuniform electric field measurement method in dielectric liquids using the Kerr electrooptic effect. Three-dimensional electric field vectors were measured as the first step in determining the three-dimensional nonuniform electric field distributions. The electric field vector to be measured was produced in a pair of inclined parallel-plane electrodes. Negative high-voltage pulses were applied to the electrode system. Nitrobenzene with large Kerr constant was used in the experiments. A He-Ne laser beam passed through nitrobenzene between the electrodes along two different orthogonal directions. The magnitude and the direction of the electric field vector were calculated from the light intensity measured by a photodiode. Maximum errors of measured electric field strength and direction were 9.3% and 4.3°, respectively.

Effect of Prestressing on the ns Range Electrical Breakdown in Polymeric Insulating Films

The electrical impulse breakdown of prestressed polymer films was investigated in the ns range. The effect of prestressing on the breakdown was observed in polyethylene terephthalate (PET) and polycarbonate (PC), but not in polystyrene (PS) or polypropylene (PP). The amount of space charge estimated from the transient currents was large enough to induce electric field distortion in the bulk for all specimens. The effect in PET and PC is attributed to field distortion due to space charge accumulation near the electrodes, which can be estimated as electrons at the cathode and holes at the anode. The reason why the effect was not observed in PP and PS can be explained as the result of their own high breakdown strength in strong non-uniform fields.

Neuron-type polypyrrole device prepared by electrochemical polymerization method and its properties

Abstract Conducting polymer, polypyrrole, with a neuron-like pattern has been prepared electrochemically using a needle-to-circle electrode on a glass substrate or a PET film. Two neuron-type conducting polymer has been connected and thus a neural network-type conducting polymer has been made. This neuron-type device has a characteristic of learning or memory effect.

Kerr Effect for Three-Dimensional Electric Fields

An optical method using the Kerr effect is useful to measure electric fields in dielectric liquids without disturbing the field. A conventional relation of the Kerr effect cannot be applied to the measurement of a three-dimensional field, the direction of which is not always perpendicular to an incident light. We have derived the relation of the Kerr effect which can be applied to three-dimensional measurement and confirmed it experimentally.