This report deals with the space charge behavior in polyethylene under high DC fields. Direct observation of time-dependent space charge profiles in 3mm thick XLPE (cross-linked polyethylene) cable insulation under high electric fields was done using the pulse-electroacoustic method. An intermittent generation of packet shaped space charges and their propagation through the insulation were observed when the average DC field was as high as 1MV/cm. This phenomenon was reproduced in sheet specimens with XLPE and with LDPE (low-density polyethylene). It was indicated that the packet charge is easy to appear when the acetophenone was diffused into the LDPE specimen, however, too uniform distribution of acetophenone prevents the packet charge generation. It was suggested from several expremental results that the local ionization in the insulation brings the packet charge generation. A numerical simulation was carried out based on the above conception to reproduce the phenomenon.

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Electrical breakdown of a polymer film generates the pressure wave, which is considered to include information about the breakdown initiation point. In this paper, we measured the breakdown pressure wave and the space charge distribution up to electrical breakdown field by using pulse electro-acoustic method in a 30μm thick polypropylene film. We discussed electrical breakdown phenomena based on the breakdown pressure wave and the dependence of space charge distribution on applied field and temperature. At room temperature, the observed breakdown pressure wave shapes were pulse-like and the width depended on the polarity of applied field. The positive space charge accumulation was observed near the cathode as a hereto space charge near the electrical breakdown field. At 60°C, the width of breakdown pressure wave showed no dependence of applied field polarity and the positive space charge accumulation was observed inside the film near the electrical breakdown field. These experimental results suggested the electrical breakdown phenomena were affected by the hetero space charge accumulation and the initiation point of electrical breakdown was correspond to the position of hetero space charge accumulation in 30μm thick polypropylene film.

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It seems that there is a confusion of the critical exponent of conductivity of composites which is caused by the way of determining the percolation threshold. In this paper, the percolation behavior, the critical exponent of conductivity and the electrical conduction mechanism of carbon black-polyethylene composites are discussed based on studying the whole change of resistivity and dielectric constant for carbon loading. There are two transitions of resistivity for carbon loading. Below the first transition, resistivity shows an ohmic behavior and the value of it is almost the same as that of polyethylene. Between the first and second transitions, the change in resistivity is very sharp, leading to a large critical exponent of conductivity, and a non-ohmic electric field dependence of current has been observed. This electric field dependence has been discussed with a tunneling conduction. Beyond the second transition, the electric field dependence of current shows an ohmic behavior and a gentle change in resistivity has been observed for carbon loading. The critical exponent of conductivity estimated by using the second transition is satisfied with the universal law of conductivity. Dielectric constant has been observed beyond the first transition and diverges around the second transition. It is concluded that the percolation threshold should be the second transition of resistivity for the carbon black-resin composites.

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In this paper, low density polyethylene (LDPE) and high density polyethylene (HDPE) were used as samples. The forming process of spherulites was continuously observed at slow-cooling rate by means of polarized light microscope with a cooling and heating cell. Morphology parameters (crystallinity and crystallite thickness) were investigated by using infrared (IR) spectrophotometer and X-ray diffractorneter. When crystallinity increases, the reason why tree initiation voltage increases, the influence of crystallinity and crystallite thickness on tree shape, and the effect of different crystallite thickness of spherulite on space charge storage were studied and discussed.

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In this paper, discharge characteristics in a simulated treeing channel have been clarified and relationship between an electric breakdown and a superstructure of PP films in a composite insulation simulated treeing channel model have been clarified on the basis of this characteristics. The following are these results.
1. The discharge voltages in a simulated treeing channel increase with channel lengths and decrease with specimen temperatures. Moreover these are higher than one in tungsten-plate electrode system.
2. In the case of a simulated treeing channel on the boundary between spherulites, the electric breakdown occurs in only boundary under DC and impulse applied voltage. In this case, properties of the electric breakdown are good according with the discharge characteristics in a simulated treeing channel.
3. In the case of a simulated treeing channel on a spherulite, the electric breakdown occurs in only spherulite under impulse applied voltage. However, for smaller specimen temperatures than 60°C under DC applied voltage, the degeneration area extend to the boundary is recognized, and the electric breakdown occurs in the boundary. For larger than 60°C, many small electric breakdown points and a bigger Point were recognized in the spherulite. In the case, electric breakdown voltage are higher than one given by case of a treeing channel on the boundary under various channel lengths and specimen temperatures.

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Barium titanate (BaTiO₃) thin films have been prepared in situ on Al/SiO₂/Si(100) substrate by backside deposition of intense, pulsed, ion-beam evaporation technique using 1.3MeV, 50ns, 25J/cm² ion beam. Very smooth surface of the films was obtained, where no droplets appear, The deposition rate was approximately 50nm/shot, which is-10% of the conventional frontside deposition. The films were perovskite polycrystals. The maximum roughness of the surface decreases from 60 to 35nm with increasing substrate temperature from 25 to 350°C, respectively The capacitance of the thin film (at 1kHz) increases from 3 to 10nF/mm² with increasing substrate temperature from 25 to 250°C, respectively.

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Thin films of ZnO doped with Al₂O₃, Ga₂O₃, In₂O₃, SnO₂, ITO, Ag₂O and CuO have been deposited on glass substrates by a pulsed laser deposition technique using an ArF laser (λ=193nm). The lowest resistivity was obtained for films deposited from the target with 2wt% Al₂O₃ (AZO(2wt%)); the resistivity of 1.43×10^-4Ω•cm was obtained at a substrate temperature of 300°C. On the other hand, there were minute irregularities on the surfaces of ZnO films doped with 4-7wt% Ga₂O₃ (GZO(4-7wt%)). Therefore, to obtain ZnO films with low resistivity and surface flatness, the laminated films were fabricated from the split target consisting of AZO (2wt%)and GZO (4-7wt%), It was found that (1) the lowest resistivity of 1.82×10-4Ω•cm and the lowest sheet resistance of 4Ω/sq were obtained for the 400nm thick film with four layers, (2) optical transmittance above 90% was obtained in the visible region of the spectrum and (3) there were minute irregularities (average roughness 0.56nm) on the surface of the films.

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Prebreakdown light emission, current and streamer in straight-chain saturated hydrocarbon liquids, n-pentane, nhexane, n-heptane, n-octane, n-nonane, and n-decanne, are investigated under non-uniform field conditions.
The light inception voltage and the breakdown voltage increase with the chain length, the liquid's density For a negative point, the breakdown voltage is much higher than the light inception voltage in all liquids but the difference between those decreases against the chain length. This voltage difference is not observed for a positive point except in n-pentane and n-hexane. The difference between the negative and the positive breakdown voltages decreases against the chain length. Regarding to the polarity effect, the negative breakdown voltage is much higher than the positive one in n-pentane, but there is no difference in n-decane.
A negative density change streamer has a bush like structure and propagates with stepped manner having an average speed of 70-160m/s, while for a positive one, the structure is a tree-like having an average speed of a few km/s. Only in n-pentane and n-hexane, a slow positive bush-like streamer is observed whose average velocity is about 200m/s, which is slightly faster than the negative bush like one.

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Electrical characteristics of a silent discharge for a rare-gas excimer excitation for 5 to 10kV of applied voltage with 3 to 15kHz of source frequency are discussed. It is found that there is a similarity relation between a consumed power at the gap and product of frequency and specific applied voltage. A number of spike discharge increases by increasing an applied voltage, while the light intensity of a spike discharge maintain constant. It is inferred from the measured power that pumping power is approximately about 400kW/cm³ and a reduced electric field strength is about 25Td. From a high reduced electric field, an effective excitation of raregas excimer may be obtained.

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Some Parameters of a laser crystal are estimated simultaneously from a laser ray 2-wavelengths method using perpendicularly polarized probe lights at wavelength of ruby laser (694nm) and auxiliary He-Ne gas laser (633nm). This method is actually applied to some ruby laser rods, and the next parameters are determined. Those are absorption coefficient α_o for ordinary ray at 694nm, that α_e for extraordinary ray, Ioss coefficients γ_o, γ_e, and normalized populationin version η. They are useful in analyzing the behavior of ruby laser amplifier by rate equations.

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The effect of a corona initiated from a needle electrode, which located near a sphere electrode relative to a plane electrode, on the discharge of the sphere-plane gap under pulse voltage was investigated in SF₆ gas under pulse voltages. The corona initiated at the needle tip was differed with a resistance connected. Under the pulse with risetime of 0.5μs, the discharge voltage of the sphereplane gap increased considerably with increasing resistance and finally reached a maximum at about 5MΩ and then decreased with continued increase in the resistance. The breakdown voltage under the slow rising pulse was scarcely influenced with the resistance used in this experiment. The mechanism of the discharge of the sphere-plane gap in complex electrode systems as mentioned above was discussed by the results obtained with an ultrahigh speed digital framing camera.

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