In this paper the influence of roughness of electrode surface on the ozone generation by the silent discharge are described. The experiments are carried out to clarify the effect of electrode surface on the discharge current, ozone yield, ozone yield efficiency and the distribution of microdischarges. The ozonizer used consists of a parallel-plane electrode contacted with dielectric films. On the surface of electrodes, ditches are worked mechanically at an angle of 60 degrees like a mesh. The depth and pitch of the ditches are varied as parameters of the surface conditions. The results obtained are as follows. As the depth is deep and the pitch is small, both the discharge current and ozone yield decrease. But, ozone yield efficiency increases to the contrary. The reason why ozone yield efficiency is influenced by the electrode surface is that the discharge current depends on the electrode flat-area rate of ditched electrodes. When the electrode flat-area rate is small. the ozone yield efficiency increases. Under this surface condition, the discharge luminous quantity is small. However, a large number of microdischarge columns take place, as compared with the plane electrode. Therefore, the discharge space becomes uniform. As a result, this electrode surface condition is effective to improve the efficiency of ozonizers.

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Cathode spots and streamer discharges in excimer laser discharges shorten the life of electrodes because they cause the current concentration. One of the problems to develop a long-lived excimer laser is to remove cathode spots and streamer discharges in excimer laser discharges. In this paper, we measured the radiation timing of cathode spats and streamer discharges, and estimated the temperature of cathode spots and glow discharges by analyzing the spectra. The following results were obtained from the measurements. Cathode spots begin to radiate at about 20 ns after the discharge initiation, and the radiation peaks appear at the first zero point and approximately at the second zero point of the discharge current. Streamer discharges develop rapidly between the anode and the cathode at the second radiation peak of cathode spots, while glow discharges diminish and almost disappear at this period. The temperature of the cathode spats and the glow discharges are about 5500K and 2600K, respectively. They are constant in a charging voltage range from 13kV to 19kV. On the other hand, the average discharge temperature, which is found to be 2700K below the charging voltage of 17kV, increases above 17kV and reaches 3300K at 19kV. From these results, we conclude that the charging voltage for the excimer laser used in this work should be kept below 17kV in order to extend the laser lifetime.

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The concept of a novel ozone generator that has a high ozone formation efficiency has been developed. The novel ozone generator consists of a dissociation chamber, an ejector, and an ozone formation chamber. In the dissociation chamber filled with pure oxygen gas at a low pressure, a nonequilibriurn electric discharge dissociates oxygen molecules into oxygen atoms. The gas containing oxygen atoms is drawn from the chamber and stirred into air of the second material gas by the ejector, and is transferred into the ozone formation chamber. The oxygen atoms are efficiently converted into ozone molecules by three body collisions under a high gas pressure in the ozone formation chamber. A simulation code describing the ozone formation process reveals the characteristics of this O/O₃ different-space-generation system. It has a high O₃ formation efficiency in a low O₃ concentration range. According to the simulation result, it can generate the O₃ of 0.135 mol% with the efficiency of about 200g/kwh, which is about three times larger than that of the conventional air-fed ozone generator.

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In this paper we propose a method for discrimination of noise-covered ultrasonic signals by making use of the distinguishing features of signals reflected from electrical trees extending toward the direction of depth within the specimen. That is to say, it utilizes the characteristics of signals due to the spacial continuity of a tree branch and also the change of the delay time of the reflected signal from the electrical tree when the ultrasonic transducer is moved slightly around near the target point over the specimen.
As the results, it is shown that the three-dimensional structure of the bush-type tree in polyethylene can be visualized in non-destructive way. The resultant shapes of the trees are agreed well with those obtained by actual sectioning of the specimen using a microtome.

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Rutile-type TiO_x films were deposited on glass substrates at substrate temperatures as low as 150°C by the ion beam assisted reactive deposition (IBARD) method. Ar⁺ ion bombardment at 10keV during Ti evaporation in an oxygen atomosphere was essential to achieve stoichiometric TiO₂ having a high electrical resistivity (1010Ωcm). Optimum Ar+ ion current density was found to be 20μA/cm², whose flux, 10¹⁴atoms/cm², was of the same order as the growing atom flux 10¹⁴ atoms/(cm²s) estimated from the deposition rate of 0.05nm/s.

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This paper describes the experimental results of localized heat generation and dielectric breakdown in lowdensity polyethylene (LDPE) film where curing by-products were coated on the surface. The variations of temperature distribution were observed by thermography. Under dc voltage application, localized heat generation of LDPE film with curing by-products, especially acetophenone, was observed under lower field than that of uncoated specimen, and the breakdown strength decreased considerably. The dc conduction current was significantly enhanced by the coating. Under ac voltage application, it was also observed that localized heat generation increase and the breakdown occurred under somewhat lower field. It was considered that the increase of heat generation was caused by promotion of electronic carrier injection due to the existence of curing by-products at the electrode interface and enhancement of the carrier mobility due to their permeation into the film.

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The pulsed electroacoustic method (PEA) has been applied to observe space charge formation under AC application (7kV_peak, 50, 0.1 and 0.001Hz) in water-treed polyethylene samples in order to understand the degradation mechanism of water trees. A system with phase-resolved capability has been developed to measure space charge distribution at any phase angle of AC voltage application. By comparing the observed charge distribution with theoretically predicted ones, it has been shown that the interfacial polarization due to the difference in conductivity between the treed and the untreed regions predominates the space charge behavior. It has become clear that the PEA method can be a powerful nondestructive method of evaluating water tree length.

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