In recent years, since 25-30 years operating oil immersed transformers have been increasing in number, development of life diagnosis method in the transformer is carried out actively.
We find that the insulating paper has property which absorbs CO₂ and CO in oil.
In this study, absorption phenomena of CO₂ and CO in the insulating paper are investigated to get good accuracy life diagnosis. Results are as follows.
(1) These phenomena are also confirmed in the actual transformers.
(2) Content of CO₂ and CO in oil decreases with decreasing temperature.
(3) Property of absorption in the insulating paper disappears above 80°C.

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A new method for measuring a horizontal plasma position using Mirnov oscillations is presented. This method for detecting a plasma position uses either a phase difference between Mirnov coil signals or an amplitude ratio of Mirnov coil signals. Experimental results obtained in the HYBTOKII tokamak device are described. Here, Mirnov oscillations with poloidal and toroidal mode numbers m/n=2/1 are utilized. The horizontal plasma positions measured by using Mirnov coil signals are compared with those measured by using magnetic probe signals, and consistency between them is discussed.

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The spatial distributions of metastable densities and optical emissions were measured in the cathode region of He glow discharge over the current density range 0.15-2.2mA/cm² at 12 Torr. In the negative glow, the light is emitted not only by the cause of direct excitation but also by recombination of atomic and molecular ions. The metastable atom densities were measured by absorbtion method, and the two sort of metastable atom, He (2¹S) and He (2³S), distribute in quite different manner. In the cathode region, it is difficult to determine the absolute production rate of metastable atoms theoretically, but it is more easy to determine the relative distribution shapes of them from the atomic line distributions. Therefore, using the spatial distributions of relative production rate, the measured density distributions and the known rate constants of destruction of metastable atoms, the absolute production rates of metastables can be estimated. The ratio of two production rates agrees well with the result from Monte Carlo simulation.

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For measuring the flow velocity of sheath region of an arc burning through a polyethylene tube (PE arc), we obseved the in-flight motion of non-vaporized bulky carbon particles which are ablated from the tube wall and emit strong continuum in the sheath region at the tube exit. The velocity was calculated from the time difference during which the particles passed through two slits located along the arc axis. The experimental parameters are arc current (DC 5 to 15A), tube inner diameter (2 and 4mm) and tube length (10 to 30mm).
The results show that the sheath flow velocity of PE arc increases with increasing arc current, decreases with increasing tube diameter and increases in proportion to tube length. The maximum value of the velocity is about 300m/s at 15A, 2mm in tube diameter and 30mm in tube length. Mass of the polyethylene tube was measured before and after arcing, and the mean velocity across the cross-section of the tube is roughly estimated from the mass difference assuming that the gas temperature is uniform inside the tube. The tendency of the estimated characteristics of flow velocity versus tube length agrees with the measured one. Also, it is deduced from the experimental results that the flow velocity inside the tube is proportional to axial distance from the tube center.

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Charges caused by ESD on PET film surfaces are neutralized with an AC eliminator. In our experiment, the space between the eliminator and a fixed film is set to 7mm, and the film is also paralleled with an earthed copper plate with distance from 3mm up to 100mm. To neutralize the charges on the film, at least several cycles of AC voltage must be applied. At low frequencies, the minimum numbers of cycles for the neutralization are 2 for the film/plate distance of 3mm and 5 for the distance of 8mm. When the frequency becomes higher than 100Hz, the charge coming to the film's surface decreases. Therefore, more cycles of AC voltage are required. It is also found that a capacity coupled eliminator neutralizes the charges faster than a direct coupled eliminator. The total charge coming to the film during the minimum numbers of cycles of AC voltage is estimated, and it seems to be the same for the two eliminators and for all the frequencies.

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Soluble polyaniline films were prepared by three different methods: (1) film formation by casting from N-methy 1-2-pyrrolidone solution, (2) film formation from the gel state and (3) film formation using isocyanate terminated 1, 2-polybutadiene as a cross-linking agent. In all three methods, polyaniline main chains were cross-linked with some bonds. These methods gave tough films comparable to engineering plastics such as Keplar. All films obtained with different method showed enhancement of conductivity about ten orders of magunitude upon doping and remarkable decrease in its activation energy. Especially these effects were most remarkable in the film formated from the gel state. The conductivity of the film cross-linked with 33 wt% of polybutadiene was as high as the other films.
In all films, the temperature dependence of dynamic modulus was very small. The dynamic modulus of the film formated from the gel was less dependent on temperature in the range from -150°C to 350°C.
The present results are very significant from the view point of the applicaton of polyaniline.

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Plastic encapsulated semiconductor devices have been accepted for most industrial applications because of their cost advantage and great improvement in moisture induced reliability problems. Since the residual thermal stress is induced after the molding process by the large difference in the thermal expansion coefficient between the plastic resin and the silicon chip, this stress can cause serious reliability problems such as cracks in passivation films and deformation of aluminum metallization. The purpose of this study has been to examine the use of photoelasticity in determining the residual thermal stresses in the encapsulation material of plastic ICs. The method to measure the stress of ICs molded with the transparent resin instead of the conventional opaque encapsulating resin is established by using photoelasticity. The shearing stress parallel to the chip surface shows the maximum value at the chip edge and it becomes smaller toward the center of the chip. On the other hand, the vertical element is tensile at the chip edge and is compressive stress from the appropriate position. The effect of the chip buffer coat is clarified by the method. The package thickness is the most effective upon the thermal stress in the package size. As it is thiner, the stress is smaller.

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Polyparabanic acid (PPA) is one of the excellent heat-resistive insulating materials. The infiuence of the chemical structure on the breakdown of PPA has been investigated. The breakdown strength was measured with dc and pulse voltages. The breakdown strength in both cases decreases with temperature in the range of 120-180°C. The results indicate the significant dependence of the breakdown strength on the chemical structure of PPA. Thermal breakdown has been proposed as the mechanism responsible for the breakdown. The results have been discussed quantitatively by taking the electric conduction mechanism into consideration.

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