In various applications of pulsed power technologies, large capacitor bank systems are used to feed high current impulse to different experimental devices. The accidental electric breakdown in one of the capacitors in a parallel connection of the large bank may result in serious damages such as mechanical explosion and oil effusion or fire.
In most fast banks, each unit capacitor has an output gapswitch, resistance or fuse, which is expected to decouple the capacitors one another. However, no such special element is adopted usually in the slow bank system, partly because of the economical consideration.
This paper gives an analysis of driving force for the development of protective switching elements on local failures of large slow capacitor bank system.

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Non-thermal plasma produced by pulsed power discharge in atmospheric pressure gases has been used for high-efficiency treatment of exhaust gases. This paper describes the chemical reactions taking place in the discharges under different gas compositions. A 3-staged Blumlein line generator providing 44kV voltage pulse of 100ns duration was applied to the discharge reactors. A coaxial electrode system, 1-m in length with 83-mm outer and 1-mm inner electrode diameters, was used as a reactor. It was experimentally found that NO_x removal ratio becomes lower when NO_x gas includes either O₂ or H₂O, but NO_x removal ratio becomes higher when the gas includes both O₂ and H₂O. Therefore, adding both O₂ and H₂O species into exhaust gases is preferable.

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The Inter-glow-arc flip-flop transition, we have reported previously^{(1), (8)}, produces a sequence of glows and arcs having random lives. Sustaining the current nearly constant we observed the jumping voltage of this transition. By the 100 times experimental test to mesure the average discharge lives (<t>i) within a single measurement duration To and on the theoretical basis of the gamma distribution expansion theory of the distribution as well as by the aid of the test of goodness of fit we found out that the distribution of the average lives <t>i can be expressed by a single Γ distribution. Applying the central limit theory to the distribution of <t>i we concluded that the distribution of discharge lives t also forms a single Γ distribution with its average life to. By using the reproducibility of the Γ distribution we could relate the density function of discharge and measured average discharge lives. Some physical meaning of glow and arc life distributions, including the reason why the paradox concerning the Kaufmann's criterion is avoided here, are discussed in this paper.

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The characteristics of our color vision are affected by various visual environments. In this experiment, we examined how colored lights look in dense fog. We used 12 kinds of colored light as a test stimulus. At first, in the absence of fog, subjects matched brightness of all the test stimuli with reference white light adjusted to 0.1cd/m² or 0.5cd/m² in luminance respectively. Then, subjects evaluated the apparent brightness of the test stimuli in dense fog with magnitude estimation of 10 grades.
In the presence of fog, test stimuli containing yellow component were given the highest point value of brightness. Test stimuli containing blue component, on the other hand, were given the lowest point value of brightness in the presence of fog.
We are confident that in visual environment involving fog, these results were extremely helpful in practical use.

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Heat transfer from transferred-type arc plasmas to a water cooled copper anode is measured with different amounts of electrical power applied by changing the arc current or gap length (arc voltage). Argon, nitrogen or helium is chosen as an arc atmosphere. In addition, heat transfer by radiation and heat transfer dominated by thermal conduction from non-transferred type arc plasmas to a water cooled copper anode are measured. Based on the results of these measurements, the mechanism of heat transfer to a water cooled copper anode and the causes of dependence of heating efficiency on experimental conditions are discussed. Nitrogen arc plasma is found to achieve highly efficient heating because of high thermal conductivity owing to dissociation and of small radiation loss. This finding is expected to be helpful for achieving more highly efficient heating.

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In the insulation design for power apparatuses which use perfluorocarbon (PFC) liquid, it is necessary to study for breakdown strength of the liquid/vapor under uniform field. Especially, for the device with SF₆, the breakdown strength is an important factor of the insulating engineering.
This paper presents the investigation on insulation characteristics of PFC liquid/vapor with and without SF₆, when the temperature is changed within 20-80°C. Experiments are performed using plane-plane electrode geometry in a closed system under AC and lightning impulse voltages. It is found that: (1) in the case of PFC vapor pressure above the liquid without SF₆, the breakdown strength is affected a little in the liquid phase by temperature rise, while increases extremely in the vapor phase under the same condition;
(2) in the other case of a mixture pressure above the liquid with SF₆ under AC voltage, the breakdown strength of the mixture vapor phase is given by adding the contribution of the two components (PFC vapor and SF₆).

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This paper describes the charging phenomena of a cylindrical insulator made of PMMA, PTFE or Al2O3 under ramped, and stepped DC voltage application. The principal content of the paper is concerning the influence of surface roughness on the charging for various insulating spacers. By using an electrostatic probe located on the cathode, we have conducted the real-time observation of the electric field due to the surface charge. It has been found that the surface roughness decisively affects the charging, which is more pronounced for more highly polished insulators. Further more, the time dalay of the charging decreases with the polished insulators. These results show the importance of surface treatments for insulating spacers in vacuum.

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A time-dependent one-dimensional model was newly developed for simulating behaviour of a pulsed discharge for electric currents of around 100 A in atmospheric pressure N₂ gas. In the model, simultaneous equations including mass, momentum and energy conservation equations were solved considering the Ohm's and Ampere's laws and equation of state. Eighteen elementary reactions in a N₂ plasma were taken into accout in the calculation of non-chemical equilibrium composition. Time variations in radial distributions of radial flow velocity, temperature and pressure in the discharge were derived. Furthermore, spectroscopic measurements of N spectral line and continuous spectrum were made to experimentally obtain transient temperature variation in an impulse arc. The temperature calculated by the developed model was found to be in good agreement with that obtained by the measurement.

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Pre-breakdown ionisation current measured by Steady State Townsend experiment in hydrogen for values of E/p0 up to 1000 Vcm^-1 Torr^-1 is analysed by applying the Townsend equation, the Lucas equation and the current growth equation considering ionisation collision between positive ions and hydrogen gas molecules as well as that between electrons and the molecules.
It is seen that the degree of fit of the measured current by applying the Lucas equation is the best of the analysis by the three equations at large E/p0 values, then it is found that the ionisation current at large E/p0 values in hydrogen is affected by the gap length dependency of geometry factor, namely, loss of photons out of the gap, for the secondary process by photons.
The value of the first ionisation coefficient obtained by the analysis applying the Lucas equation increases with an increase in E/p0 for values of E/p0 _??_ 350 Vcm^-1Torr^-1, then decreases gradually when E/p0 increases. The value of the secondary ionisation coefficient γ₂ for ions obtained by the analysis applying the Lucas equation agrees with that previously reported by the authors (Technical Papers of Electrical discharge Committee IEE, Japan ED-93-90, 1993). And the value of secondary ionisation coefficient γ_p, for photons obtained by the analysis is less than one tenth of γ_i for values of E/p0 up to 500 Vcm^-1Torr^-1, then it increases rapidly when E/p0 increases and almost equals γ_i at values of E/p0 _??_ 800 Vcm^-1Torr^-1.

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Amorphous TiO₂ thin films were deposited on glass and Si substrates with steered vacuum arc deposition (NAD; Nonfiltered Arc Deposition), shielded arc deposition (SAD), and magnetically filtered arc deposition (FAD) systems. The film deposited by NAD contained a few large droplets sized 1.0 μm and a large quantity of small droplets sized 0.1 μm. The film deposited by SAD contained no large droplets but the small droplets were remained by half of those on the film deposited by NAD. The film deposited by FAD contained almost no droplets. As for optical properties (transmittance, refractive index, and extinction coefficient) and mechanical properties (microhardness and elastic modulus), there is no significant difference among the films deposited by each method. The films were thoroughly transparent with no absorption in visual region, and harder than the glass substrate. Deposition rate of SAD decreased by three quarters of that of NAD.

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SiO₂ thin films derived by sol-gel method were fabricated on silicon wafer by means of dip coating. Investigations on the physical and chemical effects of heat treatment and electrical properties of the heat-treated films were carried out by FTIR spectroscopy, ellipsometry, etch-rate measurement, dielectric properties and resistive properties measurements as well as dielectric breakdown measurement. During heat treatment, it was found that a purification and densification process occurred simultaneously and had significant effects on the electrical properties of the films. Samples treated at 600-700°C showed respectable dielectric and bulk resistive properties. However, no obvious improvement was achieved beyond heating over 700°C. On the other hand, dielectric breakdown strength and surface resistivity were enhanced by increasing the temperature of heat treatment from 600°C to 900°C. These results were discussed to find out the relationship between heat treatment and the electrical properties of sol-gel SiO₂ thin film.

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We have tried to prepare the thick Fe₇₀Al₅Ga₂P_9.65C_5.75B_4.6Si₃ amorphous sheets with the sample width of 15 mm and investigated the relation between glass-forming ability and soft magnetic properties. The sheets can be made of single amorphous phase by single-roller melt spinning method with the thickness up to 100 μm. High relative permeability of 5500 at f=1 kHz and low core loss of 0.15 Wkg^-1 at f=50 Hz and Bm=1.0 T are obtained at the sample thickness of 87 μm. The relative permeability under 30 kHz and the core loss under 300 Hz do not depend upon the sample thickness. It is considered that the soft magnetic properties of the Fe-Al-Ga-P-C-B-Si glassy alloys are concerned with their structural homogeneity caused by high glass forming ability. These soft magnetic properties allow us to expect the Fe-Al-Ga-P-C-B-Si glassy alloy sheets are practically used as industrial materials.

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Our visual characteristics are affected by various visual environments. In this experiment, we examine how object colors look in dense fog. Namely, 8 male subjects matched the apparent color of 10 standard-color-cards in dense fog with Munsell color.
In the presence of fog, apparent color showed a drastically decrease both in the chroma and in the value.
We are confident that in the visual environment involving fog, these results are extremely helpful in practical use.

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As an application of elliptic integral and elliptic function, a calculation formula of permeability coefficient of metal laminated water-proof sheath is obtained. The solution process is applicable to other problems such as heat conduction and electric current flow.

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This paper presents a new method for localization measurement of the Seebeck coefficient by a thermoelectric probe. A two-dimensional profile of the Seebeck coefficient could be obtained for a bulk type thermoelectric element by giving a proper temperature gradient on XYZ stage. It was clarified that the location resolution is about 2mm and the error ratio is about ±5% under a proper contact pressure. This method is useful for the evaluation of FGM(Functionally Graded Material) thermoelectric element and for the sintered one to check its homogeneity.

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